an examination of today`s hydroplane

Roostertail
The best way to judge a boat's performance
from the shore is to watch the roostertail.
An even trail of water means the boat is
balanced. A choppy or disjointed roostertail
an examination of today’s hydroplane
D
rivers make the turns and
commissioners make the rules in
unlimited hydroplane racing, but the
laws of physics govern how the boat behaves on
the water.
Aerodynamics and nautical engineering
combine to make a hydroplane almost like a
hovercraft at top speeds, floating on a cushion
of air. The surface area touching the water is
about the size of a handkerchief as the boat covers
a football field per second, its speed better than
190 mph.
The boat corners like a three-ton rock, skipping
through the turns. Drivers say the turbulence is
similar to being duct taped to a chair and hit
with a baseball bat. The boats have two or three
Propeller
Rear wing
About the
diameter of
a dinner plate, the propeller weighs
17-18 pounds and costs more than
$10,000. Cut from stainless steel, it
has three blades and the edges
are sharp enough to cut
skin. The propeller is
half-submerged in
the water, turns
between 9,000 and
11,000 times per
minute, and shoots a
roostertail 60 feet high
and 300 feet long.
Ideally, the wing is
at a neutral setting,
exerting neither downforce
ce
nor lifting the boat. It actss more
as a stabilizer, and also givess teams
flexibility to correct other
her
problems by changing
nging
the setting
g of
the wing.
ing.
pedals, but no brakes. The right pedal controls
the gas and stays against the floor for the entire
race. The left pedal/pedals controls the front wing,
determining how much of the boat is out of the
water.
"It's what flies the boat," said Dave Villwock,
driver of the Miss Budweiser.
An apt metaphor, but the equation
has a flip side: the less the boat touches
the water, the more susceptible it is to
blowing over. A gust of wind, an
unexpected wave or the spray from
another boat is enough to lift the front
end, increase the cushion of air
underneath and prompt the boat
to take flight like a leaf caught
1
Exhaust
tailpipe
Then and now
Power turbine stage/
containment ring
(Kevlar scatter shield)
Key components
Gas generator
1 Rudder
About 2 feet long and
6 inches wide and made of
stainless steel, the rudder
acts just like it does on a
sailboat and determines
the arc of a turn.
Compressor
section
Starter
generator
Built half a century ago, Slo-mo-shun IV was the first
of Seattle's world champion hydroplanes. Much has
changed since it won its first race in 1950:
Engine
air inlet
curl
2 Engine
2
The boats aren't jet-propelled,
they just look and sound that
way. Their turbine engines
come from Vietnam War-era
helicopters. Purchased from
military surplus, they cost
about $80,000 each. The
engine turns more than 17,000
RPMs at maximum setting
with a high-pitched whine that
makes dogs antsy. Exhaust is
the only thing that comes out
the back.
Engine
oil tank
Slo-mo-shun IV
Material: Marine plywood,
spruce
Weight: 4,500 pounds
Engine: Allison piston engine
Horsepower: 1,800
Skid fin: 8 inches long,
3 inches deep
Drive
coupling
shaft
V-drive
gearbox
3
4
Today's hydroplane
Material: Aluminum
honeycomb, fiberglass
Weight: 6,500 pounds
Engine: Lycoming turbine
Horsepower: 3,000
Skid fin: 30 inches wide,
20 inches deep
3 Gearbox
Skid fin
A 130-pound piece
of metal with an
edge so sharp it's
covered with a
leather sheath on
shore. The fin cuts
through the water
and keeps the
energy pointed
toward the front,
preventing the boat
from sliding laterally
during a turn.
Canopy
Windshield
Canard
The
cockpit
The driver's perspective
Windshield
Most teams have gauges
monitoring engine
temperature, RPM and oil
pressure. Only a few are
equipped with speedometers
since the boat's speed isn't as
important as finishing first.
Steering wheel
Six-layered acrylicplastic composite
called Laxon. It's
required to be a halfinch thick and some
are more than
three-quarters of an
inch thick. The
driver has little
lateral vision, seeing
only what's in front.
Turning is the easy part.
Straightening out the boat is
the driver's bigger challenge,
as the resistance can feel like
a car when the power
steering breaks. The wheel
is linked to the rudder by
cables and a big gear.
Canopy
Most come from F-16 fighter planes and
are hinged at the back, popping open
just like a jet. Miss Budweiser made its
own canopy with a pop-top lid that looks
like a submarine.
The boats don't come with keys.
Instead it's a toggle switch the
driver holds down to activate the
starter. Another toggle sends a
stream of fuel to the engine.
Seat belts
A five-point harness with one
buckle that fastens just below
the sternum.
Seat
Side-view mirrors
Right pedal
Left pedal
Controls the canard,
which is the boat's
front wing. Pushing
the toe down directs
the front of the boat
toward the water.
Heel down and the
nose lifts off the
water.
Escape hatch
Hinged door that can
be opened from
inside the cockpit or
outside, allowing a
driver to be extracted
quickly from an
upside-down landing.
One on either side of
the cockpit, each
about the size of
those on a car. Except
the boat's mirrors
don't have a
disclaimer about
objects being closer
than they appear.
Mike Hanson calls it running on the
ragged edge when the boat is riding
high on a cushion of air and is no
longer being whacked by waves on
the water's surface. "Everything
kind of evens out," says Hanson.
The physics
Stage 1
The seat is about 36 inches
wide, and fitted to the driver's
taste. Most are made from
compressed foam that
absorbs energy to create a
softer ride for the driver.
Sources: Drivers and crew members of all unlimited racing teams, Competition Specialties. Research and reporting: Danny O’Neil and Mark McTyre
The less the boat touches the water,
the faster it goes, a design premise
as simple as the law of friction. But
this is also when the boat is
simultaneously at its fastest and its
most vulnerable.
Stage 2
Wind or wave is enough to bump
the nose up in the air, dangerously
increasing the air cushion
underneath. The front wing (canard)
is the tool the driver uses to
increase downward pressure on the
nose of the boat and push the front
down.
Hanson's stomach is the first
instrument that tells him he might
be in trouble. "You feel it in the pit
of your stomach," he says. Kind of
like a roller-coaster ride, and the
driver knows the nose must come
back to the surface to avoid a flip.
Ignition
Controls the gas
and stays pushed
to the floor for
most of the race.
"Mash the gas
and turn left,"
was the formula
for N. Mark
Evans, an
unlimited driver
the past two
decades.
4 Air intake
Provides air to the turbine,
but is also vulnerable because
spray from the water can pass
through the intake and douse
the engine. Too much water
and the turbine's flame is
extinguished, killing the
engine. Drivers call it
"getting hosed."
The anatomy of a blowover
The cockpit is smaller than
a refrigerator box and
custom-fit for each driver,
everyone from the 6-foot-4
Dave Villwock to the
5-8 Nate Brown.
Gauges
Costing upto $40,000, the
gearbox links the turbine
engine to the propeller. The
turbine turns at more than
17,000 RPMs, and this box
gears that down by 40-50
percent.
Stage 3
Sights and sounds tell the driver
when there is no chance at recovery.
"When it gets really quiet, and really
smooth, you know you're in trouble,"
says Greg Hopp. Then the driver
loses sight of the horizon as the
boat climbs into the air. The actual
flip can take 3 or 4 seconds. "You
know you're in deep doo-doo for a
long time," says Ken Muscatel.
Sitting upside down in a canopy
filled with water, drivers often pop
the escape hatch to let the team
know they're OK and wait for the
rescue team. Oxygen is supplied
through a mask worn during the
race, and they can hear the footsteps
of rescue team members on top of
the hull. "It seems like forever, but
it's probably about 30 seconds or
so," says Mark Weber.
The top half of the boat is
aerodynamically designed so the air
will flow around it. But the bottom
is flat like a wall, and the air pushes
against it instead of flowing around
it. At speeds of more than 190 mph,
the pressure is sufficient to lift the
6,500-pound boat into the air.
Stage 4
Rescue teams take less than a
minute to reach the boat, with the
optimal response time being 20
seconds after the crash has
occurred. However, that's not
always possible since a 1.5-mile
course like Seattle's is so big. The
driver is removed through the
escape hatch.
M ICHELE L EE M CM ULLEN / T H E S E AT T L E T I M E S