1903 Wright Engine

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nce they had decided to attempt powered flight, the Wrights calculated they needed an engine that produced at least 8 horsepower and weighed no more than 200 pounds (91 kilograms). A quick survey of the automotive market showed there was no such engine available and they would have to make their own. An acquaintance at the nearby Buckeye Irons and Brass Works advised then that they could save weight if they cast the engine block from aluminum. Although this was a soft metal, alloys had recently been developed that were much stronger both Benz and Daimler in Germany were successfully making engines with aluminum blocks. The Wrights decided to cast the block from an alloy of 92% aluminum and 8% copper.

After the castings had been made the Wrights "mechanician," Charlie Taylor, machined the parts and assembled the engine. He later described his work:

"We didn’t make any drawings. One of us would sketch out the part we were talking about on a piece of scratch paper, and I’d spike the sketch over my bench. It took me six weeks to make that engine. The only metal-working machines we had were a lathe and a drill press, run by belts from the stationary gas engine.

"The crankshaft was made out of a block of machine steel 6 by 31 inches and 1-5/8 inch thick. I traced the outline on the slab, then drilled through with the drill press until I could knock out the surplus pieces with a hammer and chisel. Then I put it in the lathe and turned it down to size and smoothness.

"The body of the first engine was of cast aluminum and was bored out on the lathe for independent cylinders. The pistons were cast iron, and these were turned down and grooved for piston rings.

"The completed engine weighed 180 pounds and developed 12 horsepower at 1,025 revolutions per minute. [It actually produced nearly 16 hp when it was first started, by this dropped to 12 hp as the engine heated up.]

"...The fuel system was simple. A one-gallon fuel tank [it actually held just 22 ounces] was suspended from a wing strut, and the gasoline fed by gravity down a tube to the engine. The fuel valve was an ordinary gaslight pet cock. There was no carburetor as we know it today. The fuel was fed into a shallow chamber in the manifold. Raw gas blended with air in this chamber, which was next to the cylinders and heated up rather quickly, this helping to vaporize the mixture. The engine was started by priming each cylinder with a few drops of raw gas.

"The ignition was the make-and-break type. No spark plugs. The spark was made by the opening and closing of two contact points inside the combustion chamber. These were operated by shafts and cams geared to the main camshaft. The ignition switch was an ordinary single-throw knife switch we bought at the hardware store. Dry batteries were used for starting the engine, and then we switched onto a magneto bought from the Dayton Electric Company. There was no battery on the plane.

"Several lengths of speaking tube, such as you find in apartment houses, were used in the radiator.

Other features included a bicycle chain turned the camshaft which operating the spark breaker arms and exhaust valves, but the "automatic" intake valves were opened by suction. Having no throttle, the motor only ran at full speed, tuned with a lever that adjusted the camshaft timing. A splash system lubricated the bearings and other moving parts in the crankcase, while a small gear-driven oil pump supplied oil to a tube that that dripped into the cylinders and onto the pistons.

The engine was first run on 12 February 1903. The very next day it overheated and seized up on the bench during a test run. New castings arrived from the foundry on 20 April 1903 and Charlie had the engine rebuilt and ready to go by early June.

After powering the Flyer on four flights at Kitty Hawk on 17 December 1903, the engine was seriously damaged when wind overturned the Flyer.  Today, the original cast aluminum engine block is displayed at the museum attached to the Wright Brothers Monument at Kitty Hawk, NC.  The Wrights sent the crankshaft and flywheel to be displayed at the Aero Club of America Exhibition of Aeronautical Apparatus in New York in 1906, and the parts were never returned.  The engine now on display in the 1903 Wright Flyer at the Smithsonian Institution was built in 1916 when Orville restored the Flyer for an exhibition at the Massachusetts Institute of Technology. Orville used some original parts (we don't know which or how many), but he made much of the engine anew.


  • Cylinders: 4
  • Stroke: 4 in (10.2 cm)
  • Bore: 4 in (10.2 cm)
  • Displacement: 201 in3 (3.3 l3)
  • Horsepower:12
  • Ignition: Make-and-brake powered by low-tension (10-volt) magneto.
  • Weight: 180 lbs (81.6 kg)
  • Unique features: Aluminum block, no carburetor.


  •  McFarland, Marvin W. (ed) The papers of Wilbur and Orville Wright. McGraw-Hill Book Co., New York, 1953, pp 1210-1214, plates 225-226.
  • Hobbs, Leonard S. The Wright Brothers' Engines and Their design. Washington, D.C.: Smithsonian Institution Press, 1971, pp 9-28.
  • Lippincott, Harvey H. Propulsion System of the Wright Brothers. In Wolko, Howard S. (editor), The Wright Flyer, an Engineering Perspective. The Smithsonian Institution Press, 1987, pp 82-86.

 [Submitted by Joe W. McDaniel]

The 1903 Wright engine on a test bench after it was restored in 1916.

The 1903 engine mounted in the Wright Flyer during restoration. As the engine heated up, the firing chambers on the left side of the engine nearest the pilot would glow red hot.

The castings for the 1903 Wright engine were made at the Buckeye Iron and Brass Works, a nearby Dayton, Ohio foundry. The engine block and bearing blocks were aluminum, the rest were cast iron.

Our working replica of the Wright 1903 engine built by Terry Hesler.

The 1903 Wright engine with the crankcase cover removed.

The spark that ignited the gasoline was supplied by a set of electrical "points" inside each cylinder. The steel arms of the points tipped with tiny amounts of platinum to forestall corrosion. As the engine runs, the points momentarily close, making an electrical connection, and then open again breaking the connection and creating a spark. This was called a "make-and-break" ignition system.

The fuel ignition doesn't happen in the cylinders, as in most internal combustion engines, but in these combustion chambers. The spring-operated "automatic" intake valves are at the tops of the chambers, while the cam-operated exhaust valves are at the bottom.

One hundred years of engineering advances separate these two aircraft engines. The 1903 Wright engine, when coupled to the propellers, produced 90 pounds of thrust (flb). The most recent General Electric CF34 Turbofan jet engine generates well over 20,000 flb.

The underside of the 1903 Wright engine, showing the oil pump as well as the cam shaft and rocker arms that operate the exhaust valves.

1903 engine installed in the Flyer at Kitty Hawk, before it flew. We're looking at the right side, opposite the pilot.

Charlie Taylor machined most of the parts of the 1903  Wright engine either from the castings or solid steel. A few, such as the gears, were farmed out to the Garrison Machinery Works, just a few blocks from the  Wright bicycle shop.

A cutaway drawing of the 1903 engine, showing the assembled parts.

Most of the engine lubrication was "splash-and-dash" -- the crankshaft churned the oil creating an oily vapor inside the crankcase. This small oil pump delivered extra lubrication to the pistons.

A detail showing the mechanism that opens and closes the points.

The 1903 Wight engine had no carburetor to vaporize the fuel. Instead, gasoline dripped onto the hot engine block through this opening. As the gasoline evaporated, it was sucked into the combustion chambers.

A detail showing a piston in its cast-iron cylinder. The cylinder is mounted in the aluminum engine block. The tube above the cylinder drips oil onto the interior surface of the cylinder where it is picked up and distributed by the piston rings.

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