A work in progress...
Vought V- Series
V-3351943 USAAF fighter project derived from XF5U-1
V-3361943 US Navy F4U-1WM fighter version with Pratt & Whitney Wasp Major engine
V-337 1943 USAAF tailless fighter 'with special engine' project (led to the CUTLASS)
V-3381944 US Navy twin-engined single-seat carrier-borne fighter
V-3391944 US Navy twin-engined single-seat land based fighter
V-3401944 US Navy VF Carrier Based Landplane (became XF6U-1)
V-3411944 US Navy derivative of XF5U-1 with Special Powerplant Research
V-3421945 US Navy variant of F4U with single stage "E" engine and compressor
V-343 
1945 US Navy two-seat high-performance carrier-based night fighter (V-343-A-1 with Westinghouse 24C-4 engines, -B-1 and -B-2 with G.E. T6-100)
V-344
1945 twin-engined cargo transport project
V-3451945 US Navy carrier-borne observation type
V-3461945 US Navy High Speed Single Place Jet Fighter (XF7U-1)
V-3471945 High speed interceptor for US Navy
V-348 1945 four-seat commercial aircraft
V-3491945 US Navy Supersonic Pilotless Aircraft (P/A VI Long Range)
V-3501945 High Performance Search Type Aircraft for US Navy
V-3511945 US Navy variant of F4U with "E" type engine (F4U-5)
V-352 1946 US Navy production version of XF5U-1 (became F6U-1)
V-3531946 US Navy Studies for Pilotless Aircraft (Model P/A VI - short range)
V-3541945 two-seat high speed trainer derived from the F4U
V-355 1946 US Navy P/A XIV unmanned concept (Model P/A XIV)
V-356 1946 VA VF Airplane Long Range Escort - heavyweight long-range fighter for US Navy.
V-357 1947 Subsonic Pilotless Aircraft for US Navy; inherited know-how and technology from the experimental V-353, (XSSM-N-8 REGULUS).
V-358
1947 US Navy Class VA High Performance Attack Aircraft.
V-3591947 US Navy Improved F6U-1 project with afterburners.
V-360 1947 US Navy remotely controlled aerial target for US Navy
V-3611947 Variant of F4U-5 for the Netherlands with "C" type engine
V-362 
1948 Class VF Interceptor Fighter for US Navy to OS-113.
V-363 1948 US Navy long-range escort fighter
V-3641948 US Navy Long Range High Speed Jet Bomber project to specification OS-111.
V-365 1948 US Navy F7U-1 production version of XF7U-1
V-366 1949 US Navy F7U-2, F7U-3
V-366F1949 US Navy VF Class fighter proposal
V-366H1949 Cutlass twin-fuselage study
V-367 1949 US Air Force Penetration Fighter project
V-368
1950 US Navy twin-engined VA Class ASW studies (XS2U-1) to specification OS-117;
V-368A
1950 US Navy AEW Studies (XS2U-1W)
V-3691950 US Navy High Speed (550mph) target, became X28A
V-3701950 US Navy Tactical Missile (XSSM-N-8A Regulus)
V-371
1950 USAF high performance interceptor project (perhaps MX-1554/WS-201A)
V-372 1951 F7U-3 re-engined with Pratt & Whitney J57 engines for US Navy
V-373 1951 VF Long Range Fighter (research)
V-374 1951 USAF interceptor project derived from F7U-3
V-3751951 US Navy land-based ASW aircraft
V-3761951 export variant of F4U (Peru)
V-3771951 USAF proposed fighter-bomber variant of F7U-3.
V-378 1952 US Navy Long Range Fighter.
V-379 1952 US Navy supersonic missile design (SSM-N-9 Regulus II)
V-3801952 US Navy Carrier Based Dayfighter, became V-383/V-384
V-381
1952 US Navy carrier-based attack aircraft, A3U-1 Design Studies
V-382 
1952 USAF fighter-bomber projected derivative
V-3831953 US Navy Carrier Based Day Fighter with J57 engines, to specification OS-130. Built as F8U-1 Crusader.
V-384Alternate design to V-383 with J65 engines.
V-385 1953 US Navy Producibility Programmer for Regulus I.
V-3861953 USAF Strategic Fighter proposal
V-3871953 US Navy air-to-surface missile proposal
V-3881953 US Navy A2U-2 projected variant of F7U, an A2U-1 with larger wing
V-3891953 US Navy A2U-2 with J57 engines
V-3901954 US Navy A2U-1 projected variant of F7U with J46 Block III engines
V-3911954 USAF long-range fighter proposal to LRI-X requirement
V-3921954 US Navy F8U-1P carrier-based photo recce variant of F8U-1
V-3931954 US Navy Limited Attack version of F8U-1
V-3941954 US Navy All Weather Fighter with Attack (version of F8U-1?)
V-3951954 US Navy VFA Class all-weather fighter/ground-attack F8U variant (Sep. 1954)
V-3961954 USAF A2U-1 missile-carrying A2U-1 variant
V-3971954 US Navy SSM-N-9 (FTM) 36 missile with J79 engine; redesignated as RGM-15A-CV REGULUS II US Navy SSM-N-9 (TM) 7 missile with J79 engine; redesignated as RGM-15A-CV
V-3981954 adaptation of REGULUS to be carried by a B-52 bomber (A/B/C)
V-3991955 US Navy F8U variant with missiles and special stores carrier version
V-4001955 US Navy all-weather F8U variant with missiles and special stores carrier version
V-4011955 US Navy XF8U-3 high performance all-weather missile-carrier
V-4021955 USAF proposed variant of F8U-3
V-4031955 long-range ballistic missile project
V-4041955 US Navy Interim AEW / C & C electronic surveillance aircraft (May 1956) to OS-139 ; lost to the W2F-1 (E-2) Hawkeye
V-405REGULUS II 1955 US Navy KD2U-1 14 VKD Class radio-controlled target project (Jan. 1956); preceded by 7 conversions; redesignated as MQM-15A-CV
V-406
1955 US Navy attack aircraft
V-4071956 US Navy development of REGULUS II missile
V-4081956 US Navy F8U-1T (TF-8A) VF Class carrier-based two-seat trainer version proposal
V-4091956 short-range ballistic missile project
V-4101957 US Navy proposed rocket-assisted F8U-1 derivative, static thrust research
V-4111957 US Navy improvement studies of F8U-1, prefigured the F8U-2N
V-4121957 lightweight ASM missile project to be carried by a B-52 (Hound Dog)
V-4131957 US Navy projected "limited" all-weather variant of F8U-2, prefigured F8U-2NE
V-4141957 US Navy X-207 development program of REGULUS under X-207 specification
V-4151957 US Navy long-range ASM missile proposal for Eagle competition with Marquardt or Aerojet General engine (1958)
V-4161957 US Navy VA Class low-altitude all-weather attack aircraft "Vigilante" to TS149 requirement (lost to Grumman A2F Intruder)
V-4171957 US Navy ASW missile project, to be launched by a submarine (Subroc)
V-4181957 US Navy F8U-3 Phase II Improvement Studies
V-4191957 US Navy F8U-3 variant with J58 engine
V-4201957 NASA exploratory rockets project (Project Orb)
V-4211957 Battlefield missile project (project FIRE)
V-4221957 Nuclear powered supersonic missile project (project SLAM)
V-4231958 US Army Type A & B tactical missile project
V-4241959 Transport vehicle utilizing solid fuel rocket motor for manned space vehicle (Little Joe)
V-4251959 airframe for four-stage satellite launcher
V-4261959 Capsule for Man-In-Space (Mercury)
V-4271959 warhead adaption kit for LITTLE JOHN missile
V-4281959 guidance system project for SSGM-type missions
V-4291959 USAF advanced ASM missile
V-4301959 US Navy adaptation of a Sperry target Drone
V-4311959 ORB satellite family (Project ORB)
V-4321959 Scout four-stage launcher project
V-433
1959 US Navy "close support aircraft" project
V-4341959 Eagle Missile Carrier "Missileer" for VFMX requirement
V-4351959 USAF adaptation of SCOUT 609A Weapon System (Blue Scout)
V-4361959 USAF "1960 communications satellite" project
V-4371959 US Navy carrier-borne ASW aircraft project (Project "Oasis")
V-4381959 USAF flight simulator project for the F-108
V-4391959 space re-entry vehicle Free-Flight Model
V-4401959 USAF Aircraft Penetration Aid study
V-4411959 NAA "Fingerprint" guidance development
V-4421959 USAF tactical SSM project
V-443Not assigned.
V-4441959 North American "Fingerprint" guidance proposal for NAA/USAF
V-4451959 development of Project Hummingbird (Hipshot Astro) (presumably a VTO tailsitter)
V-4461960 USAF TERCOM (Terrain Contour Mapping) study
V-4471960 tri-service V/STOL transport project (XC-142)
V-4481960 Typhon SAM missile project
V-4491960 projected two-seat fighter/trainer variant of F8U-2
V-4501961 Light Attack Airplane (tri-service)
V-451
1961 turboprop-powered tactical support (Close Support) STOL aircraft project for Army and Marines.
V-4521961 US Navy XAAM-N-11 missile project for TFX program.
V-4531959 US Army Missile "B" (Lance) tactical missile.
V-454Crusader for French Navy
V-4551962 projected attack version of F8U (A3U)
V-4561962 F8U Interim Attack Aircraft (Interim VAX)
V-457Model 64 Missile - Tri-Service
V-4581962 US Army COIN light aircraft project
V-459
Intra-Theatre Transport - Tilt-wing
V-460
1963 Intra-Theatre Transport - ADAM
V-461USAF VA(L) attack variant of F8U with turbofan engine, became A-7
V-4621963 Advanced V/STOL Tactical Fighter Weapon System
V-463
VA(L) carrier-borne attack aircraft project. Became A-7 Corsair II.
V-4641963 Amphibian XC-142A ASW tilt-wing transport planning study
V-465
1963 Infra-Theater transport - large V/STOL transport project with lift jets
V-4661963 proposed variant of F8U for Great Britain
V-4671963 aircraft project for DSM program
V-4681963 Army reconnaissance aircraft
V-4691963 aircraft project for SBM program
V-4701963 CLAMP - Chemical Low Altitude Missile Puny, direct precursor of "modern" cruise missiles (although supersonic)
V-471
1963 Cruise Fan - Lift Fan - study for use of turbofan in cruise and sustaining modes
V-4721963 COIN aircraft project
V-4731964 US Army surveillance and target acquisition aircraft
V-4741964 proposed variant of F8U for Lebanon
V-4751964 SOR 210 VTOL transport project (against Bell D-2022)
V-4761964 USAF V/STOL close support aircraft
V-4771965 development of elements for the Douglas C-5A
V-4781965 60 passenger tilt-wing commercial transport aircraft
V-4791965 development of elements for the Lockheed C-5A
V-4801965 supersonic ADAM aircraft project
V-4811965 quick reaction ASM (U) armament project
V-4821965 ADAM II Concept Evaluation
V-4831965 fighter project for USAF FX requirement
V-484
1965 US Navy VFAX assault aircraft project
V-4851965 ADAM II - Forward Facing Nose Fan
V-4861965 aircraft project for ARM program
V-4871965 development of A-7D/SA variant
V-488 through V-499 not issued
V-5001966 missile project, became the MAVERICK missile
V-5011967 CARA (New Design)
V-502
1967 USAF AX aircraft project
V-5031967 CARA (XC-142 version)
V-5041967 "Super Crusader (F8/A7)"
V-505
1967 USN "F-111B replacement" - VFX - scaled-up derivative of the final V-483-149 VFAX design from 1967.
V-506
1968 LIT (Light Intra-Theater Transport) project
V-507
1968 USN interceptor project for VFX program, competitor of Grumman F-14 TOMCAT.
V-5081968 USN two-seater development of A-7
V-5091968 USAF two-seater development of A-7
V-5101968 two-seater development of A-7 for USAF special operations
V-5111969 USAF instrument trainer 2 seat A-7 project
V-5121969 projected "Wild Weasel" version of A-7
V-5131969 SCAR forward air control system project
V-514
1970 projected high performance variant of USAF A-7D (F100 engine)
V-515 
1970 projected high performance variant of Navy A-7E (F401 engine)
V-516
1971 USAF FAC - Forward Air Controller, aircraft project for special operations forces.
V-516A - two-seat derivative for commercial use.
V-516B - four-seat single-engine derivative for civilian use.
V-516C - four-seat twin-engine derivative for civilian use.
V-516D - two-seat single-engine derivative for military use.
V-516E - four-seat twin-engine derivative for military use.
V-517
1971 Navy AV(X) V/STOL aircraft prototype with fixed lift engines and (V-517A) TF30 and (V-517B) F401 turbofan. Also V-517D.
V-518
1971 USAF QRI jet interceptor project (Quick Response Interceptor program)
V-5191971 US Navy demo two-seat conversion of first A-7E
V-520
1971 V/STOL aircraft project with TF30 (V-520A) or F401 (V-520B) turbofan engine and swing-out lift engines.
V-1100
Advanced Lightweight fighter to LWF requirement.
V-2000
1973 Advanced Tactical Fighter
V-521
1972 US Navy V/STOL canard aircraft project with 2 lift, 1 lift/cruise engines.
V-5221972 US Navy Falcon 20E AWG-9 Trainer TCX.
V-523
1973 Advanced Navy Fighter project (navalised V-1100 LWF), pre-VFAX.
V-524
1973 Cross-Flow Fan Sea Control Ship Fighter Attack Aircraft.
V-5251973 US Navy sub-launched cruise-missile project.
V-526
1973-74 US Navy VFAX-type fighter-bomber aircraft project.
V-1600
Navy Strike Fighter Proposal derived from F-16 - F401 Engine
V-1601
Navy Strike Fighter Proposal derived from F-16- F100 Engine.
V-1602
Navy Strike Fighter Proposal derived from F-16- F101 Engine
V-5271976 Commercial Utility Cargo Transport - medium transport aircraft project
V-5281976 A-7 VAM US Navy all-weather two-seat attack variant
V-529
1977 US Navy Single seat A-7, updated V-528.
V-529Dwith F404-GE-400 engines
V-530
1977 US Navy Type A multimission ASW/AEW VOD/MA AV/STOL aircraft project
V-5311977 projected two-seat twin F404 engine rebuild of A-7D
V-532
1978 Undergraduate Pilot Trainer System proposal - Navy (V-532B submitted to VTX-TS)
V-5331978 Undergraduate Pilot Trainer System proposal - USAF
V-534
1978 Type A CTOL US Navy Study
V-5351979 USAF projected night attack variant of A-7 ('Nightstriker')
V-536
1979 US Navy Type B series flow tandem fan powered V/STOL aircraft project
V-537
1979 US Navy Type A V/STOL aircraft project with Stopped rotor
V-538
1980 USAF NGT "Fully Responsive to Req's" - two-seat single trainer project based on VFW/RFB FANTRAINER principle.
V-539
1980 USAF NGT "Alternate (Optimised Version)" alternate version of V-538 with twin engines.
V-540"Black-Hole Project (Secret)" - classified project (related to Northrop/Boeing/LTV "SENIOR ICE"?)
V-5411981 USAF NGT configured with high wing.
V-5501982 cheap multi-mission fighter-bomber project
V-5851981 MPWS - mobile defensive weapon system project for the Marines
V-600
1983 US Navy VMX study - derivative of the ATLAS
V-601
1983 US Navy NAA/NSAA Naval Adversary Aircraft; americanization of Mikoyan MiG-21; 24 new aircraft deliveries initially planned.
