When the Wright brothers set out to fly in 1903, there were no engines on the market capable of powering their aircraft. So they built their own, and it’s a remarkable design.
Brothers Wilbur (1867-1912) and Orville Wright (1871-1948) were pioneers in aerodynamics—even before the science existed, in fact. Internal combustion engines were far from their field, it’s fair to say. In their careers they had engineered just one powerplant, a single-cylinder natural gas engine that powered the shop tools and wind tunnel in their Dayton, Ohio bicycle shop.
Their calculations indicated that to lift their 1903 Wright Flyer into the air, with its wingspan of 40 feet and projected weight of 700 lbs, they needed an engine of at least 8 horsepower and no more than 200 lbs. At the time, there was no such engine on the market, so with the help of their mechanic and machinist, Charles E. Taylor, they built one.
The Wright engine was of square bore/stroke proportions, unusual for the time, with a bore and stroke of four inches, yielding a displacement of 201 cubic inches. The crankcase was an aluminum-copper alloy casting, produced by a local foundry, while the four pistons were iron and the crankshaft was whittled from a thick steel slab by Charlie Taylor. He roughed out the shape with a hacksaw and chisels, and then finished the journals on a lathe. There were no formal drawings or plans as Taylor worked only from the Wrights’ rough sketches. The drawing above was produced decades after the fact by famed aircraft illustrator J.H. Clark.
The combustion chambers were an intriguing modular design that attached to the top of the cylinders. Each of these cartridge-like chambers contained a make-and-break spark igniter, an atmospherically operated intake valve, and a cam-actuated exhaust valve. A bicycle chain and a pair of sprockets operated the camshaft and low-tension magneto. The simple, raw-boned design did manage to keep the weight down to just 179 lbs, well below target.
While the photo above shows the engine standing upright, when installed in the aircraft it was laid down on its side (below). The primitive fuel-supply system employed no throttle and the engine ran at constant max rpm, approximately 1020-1090 rpm, turning a pair of pusher propellers. Hand-carved by Wilbur Wright, each propeller was 102 inches (8.5 feet!) in length, and the entire assembly was devised to produce somewhere in the neighborhood of 90 lbs of thrust.
Historians have long speculated how much power the Wright Flyer engine actually produced—estimates range from 12 hp to more than 30 hp. This much has been established: On December 17, 1903, near Kitty Hawk, North Carolina, the Wright Flyer made four flights, traveling 120, 175, 200, and finally 852 feet. The fourth and final journey that day lasted 59 seconds, and the era of manned, heavier-than-air flight had begun. If you had to pick just one single internal combustion engine as the most important in history, the task might be nearly impossible—but this one would make a fairly respectable candidate.
Excellent story, first rate scholarship.
Atmospheric intake valves? Sounds like this engine was actually a two stroke and the intake valves were reed valves, very much what Yamaha did with their two stroke motorcycle engines in the 70’s.
Intake valves opened due atmospheric pressure differential.
Yes many early cars intake valves were not cam operated, but were sucked open to admit the fuel!
Four stroke cycle, atmospheric poppet valves. When the piston travels down the bore, a negative pressure aka vacuum is created in the cylinder, so atmospheric pressure pushes the valve open. When the piston travels up the cylinder, pressure greater than atmospheric results and the valve is pushed closed. While the system is primitive. it has the advantage of being extremely light, so it was used on aircraft well into the 20s.
Similar to the valves of an air compressor, yes?
Unhappily the engine lacked any kind of cooling system and failed. Pieces of it can be seen in the Memorial Museum at Kitty Hawk.
Failed my behind!! It was the first recorded flight and it was damaged on landing and only one mount is broken.
Actually, the engine did have a cooling system. The radiator is visible in the side view of the aircraft. It was vertical in design and only about a foot wide (ref. centerline of aircraft). Simple water cooling system and the main cooling circulation hose from radiator to engine is also visible in the side-view.
For what it’s worth, the original engine no longer exists – and it hasn’t existed since shortly after the four 1903 flights. No one actually knows what happened to it, including Orville Wright (Wilbur died in 1912). The engine on the original (or partly original) 1903 Wright Flyer as exhibited at the National Air & Space Museum in DC is a reproduction – but there’s no certainty that it replicates the original exactly.
The original is in Kitty Hawk. One mount is broken from the final flight,
The article did not say that the engine did not have a cooling system, and would set up in about sis minutes.
I remember watching a program about the 100th anniversary. A team assembled to fly a replica of the plane. They duplicated the engine and I remember the video where they had some difficulties starting it up. But they got it running and installed in the plane in time to make that second historical flight. President GW Bush was on hand for that moment in history. Unfortunately the weather wasn’t very cooperative and the flight was short-lived. But at least they tried…