For Consolidated,I think it was developed from PB-2,with twin engine ?.
I rather doubt that. A tricycle undercarriage was preferred for X-608. Besides, the conceptual design of the 'taildragger' PB-2 dates back to 1927. (And, ironically in the X-608 context, to a Detroit Lockheed design.)
Pure speculation but I wonder if the Consolidated submission might not have been related to a design posted by
toura. That huge concept was described (in French) as being "[a]mong several preliminary projects that the Consolidated design office studied around 1937".
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https://www.secretprojects.co.uk/th...dels-first-numbering-system.1732/#post-332957
BTW, Joe Baugher says that "Lockheed was invited along with Boeing, Consolidated, Curtiss, Douglas, and Vultee to take part in a USAAC design competition X-608". However, the 1947 US Congress
Investigation of the National Defense Program: Aircraft contracts (Hughes. Aircraft Co. and Kaiser-Hughes Corp.) says that USAAC X-608 submission invitation letters were sent to Chance-Vought, Consolidated, Hughes, Lockheed, and Vultee. There is no mention of Boeing, Curtiss, or Douglas.
If Boeing, Curtiss, or Douglas responded to X-608, then these were strictly unsolicited responses. Actually, Hughes had already proposed a twin-engined intercepter to Wright Field back in May 1936.
So, the solicited submissions to Specification X-608 were:
Consolidated (??)
Chance Vought (??)
Hughes H-1
Hughes H-2
Lockheed Model 22
Vultee XP-1015 and Model 46 (XP-46-2)