In our latest article in a series on the Bell D188A (a.k.a. XF-109 / XF3L) supersonic VTOL fighter of the late 1950s, we present more primary documents concerning this aircraft in a chronological sequence, specifically Navy Bureau of Aeronautics (BuAer) correspondence and a detailed Bell armament report from the February—March 1958 period.
First we have a memorandum from Cdr. M. Fitshugh, Director, Power Plant Division to the Director, Aircraft Division (AC-20) expressing concerns about the D188A propulsion system, specifically thrust availability; recirculation; engine controls; inlet distortion; missile firing; engine bleed air requirements; engine interchangeability; diverter valve assembly; starting system; and engine cockpit indicators. In view of these issues, Fitshugh recommended:
…that the contractor be required to demonstrate, by flight experience, that all of the above problems have been satisfactorily resolved before fleet introduction of such an aircraft is planned. It is strongly recommended that at least one of the first three aircraft be devoted exclusively to solution of propulsion system problems without any interference from avionic, airborne equipment, aerodynamic or structural problems.
Of course, this never occurred, as the aircraft never made it beyond the mock-up stage.
Next is a Bell “Armament Feasibility Study” focusing on possible Sidewinder installations for the D188A from March 17. Under contract NOa(s)57-836c, Bell undertook the design of a VTOL interceptor meeting the requirements of TS-140. This specified that four folding fin Sidewinder type missiles be carried internally. In December of 1957, Bell was informed that the folding fin Sidewinder configuration would not be continued and the feasibility of carrying fixed fin Sidewinders should be investigated. In addition, the change in program to a combined Navy-Air Force program with the Navy interested primarily in air-to-air armament and the Air Force primarily in air-to-ground armament resulted in the necessity to determine the feasibility of installing a number of varying armaments with a minimum of changes in the armament bay.
This report was concerned only with the feasibility of various Sidewinder arrangements, with studies of air-to-ground and other air-to-air weapons being contained in a Phase II report. Ten basic installation configurations were studied; to read about these in depth, please click through the gallery above, which also features several high resolution schematics of these armament arrangements.
This report is followed by a memorandum dated March 31 from the BuAer Director, Aircraft Division to the Assistant, Chief for Research and Development discussing a “stretchout” of the D188A VTOL program due to severe budgetary limitations in both the Navy and Air Force, among other subjects.
Finally, we have a photo of unknown date showing a military officer inspecting a scale model of the D188A’s main gear; part of the D188A mock-up may be visible in the background.
To view the documents, drawings and photo in higher resolution, please click through the image gallery above.
All images from NARA Archives II, College Park, MD, RG 72
Report No. D188A-945-239, “Armament Feasibility Study: Phase I—Sidewinder,” March 17, 1958, in the files of the National Archives II at College Park, MD, RG 72