Sheet: 1903 Wright Brothers Engine Tests
DEARBORN, Mich. - Ford Motor
Company has conducted testing on the authentic reproduction 1903
engine that will power the first and only authentic, full-scale
reproduction of the Wright brothers' 1903 Flyer. The engine and
plane will re-enact the Wrights' first powered, controlled flight
this December - exactly 100 years from the historic moment - as
part of EAA's Countdown to Kitty Hawk Presented by Ford Motor
Results of the testing at Ford -
combined with earlier wind tunnel testing of the plane, ongoing
training of the "Pilots of the Century" and a stiff
steady wind on Dec. 17 - ensure the 1903 Wright Flyer reproduction
is ready for takeoff.
Among the theories proven and
secrets revealed during the Ford testing:
- The Wrights' water-cooled engine
produced about 12 horsepower and was capable of speeds of
about 30 mph.
- The Wrights' use of a crankcase
made of aluminum rather than cast iron to make the engine
lighter than typical engines of its time. The 1903 engine
delivers about 1 horsepower for each 12 pounds of engine
weight. In comparison, the best engines of the time were
delivering 1 horsepower for each 20 pounds of engine weight,
while typical automotive engines weighed 50 pounds for each
horsepower developed. Contrast this to the modern 4.6 liter
32-valve engine that powers the Lincoln Aviator SUV and weighs
only 1.6 pounds for each horsepower it produces.
- Based on engine displacement,
the Wrights' engine produced about 4.5 horsepower per liter
while today's Aviator engine produces 66 horsepower per liter
- The Wrights' 1903 engine used
horizontal cylinders - the perfect design to heat and vaporize
the fuel using their crude gravity-fed fuel system.
- Proper exhaust valve lash or
clearance, which results in accurate and precise valve timing,
are crucial to making the engine run smoothly. Ford engineers
determined the optimum clearance and applied it to all
- Ford Motor Company was able to
provide specific data on cylinder efficiency. Even with its
crude design, it was determined that all cylinders were able
to produce power within 20 percent of each other.
- Spark timing plays an important
role in optimizing the performance of an engine. Ford
engineers and the engine builders experimented with spark
timing much like the Wrights did: adjusting by trial-and-error
to achieve what made the engine sound best. With the addition
of in-cylinder pressure data, the team was able to determine
the best settings of spark timing.
- You could just hear the
difference in the engine when we dialed things in," said
Steve Penkevich, a Ford Motor Company engine development
technical specialist. "That was the feedback the Wrights
had and we got similar results, just a little more
- There is no throttle to regulate
the speed of the engine, which is designed to run about 1,100
rpm every time. The load provided by the propeller was what
maintained the speed when the engine was installed in the
Wright Flyer. During the testing at Ford, the dynamometer was
used to regulate the speed of the engine.
- Intake valve actuation was
atmospherically controlled. The vacuum created in each
cylinder opens the intake valve. During the days of the Wright
brothers, this design was called an "automatic intake
- Exhaust valves are actuated by a
rocker assembly, which rides on the lobes of the exhaust valve
- A water cooling system provided
thermal energy to vaporize the fuel as well as cool the
engine. The water jacket surrounds the cylinder sleeves.
Normal operating temperature was about 200 degrees Fahrenheit.
- The Wrights' engine did not have
a water pump to circulate coolant so the engine could only run
for short periods of time to prevent overheating. Normal run
duration was 1-5 minutes.
- After two rounds of tests and
exhaust cam timing adjustments at Ford, the engine produced
12-17 horsepower - just what the Wrights got to get their
first powered, controlled flight off the ground.
Ford Motor Company engineers
To accommodate the primitive engine
in Ford's sophisticated engine testing facility, Ford's team faced
many challenges, including:
- Designing a wooden frame to
support the engine so it would rest on wood just as it did on
the Wright brothers' plane.
- Adapting one of Ford's
specialized dynamometers normally used to develop engine
theories on single-cylinder models to the low-power
- Reversing the direction of the
dynamometer to mimic the motion of the plane's engine.
- Specially designing a manifold
that surrounds the exhaust ports to collect data and vent
exhaust through the standard exhaust system in the lab, for
health and safety reasons.
- Protecting the staff and engine
from damage. All test cell safety monitors remained in place
and were active throughout the tests. Additional personnel
remained on site with fire extinguisher equipment at each
entrance of the test chamber. To protect the engine and
crankshaft, a specially designed attachment method was used
that would allow a pin to shear if excessive stress existed
between the Wright engine and dynamometer.
About the 1903 Wright engine
Cylinders: 4 (horizontal)
Block composition: Aluminum casting
Bore: 4 inches
Stroke: 4 inches
Propellers: Two, which rotate in opposite directions
Top speed: Approximately 30 mph
Weight: Approximately 180 lbs (dry)
Displacement: 202 cubic inches
Ignition system: Electronic "make and break"
ignition with power provided by a DC generator, which runs against
the engine flywheel. Approximately 10 volts at 2 amps.
Fuel system: Gravity-fed fuel injection system drips raw
gasoline into the vaporization chamber from a metal tank mounted
on the wing strut.
Normal operating temperature: About 200 degrees Fahrenheit.
Lubrication methods: Splash method (internal engine);
manual lubrication using an oil can (exposed parts) for cam,
rockers' valve stems, timing gear, ignition shaft and timing
About the engine builders
Steve, 61, and Jim Hay, 63, run Hay Manufacturing in Lake Geneva,
Wis., which produces not only antique engines, but also trumpet
parts and a variety of tool-and-die jobs. The brothers hand-built
the 1903 reproduction engine after years of extensive detective
The Hay brothers were grateful for
the opportunity to test their theories and fine-tune the engine
before its big day on Dec. 17, 2003.
"It won't prove anything if it
isn't exactly the same," Jim Hay said. "The tests at
Ford showed us our own hits and misses. Now all we have to do is
get out there and fly."