In our third article in a series on the Bell D188A (a.k.a. XF-109 / XF3L) supersonic VTOL fighter, we present a letter and two progress reports on the type dating from September through November 1957.
The first document presented in the image gallery above is a letter from E.G. Bull, the Bureau of Aeronautics Representative (BAR) in Buffalo, New York to the BuAer Chief dated September 16, 1957. By this time, Bell had been officially awarded a contract for the D188A program, NOas 57-836-c. In the correspondence, the BAR comments on a configuration comparisons report (which we have yet to locate in the National Archives) that makes the case for an eight-engine design (Configuration 2). He expresses some concern over the addition of these two engines; the aft location of the fuselage air intakes; the location of the speed brakes; and the time and resources being spent on the alternate J83 engine installation. However, at the end of the letter, the BAR agrees with Bell that the eight-engine design is the most appropriate for the project.
The next document, Progress Report No. 3, dates from October 15 of the same year. (Unfortunately, Progress Report Nos. 1 and 2 have yet to be located). Over the previous 30 days, Bell had continually refined the basic airplane and systems. Simplified instrumentation and pilot control arrangements were achieved. Information from component and system vendors had been received at a satisfactory rate. The latest estimates of weight and balance indicated no change from previous estimates of weight empty, and airplane balance was satisfactory. Preliminary testing of the 0.025 scale wind tunnel model had been completed. Work had been started on the 0.048 scale wind tunnel model, elastic deformation model, inlet models and the jet impingement model. Work was started on the airplane mock-up and had been concentrated on the wing framework and the cockpit region.
Finally, there is Progress Report No. 4 dating from November 15. According to Bell, substantial progress had been made by the completion of 61 of 62 evaluation drawings for the D188A required for the Phase I design. A preliminary evaluation of the 1/40 scale model test data indicated that performance estimates for the D188A were realistic. Emphasis was placed on model fabrication and substantial progress was made on the supersonic model, the free flight model, the inlet models and the jet impingement models. Weight increases were noted in the areas of alighting gear (+35 lbs), and armament (Sidewinder missiles,+40 lbs). A general review toward weight saving to compensate for these increases was being given particular emphasis. The basic framework of the airplane mock-up was completed and assembled, and was proceeding in an orderly fashion on schedule.
To view the documents in detail, please click through the image gallery above. Both progress reports include some interesting artist’s impressions, general arrangement drawings, and mock-up construction photos.
All images from NARA Archives II, College Park, MD, RG 72
Report No. D188A-946-003, “Navy VTOL Fighter Program: Progress Report No. 3,” Bell Aircraft Corporation, October 15, 1957, in the files of the National Archives II at College Park, MD, RG 72
Report No. D188A-946-004, “Navy VTOL Fighter Program: Progress Report No. 4,” Bell Aircraft Corporation, November 15, 1957, in the files of the National Archives II at College Park, MD, RG 72