FW Lanchester and the Great Divide

Transcription

Journal of Aeronautical History
Paper No. 2014/02
F.W. Lanchester and the Great Divide
Philip Jarrett Hon CRAeS
Philip Jarrett looks at a pioneering aerodynamicist’s practical experiments with models and his
troubled flirtation with full-size aeroplanes
1.
Introduction
Frederick William Lanchester is revered by today’s aerodynamicists. His position as a pioneer
of the science is somewhat curious, however, for although he blazed a perceptive trail in
understanding the nature of airflow over wings, he really failed to communicate his findings to
most other students of the subject in a comprehensible form, this task falling to the German
Ludwig Prandtl.
Historians of aerodynamics have sought to describe Lanchester’s status in the pioneering era of
the science. Anderson says: ‘Part . . . of the problem with publication [of his papers] was
Lanchester’s poor writing style. His explanations were not easy to follow.’ Anderson also says:
‘Lanchester’s work was essentially not quantitative; he made no substantive aerodynamic
calculations of lift and drag,’ and that ‘. . . his quantitative analysis . . . had no impact on the
advancement of theoretical aerodynamics.’ ‘Because of those problems,’ Anderson remarks,
‘recognition for Lanchester’s basic model was slow in coming.’ However, Anderson points out
that when Lanchester’s aerofoil designs were tested in Ludwig Prandtl’s windtunnel at Göttingen
University in 1912-13 they produced a lift-to-drag ratio 10 per cent better than those of other
models that had been tested there. Anderson concludes by saying : ‘. . . the conceptual basis for
the circulation theory of lift was laid by Lanchester in the last decade of the nineteenth century,
but the quantitative formula relating to lift circulations was developed during the first decade of
the twentieth century by two people working independently, and without any knowledge of
Lanchester’s work.’ But he acknowledges that ‘Clearly, the coming-of–age of theoretical
aerodynamics began with Frederick Lanchester’ [1].
Abzug and Larrabee state: ‘He speculated correctly on the vortex theory of lift and the nature
of the vortex wake of a finite wing but was unable to give these ideas a useful mathematical
form’ [2]. Ackroyd says: ‘Lanchester’s position is now secure as the originator of much of the
vortex theory of wing lift and induced drag, although it has to be admitted that, as a mathematical
modeller, Lanchester does not rank in the Prandtl class . . . . Nonetheless, it is evident that during
that [early] period, and for long afterward, “official science” in Britain failed to recognise the
essential merits of Lanchester’s contributions to aerodynamics . . . . It is a matter of deep regret
and considerable shame that Britain’s full recognition of Lanchester’s extraordinary
achievements in aerodynamics took so long.’ [3]
Theodore von Karman said: ‘Whether or not he was a visionary depends on the interpretation
of the word. If it means a man who has an extraordinary vision - a deep insight into the problems
he considers - he certainly was a visionary. However, he was not a visionary in the sense that in
following his imagination he would overlook realities, or difficulties in realisation. On the
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contrary, his predictions - for example, those concerning possible developments and
performances of aircraft . . . - were rather too cautious and certainly not “visionary” . . . . [4]’
For the reasons stated hitherto, if one were to judge Lanchester’s status in aeronautical history
by his influence upon his contemporaries, he would probably not emerge in as brilliant a light
as that shone upon him by his latter-day successors in aerodynamics. His contribution has
been recognised in hindsight, but it was not at the time he expounded his theories.
2.
The Great Divide
What I refer to as the ‘great divide’ is the perceived lack of communication and understanding
in aviation’s very early years between those who made theoretical and scientific studies of
aerodynamics but failed to comprehend the requirements of a practical aeroplane, and those
who actually built and tried to fly aeroplanes but lacked scientific expertise. While there are
exceptions to this on both sides, the Wright brothers being a classic example, one cannot help
wondering whether, had there been better intercommunication between the two sides, successful
powered flight might have been achieved earlier. For example, Percy Pilcher might have
benefited greatly from closer co-operation with G.H. Bryan, who had shown interest in the
glider pioneer’s work and as a result of Pilcher’s tragic death in a flying accident in 1899 was
further inspired to investigate stability.
One manifestation of this schism was the aerodynamicists’ concentration on stability and neglect
of control. It was usually assumed that the latter would not pose a problem, and that flying
machines needed only an elevator and rudder to enable them to be steered about the sky, rather
after the fashion of ships and automobiles. Those who did dare to go aloft in gliders in the 1890s
soon found that excessive stability deprived them of control; something they did not like at all.
Unfortunately their investigations into aerodynamics were superficial at best.
Similarly, there were two clearly different approaches to flying machine design, those of what I
call the ‘heavy’ and ‘light’ engineers. The former usually designed large and weighty structures
and used shafts and gears to transmit power or operate control surfaces, while the latter employed
light wire-braced structures and levers, pulleys and wires to move control surfaces. The ‘heavy
brigade’ often had a background in automobile or marine engineering, and Lanchester’s
involvement with motor cars puts him in this category, though his leisure-time experiences as a
keen yachtsman must also have come into play. Consequently, his notion of control was inhibited
by his automobile experience, and he seems to have expected an aeroplane to be able to yaw to
turn right or left without the need for a roll control to induce bank. The Wrights, on the other
hand, having observed the flight of large birds and being keen cyclists, accepted without question
the fact that one leaned into a turn, and achieved this by adopting wing warping and coordinating it with the rudder, thereby devising, with an elevator, a full three-axis control system.
Lanchester evidently found this hard to comprehend, as early in 1910 he patented a means to
prevent the lateral tilting of an aeroplane when turning. I shall return to this later [5].
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3.
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Model gliders and concepts
In 1891, while employed as works manger at T.B. Barker’s gas engine works at Saltley in the
West Midlands, Lanchester began to study the problems of flight. Then aged 23, he was
unaware of the works of Louis Mouillard or of the successful experiments with models driven
by propellers powered by twisted rubber carried out by Frenchman Alphonse Pénaud in 187071 [6].
In his book Aerodonetics [7] , which dealt with the trajectories of bodies in free flight and the
conditions for longitudinal lateral and directional stability, Lanchester described his first model
experiments:
In 1894 [I] commenced the practical investigation of stability in flight, some preliminary
theoretical work having shown that it should be possible to obtain automatic equilibrium
with a suitably designed apparatus.
At the date in question, although Mouillard’s L’Empire de l’Air had been published
several years, [I] was not aware of the automatic equilibrium possessed by the ballasted
aeroplane, or, indeed, of the existence of Mouillard’s work at all, and it is not surprising,
therefore, that his models were designed and constructed on entirely different lines.
‘In the author’s original model . . . the various functions that are performed incidentally
by the ballasted aeroplane in the maintenance of equilibrium are carried on by special
organs, and this fact, which arises from the theoretical origin of the appliance, renders it
particularly well suited to analytical study.
‘One of the deductions from [my] preliminary investigations was . . . that the higher the
velocity of flight the greater the stability attainable; the models employed were, in
pursuance of this conclusion, designed for velocities of 40 miles per hour and upwards.
It was estimated that such a velocity would render the stability independent of any gusts
of wind such as would ordinarily be encountered, a result that was fully substantiated by
the subsequent experiments.
‘Owing to the high velocities employed the launching had to be effected by means of a
catapult . . . .’ [8]
Lanchester’s gliders (or ‘aerodones’, as he called them) were distinctive in several respects.
They were very long in relation to their span, the white pine triangular-section ‘backbone’
being some 6ft 2in long, whereas the seasoned and dried pitch pine narrow-chord elliptical
wing (the ‘unique organ of sustentation’) spanned only 3ft 4in. It had a high aspect ratio of
2
13.3, an area of 0.65ft and employed a deep-section aerofoil with a sharp leading edge and a
flat undersurface. The model was ballasted by a strip of sheet lead wound spirally round the
glider’s nose and ‘nailed or otherwise secured in position’. Immediately aft of this weight and
just in front of the tailplane were two white pine sweptback vertical fins of streamline section,
2
2
the front one having an area of 0.3ft and the rear one an area of 0.2ft . Their function was ‘to
maintain both lateral and directional equilibrium’. The function of the small triangular2
planform white pine tailplane of 0.2ft area behind the aft fin was ‘purely directive’, having
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‘the same function as is performed by the change in the position of the centre of pressure of the
ballasted aeroplane; it preserves the constant attitude of the aerodone in relation to its line of
flight, in this respect its action being analogous to the feathers of an arrow.’ The glider’s centre
of gravity was located about an inch in front of the wing leading edge, and the distance between
the centres of pressure of the wing and tailplane was approximately 3.9ft. A complete glider
weighed approximately 1lb 7oz [9].
Figure 1 Lanchester’s 1894 glider as depicted in a three-view general-arrangement drawing
in Aerodonetics, showing its high-aspect-ratio elliptical wing, long fuselage and distinctive
vertical fins fore and aft.
Figure 2
The 1894 glider, from Aerodonetics
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The launch catapult comprised a pair of parallel runners along which the glider was free to
slide, its backbone resting in the 1in groove between the runners. Power was provided by an
india-rubber band usually consisting of about four strands of black ‘elastic’. The band was
secured to a piece projecting forward of the runners and led over two pulleys or spools. At its
middle point, where it engaged in a notch in the extreme rear of the backbone, the rubber was
bound with twine. When fully extended the rubber was held in position by notches near the
runners’ rear ends, the launch being achieved by prising the rubber out of the notches by means
of a forked lever. The length of the free portion of rubber was 3ft 4in and its maximum range
of extension was 11ft 6in; it weighed ½lb [10].
Lanchester launched his gliders from a west-facing rear first floor window of his residence at
the time, a spacious three-storey, six-bedroom house named Fairview, No 25 St Bernard’s
Road, Olton, Warwickshire (nowadays described as Solihull, West Midlands B92). The launch
point was some 15ft above ground level, and the land fell away at a slope of about 1 in 25 [11].
‘Some half-dozen’ of the models were made to the one design, and some 20 or 30 launches
were made during June and July 1894, Lanchester describing this total as ‘a considerable
number’. His object at the time was ‘merely to demonstrate the stability of a high velocity
model’, and he later pointed out that ‘the records are not very complete, and the actual velocities
and times of flight were not in every case fully noted’. In Aerodonetics he provided several
diagrams depicting various forms of flight path, but stressed that they were ‘drawn as they
appeared [his italics] to observers present, and cannot be regarded as more than rough
approximations to the actual curves; the positions of the points of greatest altitude are,
however, fairly near the truth.’
Lanchester described five of the flights made by the gliders. On its initial flight, on an
unrecorded date, the first model, weighing 1¼lb, was launched in a very light wind and covered
about 200 yards following a curved path to the right. On 24 June (?) a model weighing 1lb 7oz
covered 280 or 290 yards in a 27-second flight in a ‘high wind with powerful gusts ‘probably
about 30 mph WSW’. Lanchester described this as: ‘A magnificent flight, remarkable “switchback” flight path, distance relative to wind, probably over 600 yards.’ That same day this model
covered 200 yards in about 7½ seconds in a very light wind, attaining a velocity of 55 mph. It
then made another 200-yard flight, untimed, and again on the same day covered 150 yards in
5½ seconds at 56 mph in a very light wind before colliding with a tree [12].
Lanchester then built a ‘more fully developed model’ powered by twin rear-mounted pusher
propellers, each driven by twisted skeins of six strands of india-rubber weighing 0.7lb. This
model spanned about 3ft 3in, was 7ft long from its nose to the trailing edge of its tailplane and
was braced by piano-wire guys in both the vertical and horizontal planes. The distinctive tall
front and rear dorsal fins were fitted. Its twin two-bladed propellers were of 17½in diameter,
2
each blade being of 6in in area and having a pitch of 16 -20in. The blades were of 0.3in-thick
sheet aluminium, and were mounted on arms formed by a single steel wire of 0.1in diameter.
They were so fitted as to ‘feather’ automatically if the model overran the range of the
propulsion: ‘that is to say, when the twisted rubber is spent, the blades swivel approximately
into the line of flight and do not act as a drag on the machine’. This was accomplished by
‘mounting them to pivot on the wire support (the aluminium being bent to form a hinge), and
the provision of a stop consisting of a short strip of brass soldered in position to limit the
angular motion and at the same time to locate the blade longitudinally’. One suspects that this
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remarkable feature was the result of Lanchester’s experience of rowing, and the technique of
feathering the oars when they were out of the water.
Figure 3
Figure 4
The trajectories of glider flights Nos 2, 3, and 4 as illustrated in Aerodonetics.
Frederick William Lanchester with his 1894 powered model driven by twin pusher
propellers powered by twisted skeins of india-rubber (Author’s collection)
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‘The energy of propulsion stored in the two india-rubber skeins amounted in all to about
1,000ft lb (loading energy);’ Lanchester recorded, ‘the total number of propeller revolutions
being 500, representing an average of one foot pound of energy per revolution. This requires to
be multiplied by a coefficient to give the energy available at the propeller shaft; in all
probability, after allowance also for the propeller efficiency, not more than 50 per cent of the
loading energy is usefully employed in propulsion.’
The complete aeroplane weighed 2½lb. The angle made between the ‘flat face’ of the aerofoil
and the tailplane was initially set at 3°, but was subsequently increased to 6° [13].
On 3 July 1894 the 2½lb powered model flew 133 yards in 4½ seconds (Lanchester notes that
‘The timing of this flight is in doubt’) in no appreciable wind [14]. Lanchester later observed
that: ‘The range of flight should theoretically amount to about 250 yards before the energy of
the indiarubber is expended, and there would be probably another 50 or 60 yards covered while
the aerodrome [here, Lanchester is using the term for an aeroplane wrongly adopted by Professor
Langley in the USA] is coming to earth. Unfortunately, owing to obstacles, the full range of
flight was never realised; the most satisfactory flight is that recorded, but here the machine
finished its career prematurely in an elm tree, the propulsion energy being only about half
expended.’ An attempt to take a photograph of the model in flight ‘proved abortive’ [15].
Lanchester said that these model experiments fully confirmed his views ‘as to the possibility of
securing automatic stability without the employment of any equilibrium mechanism or “brain
equivalent”.’ He said that in calm weather the models “carved their way through the air as if
running on invisible metals [rails], without the smallest visible fluctuation or quiver. When on
the other hand the flight was made in a gale of wind, the flight path took the form of a bold
sweeping sinuous curve, without a momentary suggestion of loss of equilibrium, but rather
with the appearance of some set intelligent purpose.’
The speed of the models ‘appeared to range from about 50 to 60 miles per hour, and it is
certain that at velocities of this sort there is very little to fear from any ordinarily bad weather
conditions’. ‘In general,’ Lanchester remarked, ‘the launching velocity was very much higher
than the natural velocity, and consequently the gliding angle was entirely masked and remained
an unknown quantity; the considerable range of flight obtained was without doubt due to this
cause.’
He thought the exceptional time the model remained in flight when launched in a gale (27
seconds) was ‘remarkable’. ‘Taking the velocity relatively to the air as that measured in other
experiments with the same model, say 55 mph,’ he observed, ‘this length of time corresponds
to a flight of 725 yards.’ He saw two possible explanations for this ‘anomalous flight’. Either
the model was actually soaring like an albatross or gull, or its initial kinetic energy, due to the
velocity of the model relatively to the wind, was much greater when it was launched into the
teeth of a gale, and therefore the energy disposable in the flight was greater in a proportionate
degree.
He thought both explanations were possible and could account for the enormous increase in
range. ‘At first sight,’ he wrote, ‘the first alternative seems most unlikely,’ as it seemed to
‘imply an exercise of intelligence not possible for an inanimate thing’. However, he added that
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later experiments had shown that it ‘was by no means impossible for a simple aerodone to
perform true soaring evolutions,’ and that ‘it was not at all improbable that this was actually
the case in the flight in question.’ However, he added that, on the other hand, the second
alternative alone ‘was almost sufficient to account for the additional energy as evidenced, so
the correct explanation of the case in point must be regarded as uncertain. [16]’
Lanchester pointed out that many inventors had proposed aircraft in which the weights carried
were suspended well below the lifting surface, thereby employing pendulum stability. He
believed that this notion was based upon an aeroplane’s ‘superficial resemblance to a kite, the
suspended weight being considered as the analogue to the kite string’. Alternatively, he
suggested, it might have arisen from an attempt to follow the lines of an airship, ‘the aeroplane
or aerofoil being regarded as a simple substitute for the gas bag.’ At the time he wrote this
(1908) the relative advantages of the two configurations ‘had not been thrashed out’, but he
thought it probable that the pendulum-stability machines, ‘without possessing any advantages
whatsoever, possess certain grave disadvantages which will be better understood in the light of
the subsequent investigations,’ and that it ‘also results in some considerable complication from
a theoretical standpoint apart from its demonstrable failings.’ [17]
4.
Applying the lessons
From these trials and subsequent theoretical calculations Lanchester developed his ‘phugoid
theory’, dealing with the longitudinal motion of a statically stable aeroplane having a very
small moment of inertia and a vanishing drag. As Dr Theodore von Karman described it:
It is assumed that such an aeroplane at every point of its flight path has the same constant
attitude relative to the flight path (the curve described by its centre of gravity) and the
only forces acting on the planes are gravity and a lift normal to the tangent of the flight
path and proportional to the square of the speed of the centre of gravity. It is rather easy
to compute the motion of such a system, but the picture of the family of possible
trajectories . . . was a source of inspiration to the engineer. [18]
Lanchester was mistaken in his application of Latin to name his theory, intending to call it the
‘flying motion’ or ‘flight-like’ but actually calling it the ‘fleeing motion’, having forgotten that
the Greek root already existed in the English word ‘fugitive’ [19].
Subsequent aerodynamicists were somewhat critical of his methods, and Professor G.H. Bryan
wrote: ‘Lanchester’s condition of longitudinal stability is based essentially on what we . . . call
the hypothesis of “narrow planes flying at small angles,” and it agrees with the result here
obtained in the “simplest case” of horizontal flight, although it is probably correct to say that
the method of obtaining it has the appearance of being wanting in rigour.’ [20] Reviewing
Aerodonetics for Nature in 1909, Bryan had written: ‘There has been some difficulty in making
out how Mr Lanchester arrives at his results,’ and that assumptions made in Lanchester’s
method had conflicted with later methods of calculation applied to the particular type of
machine considered by Lanchester. Nevertheless, Bryan acknowledged that Aerodonetics
represented ‘a serious effort to place the theory of flight on a scientific basis and should
convince would-be aviators that airship [i.e. aeroplane] design is a subject requiring hard
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thought, endless experiments and great care in drawing conclusions from them.’ [21] Von
Karman stated:
Lanchester used rather non-conventional mathematical methods (as Sir [Bennett] Melville
Jones put it); so much so that, for example, it took me several days to understand his
deduction of the same stability condition which Bryan gave in his book Stability in
Aeronautics in 1911 and Trefftz and I gave in 1914 as a first approximation. However,
with an uncanny insight into the mechanics of the problem, Lanchester avoided many of
the pitfalls which are usually connected with non-conventional mathematical methods. It
is remarkable that he foresaw many points in the stability theory shown later by
mathematical methods, for example, aeroelastic effects decreasing the stability of wings
due to flexibility. [22]
However, in following Lanchester’s involvement with full-size aeroplanes we must now turn
away from his theoretical analyses and see how he applied his findings to his concepts of
practical flying machines.
In 1897 Lanchester was granted British Patent No 3608 for ‘Improvements in and relating to
Aerial Machines’. While some of the interesting ideas contained in this patent have been
referred to in aerodynamicists’ accounts of Lanchester’s work, others have been completely
overlooked. In Lanchester’s words, this patent referred ‘more particularly to the construction
of a machine . . . that shall be able to traverse the air in any desirable direction, either under the
control of an aeronaut or otherwise’. One object of the invention was ‘to provide means
whereby both the lateral and fore and aft stability of the machine is automatically secured’,
while other aspects related to ‘the form and structure of the supporting surfaces and propellers,
and to the launching and controlling arrangements’ [23].
Two types of aeroplane are described in the patent, both having elongated, streamlined bodies
housing ‘accommodation for whatever purpose required’ and the gas or oil motor or motors,
which drove rear-mounted pusher propellers. The propellers were designed ‘after the manner
of cycle wheels, the wooden rims being constructed of flat strips of sufficient weight to act as
flywheels for the motor’. The propeller blades were formed by stretching fabric or fitting thin
plate between suitably arranged pairs of spokes.
Figure 5
Lanchester’s 1897 design for an aeroplane propeller, from British Patent No 3608
of 1897 (Courtesy of the Intellectual Property Office)
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The first design depicted is an ‘aerial torpedo’ launched from a slip consisting of a pair of
parallel wire ropes by a cable actuated by a winding engine or by a catapult using stretched
rubber cord, the retaining cord lashings being severed by cutter blades as the aircraft left the
launch cradle. Although this device is shown with a motor installed, it is stated that this ‘may
be dispensed with altogether when only a moderate range is required’. Lanchester also
suggests that, when a single propeller is fitted, the turning moment due to the reaction of the
propeller and its driving mechanism could be balanced by a small weight. The torpedo has a
typical Lanchester-type high-aspect-ratio, high-set elliptical wing with an aspect ratio of from
10:1 to 13:1, a small triangular tailplane immediately ahead of the pusher propeller in the tail,
and the tall fixed vertical dorsal fins fore and aft. Lanchester observes that:
‘The natural velocity of a machine may be modified at will by altering the relative angle
between the wings and tail-plane, thus causing the former to meet the air at a greater or
less angle.
‘The power of controlling the natural velocity as well as the launching velocity will in
many cases permit of an aerial torpedo being successfully directed from behind a rampart
or otherwise at a hidden object.’
Figure 6 Lanchester’s proposed aerial torpedo; a catapult-launched unpiloted flying bomb,
as depicted in British Patent No 3608 of 1897. (Courtesy of the Intellectual Property Office)
What we have here, of course, is probably the first proposal for a powered flying bomb and a
glider bomb. Another intriguing option is for the wings to be truncated and fitted with vertical
‘capping planes’; what we would now call endplates. Their function is described as: ‘to
minimise the loss of energy due to air circulation around the wind (sic: wing) extremities’.
The other aircraft described has a pod-like car with the engine, preferably of Lanchester’s ‘two
crank balanced type’ at the rear, driving contrarotating ‘spoked-wheel’ propellers immediately
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in front of and behind it. The engine was to be enclosed in a streamline casing, with the
cylinders exposed for cooling. Accommodation for ‘the aeronaut and any accessories to the
use of the machine’ was provided in the front of the body, which was positioned well forward
to bring the machine’s c.g. as near as possible to the wing’s centre of pressure. The car body
could be of ‘woodwork, basket-work, or other suitable material’, but as far as practicable a
streamline form was to be adopted.
Figure 7
Lanchester’s proposal for a piloted aeroplane with twin pusher propellers in
tandem, from British Patent No 3608 of 1897. In the plan view the
port wing is shown cut off and fitted with a ‘capping plane’ or endplate.
(Courtesy of the Intellectual Property Office)
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Tubular booms extending rearwards along each side of the nacelle formed a main frame to
carry the engine and an all-moving tailplane, and the tubular main spar of the mid-set wing
passed across them and carried the internal framework, this being covered with fabric to form a
wing section as close as possible to that shown in the patent. At mid-span on each side there
were vertical struts above and below the wing to carry wire bracing stays to support the wing
structure. As with the aerial torpedo, shorter-span wings with ‘capping planes’ (endplates) are
also proposed. Also mounted on the mainframe booms were four fabric covered dorsal fins,
two forward and two aft, comprising central wooden struts and wire bracing covered by fabric.
The two rearmost fins were coupled together and could be operated through rigid links and bell
crank levers from the cabin to act as twin rudders. The tailplane had upper and lower vertical
struts with cable connections to actuation gear control in the cabin. This was not intended to act
as an all-moving elevator, but was ‘allowed a certain amount of angular movement about its
points of attachment’, supposed to effect ‘an alteration in the natural velocity of the machine’.
Lanchester stated, however, that ‘if desired . . . steering or the alteration of the natural velocity
may be done either wholly or in part by shifting ballast, or by the movement of the aeronaut
himself, the centre of gravity of the machine being thrown laterally in the direction in which it
is desired to steer or by moving forward to increase or backward to diminish the natural
velocity.’
Lanchester also stated that, ‘in certain cases’, the flywheel rim of his propeller was able ‘to
either supplement or even supplant the tailplane and rear fin[s] by virtue of the great resistance
it offers to lateral motion in any direction. He also believed that the flat propeller rims
increased the efficiency of the blades in the same manner that the ‘capping planes’ improved
the wing’s efficiency.
Lanchester states that: ‘the tail-plane acting in conjunction with the supporting wings has for
its principal functions the preservation of longitudinal equilibrium and the regulation of speed,
whilst the fins are concerned with the maintenance of transverse equilibrium and control of
geographic direction, the inclination of the course to the horizontal is under the control of the
propeller thrust.’
He continues:
‘When a machine constructed as hereinbefore described travels through the air with a
sufficient velocity its weight is supported dynamically by the reaction of the air on the
upper and under-wing surfaces, the curved form of section developing a region of
pressure beneath and rarefaction above in the same manner as a simple inclined plane but
with the advantage of greatly reduced resistance in the line of motion.’
Regarding the matter of automatic lateral stability he writes:
‘If in the course of its evolutions the machine . . . heel over side ways one way or the
other or if a “rolling” motion be set up, the first effect is for the machine to begin to slide
down, so to speak, in the direction in which it is for the time being inclined, this motion
is very quickly arrested however by the resistance of the “fins” whose centre of pressure
is arranged above the centre of gravity of the machine and equilibrium is thereby restored,
a similar result might be brought about by inclining the wings or the tips of the wings
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upwards to the right and left [i.e. dihedral] but an arrangement of fins is specially
valuable owing to its “damping” action on any side oscillations that might be set up.’
Climb or descent was to be achieved by increasing or decreasing the fuel supply to the motor,
although Lanchester added: ‘I may in certain cases introduce a counter thrust, instead of
operating on the motor mechanism by erecting a small plane or other obstruction perpendicular
to the direction of the motion of the machine so as to cause it to take a downward course.’
‘When only a temporary change of direction is required as when evading an obstacle the tail
plane may be used with effect for vertical steering but only within the safe velocity of the
machine.’ Lanchester seems not to have perceived a need for the ‘aeronaut’ to be able to
exercise any form of positive control in roll, as any deviation in this plane was countered by
the machine’s automatic stability. He apparently visualised the machine making flat, unbanked
turns and therefore regarded the fin/rudders as sufficient to manoeuvre the aircraft in the
yawing plane. However, he stated that:
‘The lateral steering may be effected by means of a rudder as with a boat, or one of the
fins may be used as a rudder and actuated by a suitable mechanism, or an alteration in the
angle of the two wings relative to one another or parts of them will by giving a list sideways
to the machine effect an alteration of its course.’
Although the last part of this statement has been interpreted as ‘a clear anticipation of the use
of ailerons or wing warping’ [24], it is almost there, but not quite. Lanchester seems to envisage
the machine being slewed round, rather than making proper banked turns. He does not appear
to have carried out systematic tests of this proposed system, which might have proved
enlightening.
Although in this design the wings were the sole lifting surfaces, Lanchester stated that the
tailplane could act as a subsidiary supporting surface, in which case the centre of gravity would
have to be set ‘somewhat aft of the wing area’ and the tailplane would preferably have an
aerofoil section ‘in order to carry out its additional function with the least resistance possible’.
However, he added the proviso that ‘in order . . . not to infringe the necessary conditions of
stability the pressure intensity on the tail-plane should be made less than on the wing area.’
5.
More models
Lanchester continued to work on his Phugoid Theory, and in the process came upon the
experiments of Pénaud, Mouillard and Marey, all of whom had experimented with model
gliders and powered aircraft. This inspired him to return to model gliders, and during 1905-07,
after a hiatus caused by his activities in the automobile world, he accomplished ‘a considerable
amount of work . . . in the confirmation and extension of the Phugoid Theory’, claiming that
‘by the use of thin laminae of mica in combination with other improvements [he had] succeeded
in bringing flight models of small size and low velocity to a degree of perfection not previously
obtainable’ [25].
Several of these models are described and depicted in Aerodonetics. They range in span from a
tiny 2 3/8in to 26in. He describes their construction thus:
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‘A mica lamina of a few thousandths of an inch in thickness, or even less than onethousandth of an inch in some cases, is cut to the shape required to form the aerofoil
[wing] and fastened to a “bolster”, which is a piece of wood of the necessary form to give
the aerofoil the curvature desired. The tail plane and the fins are also of mica, and are
attached by fish glue or other adhesive to a wooden backbone. Which also carries the
necessary ballast, in the form of lead foil, at its forward extremity.’ All of these models
featured tall front and rear vertical dorsal fins.
‘With an aerodone constructed as above described,’ Lanchester writes, ‘the whole of the
properties of the phugoid curve can be readily demonstrated in a large room or lecture
theatre, from the simple case of the steady glide to the curves of tumbler type. With a
certain amount of practice with any individual model it becomes quite easy, by varying
the initial velocity imparted, to get any recognised type of flight path at will, and by
varying the proportions of the aerodone in accordance with the requirements of theory,
the flight path may be rendered stable or otherwise as desired.’ [26]
In 1905, soon after he had developed his method for making these models, Lanchester
embarked on his first series of experiments. The largest model did not weigh more than 5 grams,
and the smallest was about one-tenth this size. The flights were conducted indoors ‘with models
ranging up to about one half ounce weight. But Lanchester asserted that ‘the application of the
resulting equation to [his] 1894 models, and to the gliding machine of the late Herr Lilienthal,
forms an effective continuation.’ [27] (See later.) On 3 July 1905, observed by Lanchester and
Mr A.J. Hill, Model No2 of ‘Series A’, which weighed 4.7 grams, made a flight of 85ft in 6sec
(14ft/sec) and its oscillations were measured and the phase lengths calculated. [28]
Figure 8
A plan view and side elevation of Model No 2 of ‘Series A’
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Lanchester noted:
‘The sizes and velocities suitable for employment vary with the circumstances under
which experiments can be conducted; thus, experimenting indoors in a room 20ft by 30ft,
an aerodone having a natural velocity of about 5 or 6ft/sec is found to be most suitable;
the short phase length corresponding to these low velocities - some 4 or 5 feet - renders it
possible to observe six or eight undulations in the phugoid path, and so to determine
whether the amplitude is subject to change, or whether it is sensibly constant. When
experiments are conducted out of doors a natural velocity of 14ft/sec [9.5mph] is found
to be appropriate; this, whilst not excessive from the point of view of ease of observation
or of convenience of launching by hand, is sufficient to render the aerodone consistent in
its behaviour on a calm day.’
Figure 9
Left and right, two other small models, of 7½in and 4½in span respectively, used
for the initial ‘quantitative investigation’ (drawings not to same scale)
‘Models of more than a few ounces weight,’ he continues, ‘require to have a higher
natural velocity, and it becomes desirable to employ a launching device such as the
catapult [used with his 1894 gliders] . . . ; it is then no longer any advantage to keep the
natural velocity down to the minimum, and velocities of 25 or 30 ft/sec may appropriately
be employed. In this case the phase length will amount to something like 100 to 140 feet
and a flight of two or three hundred yards is desirable, involving a drop of about a hundred
feet. Thus the experiments should be conducted from the edge of a cliff or other elevated
point.’ [29]
Lanchester was sure that his Phugoid Theory made no discrimination regarding the size of the
aeroplane, applying equally to ‘flying machines of many tons weight’ [30] and full-sized models
as well as to very small models. He believed that ‘the range of the equation should be restricted
only by some inferior limit of size’, and therefore emphasised the importance of small scale
models and low velocities. He also stated that it was ‘. . . at the same time desirable to extend
the range of the experimental verification as far as possible in the direction of larger sizes and
higher velocities as representing more nearly the actual conditions of practical aeronautics’. [31]
For experimental verification of the equation of stability four models, weighing 12 grams,
4 grams, ¼ of a gram, and one grain, were used. They were designed for minimum resistance
and rough advance calculations were made to ensure that their stability was approximately
equal to unity. Once built, they were adjusted to the critical condition by observation of their
flight paths, the final measurements were made and the data thus obtained for the final
calculations. [32]
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Lanchester said his method of experiment and apparatus were: ‘of the most primitive
simplicity; a tape measure, a stop watch, and a launching staff . . . , together with the flight
model itself, constitute the complete outfit.’ [33] As to location and launching techniques, he
writes:
‘A necessary adjunct to the above apparatus is a large room or other enclosed space.
Failing this, it is necessary to experiment out of doors, a procedure that involves many
tedious delays, waiting for suitably calm moments when the weather is favourable. At the
best, outdoor experiments, unless on a rather large scale, are unsatisfactory.
‘Much of [my] work has, in spite of difficulties, been done in the open, but all the low
velocity experiments (under 10ft/sec) have been conducted indoors, in most part in a
room approximately 28ft by 20ft, and in a few cases [the 1905-1907 models] in a room
about 60ft by 30ft. The larger the room available the better, it is useful to have plenty of
width as well as length, a room 50ft wide by 60 or 70ft long would, for most purposes, be
found of ample size.
‘The aerodones may be launched either by hand or by means of the launching staff. In
general, except for ballasted aeroplanes, and for models of very rapid descent, [I have]
found hand launching quite satisfactory, but a certain degree of skill, soon acquired by
practice, is necessary, both in order to avoid giving the model initial rotation and to
ensure imparting to it the correct velocity . . . and gliding angle.
‘It is evident that any initial want of accuracy in the launching of the aerodone will affect
its flight path, the amplitude of the resulting phugoid will be greater the greater the
inaccuracy; it is thus necessary to ignore flights in which the amplitude is considerable,
and in general the flights recorded by [myself] . . . have been nice uniform glides in
which the phugoid oscillation if existent at all is barely perceptible.
‘From the above considerations it is manifestly desirable to have a range of flight of at
least two or three phase lengths, and where the amplitude is fairly constant it is evident
that if the length of flight be made an exact multiple of the phase length . . . , any error
due to the phugoid oscillation will vanish, even though the flight path be of sensible
amplitude. With due precautions the error in determination of [natural velocity] due to
the method of launching is far less than the possible error due to the method of timing by
a stop watch, and the inaccuracy in the determination of [the rate of loss of ‘head’ per
foot of horizontal flight path at natural velocity, on the basis of propulsive force]
certainly need not exceed one or two inches out of a total drop of 80 inches or
thereabouts, or a probable error not greater than 2½ per cent.’ [34]
The tests of the 12 gram model, which differed from the earlier models in having a span much
greater than its length, were conducted both outdoors and indoors, whereas the smaller ones
were flown only indoors, and he pointed out that suitable sizes and velocities varied according
to the circumstances under which the experiments were conducted. He found that a model
having a natural velocity of about 5 or 6ft/sec was most suitable for a room 20ft by 30ft, as the
short phase length of the phugoid, some 4 or 5ft, enabling the experimenter to observe six or
eight undulations of the phugoid path and thereby determine whether the amplitude was subject
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to change or ‘sensibly constant’. Out of doors, a natural velocity of 14ft/sec was deemed
appropriate; while it was not excessive for ease of observation or convenience of launching by
hand, it was sufficient to ‘render the aerodone consistent in its behaviour on a calm day’. [35]
The two larger models were adjusted from unstable to stable by adding ballast close to the
centre of gravity. With the smaller models the adjustment was made in the opposite direction,
from stable to unstable, by reducing their tail areas. [36]
The 12 gram model spanned 26in, was a little over 7in long and had a 6in span tailplane, a
mass of 12.3 grams (0.0267lb) and a velocity of 9.3ft/sec. It will be seen later to be of
particular interest. It had an elliptical wing with an extremely high aspect ratio of 13:1, and had
upturned wingtips in addition to the usual pair of very tall front and rear dorsal fins. [37]
Figure 10
A photograph and drawings of the 12 gram model
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The 4 gram model spanned nearly 14in, was just over 6in long, had a mass of 4.52 gram
(0.01lb) and a velocity of 9.5ft/sec. [38]
Figure 11
The 4 gram model
The ¼ gram model spanned 5 5/8in, was 2 5/16in long, had a mass of 0.245 grams (0.00054lb)
and a velocity of 5ft/sec. [39]
Figure 12
The quarter-gram model
The tiny one-grain (0.065 gram) model spanned 2 3/8in, was 1 5/16in long, had a mass of
0.062 gram (0.000137lb) and a velocity of 5ft/sec. In this case it was thought preferable to vary
only the size of this machine and to give it the same velocity as the ¼ gram model, ‘. . . to
make sure that the conditions are other than those of corresponding speed.’ [40]
Figure 13
The ‘one grain’ model
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The flight path of the 12 gram model was observed for three successive oscillations and
deemed ‘just stable for small amplitude’. The agreement with the theory was within 7 per cent,
which Lanchester thought ‘as close as is to be expected’, stating that the discrepancy might be
due to some imperfection in the equation, ‘for undoubtedly imperfections exist; there are
factors of secondary importance of which the theory takes no account’. However, he added
that it was equally possible that it was due to inaccuracies of observation and measurement.
The flight path of the 4 gram model, again observed for three successive oscillations, was
recorded as ‘nearly stable’ for small amplitude.
Sometimes Lanchester was ‘astonished’ by ‘long, uniform, almost horizontal glides’ that
occurred during outdoor tests. One such flight was made by the 12 gram model, which dropped
only 2ft 6in in a flight of over 50ft length. He wrote that this model’s actual gliding angle
‘when carefully ascertained indoors’, was significantly steeper. Because of the model’s low
velocity and the fact that its flight path was ‘on the verge of the unstable, Lanchester knew that
this ‘anomalous flight’ was not due to excessive launching velocity, as the resulting phugoid
would have been of great amplitude; possibly ‘sufficient to actually put an end to the stability’.
Some portion of the reduction in the gliding angle was attributed to the fact that there was ‘a
very light air moving’ at the time, ‘estimated from the rate of drift of the smoke from a
cigarette at approximately three feet a second in the direction of flight’. In addition the flight
took place from an open space towards a building, the model striking the wall of the building
about 4 feet above the ground. Lanchester observed that the air in the region traversed would
have an upward component to its motion, thus reducing the gliding angle. Moreover, as the
glider ‘automatically regulated its own velocity, and its launching velocity was, from the
evidence of its flight path, approximately correct, its initial velocity would have been 3ft/sec
higher than its final velocity, and the difference of kinetic energy due to this difference in
velocity was manifested in a gain in altitude. [41]
The foregoing provides an interesting sidelight on the observation techniques employed. In a
footnote, Lanchester remarks:
‘The drifting of a smoke cloud is certainly the most convenient way of estimating the
velocity of very light aerial currents. With two observers and a stop watch it is probably
also the most accurate; perhaps better results could be obtained by timing the drift of a
soap bubble.’ [42]
He further comments:
‘The importance of [this] example is as an illustration of how easy it would be to an
inexperienced observer to record, in perfect good faith, fictitious and misleading results,
and further, the desirability of conducting all quantitative experiments in a suitable
building. A motion of the air of one or two feet a second velocity is scarcely noticeable,
and yet it may materially vitiate the accuracy of experimental work.’ [43]
Lanchester devotes some eight-and-a-half pages to attempts to analyse ‘vagaries of the flight
path’ of various models, including the 4 gram model’s tendency to ‘[take] advantage of the
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moment of its least velocity [at the crest of a phugoid] to behave in a crooked and disreputable
manner’. [44] Another problem encountered was in-flight distortion of the structure, especially
the mica wings, which could kink where the approximately flat extremity merged into the
curved section. On the slow and relatively large 12 gram model this was actually observed. It
had originally been designed and made with only two ties on each wing, and another outer one
had to be added to stiffen the extremities and eliminate the defect. Lanchester writes: ‘In a low
velocity model of this size one can observe every detail in the deportment of the model in a
way not possible in an aerodone of small size or high velocity.’ [45]
Measurements were then made of the flight of the ¼ gram model, to ascertain if possible the
extent to which the theory might be limited in its application to models of small size. This time
the agreement with the equation was not so close, the stability ‘according to direct observation’
being apparently 50 per cent better. Further trials failed to show any error in the observation
data, Lanchester pointing out that an inaccuracy of 10 per cent would be required to account
for the discrepancy, and that it was ‘unlikely that an error of one quarter of this amount would
have escaped notice’. He concluded that the estimate of the moment of inertia was most
probably in error, pointing out that, without special apparatus, ‘The measurement of so small a
model is a matter of some difficulty’. He added that it was also possible that the viscosity of
the air had a steadying influence on such small models. [46]
The tests were then carried to a ‘still finer point’ with the one-grain model, its natural velocity
being exact to within a possible 5 per cent error. The initial adjustments imparted a degree of
stability ‘sufficient to render the flight path steady enough for the purpose of observation’,
Lanchester estimating ‘from experience with other models’ that it had a stability factor of 2 ‘or
thereabouts’, and the actual value being calculated as 1.67. The tailplane was then adjusted to
reduce stability, and another flight provided final confirmation of the truth of the equation, as
‘the flight path had become capricious’.
To reduce this diminutive model’s flight path to the ‘just stable’ condition its tail was then cut
down to half its span, ‘the portions cut off being made to adhere by capillarity to the remaining
portion so that the balance should be unaffected’. The model’s flight path was now ‘scarcely
stable’, and it proved ‘impossible to obtain flights of a sufficiently consistent character’ to
enable the required data to be gained. The model was also now on the point of developing a
lateral oscillation that initially manifested itself at the crest of the phugoid. [47]
It was concluded that, even in the case of a model weighing only 1 gram, ‘the departure from
the ordinary laws of flight is comparatively unimportant, and that the influence of viscosity
does not give rise to a new régime till the size is still very much further reduced.’ However,
Lanchester admitted that, in reality, this conclusion could only be an approximation, as he had
failed, ‘in spite of repeated endeavour’, to obtain gliding angles for the very small models to
approach those easily obtainable with models of even a few grams weight. The point was being
approached when the influence of viscosity began to have a material effect on the law of
resistance. [48]
Lanchester concluded that these model experiments demonstrated that, ‘generally speaking’, an
aircraft that was ‘just stable’ (his italics) for paths of small amplitude was unstable if the
amplitude was great, though he was uncertain whether this was universally the case. [49]
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Having gained this data, Lanchester then applied it retrospectively to his 1894 glider model and
twin-propeller powered model, calculating that the former had a longitudinal stability factor of
6.4 and the latter a factor of 4.7. He then did the same for Otto Lilienthal’s No 11 monoplane
hang glider, the Normal-Segelapparat of 1894/95, which yielded a mere 0.424, and concluded:
‘Thus the Lilienthal machine did not conform to the equation of stability, and it is literally true
that the aeronaut trusted to his instinct to maintain his equilibrium. It is a most lamentable
circumstance that Herr Lilienthal paid for his temerity with his life.’ [50]
Figure 14
Lilienthal’s Normal-Segelapparat of 1894-95
In the year in which Aerodonetics was published, 1908, powered flight was a reality but still in
the early stages of development. In his preface, Lanchester outlined the current state of the art
as he saw it, and postulated on future trends:
‘The present time is one of considerable importance in the history of aerial flight: the
motive power engine has, during the last few years, reached a stage in its development at
which its weight has become sufficiently reduced to render mechanical flight possible,
and already several partially successful machines have been built, and flights of several
miles have been made. Some of these machines are deficient in many important respects;
the propellers for example are of relatively small diameter and are commonly of too
quick a pitch and too high a revolution speed for best efficiency. The longitudinal stability
also, instead of being automatic, is only maintained by the watchful attention of the
aeronaut and the dexterous manipulation of a horizontal rudder [a forward or rear
elevator in modern parlance]. Further than this the cooling of the motor cylinder is not
altogether effective, and the duration and range of flight is largely a matter of how long
elapses before the water is boiled away. The question of weight makes it difficult to
employ a thoroughly efficient “radiator” as used on road vehicles, and without doubt
direct air cooling will sooner or later come into vogue. For the above reasons the flights
so far made have been of comparatively brief duration.
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‘In the future it is unlikely that that the flying-machine will be limited in its performance
to short flights over prepared ground at a few metres height, ready to come to earth at a
moment’s notice; it will rather seek safety in altitude, probably flying in most part at a
height of at least two or three thousand feet, where in the event of any minor mechanical
failure or other hitch the time of gliding descent will be at the disposal of the aeronaut for
adjustment, or, if it is found necessary to land, for the selection of a suitable site. Thus, if
an aerodrome [sic] be flying one mile above the surface of the earth, there will be a circle
of some ten or twelve miles diameter available within which to choose a place to alight;
or, if we assume the velocity of flight to be forty miles per hour, the aeronaut will have at
his disposal a period of some eight or ten minutes before he need finally come to earth.’ [51]
Lanchester’s understanding of the evolution of the Wrights’ aeroplane was completely awry,
and, like everyone else at that time, he clearly had no knowledge of their extensive and
unprecedented windtunnel tests of aerofoils and the resulting extensive tables of data, or of
their advanced propeller research. He was evidently unaware of the astounding efficiency of
the Wright brothers’ propellers, as will be seen again shortly. Those of the 1903 Wright Flyer
had an efficiency of 66 per cent, while those of the Flyer III of 1905 are known to have had an
efficiency of 81.5 per cent, an astonishing figure for the time, and outstanding even today. [52]
As we shall see, Lanchester found this impossible to comprehend.
6.
Studying real aeroplanes
The publication of Aerodynamics and Aerodonetics in 1907 and 1908 respectively brought
overdue recognition, and on 8 December 1908 he read a paper before the Aeronautical Society
of Great Britain entitled ‘The Wright and Voisin Types of Flying Machine. A Comparison.’ [53]
Not long before this, Lanchester had witnessed both types of aircraft in flight in France, the
former piloted by Wilbur Wright at Le Mans, where he saw three flights, and the latter at
Mourmelon le Grand near Chalons, flown by Henry Farman. Two principal features made
Lanchester favour the Voisin aeroplane over the Wright: the French machine incorporated
‘heavy engineering’ techniques in its construction and was designed to be inherently stable,
both factors that would have appealed to an automobile engineer who had experimented only
with ‘passive’ model aircraft, whereas the American aircraft, designed by bicycle designers and
manufacturers and evolved from experiments with full-size manned gliders, was simple and
light in structure and designed to be unstable.
Both types had undergone some development by the time Lanchester saw them, and they were
to undergo further development in the years ahead. The Wrights had begun to introduce
elements of stability, eliminating the anhedral angle of the wings, extending the booms
carrying the forward elevators and adding a pair of fixed fins between the elevators, and
lengthening the booms carrying the rear rudders. Farman had removed the side curtains
between the Voisin’s wings and had just added ailerons. It is unlikely that either party was
aware of Lanchester’s work at that time. Lanchester stated that accurate information on some
points was difficult to obtain, and that ‘the reticence shown is perhaps no more than might be
anticipated’, and he was obviously not familiar with the various design changes that had been
made in the preceding years. In fact he added a footnote to say that ‘Messrs Delagrange and
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Farman (Voisin’s first customers) had no more to do with the design of their machines than the
purchaser of a motor car from the manufacturer’. Moreover, many of his assessments were
quite speculative and inconclusive.
Figure 15
Figure 16
The Wright Model A biplane of 1908 (Author’s collection)
The Voisin box-kite biplane of 1908. (Author’s collection)
Viewing the machines through an engineer’s eyes, Lanchester approved of the Voisin’s heavy
chassis, said to exceed one hundredweight, with its four wheels mounted to swivel freely (‘an
essential feature of a well-designed alighting mechanism’) and the main wheels provided with
spring suspension. If the Wright Flyer’s wooden runners ‘would do all that can be done by the
Voisin mounting,’ he reasoned, the additional weight of the Voisin’s undercarriage ‘would not
be justified, but they will not do so. The Voisin machine can rise by itself from any reasonably
smooth surface, the Wright machine is unable to take flight without its launching gear, hence it
is not legitimate to attribute its relative lightness to the superiority of its design.’ (It was not
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long before the Flyers were taking off without catapult assistance, and wheels were soon added
to the runners.) However, he estimated the Wright machine to have more efficient propellers
crediting them with 63 per cent against the Voisin’s 54 per cent. In a footnote he stated that:
‘. . . Mr Wright has admitted (at least to the author) that his gliding angle is about 7
degrees; this, at a gross weight of 1,100lbs., gives 140lbs thrust required, and at 58ft per
sec, the thrust h.p. becomes14.5. Now Mr Wright also agrees 24bhp as the power of his
motor, which, if 40 per cent in excess of his requirements, gives 17.1bhp as ordinarily
utilised, or the total efficiency of the gear and screw propeller would be 85 per cent—a
manifest impossibility.’
As stated above, we now know that these large-diameter propellers were in fact 81.5 per
cent efficient, so Wilbur was not as far out as Lanchester had believed. He rightly
pointed out that the considerably lower efficiency of the Voisin propeller was at least in
part ‘a tax paid for the constructional advantage of a direct drive’, but seemed unaware
that the very design of the crude Voisin metal propeller was greatly inferior. One would
hardly expect a ‘heavy engineer’ to approve of the Wrights’ chain drive and shaft
transmission (even modern engineers wince when they look at the crossed chain on one
side to create counter-rotation and eliminate torque). Lanchester found this feature
difficult to reconcile, writing:
‘The Voisin system of metal propeller keyed direct to the crank shaft is so immeasurably
superior from the purely mechanical standpoint [his italics] to the chain drive and
wooden propellers of Wright that comparison is unnecessary. Since, however, the simple
and direct arrangement adopted by MM Voisin is paid for at the price of about a 15 per
cent tax on the transmitted horse-power, the question is evidently one of the balance of
advantages and disadvantages that are of entirely different kinds. The author has reasons
for supposing that if, in the machine of the future, the geared propeller survives (for it is
essentially the gearing in the Wright machine that permits the better proportions of
propeller to be used) it will be in the form of a propeller or propellers centrally situated,
thus resembling the Voisin arrangement rather than the distribution of propellers such as
at present employed by the brothers Wright. The simplicity of the direct drive may,
however, alone be sufficient to outweigh any economic advantages that gearing may
possess.
‘I personally consider the Wright disposition of propellers to be a source of danger. If a
torque is applied to an aerodrome [sic] about a vertical axis, rotation about this axis at
once begins, and the outer wing, travelling through the air faster than the inner,
experiences a greater lifting re-action, and if the torque is sufficient, the machine is very
soon (in nautical phraseology) on its “beam-ends”. It is evident that if one of the
propellers fail [sic] from the fracture of a chain or other cause, unless the motor be
instantly stopped, the whole power of the motor and, therefore, the whole thrust will be
transmitted through the other propeller, causing a torque about a vertical axis that must
be overwhelming. If the motor is promptly stopped then much will depend on whether
the propeller that has failed is scotched or free. If it has jambed, then it will probably
balance by its drag the other propeller, which is either stopped also or is driving the
motor against its internal friction. If, on the contrary, it is free, then the drag of the other
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propeller will be unbalanced, and there is a serious torque in the opposite sense to that
which would have existed if the motor had still been running. Whether Mr Wright can,
in the latter case, by wing twisting and other contortions, save himself from destruction I
do not know. It is said that, a short time ago, a chain actually broke in flight, and the
machine safely landed. The altitude when the accident occurred was stated to be only
four or five metres, so that Mr Wright did not have a fair chance of exhibiting his
resources. It is to be hoped that he will not have such a mishap at a higher altitude.’
In a later statement Lanchester was quite uncomplimentary about the Wright engine, though he
knew nothing about its development and technical features. His examination of it had been
quite superficial and his judgment was peremptory. He wrote: ‘I came to the conclusion that
the engine showed no evidence of having been designed for flight; there was nothing about the
design which would conduce to weight-saving, although the weight had been cut by
cheeseparing.’ Contrary to this, much more recent and detailed studies of the Wright engines
by engineers yielded complimentary comments on their good metallurgy and their ingenious
features. [55]
Lanchester’s consideration of the stability and control of the two types contains some
interesting observations. First, regarding longitudinal stability, he says:
‘In the case of the Wright machine it is claimed by Mr Wright himself that the stability
depends entirely on the skill and address of the aeronaut . . . . The author’s own
observations on the flight of the Wright machine fully confirm the statement that Mr
Wright does depend entirely upon his manipulative skill. It appears that in flight the
leading planes travel through the air, carrying little or no load; in the ordinary conditions
of straight flight their direction is as nearly as can be estimated parallel to the frame of
the main aerofoil, and both seem to move almost exactly edgeways. It follows from this
that the machine cannot be automatically stable, for if the plane were fixed for any period
of time, and if, during that period, the machine made the smallest pitching movement
either one way or the other, the resulting change of pressure on the leading plane (or
planes) would tend to exaggerate the initial movement, and the machine would turn over.
The position of the machine, with the leading planes fixed, is comparable to an arrow
travelling feather first, and this condition is one of instability.
‘In brief, not only does Mr Wright design definitely for hand-controlled equilibrium, but
he has no belief in the possibility of making a machine safe by its own inherent stability.
The success of the Wright method shows that there is at least more than one way to fly.
‘In the Voisin machine, on the contrary, it has been the intention of the designer that the
machine should be automatically and inherently stable, and unquestionably to a great
extent he has succeeded. . . . the disposition of the organs of the Voisin machine are such
as will give automatic stability if the following conditions are fulfilled:– (1) If the
pressure is less (per sq. ft.) on the tail than on the main aerofoil, so that the attitude of the
aerodrome to its line of flight is one of stable equilibrium; (2) if the areas and disposition
of the surfaces, the amount of inertia, the velocity of flight, and the natural gliding angle
are related to comply with the equation of stability, so that any oscillation in the vertical
plane of flight will not tend to an increase of amplitude.
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‘From the behaviour of the machine it is not possible to tell whether these conditions are
complied with, because it is fitted with a horizontal rudder [elevator] in front, by which
the aeronaut can correct any departure from the straight line, and this appliance is
unquestionably utilised to destroy any oscillation that would otherwise arise. It is a big
rudder, about one-quarter the area of the aerofoil, and, skilfully handled, it would entirely
mask the natural free oscillation period of the machine. From observation of the flight
the author is of the opinion that whether the machine has inherent stability or not, the
actual fact is that its motion (in the sense under discussion) is just as much controlled by
hand as the Wright machine. In the hands of a beginner the machine would, however, very
likely be able to take care of the aeronaut to some extent, performing oscillations all the
while, until the aeronaut has learned to take care of the machine. This view is suggested
by the fact that many of the observers who saw Farman and Delagrange early in their
career witnessed the phugoid oscillation, whereas the author, who saw Farman only a
few weeks back, could not detect any oscillation at all, except for a brief period after he
first left the ground, and this in spite of the fact that the day was by no means calm; a
very perceptible breeze was blowing.
Lanchester was not satisfied that the proofs of the machine’s stability offered by Voisin
engineer M. Colliex was sufficient to prove the case, and concluded: ‘There is thus no proof at
present forthcoming as to the stability or otherwise of the flight path of the Voisin machine, but
it is at least the intention of the makers that it should be longitudinally stable . . . .’
On the matter of lateral stability Lanchester writes:
‘In the Wright machine the lateral stability is under the direct control of the aeronaut.
The “two wings” of the aerofoil being given a twist by straining the structure by means
of wires arranged diagonally in the rear panels of the two end bays on either hand. This
causes the wings to meet the air at different angles of incidence and so any desired
turning moment about the axis of flight (within certain limits) is at command. This
mechanism is employed to neutralise the influence of wind gusts, and to correct the
position of the machine should it acquire an undesirable list. It is also utilised to prevent
the machine canting too much when turning, and to facilitate its employment in this
respect, the rudder aft and the twisting of the wings are operated by one lever, the motion
to the right and left being utilised to put tension on the diagonal wires one way or the
other, and the movement forward and backward works the rudder.
‘It is desirable to correct a false impression that is current on the action of the wing twist.
It has been supposed by some that it is used to give the cant required by the machine
when turning, but such is not the case. If the rudder is used the machine almost
immediately gets a cant, owing to the greater pressure on the wing that in turning is
moving faster through the air, and this cant becomes, if unchecked, far too severe. The
twist is then used to check the cant, the wing on the outer circle (that is, farthest from the
centre of the curvature) being “feathered,” the inner one having its angle of incidence
increased.
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‘In the Voisin machine no hand adjustment is provided to enable the aeronaut to control
the lateral stability, hence in this case it is definitely automatic. The Voisin machine is
steered by means of a vertical rudder arranged between the fixed tail members, and there
is apparently no special mechanism to prevent the over-canting; consequently, Farman,
in his flights, commonly turns in a leisurely manner, employing a circle of considerable
radius, whereas Wright may often be seen to perform sensational evolutions, turning with
his wings canted to nearly 30 degrees on a radius of, perhaps, not more than 60 or 70
yards.
‘It is of interest to note that Farman has recently had fitted to his machine some
adjustable flaps [ailerons] to give in effect the wing twist employed by Wright.
Presumably this is to facilitate turning, for the flight of the machine does not suggest that
they are otherwise wanted; the lateral stability leaves little to be desired.’
From what he called an ‘aerodonetic standpoint’, that is the aeroplanes’ flying qualities,
Lanchester thought that the Voisin had the advantage, ‘containing more of the features that will
be embodied in the flying machine of the future’. ‘Mr Wright’s contention that it only requires
a big enough puff of wind to upset a machine that depends upon its own inherent stability is
certainly true,’ he added, ‘but probably the same is equally true of the hand-controlled
machine. There is a limit to the extent of the control that can be exercised, and with hand
control we have, too, the possible failure of the human machine. The fact is, that the secret of
stability is contained in the one word, velocity, and until it is possible to attain higher speeds of
flight we cannot hope to see the flying machine in everyday use. The author believes that the
future of flight as a useful and practicable means of aerial navigation will depend definitely
upon the abolition of hand-maintained equilibrium and the substitution of automatic stability,
and already the Voisin machine goes a considerable way in this direction’.
We know now, of course, that every type of aeroplane embodies a compromise of stability and
control according to its role, whether it be a trainer, an aerobatic aircraft, an airliner or a jet
fighter. In addition, we can now provide artificial ‘feel’ and systems that can fly a machine that
would be beyond a human pilot’s capabilities.
Lanchester’ heavy engineering background again came to the fore when comparing the
constructional methods used in the two types, which he said presented a ‘striking contrast’. He
writes:
‘The Wright machine is astonishing in its simplicity—not to say in its apparent crudity of
detail—it is almost a matter of surprise that it holds together,’ ‘The Voisin machine has
at least some pretensions to be considered an engineering job.’
Mr Wright defends his methods by asking what would be said by an engineer to the
rigging of a sailing vessel if shown it for the first time, and, to some extent, the analogy
is a good reply to the objection. Still, the author feels (perhaps wrongly) that there is a
considerable amount of the Wright “mechanical detail” that might be revised with
advantage; at least, before the machine is placed in the hands of the private user.
However, “the proof of the pudding is in the eating,” and in spite of the rudimentary
character and aggressive simplicity of the constructional detail of the Wright machine, it
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appears not to come to pieces, but continues to fly day after day without showing any
signs of weakness or disintegration.’
One detects a degree of reluctance to admit that the Wright aeroplane was more efficient and
flew better than the Voisin. Lanchester would clearly have liked to beef up the structure and
incorporate some heavy engineering techniques. He would soon find out that this was not
necessarily a good idea if carried too far.
Lanchester sent a copy of his paper to Wilbur Wright at Le Mans, and asked for his comments.
However, Wilbur felt that nothing would be gained by discussion, and replied: ‘In glancing
over the address I note such differences of information, theory, and even ideals, as to make it
quite out of the question to reach common ground by mere talk, so I think it will save me much
time if I follow my usual plan and let the truth make itself apparent in actual practice’. As
Lanchester’s biographer points out, ‘. . . only a few years later Lanchester was able to show, in
his James Forrest Lecture to the Institution of Civil Engineers in 1914, [56] that practically the
whole of the distinctive features of the early Wright machine had disappeared and that type of
machine had been abandoned because of its unstable character.’ [57] Things were rather
different in 1909, and Lanchester, too, still had lessons to learn.
7.
Patents again
In 1909 Lanchester was appointed to the British Advisory Committee for Aeronautics,
established under the presidency of Lord Rayleigh, and that same year he also became
consultant to the British Daimler Company. These responsibilities must have distracted him
from his experiments to no small degree, but early in 1909, when he was living at 53 Hagley
Road, Edgbaston, Birmingham, he took out two more aviation-related patents, which seem to
have resulted, at least in part, from his study of the Wright and Voisin aircraft.
The first of these, No 8849, applied for on 14 April 1909 and accepted on 6 January 1910, was
entitled ‘Improvements relating to the Steering of Flying Machines or Aerodromes’. (He had
evidently adopted Professor S.P. Langley’s erroneous Latin adaptation to define an aeroplane.)
This patent reveals that Lanchester had revised his earlier basic thoughts about lateral control,
as it related to ‘. . . improvements in the steering of flying machines or aerodromes’, and ‘[had]
for its object to permit of the course of the machine being varied in azimuth without any
objectionable torque arising about the axis of flight’.
Lanchester writes:
‘It is now understood that one of the difficulties of manoeuvring a machine of the socalled aeroplane type is that when the machine is moving in a curved path the one wing
of the supporting member is moving faster than the other and so experiences a greater
lifting reaction. It has hitherto been the custom in some of the machines constructed to
neutralise or partially neutralise the torque so produced by twisting the wings or by some
equivalent means.
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‘According to the present invention the motion given to the supporting member is such
that the said objectionable couple does not arise and there is consequently no need for
any correcting mechanism.’
Lanchester had adapted his tall vertical front and rear fins to work as interconnected all-moving
rudders controlled by the pilot, the forward surface having an angular movement greater than
that in the rear. They were so arranged that they caused the aircraft to rotate about a point well
behind its centre of gravity, the aim being to prevent the lateral tilting (banking) of the
aeroplane when turning caused by the outer wing travelling through the air at a higher speed
than the inner one.
Figure 17
The diagram from Patent No 8849 of 1909, showing the supposed action
of the interconnected all-moving rudders
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He claimed that ‘This disposition results in there being no unbalanced couple when turning, for
what is known as “end effect” (due to the lateral component of its motion) gives rise to a torque
in the opposite sense to that due to the difference of velocities of the wings.’ He specified that
the essential condition was that the angular movement of the rear rudder was less than that of
the front rudder, and said that by extending the member carrying the rear rudder sufficiently far
aft this rudder’s angular motion could be decreased to any extent desired, and that ‘Where such
rearward extension can be carried far enough astern it may be found possible to definitely fix
the after rudder’ (i.e. making it a fin). He also added that ‘The end effect which exists even in
a simple aeroplane may be enhanced as required by upturning the extremities’.
The second patent, No 10,422, applied for on 3 May 1909 and accepted on 28 April 1910,
referred ‘more particularly to improvements in the organs of stability and control, his intention
being ‘to avoid as far as possible any interference with the lateral trim of the machine due to
variations of propeller torque, and secondly to render the control of the vertical course and
velocity of the machine more complete and secure’. [59]
This invention consisted of the provision of ‘directive organs’ mounted on horizontal axes on
booms extending in front of and behind the main wings. Ahead of the wings was a freely
mounted horizontal surface ‘so mounted as to take up automatically the direction of the relative
air current after the manner of a weather vane’. When unconstrained by the pilot it was
inoperative, but control was preferably directed by the pilot, who could elevate or depress the
surface to alter the machine’s horizontal course, or, as Lanchester puts it, ‘for modifying at will
the amplitude of the “phugoid oscillation” so that the effect of wind gusts may be readily
corrected or temporary obstacles may be avoided’. Release of the actuating mechanism
automatically ensured that the aeroplane returned to the condition to which it had been
adjusted.
The patent diagrams depict a biplane with a single pusher propeller behind the pilot’s nacelle,
coupled directly to the motor shaft (Figure 18). The rear ‘directive organ’ was a cumbersome
multicellular hexagon made up of 12 surfaces of equal size, roughly of the same diameter as
the propeller and comprising six triangular cells. Viewed from the front the structure resembled a
wire wheel, its division into six cells being made by wire bracing covered with fabric or sheet
metal. The whole unit could be tilted back and forth by means of ‘a screw or worm of fine
pitch’, with the aim of securing the longitudinal stability of the aircraft and regulating its
‘natural velocity’. The aeroplane in the diagrams has a pair of small rear wheels attached to the
base of the hexagon.
Significantly, there seems to be no means of moving the rear cellule laterally to work as a
rudder, and no separate vertical surfaces, either fixed or moveable, are shown. The question of
lateral control is not relevant to this patent.
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Figure 18
8.
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Lanchester’s cumbersome biplane with its multicellular-hexagon tail surface
Full-size aeroplanes
Having examined the small-scale extreme of his field of research, Lanchester now needed to
seek experimental verification using larger aircraft and higher velocities, as he had stated in
Aerodonetics. This aspect of his research has hitherto remained unknown, but at an Aircraft
Enthusiasts’ Fair in the late 1990s the author discovered a large fully-dimensioned blueprint of
a general-arrangement drawing buried incongruously in a box of post-WW2 ephemera. [60]
The blueprint bears the stamp of ‘Camper and Nicholsons Limited, Yacht Builders, Gosport’ at
bottom left, and the small inscription ‘Tracing No 192, 15/9/09’ (15 September 1909) at bottom
right (Figure 19). It is entitled ‘Single Screw Monoplane, Construction Plan and General
Arrangement, Scale 1” – 1 Foot’. The aircraft’s principal dimensions are given as: ‘Main Plane
36’.0” x 3’.0” [at root] – 9” [at tip]; Tail Plane 12’ 0” x 2’ 0”; Length OA [overall] 14’ 0”.’
Camper and Nicholsons is still going strong, but sadly there is nothing in their records
regarding this drawing.
Although Lanchester’s name does not appear on the blueprint, even a cursory glance at the
machine depicted betrays unique features that link it with him beyond any shadow of a doubt.
The link with a yacht-building company serves to strengthen this connection, as Lanchester
had recently been initiated into the delights of deep-sea sailing by Dr Bostock-Hill, an old
friend in Birmingham. In 1910 he bought a cutter which he named Iseult and kept at Bembridge,
where he had a winter anchorage. He sailed on long weekends and holidays, and before 1914
he sailed a lot in the Channel and over to France and Belgium. [61] A boatyard of that time,
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dealing with wire-braced wooden structures and fabric sails, might have seemed admirably
suited to aeroplane construction; indeed, Camper and Nicholsons also built a biplane glider for
naval Lieutenants John C. Porte and W.B. Pirie that same year. [62]
Figure 19
The author holding the original Camper and Nicholsons blueprint of a
Lanchester-type monoplane
In planform the monoplane bears a striking resemblance to Lanchester’s 12 gram model 190507. Its very-high-aspect-ratio shoulder-mounted wings and upturned tips are also reminiscent
of a modern sailplane’s wings, though there are far fewer ribs than one would expect nowadays;
22 across the 36ft span, spaced at intervals of 1ft 6in. The wing has a thin central spar and
spars forming the leading and trailing edges. The aerofoil section is typical for the period,
being deeply arched and a mere three-quarters of an inch deep at its deepest point and half an
inch deep at the leading and trailing edges. The central spars were ‘halved inlo beams’
(apparently an oval-section yacht beam cut in half longitudinally), tapering from 2in x ½in to
1in x ½ in. The leading- and trailing-edge spars were tapered to streamline section. The wing
had no dihedral apart from that imparted by the undersurface rising as the wing section became
progressively shallower towards the tips. The upturned tips were set at a dihedral angle of 40
degrees. In true Lanchester tradition there is no lateral control system.
The all-moving square-cut slab tailplane, again very similar to that of the 12 gram model, had
leading- and trailing-edge spars and only six ribs. It was completely flat, having no aerofoil
section, and was pivoted about a third of the way back from the leading edge to enable it to be
rotated between +5 degrees and -5 degrees of incidence through a rigid pushrod and lever
system from the cockpit. The vertical vee bracing struts above and below the tailplane doubled
as control levers and as a kingposts for bracing wires.
The basic square-section fuselage was a wire-braced girder of longerons and struts, 1ft 6in
square at its widest point, and tapered to 3in square at the nose and 5½in square at the sternpost.
The pilot was seated immediately in front of the rear spar, and immediately behind the front
spar was mounted a large two-cylinder vee air-cooled engine of unspecified type or horsepower,
with a direct-drive shaft some 2ft 9in long to a 6ft-diameter propeller in the nose. Just in front
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of the engine is a small streamlined cylindrical fuel tank. On each side of the fuselage, between
the pilot and engine, two 7ft vertical kingposts extended above and below to carry bracing wires
out to the wings; six above and six below on each side. A further bracing wire was carried from
the fuselage nose to the wingtips. The upturned wingtips were braced by wires above and by
struts and wires on the underside.
Another distinctly ‘Lanchesterian’ feature was the pair of tall vertical fins; one mounted right
on the nose and the other immediately in front of the tailplane. Simple tapering angular
structures, they extended some 4ft above the fuselage, giving the machine an overall height of
8ft 6in. The rear fin, which had two ribs, was stepped in the fuselage and clearly fixed. The
front fin had three ribs and was mounted clear of the fuselage on a vertical post, but there
appears to be no means to make it pivot as a rudder, and no range of movement is indicated on
the drawing. Both fins were braced by wires to horizontal kingposts extending from each side
of their bases.
The aircraft was mounted on a tall wooden, wire-braced skid undercarriage formed from a
series of inverted vees to which were attached a pair of 6ft 10in skids, 4ft apart. On the drawing
a pair of what appear to be leaf springs have been roughly drawn in beneath the skids in the side
elevation. In view of Lanchester’s praise of the Voisin’s wheeled chassis, it seems surprising
that no wheels are incorporated in this design. The airframe was to be fabric covered, and it is
specified that all struts ‘exposed to action of wind’ were to be given streamline section.
Figure 20
General-arrangement drawings of the 1909 monoplane, by Giuseppe Picarella.
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Figure 21
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A perspective impression of the 1909 monoplane, by Giuseppe Picarella
Using this blueprint, technical artist Giuseppe Picarella has produced a general-arrangement
drawing and a perspective drawing of this singular aeroplane. No photographs of any aeroplane
remotely resembling this have ever been seen, so it seems unlikely that it was actually built.
Had it been built, one has to wonder whether Lanchester would have been able to find a pilot
who was prepared to try to fly it. The airframe is sparse and fragile, and the pilot control is
inadequate. The longitudinal stability of such a short fuselage might have been poor, and the
range of tailplane movement was small; perhaps more of a trimming effect rather than positive
control.
9.
The Grey Angel
In 1907 a bookseller had sent a copy of Aerodynamics to one of his clients, an electrical engineer
named Norman Arthur Thompson, who subsequently acquired Aerodonetics as well and was
thereby inspired to indulge in the design and manufacture of aeroplanes. Early in 1909, along
with Doctor John White, and old and very wealthy friend from his days at Trinity College,
Cambridge, he approached Lanchester about his plans. Although Lanchester sceptically told
them they would lose their money, Thompson’s persuasive arguments about Britain’s failure to
keep pace with other nations in the development of aeronautics and Dr White’s readiness to
finance an experimental aircraft convinced Lanchester that their motives were not merely
commercial but also patriotic. He consequently agreed to act as their aeronautical consultant
from 31 March 1909. [63]
During 22-29th August that year Thompson and Lanchester attended ‘La Grande Semaine
d’Aviation de la Champagne’, the great aviation meeting at Reims in France. According to his
biographer, ‘Lanchester was tremendously stimulated but, according to his habit, he was not
carried away by the enthusiasm evident there’. He observed the great variety of designs, noting
that ‘all were much alike in the fact that the power installation was very little more than that
dictated by necessity’. [64]
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Lanchester started work on a design incorporating many of the ideas featured in his Patent
3608 of 1897. At the same time, or shortly thereafter, he must also have begun to conceive the
machine in the Camper and Nicholsons blueprint. They could hardly have been more different.
Work on the aircraft was to be undertaken by Daimler of Coventry, for whom, as mentioned
previously, Lanchester was a consultant. In search of a suitable location from which flight trials
might be made, Thompson and Lanchester visited many sites on Britain’s south coast, eventually
opting for a site on the foreshore midway between Bognor and Middleton-on-Sea in Sussex.
There were several miles of gently sloping firm sand some 300-400 yards wide at low tide,
which drained well and was free from seaweed and obstructions. Early in 1910 Thompson and
White installed themselves in an office building and sheds 20 or 30 yards above the high-water
mark, with a slipway on to the sands. This marked the birth of the White and Thompson firm.
Machinery was installed and a small workforce engaged, and the aeroplane was brought down
from Daimler for completion. It then transpired that the ground was prone to flooding at high
spring tides, the buildings being flooded several times before the coastal defences were
improved. [65]
Lanchester’s design, the Thompson-Lanchester No 1 Biplane, became known to the workforce
and local inhabitants as the ‘Grey Angel’, but it is hard to imagine anything less angelic in
appearance. As initially designed by Lanchester the machine was to be a single-seater powered
by the 50hp Gnome air-cooled rotary engine that had so impressed the partners at Reims,
weighing some 800lb with pilot and fuel and having an envisaged high speed of 90 mph
Lanchester believed that, if the aircraft was inherently stable, the pilot himself could operate a
gun or camera and make visual observations, and that weight, power and cost would thus be
kept to a minimum. [66]
Before construction began, however, it was found that the War Office wanted an aeroplane
able to carry a pilot and an observer, and as the War Office was the principal potential client it
was concluded, despite Lanchester’s great reluctance to make any changes, that the design
needed to be modified. The fuselage was therefore lengthened to accommodate the second
crew member behind the pilot, but there was no single engine powerful enough to power the
heavier machine. Consequently the design was further amended to incorporate two 50 h.p.
Gnomes. To equalise the thrust of the two propellers and counteract drag and adverse yaw in
the event of the failure of one engine, these were linked by a crossed belt drive running round
flanged pulleys. As a result of these major alterations the estimated weight rose to 1,200-1,300lb
and the estimated maximum speed fell to 75 mph [67]
The Daimler-built fuselage, some 14ft long, used the conventional automobile construction
techniques of the time, comprising an ash framework covered with mild steel plates of the
quality of those used for automobile panels, hand-beaten to shape; little regard apparently
being given to the need to combine strength with lightness. The wings were built at Middleton,
each having a main spar positioned at about 40 per cent chord from the leading edge, and a
second spar that formed the leading edge itself. They were linked by primary and secondary
ribs, and the wings were sheathed above and below with 23 IWG high-tension aluminium alloy
sheeting, riveted by embossing the metal into counter-sink. The resulting wings had a perfect
streamline section and were very strong. The biplane structure was trussed using tubular steel
struts in a Warren Girder system, with wire cross-bracing between the front and rear struts. The
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outermost front inclined interplane struts were fitted with small ailerons. [68] The upper wing
spanned 25ft 0in and had an aspect ratio of 10:1, and the lower spanned about 20ft 0in and had
an aspect ratio of 8:1. Both wings had a chord of 2ft 6in and the total wing area was some 105
square feet.
Mounted on the rear of the fuselage was a box-kite biplane tail structure with four vertical fin
surfaces. Comprising a wooden framework covered with 26-gauge aluminium, it was mounted
on a horizontal pivot and provided with a slow-motion screw control that enabled the incidence
of the whole unit to be adjusted by the pilot. Lanchester later wrote: ‘This is well known as a
means of controlling the natural velocity of flight’. On the nose was a small free-moving
elevator controlled directly by the pilot, intended for ‘temporary variations’ during take-off and
landing and for rapid in-flight manoeuvring. Rising up from the nose was a tall wire-braced
vertical rudder, so positioned ‘with the intention that when turning, the excess of lift of the faster
moving wing would be counteracted by the slower moving wing “eating into” the wind’. [69]
Initially an undercarriage mechanism patented by Lanchester (Patent No 18,384 of 1909 [70] )
was fitted. This somewhat curious device consisted of an oval-section underfuselage roller or
bolster held in an inverted Y-shaped bracket and fitted with an inflated tyre, the vertical leg of
the Y housing an hydraulic cylinder to absorb the shock of landing. The roller was retractable
into the fuselage to reduce drag in flight, and it was also suggested that the roller could be
retracted after landing so that the fuselage itself rested on the ground and ‘act as a brake’. In
addition, four spring steel outriggers extending sideways from the fuselage at front and rear
carried auxiliary swivelling stabilising wheels.
Figure 22
Lanchester’s original patented undercarriage for the Grey Angel
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The engines drove a pair of four-bladed pusher propellers of 5ft 2in diameter, with sheet-steel
blades riveted to steel-tubes fitted into a cruciform hub. Apparently the pitch of the blades was
adjustable on the ground to vary the thrust. [71] As the discs of the revolving propellers
overlapped, the port engine was positioned slightly aft of the starboard unit.
It has been said that the Thompson-Lanchester No 1 ‘had many unusual points’ [72] and was ‘in
some ways many years in advance of its contemporaries’ [73], its metal skinning being
described as ‘in advance of current practice’ [74]. These statements appear to be attempts to
find some merit in a design that was, in hindsight, poor. Although they are true to some extent,
they are somewhat invalidated by the basic fact that the aircraft was ill-conceived, quaint,
cumbersome and, to the informed observer, unlikely to fly well, if not foredoomed to complete
failure. It was a classic example of an inventor trying to incorporate too many original and
insufficiently proven ideas into one untried airframe, and moreover, in this case the creator had
the mind of an automobile engineer and too little understanding of the requirements of a
practical aeroplane. The added weight of Lanchester’s complex patented undercarriage, for
example, would have been substantial.
Unfortunately, before the machine was ready for testing the beach was ravaged by a series of
terrific storms, which stripped off great quantities of sand and uncovered the stumps of long
forgotten groynes and chalk boulders and left the surface littered with heaps of seaweed and
pools of water.
During initial taxying trials the pneumatic roller repeatedly became choked with sand and
seaweed and was removed, leaving only the four sprung outrigger wheels. Beneath the rear
fuselage was a claw-type drag brake. Unfortunately the outrigger wheel structures were not
strengthened to compensate for the removal of the roller, and when Thompson attempted to
make the first take-off, with the engines running flat out, the two starboard wheels buckled and
the aircraft nosed over and turned upside down. Thompson unstrapped himself from the patent
White and Thompson safety belt and emerged unharmed, then had the wreck photographed. [75]
Figures 23 and 24 The wrecked Grey Angel. Note the four-bladed propellers, the buckled
undercarriage axle, and the fitting under the hull that was probably the attachment point
for the removed roller-bellows.
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Figures 25 and 26
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The wrecked Grey Angel
Prints of the upturned aircraft are dated 31 January 1912, but the event might well have happened
earlier than this, as the following report, evidently inaccurate and rather contemptuous,
appeared in the October 26, 1911, issue of The Aeroplane:
Mr. Lanchester in Practice
Many readers of The Aeroplane will recollect that some time ago an extremely clever
radial engine was being built as an experiment by the Daimler Company, of Coventry, to
the designs of Mr F.W. Lanchester. At approximately the same time an all-metal
aeroplane was also being built to Mr Lanchester’s designs, the machine being constructed
to carry two radial engines driving independent propellers. This machine was started
something over a year ago, but was never brought into the fierce light of publicity. It is,
however, reported on fairly good authority, that the machine was ultimately fitted with
two Gnome engines instead of Lanchester Radials, and that an experiment was made
with it in the South of England, on which occasion the machine left the ground with
considerable facility, but failed to manoeuvre to the satisfaction of its inventor after doing
so, and on its return to the ground was somewhat deranged. Though this occurred some
little time ago the machine has not yet made another appearance, and Mr Lanchester’s
next effort is awaited with keen interest by those who, while continuing to regard him as
the most eminent of our aeronautic scientists, are anxious to see his theories carried out
in practice. [76]
This throws an interesting sidelight on the rift dividing the theorists and the practical
experimenters. Lanchester’s attempt to bridge that gap can hardly be regarded as a success.
Nonetheless, his biographer, attempting to put a positive spin on the mishap, reported that ‘The
structure itself, with its steel struts, stood up well to the unrehearsed test’. [77]
During repairs the Thompson-Lanchester No 1 had its undercarriage modified and strengthened,
the upper halves of the wheels being covered by semi-circular fairings. The four-bladed sheetsteel propellers were replaced by three-blade units with blades of more curvaceous form.
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Figures 27 and 28
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The Grey Angel during modification following its crash.
Figures 29 and 30 The Grey Angel after modification, with spatted wheels and three-bladed
propellers. The ailerons attached to the outermost front interplane struts have been removed.
(Author’s collection)
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The test pilot for the trials of the repaired machine was Captain Wilmot Nicholson RN, whose
post was Captain Superintendent of Torpedo Destroyers (Building by Contract). Based at the
Admiralty in London, he travelled from there to Middleton to conduct the trials. It proved
necessary for company employees to run along after the machine, carrying planks to place
beneath the wheels when it stopped to prevent it sinking into the sand. The unsuitable surface,
coupled with the machine’s high wing loading of 12-12½lb per square foot, made any prospect
of flight extremely dubious. It has been written that Nicholson conducted the trials ‘during 1911’,
but the unreliable dating of the crash at 31 January 1912 suggests that he might have tested the
repaired and modified machine later in 1912. Whatever the case, the Grey Angel could not be
induced to fly, and was eventually scrapped. It is said that its remains were committed to a local
duck pond. White and Thompson was registered as a private limited company on 8 June 1912,
by which time it had been decided to concentrate on more commercial activities that would
hopefully bring financial success. Lanchester resigned his position as the company’s
aeronautical consultant in September 1913, but continued to visit Middleton periodically to
keep in touch with developments. [78]
It has been said that Lanchester believed that the chances of success would have been much
greater had the original design been adhered to, and that the machine might well have flown
before even half of the expenditure invested by Dr White was used. However, the lack of
details of the original aircraft makes it impossible to assess its potential, and this has to remain
pure speculation. He maintained that such experimental work ought to be undertaken ‘without
too much regard to its ultimate commercial application’, and that it raised the ‘eternal question
as to whether the customer should be supplied with what he wants, or with what he thinks he
wants’. [79] It has to be said, however, that in this case it seems doubtful whether Lanchester’s
design, even in its original form, would have been capable of flight, let alone of answering the
customer’s requirements. With its four-wheeled undercarriage it really did look more like a
streamlined car with wings than an aeroplane. It represented an unhappy and unsuccessful
marriage of theory and practice.
10.
Further inspiration
Although the unbuilt 1909 monoplane design and the Thompson-Lanchester No 1 Biplane are
the only known full-size early aeroplanes with which Lanchester was directly involved, another
machine was built incorporating some of his ideas. This machine, a large biplane, was built in
1910 by Piggott Brothers & Co Ltd, a London based manufacturer founded in 1780 and
particularly well-known for its marquees and tents for all purposes, which in 1909 had added
tents to house aeroplanes and airships to its expanding product range. Piggotts also offered ‘tents
on hire for aeroplane experiments’, grand stands, temporary pavilions, refreshment tents, canvas
screens, turnstiles, pay boxes and such like for flying grounds and aviation meetings. Described
in Flight for 21 May 1910, [80] the Piggott Bros. No 1 was designed by the company’s
engineer, Mr. S.C. Parr, who ‘embodied a very great deal of what may be described as
Lanchester’s theory’. The magazine said the biplane was ‘in every way uncommon’, adding
that:
Those who have studied F.W. Lanchester’s works on Aerial Flight will recognise certain
characteristics in the general form of the aeroplane surfaces; and in other details, too, it is
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possible to discuss the design from Lanchester’s standpoint . . . . the designer is to be
congratulated in having taken the trouble at the commencement to master another man’s
line of thought and to build up his own experience on that basis. We do not wish to imply
that the design itself is in any way due to Lanchester, who possibly would disagree with
much that is represented.
Figure 31
The Piggott No 1 under construction (Author’s collection)
Like the Thompson-Lanchester No 1, the Piggott No 1 suffered from its designer’s attempt to
incorporate too many novel features in a new and untried machine. It was very large, spanning
60ft and being 34ft long, and the airframe made extensive use of aluminium. A pusher biplane,
its wings, forward monoplane elevator and rear tailplane all displayed the distinctive
Lanchester high-aspect-ratio, elliptical planform. The double-surfaced wings, covered with a
special cotton fabric that had been waterproofed and fireproofed by Piggott Brothers, had a
maximum chord of 6ft and tapered to elegantly curved tips. They had a maximum camber of
3½in, and the total wing area was 568 sq ft. A large elliptical rudder was mounted between the
upper and lower booms carrying the tailplane, and there were two arched stabilising fins on the
upper surface of the top wing. Elliptical ailerons (‘balancing planes’) were fitted between the
outermost struts, midway in the 7ft gap between the upper and lower wing. The structure was
mounted on a 5ft-high chassis with two pneumatic-tyred triple-spoked wire wheels mainwheels
arranged in tandem and carried by a pivoted arrangement of cantilevers with helical springs for
suspension.
The central framework that supported the wings and other surfaces was mostly of aluminium.
This structure also carried the pilot’s seat and the 80hp Vivinus four-cylinder in-line water
cooled engine immediately behind the seat. This engine turned two four-bladed contra-rotating
propellers turning on a common axis. These were ‘Piggott Bros. & Co.’s beaten aluminium
propellers of thin hardened plate with double surfaces . . . the lightest and strongest obtainable’.
The largest, of no less than 13ft 6in diameter, was closest to the engine and attached to a short
hollow extension shaft; the other, of 8ft 4in diameter, was at the end of a long solid extension
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shaft that ran through the shaft for the larger propeller. Both were able to have their blade pitch
adjusted on the ground. The pointed, sheet-aluminium propellers were of hollow section and
were driven by chain transmission from the engine through a differential gear that ensured each
propeller took up its full load. The differential gearing was so arranged that, if there was less
load on the smaller propeller than on the larger, the smaller propeller would revolve faster. If
the smaller propeller experienced the greater resistance, however, this was compensated for, so
that, whatever happened, the two propellers would ‘essentially balance one another’. To
compensate for any springing of the frame a flexible coupling was incorporated in the solid
shaft. The larger propeller was designed to give a flight speed of 48 mph ‘when the slip [was]
33 per cent of the pitch velocity’, and the smaller propeller was designed to receive the slip
stream from the larger propeller under those conditions, advancing through the air at 104ft/sec.
Figure 32 The engine and propeller installation of the Piggott No 1 (Author’s collection)
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The complete aeroplane weighed 1,150 lb and its coefficient of longitudinal stability,
‘calculated in accordance with Lanchester’s equation’, was 2.85.
Figures 33 and 34
The completed Piggott No 1 (Author’s collection)
Even before Piggott’s first aeroplane had begun its tests, the company was advertising itself as
‘Builders of Aeroplanes’, stating its readiness to estimate for constructing aeroplanes to
customers’ own designs, and proclaiming the merits of its beaten aluminium propellers,
exceptionally strong aluminium castings, aluminium and steel tubes, and ‘stay wires, petrol
tanks, steering wheels, etc, etc.’ [81]
97
Figure 35
Paper No. 2014/02
Piggott’s ambitious full-page advertisement in the July 30, 1910, issue of Flight
An advertisement for its portable canvas hangars for aeroplanes depicted the Piggott No 1 in a
‘Giant Canvas Hangar, 90ft long and 25 feet high, erected near London [possibly on Dagenham
Marshes], which has been in use for several months’. [82]
98
Figure 36
Paper No. 2014/02
The advertisement for the Piggott portable canvas hangar
Alas for ambition; there is no evidence that this extraordinary machine ever managed to leave
the ground, and it quickly and silently disappeared from the scene. Piggott Brothers built two
more aeroplanes, an enclosed monoplane in 1911 and a small biplane entered for the 1912
Military Trials. Neither incorporated any recognisable Lanchester-derived features, and neither
was successful. Then, having learned a costly lesson, the company abandoned aeroplanes and
concentrated on the business by which it still thrives today.
11.
Other problems
Lanchester continued to have difficulties reconciling theory and reality. In 1912 he declared
that the square-cube law would prevent aeroplanes larger than those then being built from flying.
The theory held that, on the basis of constant velocity, the span must vary as the square root of
the gross weight. Lanchester therefore maintained that, as size increased, structural weight (as a
percentage of all-up weight) would increase to the extent that the useful load would be virtually
nothing. He was still adhering to this theory as late as February 1916, when, in a magazine
article, he referred to the ‘Russian failure’, virtually dismissing the achievements of Igor Sikorsky
and his Grand and Il’ya Mouramets giant aeroplanes as fiction (and also the work of Caproni in
Italy in this regard). In England, Frederick Handley Page and others knew it was possible, by
careful structural design, to improve on the ratio of empty weight to all-up weight. In May 1916
pioneer aircraft designer-builder José Weiss produced a pamphlet entitled Notes on Giant
Aeroplanes, in which he challenged Lanchester, saying: ‘Until we are definitely certain that we
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are introducing correctly each and all of the laws and factors coming into play, empirical
coefficients based on practice are much safer than theoretical equations’. Lanchester was obliged
to think again, and recanted, acknowledging Handley Page’s achievements. On 26 June 1916
he went aloft in the rear crew position of a Handley Page O/100 bomber prototype to investigate
and suggest a remedy for persistent tail oscillation, attributing the cause to anti-symmetric
movements of the port and starboard elevators, eliminated by a few additional connecting
wires. [83]
12.
Bridging the divide
Aviation’s ‘great divide’ between mathematical theoreticians and practising designers and
engineers persisted into the interwar years. In 1936, in his preface to the ‘Performance’
volume of the second edition of his book Airplane Design, Edward P. Warner, the Head of
Aerodynamics at NACA Langley, summed up the status quo at that time:
. . . the most important features of the decade [i.e. 1927-1936] in applied aerodynamics
have been the provision of wind tunnels allowing tests to be made substantially under
full-scale conditions, and an enhanced recognition by engineers of the practical usefulness
of basic aerodynamic theory. In 1927, except for an occasional and gradually increasing
use of induced-drag formulas, the typical designer thought of himself as having very little
use for the offerings of the mathematicians, and he had very little disposition even to
inquire into their application to his own work.
He is much more disposed in that direction now. The higher branches of mathematical
physics have taken a place, and gained a universal respect, such as they hold in no other
branch of engineering science . . . . But however favourable the designer’s inclination
may now be toward the mathematician, his competence to co-operate directly in the
mathematician’s work is still in most cases very limited. Mathematical aerodynamics
remains a pursuit returning results only to the specially trained and specially gifted few.
Among students of aircraft design not one out of fifty will ever make, or will have the
special qualities required for making, a personal contribution to the extension of basic
theory. Not many more than that one out of fifty will ever experience any need to have
followed the theory’s derivations from source to final conclusion, and indeed only a
small minority of students have the training and the gift in general mathematics that
would qualify them even to tread those lofty paths in the footprints of a preceptor.
For the few so favoured and distinguished, preceptors are at hand . . . . Few as the
successful students if the theory may be, all who engage in aircraft design must use the
theory’s results. For them, a physical explanation of the phenomena, a mechanical
analogy, a demonstration that the indications of the rule and the formula furnished by the
mathematicians are essentially in accord with common sense, seem far more important
than an attempt to hammer through the process of mathematical analysis. [84]
The relationship had evidently improved, and would continue to do so thenceforth.
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Acknowledgements
Thanks are due to Mark Wagner of Aviation Images and Nick Stroud, editor of The Aviation
Historian, for help with images. Illustrations from Aerodonetics by F.W. Lanchester
(Constable & Co., 1908) are reproduced by kind permission of the Little, Brown Book Group.
References and notes
1
Anderson, J.D., A History of Aerodynamics and its Impact on Flying Machines
(Cambridge University Press, Cambridge, 1999), Chapter 6, pp.246-247
2
Abzug, M.J., and Larrabee, E.E., Airplane Stability and Control, second edition
(Cambridge University Press, Cambridge, 2002), Chapter 1, p.9
3
Ackroyd, J.A.D., ‘Lanchester—The Man’ (The 31st Lanchester Memorial Lecture); The
Aeronautical Journal, April 1992 (Vol 96), p.134; Ackroyd, J.A.D., ‘Lanchester’s
Aerodynamics’, in Fletcher, J. (Ed.) The Lanchester Legacy (Coventry University,
Coventry, 1996) Vol.3, Chapter 5, p.96
4
von Karman, T., ‘Lanchester’s Contributions to the Theory of Flight and Operational
Research’, The First Lanchester Memorial Lecture, The Journal of the Royal
Aeronautical Society, Vol 62 No 566, February 1958, p.81
5
Lanchester, F.W., ‘Improvements relating to the Steering of Flying Machines or
Aerodromes’, Britsh Patent No 8849 of 1909. Applied for on 14 April 1909, accepted 6
January 1910. See also ‘Steering System’ in The Aero, 15 February 1910, p.130, col 2.
6
Kingsford, P.W., F.W. Lanchester: The Life of an Engineer (Edward Arnold, London,
1960), chapter 7, p.88
7
Lanchester, F.W., Aerodonetics: Constituting the Second Volume of a Complete Work
on Aerial Flight (Constable, London, 1908)
8
Ibid, chapter 1, pp.17 & 19
9
Ibid, chapter 1, pp.19-24. This glider is currently on display in the aeronautics gallery
of the Science Museum, South Kensington, London
10
Ibid, chapter 1, pp.24-25
11
Ibid, chapter 1, p.26-27
12
Ibid, chapter 1, pp.26, 29-31
13
Ibid, Appendix III, pp.356-360
101
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14
Ibid, chapter 1, p.31
15
Ibid, Appendix III, p.359
16
Ibid, chapter 1, p.31-32
17
Ibid, chapter 1, pp.32-33
18
von Karman, op.cit., p.87
19
Ibid., p.87, and Abzug and Larrabee, op. cit., p.9
20
Bryan, G.H., Stability in Aviation (Macmillan and Co, London, 1911), p.173
21
Boyd, T.J.M., ‘One Hundred Years of G.H. Bryan’s Stability in Aviation’, Royal
Aeronautical Society Journal of Aeronautical History, Paper No 2011/4, p.108
22
von Karman, op.cit., p.88
23
British Patent No 3608, date of application 10th February 1897; complete specification
left 10 December 1897; accepted 10 February 1898
24
Goodall, M.H., The Norman Thompson File (Air-Britain, Tunbridge Wells, Kent,
1995), p.10.
25
The information and quotations in this section are taken principally from pp.102-127 of
Chapter VI of Aerodonetics, ‘Experimental Evidence and Verification of the Phugoid
Theory’. Details of the design, construction and testing of the models are found in
Chapter X, ‘Experimental Aerodonetics’, pp.313-346.
26
Lanchester, F.W., Aerodonetics, op. cit. chapter 6, pp.110-111
27
Ibid., chapter 6, p.115
28
Ibid., chapter 6, pp.111-112
29
30
31
32
Ibid., chapter 6, p.116 & 118
33
34
102
Paper No. 2014/02
35
36
37
Ibid., chapter 6, pp.107, 117, 118-120
38
Ibid., chapter 6, p.120-122
39
40
41
42
43
44
45
Ibid., chapter 10, p.345, footnote
46
47
48
49
50
51
Ibid., preface, pp.vi-vii
52
Carroll, T.J., and Carroll, T.R., ‘Wright Brothers’ Invention of 1903 Propeller and
Genesis of Modern Propeller Theory’, American Institute of Aeronautics and
Astronautics Journal of Aircraft, Vol.41 No. 1, PP.218-223
53
Lanchester, F.W., ‘The Wright and Voisin Types of Flying Machine. A Comparison.’
The Aeronautical Journal, No.49, Vol.XIII, January 1909, pp.4-12, plus Figs 12 & 13.
54
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter VII, p.105.
55
Hobbs, L.S., The Wright Brothers’ Engines and their Design, Smithsonian Annals of
Flight No 5, Smithsonian Institution Press, Washington, DC, USA, 1971.
103
Paper No. 2014/02
56
Lanchester, F.W., ‘The Flying Machine From an Engineering Standpoint’, James
Forrest Lecture given to the Institution of Civil Engineers on 5 May 1914. Proceedings
of the Institution of Civil Engineers, Vol 98, Session 1913-14, part 4, pp.3-80;
appendices and discussion on pp.80-96. Published separately by Constable, London,
with the same title, in 1916.
57
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter VII, pp.105-106.
58
Lanchester, F.W., British Patent No 8849 of 1909, ‘Improvements relating to the
Steering of Flying Machines or Aerodromes’; applied for on 14 April 1909, Complete
Specification left 13 October 1909, Accepted 6 January 1910.
59
Lanchester, F.W., British Patent No 10,422 of 1909, ‘Improvements in Flying
Machines’; applied for on 3 May 1909, Complete Specification left 2 December 1909,
Accepted 28 April 1910.
60
Original blueprint in the author’s collection.
61
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter X, p.171.
62
E-mail to the author from Jeremy Lines, voluntary archivist for Camper & Nicholsons,
23 April 2014.
63
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter VIII, pp.118-119; Goodall, M.H.,
The Norman Thompson File, op. cit. p.7.
64
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter VIII, pp.118-119.
65
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter VIII, p.120; Goodall, M.H., The
Norman Thompson File, op. cit. p.8.
66
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter VIII, p.119.
67
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter VIII, p.119; Goodall, M.H., The
Norman Thompson File, op. cit. pp.9-10.
68
Ibid.
69
70
Lanchester, F.W., British Patent No 18,384 of 1909, ‘Improvements in Alighting
Mechanism for Flying Machines’; applied for on 10 August 1909, Complete
Specification left 10 February 1910, Accepted 10 August 1910.
71
Goodall, M.H., The Norman Thompson File, op. cit. p.11.
72
104
Paper No. 2014/02
73
Goodall, M.H., The Norman Thompson File, op. cit. p.8.
74
75
Goodall, M.H., The Norman Thompson File, op. cit. pp.8 and 11; Kingsford, P.W.,
F.W. Lanchester, op. cit., Chapter VIII, p.120; Lewis, P.M.H., British Aircraft 18091914 (Putnam, London, 1962), pp.529-530.
76
‘Mr Lanchester in Practice’, The Aeroplane, 26 October 1911, Vol 1 No 21, p.493.
77
78
Goodall, M.H., The Norman Thompson File, op. cit. pp.11-12; Kingsford, P.W., F.W.
Lanchester, op. cit., Chapter VIII, pp.120-121.
79
Kingsford, P.W., F.W. Lanchester, op. cit., Chapter VIII, pp.120-121.
80
‘The Piggott Bros. Biplane’, Flight, 21 May 1910, Vol 2 No 21, pp.383-386.
81
For example, see the full-page advertisement on p.viii of Flight for 16 July 1910 (Vol 2
No 29).
82
For example, see the half-page advertisement on p.xix of Flight for 16 July 1910 (Vol 2
No 29).
83
Woodman, H., ‘Database: The Sikorsky Grand’, Aeroplane Monthly, March 2004, Vol
32 No 3, pp.86-87
84
Warner, E.P., Airplane Design: Performance, second edition (McGraw-Hill, New York
and London, 1936), pp.v & vi
105

FW Lanchester and the Great Divide

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