Looking through the Case History Report on the Whittle jet engine this morning, I noticed this summary of a 29 October 1943 letter from Brig Gen F. O. Carroll to Commanding General AAF, AC/AS, MM&D, Devel. Eng. Br., Lt Col M. C. Demler: "The [GE] I-16 engine was being considered by Consolidated Vultee Corp. for installation in an airplane that had been designed for the I-40. The reason for this was that the I-16 engine would be available much sooner than the I-40. Characteristics of the airplane both with the I-16 unit and the I-40 unit were listed." I'm not familiar with any such aircraft, does anyone know what it might have been and why it was being studied? I know there were huge numbers of purely conceptual designs being tossed around at the very dawn of the Jet Age, but this one has escaped me.