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In a message dated 9/28/2004 9:50:29 AM Eastern Daylight Time, HLFrancis
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Ercoupe Flight Tests With Solid Propellant JATO Units
A message was sent to the Air Corps in the spring of 1941 that we were ready for flight tests of an aircraft equipped with solid propellant JATO’s each delivering around 28 lb. thrust for about 12 seconds (cf. Section III). The Air Material Command selected the Ercoupe-low-wing monoplane, bearing the designation YO-55, for the tests and selected Homer A. Boushey, Jr. (then a Captain) as the test pilot. Boushey in 1941 was doing graduate work at GALCIT and also acted as liaison officer between the AAF and the Project. An analysis of the performance and flight characteristics of the Ercoupe and of the manner of installing multiple JATO units designed by the Project was made by C.F. Damberg and P.H. Dane of the Army Air Corps, as their GALCIT master’s thesis 53.
The Ercoupe was flown from Dayton, Ohio to March Field, California, at the end of July 1941, where modifications were made for installing the JATOs. The flight test group consisted of the following : (Project personnel) J.W. Parsons, E.S. Forman, F.S. Miller and myself, as director of the tests ; (AAF personnel) Capt. H.A. Boushey, Jr., Capt. R. Hamilton and Pvt. Kobe (figure 15). Von Karman and C.B. Millikan joined the group at various stages of the program and some of the tests were witnessed by W.F. Durant, Chairman of N.A.C.A. Jet Propulsion Committee, and Fischer of the Bureau of Aeronautics of the Navy Department 54.
A front view of the Ercoupe is shown in figure 16 with three JATOs installed under the wing of each side of the fuselage (cf. Figure 11) Each JATO was mounted on fuselage, ripping a 10 in. hole in the skin and shearing a bulkhead. The combustion chamber flew about 100 ft. ahead of the airplane before hitting the ground. Some damage was also done to the attachment installation. The report on the flight tests 55 contains the following laconic comment : " The pilot deserves credit for his willingness to continue flight tests as soon as the airplane was repaired ". Much to everyone’s relief there were no further explosive failures of the JATOs for the remainder of the test program during which 152 units were fired.
Figure 16
Front View of Ercoupe With Three JATOs Attached
Under Each Wing
On August 16, 1941, Boushey made the first take-off of the Ercoupe with six JATOs firing. A view of a take-off is shown in figure 17. The salient results of the test program are summarized in Table 1. They were found to be in reasonable agreement with the theoretical predictions made by Millikan and Stewart. It will be noted that the use of JATOs reduced the take-off of the Ercoupe by about one-half of the distance normally required. The flight characteristics of the airplane were not significantly affected.
Figure 17
View of Ercoupe Take-Off Assisted
By Six JATO Units
The first American manned flight of an aircraft propelled by rocket thrust alone was made by Boushey on August 23, 1941 (figure 18). The propeller of the Ercoupe was removed and 12 JATO units installed, however, only 11 functioned. The Ercoupe was pulled by a truck to a speed of about 25 m.p.h. before the JATOs were ignited. The airplane left the ground and reached an altitude of about 20 ft 56.This flight was not originally scheduled but we could not resist the opportunity to make the improvised demonstration of a future possibility of rocket propulsion.
Figure 18
View of Ercoupe About To Take-Off With
Rocket Propulsion Alone
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