Restoration Project Lists - Seattle Fortress Bombers

Transcription

RESTORATION PROJECT LISTS
B-29 Superfortress T-Square 54
MARCH 25, 2014
MUSEUM OF FLIGHT
Seattle, Washington
Restoration Projects- B-29 Superfortress-T-Square 54
Table of Contents
AMMUNITION STORAGE RE-CREATION ....................................................................................... 3
Configuration Research .....................................................................................................................................5
Manufacturing Process .................................................................................................................................6
Final Assembly .................................................................................................................................................7
AUXILIARY POWER UNIT (APU) RESTORATION ....................................................................... 9
CENTRAL FIRE CONTROL SYSTEM (CFC) - B-29 - Defined ................................................. 10
CENTRAL REMOTE CONTROL (CRC) COMPUTER RESTORATION .................................. 12
COMPUTER FIRE CONTROL SYSTEM RESTORATION ........................................................... 13
COCKPIT FLOOR/AISLE STAND RESTORATION ..................................................................... 15
ELECTRONIC CONNECTOR BOX RESTORATION ..................................................................... 18
EXHAUST PIPES RE-CREATION B-29 T-SQUARE .................................................................... 19
THE MIGHTY WRIGHT R3350 ..................................................................................................................... 21
The male model ............................................................................................................................................ 21
Digitizing the male mold ........................................................................................................................... 22
Laying up the parts...................................................................................................................................... 23
Mounting ring ................................................................................................................................................ 23
Cold air inlet and dome.............................................................................................................................. 24
TURBOCHARGER DISPLAY UNIT ............................................................................................................... 25
Waste Gate Function ................................................................................................................................... 26
GROUND POWER UNIT (GPU) RESTORATION......................................................................... 28
GUN TURRET PRESSURE DOME RE-CREATION B-29 T-SQUARE .................................... 29
Associated Hardware on display ................................................................................................................ 31
Dome purpose .................................................................................................................................................... 31
The basic dome shape ..................................................................................................................................... 33
The Dome mold.................................................................................................................................................. 33
Dome configurations ....................................................................................................................................... 34
Pressure Dome purpose: ............................................................................................................................... 36
Dome installation - ........................................................................................................................................... 36
Insulation: ............................................................................................................................................................ 37
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INVERTOR, ELECTRICAL BOX, OVERFLOW TANK AND PRESSURE CONTROLS
RESTORATION ...................................................................................................................................... 38
R-3350 DISPLAY ENGINE RESTORATION B-29 T-SQUARE ................................................ 39
R-3350 ENGINE PROPELLER DOME RESTORATION B-29 T-SQUARE ........................... 40
RADAR ASSEMBLY RESTORATION B-29 T-SQUARE ............................................................. 41
RADOME RE-CREATION FOR B-29 T-SQUARE ........................................................................ 42
Restoration of APQ-13 Antenna- ................................................................................................................ 44
Background research- ............................................................................................................................ 44
Determining the Radome geometry - ....................................................................................................... 47
Antenna mount-................................................................................................................................................. 50
Determining radome material- ................................................................................................................... 51
Fabrication method- ........................................................................................................................................ 52
Radome attachment- ....................................................................................................................................... 54
TAIL TURRET RESTORATION B-29 T-SQUARE ....................................................................... 56
Turret in Renton - ........................................................................................................................................ 58
Fake Tail Turret - ......................................................................................................................................... 59
20 mm Cannon -............................................................................................................................................ 60
Armament Location – ................................................................................................................................. 60
Gimbal System - ............................................................................................................................................ 61
Gunner’s Cupola – ........................................................................................................................................ 62
Rear dome and fairings- ............................................................................................................................ 63
Entry Door - .................................................................................................................................................... 64
Electrical Systems- ...................................................................................................................................... 64
Armor Plate Glass - ...................................................................................................................................... 65
Oxygen and flight suit heater system – ............................................................................................... 66
Installation of Gunner’s seat – ................................................................................................................ 66
Insulation - ...................................................................................................................................................... 66
Dome protective cover fabrication - .................................................................................................... 67
Final thought- ..................................................................................................................................................... 67
TURBOCHARGER RESTORATION .................................................................................................. 68
2
AMMUNITION STORAGE RE-CREATION
B-29 TAIL TURRET
SYD BAKER
Photo by Syd Baker
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Acknowledgements B-29 Ammunition Storage:
The Volunteers:
Sam Lehtinen
Paul Lehtinen
Richard Greer, CimTech
Syd Baker
The Companies :
CIMTech, Steve Kidd, President, Seattle
Mapeltex, Tacoma,
Fiberlay, Seattle
Photographs :
Syd Baker
Front page picture –
Left and right ammunition boxes are shown below the horizontal
stabilizer lower skin, the tail bumper retraction cylinder
Is mounted between boxes and is normally covered.
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AMMUNITION STORAGE FOR REAR GUN TURRET B-29 T-SQUARE
Of all the defensive gun turret positions, arguably, the rear turret is the most critical.
Consequently it was logical to provide each of its two 50 caliber machine guns with
plenty of ammunition, 800 rounds per gun.
Since T-Square had all of this system completely removed during one of its post war
assignments, my job was to re-create both the storage and feed system for the rear
turret.
Configuration Research
As was the case in many of the contemporary drawings, the manufacturer was given an
option whether to make the parts from aluminum sheet metal or a fiber board material
called Phenolic. Our airplane apparently used Phenolic. This material has a distinctive
reddish brown color and is translucent so that the weave of the compressed canvas
from which it is made can be detected
below the surface. Phenolic is still being
used today but since the ends of each
storage box have large holes which were
molded into the Phenolic under heat and
pressure, I had to come up with an
alternative.
During one of my trips to Duxford I was able
to get a very good idea of the color and
texture of the original storage boxes.
In discussions with nice Folks at Fiberlay in
Seattle, where I have been buying all my
previous fiberglass supplies, they came up
with a resin tint product which, when mixed
into the clear fiberglass resin provides
Photo by Syd Baker
about the correct reddish brown color,
but still remains translucent. Since the majority of the box is made from plain sheet
stock I set about making enough material for the side panels as well as for the bottoms
and lids. This was simply done on a sheet of flat Formica upon which I laid up four
layers of 3 oz. Fiberlass cloth carefully rolled with a special roller to ensure that all the
air bubbles were removed when the resin was fully cued, I simply bent the Formica
sheet slightly and the raw fiberglass sheet came right off. Both the outside texture and
the color were very similar to the original Phenolic.
The end panels were an entirely another story since I had to devise tooling to replicate
the large round flanged inspection holes located in each end. The ends also have
integrated 90 degree attached flanges running down the entire length to which the fixed
side panels are riveted.
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Manufacturing Process
Time to go to Steve Kidd at CIMtech again for help.
This time I had actual drawings of the parts that I had to re-create so it was a matter of
Richard Greer creating the necessary digital programs from the dimensions on the
drawings. This, I am sure took many hours of programming and later machine time
which was extraordinarily generous of Steve to provide this level of help to our project.
The first decision was what do we use to manufacture the box end tooling from and also
how do we make the feed chutes. The chutes had to look as much like Phenolic as
possible. At first I proposed to Steve that if he would make the tooling for the chutes I
would then lay up the actual hardware in fiberglass.
Steve recommended that I should go and look at some material that he had been able
to machine very well previously which he thought looked something like Phenolic, He
suggested that instead of him making the tooling for the chutes he would make the
actual hardware. He would put me in touch with Steve at Mapletex in Tacoma, and see
what I thought.
My visit to Mapletex was very informative. The irony is that the Mapletex product is
manufactured in almost exactly the same way as Phenolic, except Mapletex uses large
sheets of paper impregnated with a heat sensitive adhesive. They simply kept adding
layers of this paper until they achieve the thickness of material they want. These sheets
are placed on a very strong flat steel pattern are then cooked under pressure and heat
in an autoclave. The difference between Mapletex and Phenolic is one uses a paper
sheet, the other canvas. The Mapletex is not quite as dark reddish brown but has a
very nice layered look which I thought would be quite acceptable. Steve at Mapletex
gave me not only enough raw material to manufacture the chutes and their caps but
also enough to make the box end tooling for my fiberglass mold – most generous of
them!
When I returned to CIMtech with all the detailed drawings, Steve Kidd still insisted that
they would build not only my box end mold but also the left and
right feed chutes and the four longitudinal angle pieces which
get riveted along the sides of each chute and stop the 50 caliber
ammunition belt from levitating out of the chute, either from
aircraft turbulence or inertia as the belt stops running when the
guns stop firing. This was major job that Steve was taking on
requiring many hours of programming and machining.
This picture shows the Steel end tool on the left and on right is
the one of the feed chutes without the side covers. In the
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Photo by Syd Baker
background are the two completed boxes with one lid removed and one side folded
down. A short length of 50 caliber ammo belt is also shown.
When I received the box end mold I had to manufacture a sheet steel channel section
the same length as the Mapletex mold, with large holes through which I inserted two
aluminum plugs to insure that the fiberglass was pressed accurately into the machined
cavities, to insure a smooth transition of the fiberglass into and around the large
inspection holes. The sheet steel insured that the fiberglass also folded around the long
side edges to
insure a tight
90 degree
attach flange.
In actual
practice the
mold and the
pressure
cover worked
quite well,
Photos by Syd Baker
after I added some small holes to vent
trapped air which caused some unacceptable voids in the part.
Final Assembly
At this stage Sam Lehtinen became a very involved partner in this project. He and I laid
out all the side and end panels with all the various aluminum angles, hinges, sheet metal
brackets, to assemble the two boxes. After an extensive search of the internet I came
up with an identical slide snap fastener which is used extensively to provide quick
release for the lids and side panels After Sam and I had completed all the riveting and
final assembly, Sam’s brother, Paul, did a wonderful job of final painting of all the steel
parts green.
The boxes are installed in the rear of the aircraft on either side
of the tail skid retraction cylinder, which is actually a very robust
retractable device which protects the lower side of the B-29
should the pilot inadvertently make tail strike on landing.
Sam replaced the missing and damaged attach brackets and
very accurately drilled the matching mounting holes in the sides
and bottoms of the ammunition boxes.
The boxes had to be mounted very precisely to insure that the
left and right feed chutes would match up with the feed
through ducts which pass through the gunner’s compartment.
On the rear end of these ducts are high torque electric motors
with an ingenious drive sprocket which engages with the 50
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Photos by Syd Baker
caliber rounds in the belt, and when the gunner fires each gun, the respective drive
motor pulls the very long belt all the way from the ammunition boxes along the chutes
through the pressure ducts and up into each gun, a distance of approximately eight feet.
Once the belt is in motion it has a lot of inertia, so that when the gun stops firing the
belt tends to keep coming and a standing wave occurs down the length of the belt. This
is the main reason for the flanges on each side of the feed chutes - to stop the belt from
spilling over the sides of the chute.
Each box has a removable lid and fold down sides to make it easier for the armorer to
load the 800 round belt into each box, along the chutes and finally up into each 50
caliber machine gun. It must have been a very different task especially in the hot
tropical Pacific Islands.
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AUXILIARY POWER UNIT (APU) RESTORATION
Team of Volunteers:
Primary: Dennis L. Dhein, and
Scott Taylor, Don England, Jerry Brown, Bill Wiesner , Syd Baker.
Before
After
In the aircraft
The assembly was completely taken apart, cleaned, straightened a bent frame,
removed paint as required, cleaned and repainted with stencil work added.
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CENTRAL FIRE CONTROL SYSTEM (CFC) - B-29 - Defined
By Dale Thompson
The B-29 was equipped with a unique method of operating its machine guns, called the
Central Fire Control System. The fact that the plane was pressurized precluded the
gunners from having physical access to the guns. So, the General Electric Corporation
was contacted to provide a means of remotely operating the guns. GE had experience
stabilizing shipboard naval guns in the 1930s, which gave them a head start.
Each of the five turrets on the B-29 is controlled using a sighting station, some of which
can control more than one turret.
This allows the aiming and the firing of two turrets simultaneously. Each turret and each
sighting station has two elevation selsyns, for coarse and fine resolution, and azimuth
selsyns, also for coarse and fine resolution.
A selsyn is a system comprising a generator and a motor connected by a multiple wire
circuit of appreciable length, transmitting currents that turn the motor simultaneously
to the same relative position as existing or established for the generator, and repeating
instrument indications and valve settings remotely —called also synchro.
As the gunner moves the station to track the target, an error signal is developed
because the sighting station selsyns and the turret selsyn are not in line. The error signal
is first amplified using vacuum tubes in the servo amplifier in an amplidyne, which is a
rotary generator-amplifier. The direct current output voltage of the amplidyne is sent to
the azimuth and elevation motors in the turret, moving it until it is aligned with the
sighting station, causing the error signal to go to zero.
Because the sighting stations and turrets are separate from each other, an aiming
correction must be applied for the distance between the sighting station and its turret.
This is called a parallax correction, and it is supplied by an electro-mechanical computer
that modifies the sighting station selsyn signals before sending them on to the turret
selsyn. In addition, to the parallax correction, the computer also adjusts for target
speed, target range, aircraft speed, and air density. Aircraft speed and air density are
supplied by the Navigator, who sets the aircraft speed, aircraft altitude and outside air
temperature on a unit called the Altitude and Airspeed Handset. Target speed and
target range are supplied by the sighting station. The sighting station has a display of a
circle of dots with a center dot. The gunner keeps the center dot on the target aircraft
and the circle of dots on the targets wing tips. As the gunner tracks the target, the
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sighting station’s gyroscopes allow the computer to estimate the target’s speed. The
circle of dots on the target’s wingspan give the computer a range estimate. With all this
information, the computer can adjust the turret’s position so that it leads the target and
compensates for bullet ballistics. The gunner fires the guns electrically by depressing a
button on the sighting station. Each turret has its own computer, adjusted for parallax
with its primary sighting, five in all.
The paths of these various signals converge in one of four control boxes located in the
nose, waist and tail of the aircraft. The control boxes allow the switching of sighting
stations between their primary turret and their secondary turret. Sighting stations are
located in the nose, at each of the two blisters in the waist, at the top of the plane, also
in the waist and at the tail. Turrets area located above and below the cockpit, above and
below the aft waist, and in the tail.
The forward gunner, who is also the bombardier, has primary control of the upper and
the lower forward turrets. The upper gunner has primary control of the upper aft turret.
The blister gunners have primary control of the lower aft turret, and must choose which
of the two sighting stations control the turret. If the forward gunner releases control of
his gun, the blister gunners get control of the lower forward turret, and the upper
gunner gets control of the upper forward turret;. If the tail gunner releases control of his
turret, then either of the blister gunners can fire the tail turret. The tail gunner fires only
the tail turret. The upper turret gunner is called the OFV+C gunner and is in control of
the defense if the airplane, calling out which gunner should fire which turrets. Gunners
coordinate among themselves using the intercom system.
All of the turrets are operable on T-Square 54, the Museum’s B-29, and may be
operated from various locations inside the fuselage, and from two locations outside the
airplane, giving a better view of their movement. Also, a complete, additional upper
turret has been mounted on a stand outside of the airplane, and can be operated from
the outside sighting stations. A recording of the actual firing of a .50 caliber machine gun
is amplified and sent to a speaker located in each of the turrets when that turret is fired.
The operational checkout of our CFC system started with all of the restored components
for one turret-sighting station combination assembled on a test bench, including a turret
mounted on a test stand. As each combination was made operational, it was mounted in
the aircraft. Three of the control boxes were fabricated, as none were available. The tail
turret was a very major project with complete physical construction required. Extensive
work was done to the amplidynes and motors, and all of the active electronic elements
were refurbished.
The CFCC restoration team:
Syd Baker
Dick Peterson
Doug Bulloch
Richard Peterson
Roy Foote
Paula Schmitz
Rich Heasty
Larry Tietze
Neale Huggins
Dale Thompson
Hal Lyon
Ken Williams
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CENTRAL REMOTE CONTROL (CRC) COMPUTER RESTORATION
Team of Volunteers:
Dale Thompson, Scott Taylor, Don England, Jerry Brown, Bill Wiesner , Syd Baker.
Front view before
Rear view after
Front view after
The computer covers were removed, and stripped of paint, internal parts were
cleaned and clear plastic covers were made so the inner workings could be
displayed and not touched. Also, a base frame was made for the CRC computer to be
displayed on a simulated mounting in the aircraft.
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COMPUTER FIRE CONTROL SYSTEM RESTORATION
This is a close-up of the test bench
used to check out the electronics
associated with each gun turret
and to operate that turret before
installation in the plane.
This is the whole test
bench. On the right is the
gun sighting station which
each gunner uses to aim
the turrets.
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Computer Fire Control System Restoration - continued
On the right of the aircraft are the servo amplifiers
which amplify the error signal with vacuum tubes to
drive the amplidynes on the left, one for elevation and
one for azimuth for each turret, which in turn operate
the motors on the turret. At the top is the upper
system control box which was constructed by the
crew.
This is one of the turrets, located next to the test
bench. The larger vertical cylinder is the motor
which rotates the turret in the azimuth direction.
The two smaller cylinders are the course and
fine selsyns, which produce a signal indicating
the direction the turret is pointing. These
components are duplicated on the far side of the
turret for the vertical direction of travel
This is the control box for the tail turret during
construction. It, along with the upper system control
box had to be built by the restoration crew as none
were obtainable.
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COCKPIT FLOOR/AISLE STAND RESTORATION
A stand is provided in the aisle between the pilot and copilot, allowing easy each
access to the controls.
The controls located here consist of the:















Control surface lock lever,
Emergency brake levers,
Wing flap normal and emergency control switches,
Propeller feathering switches,
Emergency alarm switch,
Formation light bright/dim switch,
Position light switch,
Recognition light switches and code key,
Propeller RPM switches,
Propeller pitch circuit breakers,
A.F.C.E. (autopilot) system controls,
Turbo boost selector,
Wing flap normal and emergency switches,
Bomb salvo switch and
Bomb bay door open/close switch.
15
COCKPIT FLOOR/AISLE STAND RESTORATION - continued
Aisle
Stand
Autopilot
Control Box
CAUTION
THESE CONTROL HANDLES
METER PRESSURE TO THE
BRAKES FROM AN EMERGENCY
PRESSURE ACCUMULATOR THE
VOLUME OF WHICH LIMITS THE
NUMBER OF COMPLETE BRAKE
APPLICATIONS TO
APPROXIMATELY THREE.
MAINTAIN A CONSTANT BRAKE
PRESSURE WHEN POSSIBLE TO
CONSERVE THE PRESSURE
SUPPLY.
The electronic turbosupercharger control system on
B-29s consists of separate
regulator systems, all
simultaneously adjusted by a
single turbo selector dial
located on the pilot's aisle
stand.
Automatic
Flight
Control
Gyro
Photo by Syd Baker
The Aisle Stand restoration proceeded as follows:
The Aisle Stand aluminum shell (5 sided box) was dent free and matched the configuration
drawings for our serial number, 44-69729. There were the early configuration (serial 42- )
and the later configuration (serials 44 - ), plus about six sub variants. The later
configuration could be identified, among other details, by the “bomb salvo” switch in place
of the “propeller pitch circuit breakers” in the lower right corner.
The restoration concentrated on placing the correct switch (31 including 6 breakers) in the
proper place. Years of field modifications and conversion from a bomber to tanker had left
many extra and often overlapping holes.
SAM LEHTINEN machined a proper repair plate. PATRICK STEPPIC selected the right
switches and often had to rebuild them. ROGER CALDWELL straightened the bent and
crushed propeller-feathering switch guards. TERRENCE McCOSH assembled a mock-up
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COCKPIT FLOOR/AISLE STAND RESTORATION - continued
aisle stand to inventory restored components, and verify position and function while
repair/adapter plates, paint and decals were applied to the actual aisle stand.
In addition to the above, the brake quadrant guide had been radically modified in an
apparent effort to simplify assembly. An undamaged guide was found in the sheet metal
parts pile (luckily) and installed. Turbo control knob inlay was reworked. White coloring
was replaced on recessed legends, and rheostats were refurbished. It was necessary to
replace barrel insulators on “bomb door” indicator light, install a bat handle extension on
flap switch, and recondition and lubricate ganging bar hinges for propeller speed control
switches.
Best guesses were applied to the following two items as no documentation could be found:
Item one was the propeller-feathering switch buttons were enlarged and space between
them increased. Each switch was guarded by its own aluminum can (see CALDWELL above)
rather than the all-in-one plastic box depicted in the drawings and operating manual.
Spacing and mounting were facilitated by a “factory” adapter plate. This is believed to be a
war time, field revision and thus retained.
Item number two was a pair of toggle switches that turned on the landing lights while
retracted. Although echoed on the aisle stand of 44-61748, the configuration was believed
to be a tanker docking aid and thus was rejected in favor of the “landing lights
up/off/down” switches.
The AFCE (Automatic Flight Control Equipment) is a project in itself. The control box drops
into a well in the lower left corner of the aisle stand. To make it presentable the following
was done:
ROY FOOTE made the missing ganging bar that allows for
simultaneous activation of controls surfaces, SAM
LEHTINEN machined several missing control knobs,
TERRENCE McCOSH fabricated the mechanical dimmer by
copying the B-17’s C1 AFCE. Thanks to HERB PHELAN, Crew
Chief, for allowing access to 42-29782 and its C1.
Work remaining: Apply the fluorescent legends adjacent all knobs and switches.
That leaves us to contemplate the mystery decal: “MAXIMUM GROUND OPERATION TIME
TEN (10) SECONDS.
17
ELECTRONIC CONNECTOR BOX RESTORATION
Team of Volunteers:
Dale Thompson, Scott Taylor, Don England, Jerry Brown, Bill Wiesner , Syd Baker
AAl
All cables and connectors were removed from the box. Everything was cleaned and
repainted as required.
18
EXHAUST PIPES RE-CREATION B-29 T-SQUARE
(ENGINE AND TURBO CHARGER)
SYD BAKER
Photos by Syd Baker
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ACKNOWLEDGMENTS - B29 EXHAUST PIPE PROJECT
The Volunteers - Herb Phelan
Richard Greer, CIMtech
David Arena, CIMtech
Bill Weisner
Scott Taylor
Dennis Dhein
Syd Baker
Companies - Steve Kidd, President of CIMtech, Seattle.
High Tech. Molding Foam provider
General Plastics , Tacoma
Fiberlay-,David Chamberlain
Photography - Syd Baker
Front cover picture:
Picture of exhaust pipe and waste gate pipe taken at Duxford on the B-29 Haug Will
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THE MIGHTY WRIGHT R3350
Each of the mighty Wright R3350 2200HP engines on the B-29 have two
large (12 inch) diameter turbo chargers mounted on either side of the
rear engine cowling. Each turbocharger has two outlets, the smaller
one for the waste gate and the larger to direct the main exhaust gas flow
downwards, and to the rear under the wings. On the Museum of Flight’s
B-29 T-Square, the larger of these pipes was missing on all of the four
engines.
Since the exhaust pipes are a very prominent feature of the cowlings, it
was, after a protracted search for some real steel units decided to
fabricate replacement units using fiberglass.
The male model
Herb Phelan had
found the original
manufacturing
drawings and
constructed a full size
replica. (The white
unit in photograph)
He asked me if I could
use this to make nine
realistic fiberglass
parts. (one extra for
a display unit).
Looking at the drawings, which were of course intended to produce
parts from18 SWG high temp steel, not fiberglass.
I realized that to make the fiberglass look like metal I had to make a
female mold to obtain the desired smoothness on the outside of the
parts. Also that the mold had to make, if possible, the complete part in
one operation, since joining two halves of such thin material would not
be practical.
My first big problem - how to convert Herb’s full size male model into
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a female mold. Then a small miracle occurred. Quite by chance, Herb
had invited Steve Kidd, president of CIMtech to come and look over our
B-29 restoration. When Steve asked me about my exhaust pipe project,
he said “Would you like me to make the mold for you?
We could use this in our seminar on high tech. manufacturing which I
am organizing.” I of course said that would be great.
Digitizing the male mold
The first operation at CIMtech by Dave Arena was to scan the full size
model made by Herb. This operation uses a hand held laser scanner
made by Creaform. This scanner can best be described as a miniature
GPS system in which three scanning lasers are mounted in a triangular
pattern similar to GPS satellites which is then carefully passed over
every surface at a consistent distance of about 12 inches of the male
mold, this through software by Rapidform creates a 3-dimentional
virtual part which is displayed on a computer screen in real time.
Magic! This can then be rotated and viewed from any angle and
changed if required.
The data from this scan
was then taken by Rich
Greer and programmed a
data file for later use on
the VF-4 5 axis Hass
Milling Machine. During
this, Rich was able to
refine the data so that
any imperfections in the original model scanned part were corrected.
The next issue was what to machine the mold from. Steve Kidd
contacted General Plastics of Tacoma who donated a very expensive
block of 45 pound high density foam specifically formulated to be
machined and to take a very smooth non-porous surface finish, while
not abrading the milling equipment.
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The mold was machined in two
pieces split down the longitudinal
axis, each half had extremely
accurately located bushings and
using tooling pins so that when the
two halves of the mold were finally
finished and joined together, one
could see the split line but it was so
well aligned that the joint was
undetectable by feel.
Laying up the parts
The mold was made in two halves for the obvious reasons -1) the 5 axis
milling machine could not reach into the enclosed area, and 2) in order
to remove the completed fiberglass part the mold had to be able to be
separated. After coating the working surfaces of the mold with Carnuba
release wax. I assembled the two parts of the mold together and sprayed
20 mils. of black gel coat to the inside surfaces.
To lay up a fiberglass part inside a very narrow tube is extremely
challenging. It is very hard to reach into the small opening to make
absolutely sure that the fiberglass cloth is laying down smoothly with no
wrinkles or air pockets.
To keep the exhaust pipe as thin as possible I used one layer of random
weave cloth and one layer of 10oz. fiberglass cloth. The result is similar
to an eggshell because of its ovid shape it is extremely strong.
Mounting ring
Where the pipe attaches to the turbo hosing I manufactured 14 inch
diameter, 1/8th inch aluminum rings which were bonded to the large
opening of the exhaust pipe and significantly increased the overall
strength of the part.
23
On the outlet end of the
pipe the drawing calls
for the metal to be bent
back on itself for a½ inch
reinforcing lip. This is
to stop the thin edge of
the pipe from splitting.
How to replicate this
feature on my replica
part was the next
challenge.
Steve Kidd to the rescue! Since the geometry of the pipe was now
digitally defined, Richard Greer could slice the outlet of the pipes at
precisely the correct angle – one for inboard pipes, another for outboard
pipes. Now for the really clever part! Richard created a left and right
data file which described the shape of the outlet reinforcing, these files
were then loaded into a 3D printer which printed out my parts.
I simply bonded these printed parts to the outlets of the inboard and
outboard pipes. As can be seen from the picture on the, It looks just like
the real thing!
Cold air inlet and dome
On closer examination of the exhaust pipe drawings and photographs
(see picture page 7) from Duxford, I realized that inside each pipe there
is a dome shaped part which sits right up against the outside edge of the
turbine wheel.
This dome is suspended inside the large inlet of the exhaust pipes with
four bolts and spacers. At the forward edge there is an inlet pipe which
feeds cold ram air from inside the intercooler housing. This cold air
enters the inside of the dome which is very close to the turbine disk and
provides cooling air for the extremely hot bearings as well the disk
itself.
24
This photograph
shows the
reinforcing lip
and on the right
the cooling pipe,
before I made the
inside dome and
matching inlet
connection.
Bill Weisner
fabricated all the
missing
surrounding
stainless steel closure panels and connected up all the cooling pipes.
Making the small dome assembly and feed pipes was relatively straight
forward, using a plaster mold and the usual fiberglass layup. The feed
pipes on the aircraft parts were made from wood, but the Turbo display
unit pipe was made exactly like the original, out of sheet metal.
TURBOCHARGER DISPLAY UNIT
The ninth exhaust pipe
was used on the
beautifully cosmetically
restored spare engine
where one of the two
turbochargers is
connected to the
engine. This amazing
display was created by
Dennis Dhien and Scott
taylor.I partially cut
away this exhaust pipe
so that the cooling
dome and turbine disk
blades could be seen. This picture also shows the heat shield between
the turbine and compressor sections of the Turbocharger assembly. The
vertical shaft on the left controls the waste gate.
25
Waste Gate Function
When the B-29 is at ground level and the air density is high, the waste
gate is seen positioned almost fully open allowing the majority of the
exhaust gas to
pass freely out
of the waste
gate pipe rather
than over the
turbine blades
and out of the
exhaust pipe.
The result is
that the turbine
spins relatively
slowly, which
provides only
low blow to the
engine and cabin pressurization.
The inboard turbochargers on engines # 2 and # 3 have double duty.
They not only provide boost to the engines but pressurized air to heat
and pressurize the three crew compartments.
As the aircraft gains altitude and the air density thins, the waste gate is
slowly closed to increase the flow to the turbine which of course spins
faster, which provides more boost to the engine to compensate for the
lower ambient air density.
The cabin pressurization system is intended to keep the crew
compartment at a nominal 13,000 feet when at altitude. However when
the B-29 was at high altitudes (29,000 feet over Japan), the cabin
pressurization system was deactivated and the crew went on to oxygen.
This was to avoid explosive decompression if the aircraft skin were to
be punctured by enemy flak or bullets.
The early R.3350 engines were problematic, especially when operated
at extreme altitudes, suffered from many different kinds of failures –
some of which involved detonation of the gasoline in the cylinders, as
opposed to the properly controlled compression during normal engine
operation. This detonation had two major causes – ignition timing and
over boost. Over boost causes, in effect an excessively high compression
ratio, which causes the gasoline too spontaneously to ignite on entering
26
the combustion chamber. This causes over temperature and in some
cases, catastrophic failures, cylinder head breaks away from the engine,
or valves fail.
Ironically one of the periods likely to produce over boost was during the
return trip from Japan. The aircraft would slowly be brought down to a
lower altitude for the cruise home and the waste gate would stay shut
so as the air density increased the turbine pumped higher and higher
pressurized fuel air into the engine until detonation occurred in the
engine.
Consequently the flight engineer had to be extremely vigilant to always
be ready to over-ride the automatic boost levels.
27
GROUND POWER UNIT (GPU) RESTORATION
Team of Volunteers:
Dale Thompson, Scott Taylor, Don England, Jerry Brown, Bill Wiesner , Syd Baker
This is a modified commercial power unit that was acquired and disassembled, glass
beaded and completely painted all body and panels. The painted “star” represents
the Army Air Force for the WW II time period.
28
GUN TURRET PRESSURE DOME RE-CREATION B-29 T-SQUARE
SYD BAKER
All Photos by Syd Baker
29
ACKNOWLEDGEMENTS – PRESSURE DOMES B-29 PROJECT
The Volunteers:
Sam Lehtinen
Paul Lehtinen
R.W. Johnson
Dick Peterson
Dale Thompson
Syd Baker
Photographs:
Syd Baker
Companies:
Fiberlay, David Chamberlain,
Front cover picture –
Aluminum cylinder entering overhead is the housing for the aft upper remote
turret and its ammunition.
The green hemisphere is one of the new pressure domes – the drain line is yet to be
connected to the bottom fitting.
GUN TURRET PRESSURE DOMES – B-29 T-SQUARE
Three of the remote control gun turrets on the B-29 protrude into the
pressurized crew compartments. Consequently each has to be provided with
its own unpressurized circular enclosure to accommodate all of the ancillary
components which make up each remote turret system.
30
Associated Hardware on display
This photograph is of the top forward four gun turret which, when mounted
in its entirety, extends into the front cabin between the radio operator and
the navigator’s stations, leaving just enough space for the crew to pass
around this intrusion.
Because of this
intrusion we chose not
to install the pressure
cylinder in which all the
lower equipment is
located – ammo storage
bins, belt feed system,
etc. This is the unit
which was provided to
the Museum of Flight
by the Imperial War
Museum at Duxford,
U.K., and we will be able to make it functions independently from the
aircraft. It makes a great display. We can make either the ground unit
function, or the unit on top of T-Square.
Currently on T-Square only the top segment of this
turret is installed which included the 50 caliber
machine guns and their mounts, the aerodynamic
faring and drive motors, so that from outside the 4gun turret looks complete.
Dome purpose
My job was to provide the pressure domes to close out the open ends of
the remote gun pressure vessels in which the remote gun pressure
mechanisms are mounted.
31
Picture shows the lower ring of the mid aft turret housing where one of the
gun control cables can be seen, as
well as the lower components of
the ammunition storage racks, all
mounted inside the outer housing
which is of course fixed and is
part of the aircraft cabin
structure. This housing has a
large removable access hatch in
the side through the gun
magazines are reloaded.
There are three domed closures
for each aircraft and the original drawings show the cross section shape and
calls for the parts to be made from aluminum. This is entirely beyond our
capability and could only be remanufactured this way at prohibitive cost.
The answer was to use fiberglass.
To ensure a fine
metal-like finish on
the parts I had to
make a two part
female mold. This
mold had to produce
a part which was
“perfectly” round and
the correct diameter
42 inches to fit
precisely into the
open ends of the
turret enclosures.
To obtain the required accuracy I had to construct a “lathe” on which I could
machine a 42 inch diameter male replica of the basic dome.
32
The basic dome shape
To create this lathe I obtained from an
auto junk yard a rear stub axel complete
with wheel bearing and wheel from a
Dodge Minivan. I welded up a crude
fixture to mount the stub axel and the
electric motor and a suitable size fan belt –
the wheel rotated at about the right speed.
Then I bolted a 42 inch, roughly circular
piece of ½ inch plywood to the wheel. By
using a fixed work surface clamped to the
motor mount and close to the ½ inch
plywood disc. By using a wood turning chisel machined the diameter to 42
inches exactly, and “perfectly” circular. After making a template of the dome
cross section, I built up layers of foam until I had a rough shape of the
finished mold.
After smoothing the surface with automobile body filler, I was able to
machine the entire surface to the correct profile and diameter.
This was a pretty hair raising
operation since the entire
assembly rotated much too fast
and wobbled alarmingly, until I
was able to achieve a reasonable
balance
The Dome mold
After the male plug was complete I made the female mold by spraying a
coating of white Gelcoat over the male plug. This was after applying the
usual Carnauba wax release agent.
33
After encasing the male plug with six layers of 10 oz. glass cloth. I made a ½
inch plywood base and frame, split across the major axis for part removal. I
then bonded this plywood frame to the male
plug. The problem then was to remove the
male plug from the inside of the female mold.
Even though I had made the foam build up in
the male plug in four segments for easy
removal, it was extremely hard to remove and
was literally destroyed in the process.
The manufacture of each dome from the
resulting female mold was a straight forward
fiberglass lay up using 20 mils of white gelcoat on one layer of random weave
cloth, followed by four layers of 10 oz. cloth.
Dome configurations
There are two configurations of Dome. Two for the two top turrets, which
have lips around the base which are fixed to the inside of the dome rim.
This provides a surface for the rubber sealing gasket mounted on a groove at
the lower rim of the fixed gun mount which obviously provided an airtight
seal when the dome is in place and all the latches are fastened.
The latches are not particularly substantial, but they are only to hold the
dome place. When the cabin is pressurized there is literally hundreds of
pounds of pressure pushing the dome tighter against the seal. (This is the
dome shown on page 32)
The third dome for the forward lower turret has a lip around the base the
outside the edge of the rim. This is because this dome is mounted on the
cabin floor above the turret. The outside flange is trimmed to fit around the
skin of the fixed cylindrical cabin structure which houses the gun mount, and
is sealed against its structure with an airtight gasket. This dome normally
protrudes above the cabin floor by about 6 inches and is a trip hazard for
visitors standing in the cabin.
Dale Thompson who gives wonderful talks inside the B-29, asked me if I
could make a special low profile dome which would cover the 42 inch hole and
protect the rotating gun mechanism below the floor but would have to
support the weight of visitors standing on the cabin floor.
34
To make this special dome I cut a disc of Formica and laid it onto the dome of
the female mold cutting down the height from six inches to two inches, made
one more dome as
before but I had to
reinforce the new
flat profile, which
was obviously not
as strong, as the
normal dome. I
made a lattice
work of reinforcing
ribs on a 2 inch matrix which was then bonded
to the underside and judiciously cut away only as required to clear the remote
gun equipment cable mounted below.
Almost directly above the forward two gun mounts is the upper forward four
gun mount. Since we chose not to install the complete upper gun turret
mounting cylinder, as discussed previously, we were left with all of the lower
side of the upper turret exposed. This looked very unfinished and potentially
a source of rain water entering the cabin since one of the functions of the
pressure domes is to collect a any water which flows around the gap between
the fixed and rotating part of the top turret.
This of course called for another special
cosmetic dome to close out the opening and
collect any water, and direct it into the drain
hole provided in the nose wheel landing gear
compartment.
If the complete turret system had been
installed, the lower dome would have been
approximately six inches above the floor.
The special closure
dome was six feet above the floor. To make the
water drain invisible I managed to squeeze a ½
inch diameter water line from the dome down the
inside of the floor to ceiling vertical grab post,
completely out of sight. Behind this cosmetic
dome Dale Thompson installed a pair of high
quality loud speakers so that tour visitors get
some impression of what the four gun turret
sounded like when “firing”.
35
Pressure Dome purpose:
The pressure domes have three purposes, One, to retain cabin pressure.
Two, to collect and drain away any water which passes around the top side of
the gun turrets, and three, to collect used 50 caliber cartridge cases when the
upper guns are fired. The lower turrets, as well as the tail gunner’s, eject
their cartridges directly into the airstream out of the bottom of the aircraft.
To enable the armorers to remove the spent cartridge cases more easily, the
two top turret domes are easily removed by unlatching five retaining latches.
Unfortunately these latches were missing on T-Square but fortunately the
gun turret from the Imperial War
Museum at Duxford had a complete
set. Sam Lehtinen skillfully made a
complete set by copying the Duxford
units, since there were no drawings
available. These are complex
assemblies, consisting of machined
fittings and a unique over center
latch made from bent sheet metal.
The result of Sam’s work is that the
latches are indistinguishable from
the originals.
Sam also made a pair of drain fittings which are mounted at the lowest
surface of the upper domes. Interestingly, the threaded connector is a nonaircraft size and is identical to a standard garden hose!
R.W. Johnson undertook the task of removing specific cabin flooring panels to
access the drain fitting in the belly of the of the B-29 fuselage, immediately
to the rear of the aft bomb bay.
He then completed the installation by fabricating and running a suitable
hose and securing it appropriately between the bottom of the dome and the
lower fuselage drain fitting.
Dome installation One issue with the rear upper dome was that in order to install it below the
mid upper turret, it had to pass through the rear entry door and the circular
mid compartment pressure hatch – neither of which was big enough to allow
the passage of a completed 42 inch diameter by 6 inch deep dome enclosure.
Fortunately in the forward crew compartment the crew entry door over the
forward wheel well is just large enough to allow the completed domes to pass
through intact.
36
Consequently I had to saw the completed dome in half. I made cuts straight
towards the center drain then in a 4 inch radius around the hole to preserve
the integrity of the reinforcing hole boss.
The re-bonding of the two dome halves inside the rear cabin had to be done
using typical fiberglass repair procedures. The mating surfaces were
carefully aligned, with Sam Lehtinen’s invaluable assistance, beveled, then a
series of 3/16th holes were drilled along the joint line, approximately every six
inches. Temporary aluminum spliced plates were then used to insure that
the two halves would be precisely in alignment. All this was done outside
the cabin to minimize fiberglass dust from contaminating the cabin lining
and electronics.
After reassembling the two halves inside the airplane using the screws and
temporary splice plates and bonded fiberglass strips inside the dome between
each of the alignment plates. When the resin was fully cured, the screws
and alignment plates were removed and an additional fiberglass doubler
bonded over the whole length of the cut. This left a very narrow saw cut gap
on the outside the edges of which I had previously beveled slightly. Auto
body plastic filler was applied and smoothed over this joint so that minimal
sanding was required, followed by touch up of green paint. As a result this
joint was completely invisible from the outside, and only the reinforcing strip
is only visible on the inside of the dome by looking through the maintenance
hatch.
Insulation:
Unfortunately the pressure dome insulation blankets were not able to be
manufactured and installed by
Dean Paul before the aircraft had
to be prepared for outside storage,
and all work has stopped until a
covered building for the large
aircraft is completed.
This photograph was taken at
Duford of aft the rear top turret
the showing how the blanket fits
around the lower part of the fixed
turret enclosure.
37
INVERTOR, ELECTRICAL BOX, OVERFLOW TANK AND PRESSURE
CONTROLS RESTORATION
Team of Volunteers:
The invertor was cleaned, sanded and touched up. Made some mounting feet and
located the unit in the fuselage. The overflow tank was cleaned and painted with a
new holding assembly (straps & Blocks) installed. The electrical box was cleaned,
painted and mounted in its location. The vacuum line controls were disassembled,
cleaned, painted and installed appropriately.
38
R-3350 DISPLAY ENGINE RESTORATION B-29 T-SQUARE
Team of Volunteers:
The engine was partially disassembled when the project started. Everything except
the cylinder heads were removed from the engine. Everything was hand scrapped
of oil and dirt, all the bolts were removed and polished and sealed. The parts that
were disassembled were cleaned and repainted, glass beading was done to the
entire engine (60 hours of work) to get the engine clean all around. The engine body
was painted. Accessory parts were gathered cleaned and painted. Partially
disassembled components were reassembled and safety wired, as applicable. The
dual distributor heads and lines were removed and glass beaded clean, sealed
and/or painted prior to reassembly. All engine baffles around each cylinder were
removed, cleaned and polished.
All old “fabric” from the cowling pieces were removed and replaced with new fabric.
The typical fire detector sensors and wiring were added around the engine. The
cowling flap drives were cleaned and reworked as needed, the exhaust system was
cleaned and were some was missing it was created new. All accessories were
remounted on the completed engine (pumps, generators, etc.)
The engine cover panels mounted above the cylinders were repaired, cleaned and
polished. The covers on the right side were installed to reflect a full installation.
Those covers on the left side were cut away to provide the viewer access to the
engine assembly below the panels.
39
R-3350 ENGINE PROPELLER DOME RESTORATION B-29 T-SQUARE
Team of Volunteers:
Cleaned and then polished to a new like luster.
40
RADAR ASSEMBLY RESTORATION B-29 T-SQUARE
Team of Volunteers:
The radar assembly was completely disassembled, cleaned and repainted. The
waveguides were silver plated, the dish and frame were repaired and polished the
radar dish. A radar dome was later fashioned and built from scratch.
41
RADOME RE-CREATION FOR B-29 T-SQUARE
SYD BAKER
42
Acknowledgements – B-29 Radome Re-creation Project
THE TEAM OF VOLUNTEERS:
Syd Baker.
Herb Phelen
Dick Peterson
Dennis Dhein
REFERENCE SOURCES
The author wishes to acknowledge the valuable historical radar
information and
Photographs, obtained from the 482nd Bombardment Group – see
http://www.482nd.org/radar
WITH THANKS TO THE IMPERIAL WAR MUSEUM, Duxford, England (Chris
Knapp) which provided access to its B-29 for research for this project
Companies
Fiberlay-David Chamberlian
Photographs:
By Syd Baker
Cover Picture:
Picture shows new radome mounted between front and rear bomb bay
43
RE-CREATION OF RADOME FOR APQ-13 RADAR ON B-29 T- SQUARE
The recreation of the large radar radome located between the forward and rear
bomb bays on the B-29 was by far the most challenging and technically interesting
job that I have so far undertaken for T-Square.
Restoration of APQ-13 AntennaIt started with a call from Dick Peterson, who said that
Dennis Dhein had just finished a beautiful restoration of
the gimbal mounted dish antennae for the APQ-13 radar
system.
Since there was compelling evidence that T-Square had
such a system, would I build a radome to cover the
antennae? I immediately said I would. At this stage I only
had a brief idea of what I had taken on – a project that
would last for the next three years! Shortly after this I found out that we had no
Engineering drawings for any of the required hardware or installations!. That was
going to make life even more interesting.
Background researchWhenever I undertake a project like this I find that it helps to take an in depth look
into the history and evolution of the system I am about to work on. All I knew at
this point was that the APQ-13 system evolved many years before from the British
H2S used extensively over Europe by RAF Bomber Command.
The following information was obtained from the 482nd Bombardment Group web
site. (The) “8th Army Air Force and the need for Radar As the 8th Army Air Force
continued to build up in England during 1942 and 1943, it became obvious to VIII
Bomber Command (BC) that the success of an offensive strategic bombing offensive
would be contingent on the ability of the VIII BC to operate above the weather and
44
bomb through overcast. In December of 1942 the VIII BC had an average of 72 heavy
operational bombers available to strike at enemy targets. The weather in December of
1942 did not permit one operational day and the first 15 days of January 1943 did not
allow the 8th to complete a mission. England and Western Europe experienced a storm
on average every three days. In addition, fog and low hanging clouds created early
morning delays and challenges in aircraft forming up over England for the trip across
the channel. It was a very complex problem for VIII BC. Estimates by 8 th Army Air
Force Meteorologists suggested that visual bombing opportunities against targets in
Germany would exist on average between 20 and 30% of the time.
Ira Eaker, commanding General of the 8th Army Air Force, proposed that there were
only 75 days per year where the weather would ground all aircraft. What was needed
was the ability to Bomb through Overcast (BTO) on days when visual bombing was not
an option. The U.S. 8th looked to the British who had developed “Oboe” and “Gee”.
Although both Oboe and Gee would become very effective navigational aids they did
not solve the problem of BTO as the Germans had discovered ways to jam them and
their range was limited during day light hours. Eaker turned instead to the British
H2S “Stinky” unit.
Development of “BTO” – Bomb through Overcast Radar
In March of 1943 Ira Eaker formally requested the RAF for eight H2S units for
installation in 8th Army Air Force B-17s. In
March of 1943 four radio mechanics and two
officers were sent to the British
Telecommunication Research establishment
(TRE) at Great Malvern to learn about H2S
Radar. That same month B-17F#42-5793 was
sent to RAF Deford for installation of H2S. It
was with the first H2S installation that
America’s Army Air Force entered the radar
age. The scanner and radar dome were placed
under the nose and was shielded by a bath-tub shaped plastic cover. The radar scope
and navigation unit was placed on the left side of the navigator’s station and required
45
some equipment movement. The radar units were found to be temperamental during
early test flights. With patience hard work and resiliency the first Pathfinder equipped
aircraft were about to lead their first mission.
H2S Stinky was the RAF’s primary air to ground radar system utilizing a 10 centimeter
frequency for airborne terrain scanning radar. It was developed by the RAF bomber
command and was utilized on the Halifax, Sterling and Lancaster bombers. Command
for nighttime bombing of German targets. The H2S set transmitted energy through a
high frequency electrical energy impulse downward through a revolving antenna;
these impulses were reflected back to the aircraft and converted the images to a
cathode ray tube. The reflections on the scope would allow the specially trained H2S
operator to determine contrast between land, water and cities, H2S could be used at
25,000 feet and had a 50 mile radius.
H2X – “Mickey” –
Designed at the famous Massachusetts Institute of Technology (MIT) – H2X radar was
the American version and an improvement upon the British H2S unit. H2X utilized a 3
centimeter micro-wave versus the British 10 CM. Often referred to its official
designation of the AN/APS-15. It was more commonly known as “Mickey”. The first
12 H2 X was installed on one B-17 F model and the remaining eleven were installed on
the newer B-17 G equipped with a chin turret. The installations took place in Rome,
NY, and the unit was placed in under the nose similar to the H2S in placement. The
H2X was semi retractable and cylindrical
in shape. It was Major Fred Rabo who
was responsible for bringing the first 12
B-17’s equipped with H2X back to
Alconbury. Major Rabo arrived in
Alconbury o September 21, 1943, with the first H2X B-17’s.”
In the Pacific theater, B29’s were equipped with the improved H2X radar called the
AN/APQ-13, a ground scanning radar developed by Bell, Western Electric, and MIT.
The radome was carried on the aircraft belly between the bomb bays, and was
partially retractable. The radar operated at a frequency of 9,375 +/-45 megahertz
46
and used a super heterodyne receiver. The radar was used for high altitude area
bombing, search and navigation. Computation for bombing could be performed by
an impact predictor.
Determining the Radome geometry In looking at T-Square I found the original radome attach fasteners under a crude temporary
Patch which had covered the original rotating antenna opening. This was absolutely critical in
The re-manufacture of my radome since this accurately defined the footprint of the radome
beneath the B-29 belly.
The only other data I had were two pictures which Dick Peterson took of an existing
B-29 radome one from the side on from the rear.
In order to develop the remaining lines for the radome I first taped sheet Mylar to
the bottom of T-Square and accurately located every radome attachment fitting bolt
hole.
47
By measuring the marks on the skin, I determined that the
Radome was originally 0.5 inches thick. I laid out the mylar
on 4 ft x 8ft x one half inch plywood and using a one inch
set back from the attach screws, defined the full size
exterior profile of the radome in plan form.
By this process I was able to calculate an accurate overall
length and width of the old radome.
I then had Dick’s pictures put on to Power Point so I could project these pictures on
to the wall of the Museum of Flight Red Barn class room.
On the wall I hung another large sheet of Mylar on which I had marked a reference
datum line and the overall
length and width of the radome
footprint derived from the B-29
belly back and forth until the
picture length exactly coincided
with my marks. I then
carefully traced the full size
side profile projected image on
to the Mylar with a permanent
magic marker.
I then repeated the process to establish the cross section front profile. On the side
profile I added 2 inches of depth to allow for the curvature of the B-29 belly.
48
After transferring the derived profiles to ½ inch plywood, I made a large box-like
structure using 2 in x 4 in and the large profile cutouts.
The side profile I made twice so that when
finished, the large box (mold) could be
separated on the vertical center line to insure
that the finished radome could be removed
from the mold.. At this time I realized that the
resulting bath tub like mold would be too deep
for me to reach into the bottom, I cut the base
and made two 45 degree surfaces for the mold to sit either flat or tilted 45 degrees
one way or the other.
Now I had an accurate picture of the very basic radome geometry but I had to fill in
the large gap forward and aft of where the bulkhead which defined the largest cross
section of the radome – which I assumed to also be the center line about which the
antennae rotate on its gimbals.
Since the antenna rotated 360 degrees in azimuth and was able to nod up and down
at the same time, it presumably described a hemisphere, which is the volume of the
interior that the antenna had to clear. It turned out that there is only about one half
an inch of clearance between the edges of the antenna dish and the interior of the
radome as it goes through its various scan modes .Not very much!
In order to blend the rest of profile of the radome mold I had to fall back to 1946
where, on my very first assignment as an apprentice at Vickers Armstrong’s in
Weybridge, England, I was assigned to work in “the loft” where we took drawings of
aircraft parts, such as wing to body faring, and laid them out full size on sheets of
white painted aluminum, using sheets of data and wooden splines we had laid out
from a datum line. The profile of these templates were used to make stretch form
blocks which would form the aircraft skin to its required shape.
49
So I developed the shape of the radome at 4 1/8 inch slices just like the Vickers Loft
work. After developing the cross section profile every 4 1/8
inch, I cut out 1/8 Masonite forms which I glued to 4 inch
thick special high density foam – specifically made for the
fabrication of fiberglass parts. As each layer progressed, the
final shape of the radome began to emerge. After the glued
blocks were thoroughly set, I began the laborious task of
blending the profile of each bulkhead into one smooth continuous curve, the
Masonite template insured that I had the correct profile as I went – no need to
frequently check as I progressed. It worked very well.
However because of the difference in hardness between the foam and the Masonite,
the area between each form was slightly lower.
This was anticipated and resolved with a skim
coat of high tech body auto filler which I used by
the gallon. This filler was then checked for
smoothness with a steel spline which insured that
there were no high or low spots between Masonite
frames.
Antenna mountWhile this was going on, a mount had to be constructed to hold the antennae and its
drive system so that the antennae ended up in exactly the right place inside the
radome!
The original B-29 radomes were semi retractable and just as was the case in the
original B-17s, this was unreliable and scrapped in favor of a fixed system.
There were no engineering drawings available for the mount, but Herb Phelan and
Dick Peterson was able to reverse engineer the unit based on photographs I was
able to take during my many visits to England to photograph the very complete B-29
at Duxford, “Hawg Wild.”
50
Dick Peterson made very elaborate measurements from below the bottom skin of
T-Square to insure that the antennae ended up in
just the right place with no interference and only
about ½ inch clearance.
What made this four legged mount so unusual is
that the feet of the legs sit on the same skin
stiffeners which support the radome attach
brackets and the top of the pedestal which
actually supports the entire antenna is also attached to the underside of the B-29
massive center wing box.
All the intricate fuel control systems oxygen lines as well as the large feed cables for
the radar antenna have to fit around this
mount. The whole antenna drive and
antennae are finally covered in a canvas cover.
This is probably to protect the antenna from
water and dirt from the nose wheels, which
would probably spray into this area when the
forward bomb doors are opened.
Determining radome materialThe major issue at this time, when the mold was reaching a satisfactory level of
smoothness, was to find out what the radome was made of in 1943. Since here
were no drawings, my best bet was to look at other WWII radomes.
51
During my trip to England I paid particular attention to the H2S radomes mounted
underneath the Halifax and Lancaster bombers. I was told that they were made out
of “plastic”. The H2S antenna is virtually identical to the one for the HPQ13 B-29
radar, so the radome is very similar in size and shape. Two noticeable differences
however – the British radomes are about one third longer giving them a 4 to 1
fineness ratio. The B-29 is 3 to 1. I realized that
this was due to the limited space on the B-29
between front and rear bomb bays. This is
unfortunate as the longer radome must have quite
a bit less aerodynamic drag. On some Lancaster’s
I found the rear one third made from clear plastic.
This I found particularly interesting and nobody
could tell me why this was so. Since I knew the
Editor of Aeroplane magazine, I asked them to ask their subscribers if they knew
why the back end of some Radomes were clear, and what the radomes were made
of. Eventually three replies indicated that the clear part of the radome was to
enable high intensity flash photographs to be taken, which were timed to coincide
with that aircraft’s 4000 lb. bomb detonation. This was obviously used to help
evaluate bombing accuracy. The radomes were all made from Perspex (British
Plexiglas) in the same fashion as Fighter cockpit covers - then they are painted flat
black as required to blend in with the aircraft paint scheme.
In looking at the B-29 radome on “Hawg Wild” at Duxford, it appeared to me as if it
was fiberglass, but I could not tell how it as manufactured – solid or with core.
Fabrication methodSince I spent a significant part of my time at Boeing as Manufacturing Manager for
the E-3A AWACS, one of the areas of my responsibility was the tooling and
production at the Auburn plant for the very large Radomes (30 ft. diameter) for the
E-3A. The beauties were made by very skilled ladies who cut and shaped the layers
of 1 ½ inch thick Hexel honeycomb core which is interleaved with multiple layers of
pre- impregnated (with adhesive) glass cloth, as each critical layer is built up. It is
52
cooked under vacuum bags in an autoclave. This partially melts the adhesive and
insure there are no air bubbles in the layers of fiberglass. The resulting radome is
over 3 inches thick and is virtually impervious to hail and bird strikes.
The net result of this research was that I would use 3/8 inch thick Hexcel
honeycomb cone with one random weave 3 oz. fiberglass cloth backed up with two
layers of 3 oz. fiberglass cloth on the interior, totaling a thickness of ½ inch.
After applying ten coats of special Carnauba wax as a release to the mold skin, I then
applied one layer of 10 oz fiberglass mat followed by 30 mils of black gel coat as
sprayed evenly as I could over the entire
surface. Then came the hard part!
After an extensive research, I found a
supplier of the 3/8th honeycomb core
who would sell me the small quantity I
required. Honeycomb has a very
peculiar characteristic when one tries to
form it into a curved shape. When you
simply bend it around a cylinder,
it takes on the shape of a saddle!! Consequently when I layered it into the mold, it
would only conform to the contours in small areas. This required many hours of
slicing and splicing to insure that the honeycomb was laying down correctly. When
satisfied each area – about 10 square inches - had to be carefully covered with
fiberglass resin, then covered with mold release polyurethane film, then held in
place with small canvas bags filled with bird shot until the resin cured.
This of course meant that the mold had to be turned so that gravity would hold the
core in place against the outside skin until the fiberglass resin set up. No vacuum
or autoclave were available to me.
Once all the core was bonded with no gaps or bumps I applied the two inner skins.
53
Radome attachmentA major consideration of building such a radome is how does one attach it to the
aircraft, and how to fit it accurately to the metal skin? On the AWACS radome, at the
edges where the bolts fasten the radome to the aircraft structure, we installed what
we called hockey pucks. These were solid laminated
fiberglass designed to avoid crushing the honeycomb by
the attach bolts and to spread the attach loads into the
surrounding radome. On the B-29 radome I used exactly
the same idea. These hockey pucks were bonded to the
radome edges prior the radome being removed from the
mold.
To insure an accurate fit with the belly of the B-29 I made a mock-up out of steel
sheet so that the radome could sit upright while I adjusted the edge profile to fit.
I made a large access hole in this steel mock-up so
that I could stand up inside the radome and very
accurately locate each attach fitting, and its location
relative to each strong pint (hockey puck) in the
radome. Once a satisfactory fit had been obtained
between the radome and the aircraft skin, I routed
½ inch deep where the edge of the honeycomb was exposed. I then filled each area
with a black polyurethane plastic filler to ensure that water would not migrate up
into the honeycomb. I finally drilled a 3/8 inch drain in the lowest part of the dome.
Then the moment of truth! We had previously located all the 26 attach brackets to
the belly of the B-29, and using a very small car jack and an old tire, we raised the
radome into position.
54
Much to my relief it fit very nicely and after Dick Peterson made some careful
measurements from Herb Phelan’s
antenna mount, we decided that
everything looked just fine.
The radome attach fitting fastener
locations were marked on the radome
inner skin, the radome screw holes
drilled, and the attach screws all fitted,
the jack removed, was then lowered!
While the radome was being painted at our restoration center in Everett, the
antenna was attached to its new mount.
It is amazing how close to the ground the bottom of this antenna is, and we were
concerned that we would be able to re-fit the radome with the antenna hanging so
far down. We did not want to jack
up the aircraft just for this.
When the radome finally came back
we were able to spread a cargo
blanket on the ground and slide the
radome under the antenna. The
radome was then rotated and jacked
up into place, fasteners put in place,
after swinging the antenna through
all its various motions and verifying
that it did not hit the radome.
We all deemed the job a success!
55
TAIL TURRET RESTORATION B-29 T-SQUARE
SYD BAKER
56
Acknowledgements – B-29 Restoration Project
THE VOLUNTEERS:
B29 Crew Chief - Dale Nicholson
Engineering Support - Tom Dawson and Herb Phelan
Turret Project Leader - Syd Baker
THE TEAM :
Syd Baker, Jim Foreman, Aaron Gaponoff, Rich Heasty, R.W. Johnson, David
Lang, Paul Lehtinen, Sam Lehtinen, Bob Martin, Brian Nordby, Dean Paul,
Dick Peterson, Dale Thompson, Larry Tietze, George Bowling (Enactment)
THE SUPPORTIVE LOCAL COMPANIES:
Foreman’s Welding - Jim Foreman
Boeing Wind Tunnel Model Shop
Pacific Aero Tech. - Mike Singley
Machinists Incorporated – Dave Miner
The Sheet Metal Man – Brian Nordby
Seattle Pottery – Jim Lunz
With thanks to The Imperial War Museum, Duxford, England (Chris Knapp)
which provided access to its B-29 for research for this project.
Photographs:
All pictures by Syd Baker.
Front cover picture:
Completely rebuilt tail gunner’s turret, all new sheet metal, glass, and fairings, tail
lights.
57
RESTORATION OF B-29 T-SQUARE TAIL TURRET - SYD BAKER
When I retired from the Boeing Company in 1994 after 37 years of wonderful and
exciting experiences throughout the world, I was told that the average life
expectancy of a Boeing executive in retirement was 18 months to two years.
Unbelievable!
After completing my two year retirement project, the complete restoration, groundup, of a 1957 Porsche Speedster, I realized that I had beaten the life expectancy
odds, and I now needed a longer term project. So I volunteered at the Museum of
Flight as a Docent – which I dearly loved.
As a docent I became aware of the need for hands-on people to work on various
aircraft, Comet, B-29, etc. Since I had worked for the British Aircraft industry –
Vickers-Armstrongs - starting in 1946, I thought the Comet would be the most
appropriate aircraft for me.
I phoned the Museum Restoration Center in Everett and made an appointment to
see Tom Cathcart, the Restoration Manager. Tom was very helpful after I explained
my early background as an Aircraft Aviation Engineering Apprentice in England,
where I went through most of the aircraft manufacturing shops, learning the basics,
and that I now have my own small machine shop at home.
My career at Boeing was in design and manufacturing areas. I had just finished my
fourth ground-up automobile restoration, and wanted to try something different –
how about the Comet?
After learning of my history and experiences, Tom said that The Restoration Center
was in fact looking for help on the Comet, but since I lived in Bellevue, would I like to
work on the B-29, which was closer to my home?
One of my assignments out of England in 1954-55 was to fly in a British Royal Air
Force “Washington” (B-29) performing air launched missile experimental trials at
Woomera in South Australia. So my interest in the B-29 was long term. I told Tom I
was interested but did not think it was a smart idea for me to work on aircraft
parked outside the south end of the Museum of Flight with small portables used as
workshops during the Seattle winter.
Turret in Renton Tom smiled and said “I don’t blame you, but we have removed the tail turret from
the aircraft, and it is in storage at Renton where a Museum team is working on the
B-17. Why don’t you go down, look at the tail turret, and let me know what you
think!”
58
He said he would talk to Tom Dawson, ex Boeing Engineer who was in charge of the
B-29 restoration project.
After a quick look at the turret at Renton, I went to see Tom Dawson at the Museum
of Flight. After one hour of exchanging experiences, we agreed that I would take on
the restoration of the turret.
Tom had a complete set of B-29 drawings on microfilm, and a very old
reader/printer. These drawings have since been converted to digital format. It
was obvious that Tom had the necessary resources and contacts to support the very
considerable amount of work that I realized would be required. Since I had my own
reasonably equipped machine shop I felt that I could reasonably undertake this
project.
Fake Tail Turret The tail turret on the B-29 is approximately eight feet
long and weighs about 1,500 lbs. The unit taken from
T-Square, located in Renton, had been stripped
sometime in the past and was just a shell with fake
windows, fake dome, emergency door, no machine
guns etc.
Research At this point I made arrangements to visit and photograph the very complete
original
B-29 “Hawg Wild” at the Imperial War Museum at Duxford, where I met with Chris
Knapp, the Director of Artifacts.
Since I was part of the overall Museum of Flight B-29 restoration team, I took this
opportunity to document other areas of the airplane – cockpit, bomb aimer’s
position and other areas that I knew the team was working on in Seattle. It turns
out that some years prior to my trip, Duxford had arranged to provide to the
Museum of Flight, a complete forward 4-gun turret, with all drive systems,
ammunition storage bins – virtually ready to install.
This was apparently provided to Duxford when the B-29 was delivered to them by
the U.S. Air Force. Since the B-29 was complete, this turret was surplus to their
requirements, so the relationship between the Museum of Flight and Duxford was
long standing. I noticed during my first inspection of their airplane that there were
certain minor details which were either incorrect or missing. Since these were in
the area that I would be building parts, I believed I could build a second set for
Duxford. As a result of this the Museum of Flight subsequently provided a correct
tail light fairing assembly, a set of fairings for the lower aft turret, and a “barber’s
chair” base.
59
The Rear turret is divided into two compartments, one of which was pressurized for
the gunner. This provided for the gunner’s comfort in a self-contained compartment,
lighting, heating, seating, oxygen system, armor plating, tracking computers, power
conversion for motor drives, as well as the provisions for aiming and firing the two
50 caliber machine guns and one 20 mm cannon. The rest of the turret is
unpressurized.
20 mm Cannon The original airplanes of this vintage included, in the tail turret, a 20 mm cannon.
However, it was found in service that the cannon was not as effective as hoped, and
to some extent was also limiting the effectiveness of the 50 caliber machine guns.
The extra mass of the 20 mm cannon with its co-located ammunition storage drum
resulted in a less agile system in spite of increasing the size of the amplidyne and the
horsepower of the elevation and azimuth drive motors.
However the main problem appears to have been that the ballistic trajectory of the
20 mm shell was different from that of the 50 caliber round. This resulted in the
inability of the computing system to predict the lead angles for both weapons.
This, together with the different rate of fire, resulted in a disappointingly
effectiveness of the 20 mm cannon. As a result of this, and to remove critical weight,
all of the 20 mm cannon systems were removed in the field.
Armament Location –
The unpressurized section of the turret contains the gun mounts and all the
mechanisms for traversing the guns in elevation and azimuth. This section also
contained the feed system for the 50 caliber ammunition belts together with the
external shutes to eject spent cartridge cases, plus many other details such as gun
camera and remote gun charging system as well as many access panels for
maintenance.
Tom indicated that the goal for the aircraft was to return it to as close as original
factory condition as possible!
One coincidence was that the gentleman who was the Crew Chief on the B-17
project at Renton was Herb Phelan. I worked at Boeing in various programs for
many years. I was Manufacturing/Operations Manager, and Herb worked as Head of
various Engineering Departments, so we were long-time acquaintances with a
mutual respect for each other’s capabilities.
60
Herb obviously had been asked to keep an eye on this new volunteer, and we
subsequently got on famously with one another for the next 15 years I have worked
on T-Square.
In 1999 I was joined by David Lang, who became a great colleague! He took care of
drilling out all the rivets which fastened the cupola to the main structure, and
repairing the damage caused to the airplane while at the Navy gunnery range at
China Lake, as well as replacing damaged skins and fairings and later the installation
of a different cupola top.
Gimbal System I took on the job of building, from scratch, the gun mounts and gimbal system. The
heart of the system is a large 3 ½ inches diameter aluminum ring 33 inches in
circumference which has a large load-bearing ball race at the top 12 o’clock and a
steady bearing at 6 o’clock. These two bearings not only support the entire weight of
the guns and absorb their recoil, but also
provide for the guns to swing in azimuth 30
degrees left and right.
Located in a 3 o’clock and 9 o’clock are two
ball bearings which allow the guns, mounted
in a complex welded hemispherical housing
to move in elevation +/- 30 degrees.
During the initial discussions with Tom
Dawson, we intended to just mock up
components in plywood. However I was fortunate to be able to find critical
resources which avoided this, to me, an unacceptable compromise.
61
The 33 inch ring was rolled by a local shipyard. The very complex hemisphere which
was originally a magnesium or aluminum casting, I redesigned to be fabricated from
¼ inch aluminum plate.
I first made 3/8 inch plywood components to check fit the assembly and then using
material provided by Dave Minor at Machinists Inc., routed out all the details in ¼
inch aluminum plate. Dave also bent the complex
pieces for the gun mount carriage. The third major
resource to us was Jim Foreman’s Welding. It turned
out that Jim’s father actually welded these same
structures in WWII, and was happy to provide me,
free of charge, with hundreds of hours of the most
exquisite aircraft quality welding you will ever see!
Norm also welded up a pair of simulated 50 caliber
machine guns using real barrels which I found glued to the inside of the fake turret
on T-Square.
After locating and boring the ring to accommodate all
the components on the Azimuth ring, and moving the
gun carriage, I (just for fun) decided to check the
accuracy of their relative motions, and found, much to
my surprise, that the maximum deviation was 0.020!
On hearing this, Tom agreed with me to make the
system really operate under power. As we had all the
gear boxes and motor mounts, the only things missing
were the large segmented gear racks for the azimuth,
and elevation drive. These were machined for Tom by
the Boeing Wind Tunnel Experimental Model Shop.
Gunner’s Cupola –
In the meantime, Dave Lang and I had removed the out-of-square cupola and
replaced it with another which was in better condition. However we ran into a
situation. It turned out that the production lines and Renton and Wichita only
required tooling to control what is known as “controlled interchangeable”
assemblies which could be switched out “in the field” to repair battle damage.
62
The interface between the turret and the rear of the T Square was a controlled
interchangeable interface, but removing the glass house from the lower structure by
drilling out the rivets was never intended to be done in the field.
The resulting mismatch of all the riveted holes was resolved
with a simple adapter strip.
An interesting aside occurred at this time. Tom found out that
there were a group of ladies who were WWII “Rosie-theRiveters” who built turrets at Renton in 1943-44, and asked,
“Would they like to come and see the Project”? They of course
came to visit and were presented with the old glass cupola
which we had removed. So T-Square now has a Renton-made
glass cupola, while the rest of the airplane came from Wichita.
Rear dome and fairingsBy this time, Dave and I had been working on the turret for three years and it was
time to build the complex rear exterior sheet metal skin. For this we transferred the
80% complete turret assembly from Renton to Brian Nordby, AKA the Sheet Metal
Man, in South Seattle. Brian is one of
those fellows who is a true artist
with an “English wheel” - a device he
has used with great effect to restore
show quality collector automobiles
for the local aficionados.
I was privileged to be able to work
alongside Brian in his Shop for the
next two years where we built
the main dome, which is bolted
to the Azimuth Ring and swings
back and forth with the guns.
The really challenging part
of this is that the dome has
to be a nearly perfect
sphere so that as the dome
swings, the gap between it
and the fixed left and right
closure panels remain
constant!
The upper main load carrying bearing with its magnesium casting is enclosed in a
hinged cover which provides access for maintenance, and keeps water from
entering the top of the gun drive system.
63
Entry Door During this time, while the fairings and spent cartridge casings shute were being
made, I completed the flooring inside the gunner’s compartment, and started the
layout of the missing circular compartment entry door.
This is a typical pressurized dome structure with a
circular viewing port in the center and provisions for
hinges on one side and a door latch system on the other.
While Brian Nordby made the dome door assembly, I
made the latch and handle fittings. Since there were no
drawings of this latch, I used one of the other door
latches from the forward entry door, and reverse
engineered to create the rear latch with inner and outer
handles
Electrical SystemsIt was at this time that Dale Thompson’s crew and I started working together ,to
make and install
components which
would eventually make
the tail turret come
alive. The structurally
completed tail
compartment was sent
from Brian Nordby’s
shop back to Plant 2
where the rest of the B-29 restoration was well
underway.
64
Armor Plate Glass The last remaining mechanical job on the tail turret was the fabrication of all of the
armored plate “glass” windows. I was fortunate to find a local supplier, Pacific Aero
Tech., Mike Singly, who, over the period of three years built an
entirely new set of windows for the tail turret, and replaced
many of the complex curved windows in the iconic B-29 nose
section.
The side windows on the rear turret were originally ¾ inch
thick, double glazed armor glass, the cavity of which was kept
moisture free with a silicone gel dehumidifier. The reproduction
windows which I had fabricated are ¾ in thick solid Plexiglass
with a 1/8 deep flange machined around the periphery so that
the window partially extends through the opening – and the
outside window skin ends up flush with the metal skin of the
turret structure.
The rear window is three inches thick and provides additional protection from the
rear, while the gunner tracks the target through the remote gun sight . To simulate
the original seal I made a mold for each window and poured a liquid plastic obtained
from Seattle Pottery, into this mold the end result of which looks like the original
resin seal. The windows are then held in place from the inside using a series of metal
clamps. Any gap between the outside glass profile and the metal window cut-out
was filled with a modern two-part polyurethane sealer. The inside window corners
were drilled to receive a simulated silica gel dehumidifier system, just like the
originals.
Below the 3 inch armored glass is an armored
steel pressure bulkhead which protects the
lower half of the gunner’s body. Between this
and the windows there are numerous small
pieces of armor plate in an attempt to provide
full protection for the gunner from the rear.
An equipment access hole is provided in the
center of the armored bulkhead
By this time, Dale Thompson’s team had the electronics hooked up and we were
testing the motion of the gun system in response to inputs from the gun site in
azimuth and elevation. The biggest challenge was to avoid slamming into the stops
at the end of travel, with potential damage to the gun carriage system. Otherwise the
system worked very well.
65
Oxygen and flight suit heater system –
This was installed by Bob Martin on the panel to the right hand side of the gunner’s
seat in the overhead, and on the left hand side of the gun sight.
Installation of Gunner’s seat –
The gunner’s seat is mounted on a vertical
track against the front bulkhead. This allows
the seat to be raised about ten inches to allow
the gunner to crawl through the circular
pressurized entry door under the seat, then
stand up and unlatch the vertical seat travel,
and push the seat down against the counter
balance springs to adjust his eye level in line
with the gun sight.
If the gunner is seriously injured and unable to evacuate the turret, there are
emergency provisions to unlatch the door hinges and disconnect the seat back so
that the rescuer can assist the wounded gunner.
The normal entry and exit to this compartment,
however, is through the circular pressure door below
the gunner’s seat. The large glass panel on the left
hand side of the gunner’s cupola is also an emergency
escape hatch. All these mechanisms had to be
recreated, adjusted, and tested.
Insulation To limit the heat loss through the skin of the gunner’s
compartment every exposed metal surface is covered with an olive green quilted
material which is glued to the skin or held on with snap fasteners if removal for
access is required. This job was performed throughout the entire airplane by Dean
Paul, who did a wonderfully neat job around the gun sight and other intricate
surfaces.
66
Dome protective cover fabrication The rear 50 caliber machine gun barrels in the rear turret are enclosed in a heavy
canvas bag assembly. In all other B-29s that I have seen, this enclosure has not been
fitted correctly and looks very odd. Unlike the
B-17G forward turret which uses a very neat
zipper to keep the water and air out, the B-29
uses two canvas sleeves which are much like
the arms in a man’s suit jacket – the wrists of
which are clamped around the base of each
gun barrel, with provision for quick change out
of the gun barrels by the armorer on the
ground, when required.. The “jacket” is fixed
around the opening in the rear aluminum
closure sphere. In azimuth the closure bag
swings back and forth with the sphere but in elevation the arms of the jacket have
sufficient excess material to allow vertical gun barrel motion without tearing or
snagging. To make this “suit” fit correctly, Dean Paul spent many hours, and the
result speaks for itself. It is a demonstration of skilled craftsmanship!
Turret re-installation and systems integration testingHaving resisted the clamor to install the tail turret back on to the airplane, I finally
released my temporary ownership after ten years, when the turret was reunited
with the fuselage by R.W. Johnson, who was the volunteer who helped rescue the
airplane originally from China Lake, and was responsible for the removal of the tail
turret for its temporary location in Renton some ten years earlier.
After re-installation final systems installation testing was completed to confirm it’s
compatibility with the rest of the B-29.
Final thoughtDale Thompson redesigned the control electronics for the Tail turret and installed a
large diameter loud speaker behind the canvas protective cover between the barrels
of the 50 caliber machine guns. Dale made a sophisticated remote control box with
a long umbilical cable which connects into the central fire control system. This will
enable a properly trained Docent to demonstrate from the ground how the remote
gun sights controlled the movement of the guns and what they sounded like when
firing.
” Very cool”, as they say.
67
TURBOCHARGER RESTORATION
The volunteers: Primary: Dennis L. Dhein
Assistants:
Don England, Jerry Brower, Scott Taylor, Bill Wiesner, Syd Baker and
Scott Taylor - Sid made the exhaust tail pipe and Scott installed it.
Turbocharger
Before
Turbocharger
After
The turbocharger was completely disassembled, scraped, brushed, cleaned and
reassembled. Everything works now.
A stand was constructed to mount
the turbo charger so to position it
behind the static engine display
simulating the position on the
aircraft.
68

Restoration Project Lists - Seattle Fortress Bombers

Transcription

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