Cooperative Airplanes of the U.S. Army Air Corps, 1930-1934

Today it is an extreme rarity for a manufacturer to develop and build a military type airplane for consideration by the U.S. Air Force or Navy without some commitment from the government to bear part or all of the development expenses. The risks associated with the millions of dollars required for such a development program are just too high without some guarantee of a return on the investment. In the late 1920s and early 1930s this was not the case.

Aircraft designs were progressing rapidly, particularly with fighters and trainer type aircraft. Aircraft companies were exploring new designs on their own and looking for opportunities to sell these to the military. Because of this rapidly changing environment, the standard government acquisition process using a request for proposal and competitive bidding was producing designs that were essentially antiquated before the delivery of even a prototype.

Recognizing this situation, the U.S. Congress passed legislation with the Act of July 2, 1926, that allowed the services to pursue contracts without requiring competitive bidding. The Army Air Corps chose to pursue this option on a limited basis while the Navy continued with procurements through standard bidding practices. This non-competitive bidding option was one of the driving forces behind what became the Cooperative Airplane Proposals (CAP).

Background
The Army Air Corps during the late 1920s and early 1930s frequently received requests to consider aircraft that a company was proposing to build and submit without a specific order or requirement having been specified. In each case, the Air Corps carefully advised the manufacturer that it would offer guidance, inspect mockups, provide equipment under a bailment contract for the prototype and test the model submitted. But, that this participation was done with the clear understanding that the Air Corps had no obligation whatsoever to purchase the type or bear any part of the development costs.

By 1930, the number of inquiries made to the Air Corps Materiel Division at Wright Field, Ohio, had reached such proportions that a system was needed to identify and track each proposal. Wright Field was the focus for evaluating and testing new designs and technology. The field had in use an airplane numbering series that dated back to the organization’s earliest days when it was located at McCook Field in Dayton. The practice, started in 1918, was to assign a number to each airplane undergoing trials at the field prefixed with a “P” (P-1, P-2, etc). Around 1926 an “X” prefix had been added to indicate “Experimental” types. By 1930 these numbers had reached XP-600 and it was realized that another series of numbers was needed to control the CAP being received by the Air Corps.

Modeled off the existing numbering system, but to avoid conflict, the CAPs were started with 900 and are believed to have extended up to number 950. All type numbers were preceded with an “X”, indicating their strict experimental status. The one change made in the new designation system was to indicate by the second letter the airplane’s function, e.g. in XP-900, the“P” stood for “Pursuit.” These designations matched . . .