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Fact 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 Company.

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 of displacement.
  • 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 cylinders.
  • 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 efficiently."
  • 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 valve."
  • Exhaust valves are actuated by a rocker assembly, which rides on the lobes of the exhaust valve cam.
  • 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 overcome challenges

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 application.
  • 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 reproduction

Horsepower: 12-17
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)
Cooling: Water-cooled
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 chain.

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 work.

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."


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