Seversky/Republic AP series - AP-1 to AP-100

elmayerle said:

I'm going to argue for Advanced Project, but I don't know for certain.

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Also, I am told by the archivists at the Cradle of Aviation Museum (the Republic archive) that AP is indeed 'Army Project' and NP 'Navy Project'. I guess AP eventually became 'Air Force Project' after 1948, but cannot confirm that. The thing is the two prefixes are not duplicated - e.g. NP-48, NP-49, NP-50 and NP-52 are US Navy designs, AP-54, AP-55, AP-57 (F-103) are US Air Force, etc. I understand that there is no complete listing still surviving for Republic projects, and there are plenty more without project numbers. If your readers want some tasty Republic Projects, take a look at 'Aviation Week' for 5-12-58.

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Some time ago you had a thread looking at Republic project numbers. I put together a list using the numbers and information presented by forum members plus other projects that were known to me. I then sent it to the Cradle of Aviation Museum archive in America (where the Republic documents are stored) to see if they could add anything to it. Sadly, they could not, but they pointed out that quite a few versions of real aircraft would have received some of the missing numbers in the series. Consequently, the attached list is, as far as I know, the most complete that is currently available. Some of the text comes from American Secret Projects.

Republic Project Number Listing

The following are known project numbers.

AP-1 Modified P-35 for trials 1937

AP-2 Lost out in 1937 pursuit competition. Featured flush rectracting gear.

AP-3 Proposal with liquid cooled Allison V-1710 engine – abandoned in favour of AP-4.

AP-4 Adaption of P-35. Order of 13 aircraft in March 1939 (YP-43) delivered in September 1940 as P-43 Lancer.

AP-4J 1400hp Pratt & Whitney R-2180-1 powered proposal. 80 ordered Sept 13, 1939 as P-44 Rocket. Order cancelled.

AP-4L Proposal with 2000hp R-2800-7-also not constructed. Some sources use the name "Warrior" instead of "Rocket".

AP-7 Speed record aircraft. In 1938 Major Seversky used this a.c to establish a new transcontinental speed record.

AP-8 Never completed. Formed the basis for the AP-9

AP-9 Entrant in 1939 Air Corps fighter competition based on AP-8. Used improved airfoil. Air Corps turned AP-9 down in favour of Bell XP-39.

AP-10 Response to Air Corps circular proposal 39-770. Design submitted in August 1939 for a light weight fighter to be powered by a Allison V-1710 liquid cooled engine. Army placed an order as XP-47. XP-47A stripped version of XP-47. Contract signed January 1940. September 1940 all work on XP-47 and XP-47A was terminated. Full scale wind tunnel model handed over to Langley Field for testing. In same month contract placed for XP-47B - later to become the Thunderbolt.

AP-12 Republic answer to R40C. Highly streamlined design with engine behind the cockpit driving tractor contraprop in the nose via long shaft. Illustrations showing the design as the "Republic Rocket"

AP-18 Development of AP-12 "Rocket". Intended powerplant Wright R-2160. Design ordered as XP-69 in July 1941. Scale mock-up June 1942. Final configuration had long bubble cockpit. Cancelled 1943.

AP-23 Straight wing fighter project, 19.9.44. Became XF-84 Thunderjet fighter bomber prototype first flown 28.2.46.

AP-23X Preliminary design - March 1947 - for a sweptwing F-84. Not accepted by Airforce Material Command.

AP-23M Final sweptwing proposal . On the 10th November 1949 ordered as the YF-96.

AP-31 Proposal for high performance research aircraft and day interceptor, 1.46. Competition won by Convair XP-92 but AP-31 design ordered as prototype XF-91 Thunderceptor. XF-91 first flew 9.5.49 but no production.

AP-42 Heavy USAF bomber, c1944/45. Rival design to XB-46/B-47/XB-48??

AP-44A Mach 3 all-weather high altitude interceptor, early 1948.

AP-46 Development of F-84F fitted with turboprop engine as XF-84H and first flown 22.7.55. Apart from wing and cockpit, pretty well all new aircraft. No production.

NP-48 Proposal for US Navy interceptor based on XP/XF-91, c9.48.

NP-49 Proposals for US Navy interceptor with V-tail and underwing engine nacelles, c9.48.

NP-50 Naval bomber, late 1940s. Possible competitor in Douglas A3D competition (OS-111).

‘1954 Interceptor’ Three proposals made to this requirement, 1.51. One was development of AP-44A with turbo-ramjet powerplant, second the ‘XF-91B’ jet/rocket-powered development of XF-91, third a conventional turbojet plus afterburner design. Turbo-ramjet project one of competition winners and developed into AP-57 and XF-103.

NP-52 Twin-engine anti-submarine aircraft, early 1950s.

AP-54 Single engine swept wing all-weather interceptor fighter study with F-91-style wing and large tip fittings, late 1949/1950. May have been one of submissions to the ‘1954 Interceptor’ requirement.

AP-55 Twin-boom inverted V-tail lightweight fighter/interceptor project, early 1950. Later believed in competition with Lockheed F-104. Several versions drawn but none built.

AP-57 ‘1954 Interceptor’ proposal and full development into Mach 3 XF-103, 1951. Three prototypes ordered but project cancelled 8.57 before had flown.

All Weather Fighter-Bomber Study to MX1764, c1950/51.

AP-63 Swept wing fighter bomber, 1951 onwards. Numerous layouts covered by designation. Eventually design AP-63-31 built as F-105A Thunderchief to WS.306A. First example flew 22.10.55.

AP-75 Long range interceptor to WS.202A, c5.54.

AP-85 Two-seat swept-wing development of F-84F Thunderstreak, c1955.

AP-100 V/STOL fighter-bomber proposal with three large lift fans mounted in centre of wide fuselage, 1959/60.

TFX Believed Republic undertook Tactical Fighter studies to TFX requirement, 12.61. Competition won by General Dynamics/Grumman F-111.

FX Proposals for new fighter, 1965 onwards. One possibly designated FH-100. Studies included variable geometry wings but final fixed-wing proposal of 1968 rejected for McDonnell Douglas design that became F-15.

FR-150 V/STOL fighter design proposed for Sea Control Ship, 30.12.71. Lost competition to Rockwell XFV-12A.

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AP-55 Twin-boom inverted V-tail lightweight fighter/interceptor project, early 1950. Later believed in competition with Lockheed F-104. Several versions drawn but none built.

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