In our seventh article in a series on the Bell D188A (a.k.a. XF-109 / XF3L) supersonic VTOL fighter of the late 1950s, we present a pair of Bell reports from December 1957, along with some internal BuAer correspondence critiquing the design.
The first document is Progress Report No. 5 dating from December 15, 1957. At the time, particular emphasis had been placed on the model test program which had proceeded according to or slightly ahead of schedule. Wind tunnel testing was continuing at Pt. Mugu on the 1/40 scale model and 1/6 scale inlet model. The .048 scale model was complete and testing would start in mid-December. The 1/10 scale fuselage inlet model was in test at FluiDyne. Fabrication was continuing on the free-flight and elastic deformation models. The jet impingement model had been completed and was being readied for testing.
A mock-up of the instrumentation and control panels was completed. Studies were in progress to eliminate weight increases indicated in the weight analysis of the preliminary design by further design refinement. A full scale mock-up of the fuselage, wing and nacelle had been assembled.
The second report dating from December 31, 1957 presents an overall plan for the D188A program. This is the first document thus far located to mention Bell’s submission to the Air Force SR-141 aircraft competition. Due to the marked similarity of the aircraft, it became apparent that perhaps one single airplane could be developed that would meet both the Navy and Air Force requirements; moreover, such an airplane could provide the Navy and Marines with a substantial attack capability in addition to satisfying the Fleet Defense requirement.
In view of these facts, both the Navy and Air Force immediately saw the many advantages afforded by undertaking a joint development program for a single common airplane. To this end, many joint meetings were held between the Air Force, Navy and Bell during which the configuration of the airplane was established and a joint Development Plan was prepared. In mid-December 1957, Air Force funds were transferred to the Navy to continue the program on an equal participation basis. At the time, the program was in its Phase I design stage.
Finally, we have an internal BuAer memorandum dating from December 17, 1957 discussing Bell’s VTOL structural design proposal. Attached to this were some interesting comments from the Aerodynamics and Hydrodynamics branches of BuAer. For example, here is the reaction of a Mr. Shaffer, PP-210, X-62766 on October 22, 1957:
Since PP-31 and PP-3 have been blunt with their comments I will also be blunt. Consider that the 8-engine version (and the 6-engine to a lesser extent) to be a monstrosity and impracticable for fleet operational and maintenance requirements. The J85 (and J83 also) will be just as complex to make into a workable installation free from instabilitys (sic) (Stall, etc) with adequate cooling, etc. as any of our current engines. Multiply this problem 8-fold for each fighter airplane, plus the 2 different engine configuration (sic), per airplane rotating mounts and the buried installations and a power-plant combination is arrived at which can’t be beat for making an airplane a hanger (sic) queen, not to mention the high power plant cost. Concur strongly with PP-31.
Despite the reservations of Shaffer and other BuAer personnel, the Navy’s involvement in the D188A program would continue until 1959. To view the documents in high resolution, please click through the gallery above.
All images from NARA Archives II, College Park, MD, RG 72
Report No. D188A-946-005, “Navy VTOL Fighter Program: Progress Report No. 5,” Bell Aircraft Corporation, December 15, 1957, in the files of the National Archives II at College Park, MD, RG 72
Report No. D188A-989-001, “D188A VTOL Weapon System Over-All Plan,” Bell Aircraft Corporation, December 31, 1957, in the files of the National Archives II at College Park, MD, RG 72