Obtaining an engine for a lightplane was the greatest challenge facing amateur builders in the 1930s.
The prices for light airplane engines were prohibitive for most builders. The powerplant of the average small plane amounted to 60% of the cost of the complete plane.
That led builders to look to other sources of power. Auto engines, being cheap and plentiful compared to certified aircraft engines, proved tempting — so tempting, in fact, that in the 1930s there were 200 aircraft registered using Ford engines.
This widespread use caught the attention of the Bureau of Air Commerce, which was trying to foster the development of low-priced airplanes. By 1939 three aircraft using converted Ford engines would be successfully certificated for production.
THE $700 AIRPLANE
In November 1933, Gene Vidal unveiled the Bureau of Air Commerce’s plan to make owning a personal aircraft as commonplace as owning a medium priced car.
The bureau invited aircraft manufacturers to design a simple, safe vehicle that would sell for a target price of $700 and invested money in developing Ford auto engine conversions for aircraft use. The use of converted auto engines was supposed to drop the cost of an airplane’s powerplant to 25% of the total cost.
Out of this program two Ford powered aircraft would be put into production: The Arrow Sport and the Funk Model B.
But an independent effort would beat these two aircraft to the market — the Wiley Post.
WILEY POST MODEL A
At a time when interest was centered on the development of a low-cost plane, a new aircraft of this class appeared in Wichita. It was a small biplane produced by the Straughan Airplane Co., built around a converted Ford Model A four-cylinder engine rated at 40 hp.
This plane was later produced by the Wiley Post Aircraft Corp. The Wiley Post Model A was the first aircraft powered by a converted auto engine to receive a type certificate.
The plane was financed by Frank Straughan, a Ford auto dealer in Marshall, Okla. It was designed by and built by Ross Holmes, who had previously built a parasol monoplane powered with a Ford Model A engine.
The construction was typical for the time period, with a steel tube fuselage and an all-wood fabric-covered wing. The aircraft was devoid of some basic equipment, such as brakes and a tailwheel, which helped keep the original advertised price down to $990, which was the cheapest approved, factory built airplane one could buy at the time. Later the plane’s price would go up to $1,438.
The factory claimed a rate of climb of 400 feet per minute and a landing speed of 28 mph. The service ceiling was listed as 10,000 feet. Fuel capacity was seven gallons, which allowed a range of 140 miles.
The Wiley Post Corp. advertised the plane in 1935 as “The Training Ship for American Youth” and noted that engine parts were available at all Ford dealers.
The open cockpit featured side-by-side seating with dual stick controls. One flight instructor offered instruction in this Wiley Post for $1 a lesson and said that 40 lessons would be needed to be ready for solo.
The registration records show that 13 were built.
ARROW SPORT F
New in 1932, the Ford V-8 engine came into consideration by the Bureau of Air Commerce for its effort to secure a low-priced powerplant for lightplanes. The Ford V8 was the first that made an 8-cylinder affordable for the emerging mass consumer auto market. The Bureau worked with the Arrow Aircraft & Motor Corp. of Lincoln, Neb., to develop the engine for aircraft use.
The only part of the engine that had been changed from the automobile powerplant was the cooling system. The radiator was streamlined to fit under the engine cowling and one large water pump replaced the two regular ones. The motor was mounted backwards in the plane and gears built to turn the propeller at 1,000 rpm at cruising speed. It was rated at 82 hp at 3,000 rpm.
The Arrow was a strut-braced low-wing monoplane with side-by-side seating. The plane had dual wheel controls and dual brakes and a tailwheel instead of a tail skid.
The plane was initially priced at $1,500. Developers had originally planned to use the popular Kinner K5 aero engine, but that would have upped the selling price to $3,495.
The plane was listed with a rate of climb of 400 fpm and a landing speed of 48 mph. The service ceiling was listed as 12,000 feet. Fuel capacity was 20 gallons, which allowed a range of 300 miles.
The Arrow Sport proved itself to be a popular seller, with more than 100 built.
FUNK MODEL B
The last Ford-powered aircraft to receive a production certificate was the Funk Model A. It was produced by the Akron Aircraft Co., which was formed in 1937 to produce the aircraft designed by Joe and Howard Funk.
First developed in 1934, the plane developed interest with its appearance at the 1937 Miami Air Races.
The Civil Aeronautics Administration purchased one for evaluation. A more substantial aircraft than the Wiley Post or Arrow Sport, it was an enclosed cabin, high-wing monoplane designed for the $700 aircraft program.
The construction used a welded steel-tube fuselage with fabric-covered wooden wings and fabric covered. The cabin provided side-by-side seating for two.
The original aircraft built by the Funk brothers was powered by a Szekely three-cylinder radial engine of 45 hp, an engine they found to be unreliable. They looked at other engines, including the 40 hp Continental, which they felt didn’t have enough power, and the LeBlond 70-hp radial, which had sufficient power but was too costly at $1,000.
Impressed by the performance obtained by amateur builders with Ford Model B engines, the brothers decided to do their own conversion. The Bureau of Air Commerce became interested in the development work and helped finance the project.
To lighten the engine they used aluminum for the cylinder head, valve cover, coolant pump and end housing. The final weight of the powerplant, including the radiator and and coolant, was 300 pounds compared to the 350 pounds of the original Ford.
The Funk engine produced 80 hp compared to the original 40 hp of the Ford. The cost of the engine was $400, much more reasonable than most aircraft powerplants.
To improve aerodynamics, the engine was inverted and used a novel tunneled radiator installation. In production in 1939 and 1940, the Funk became the most produced of certified converted auto engine powered aircraft, delivering more than 100.
END OF THE FORD ERA
The era of Ford-powered production aircraft was short lived, with only the three aircraft receiving type certificates in 1935 and 1939. The Ford conversions were not offering any real advantages over the engines designed for aircraft use.
Aside from a fair amount of improved reliability and lowered manufacturing costs resulting from mass production, the converted automobile engines remained relatively heavy and bulky, weighing five to six pounds per horsepower, even more than the old OX-5 V-8 of 1915 design. The liquid cooling systems, radiators and plumbing, of the converted engines also added weight and complexity to the installation.
The new lightweight air-cooled engines from Lycoming, Continetal and Franklin coming on the market in 1935, weighing in the two to three pound per horsepower range, showed the auto engine conversions didn’t make engineering sense.