List of experimental aircraft

For other uses, see Experimental aircraft.

As used here, an experimental or research and development aircraft, sometimes also called an X-plane, is one which is designed or substantially adapted to investigate novel flight technologies.^[1][2][3]

A group of 1950s NACA research aircraft

Argentina

• FMA I.Ae. 37 glider – testbed for production fighter

Australia

• GAF Pika – manned test craft for drone program

Brazil

• Baumgartl PB-60 – towed experimental rotor kite

Canada

Canadair CL-84 Dynavert tilt-wing VTOL research aircraft

• AEA Silver Dart (1909) – First aircraft to fly in Canada
• Avro Canada Avrocar – Ducted fan VTOL
• Birdman Project 102 –
• Canadair CL-52 – jet engine testbed (converted Boeing B-47)
• Canadair CL-84 Dynavert – tilt-wing VTOL
• de Havilland Canada C-8A – Quiet Short-Haul Research Aircraft
• de Havilland Canada C-8A – Air-Cushion Landing System
• de Havilland Canada C-8A – Augmentor Wing
• Marsden Gemini – variable-geometry glider
• NRC tailless glider – tailless flying wing
• UTIAS Ornithopter No.1

France

Breguet-Dorand Gyroplane Laboratoire

• Aérocentre NC.130 1939 – High-altitude flight
• Aérospatiale Ludion 1967 – Thrust vectored rocket VTOL
• Arsenal-Delanne 10 – Tandem wing
• Arsenal VG 70 – High speed research
• Arsenal O.101 – Aerodynamic research
• Arsenal 2301/SFECMAS 2301 and SFECMAS 1301 – Supersonic research glider
• Breguet-Dorand Gyroplane Laboratoire – Experimental helicopter
• Breguet-Richet Gyroplane – Experimental helicopter
• Breguet Laboratoire Eiffel [fr] – Monoplane testbed
• Dassault Balzac V – VTOL testbed
• Dassault Mirage IIIV – VTOL testbed
• Dassault Milan – Canard research
• Dassault Mirage G – Variable geometry
• Dassault LOGIDUC – Unmanned combat aerial vehicle UCAV development
• Dassault nEUROn – UCAV technology demonstrator
• Farman F.1010 – Heavy cannon flight testing
• Farman F.1020 – Semi-circular wing
• Fouga Gemeaux – Engine testbed
• Gastambide-Levavasseur Variable Surface Aircraft – Variable chord wing testbed
• Gérin Varivol – Variable chord wing testbed

SNECMA Coléoptère experimental tailsitter in 1959

• Hanriot HD.28 – tested a Vee tail
• Hurel-Dubois HD.10 – Very high aspect ratio wings
• Leduc 0.10 – Ramjet
• Leduc 0.21 – Ramjet
• Makhonine Mak-10 – Variable span wing
• Messier Monoplace Laboratorie – Retractable bicycle undercarriage testbed.
• Nord 500 – VTOL tilt ducted fan research aircraft
• Nord 1402/1405 Gerfaut – Delta wing research aircraft
• Nord 1500 Griffon – Ramjet
• Nord 1601 – Swept wing research aircraft
• Payen PA-22 – Tandem delta/normal wings
• Payen Pa 49 – Tandem delta/normal wings
• Potez-CAMS 160 – 5/13th scale six engine aerodynamic testbed for development of CAMS 161
• Robin X4 – Materials and configuration testbed
• SNECMA Atar Volant – Vertical lift jet
• SNECMA Coléoptère – Vertical lift annular wing
• Sud Est SE-1210 scale aerodynamic testbed for SE-1200 transatlantic flying boat
• Sud-Ouest Ariel – Tip-jet rotor helicopter
• Sud-Ouest Farfadet – Convertiplane
• Sud-Ouest Triton – First French jet aircraft

Germany

Dornier Do 29 tilt rotor STOL

• Akaflieg Berlin B 9 1943. – Prone pilot
• Albatros L.81 – Elektron metal structure testbed
• AVA AF 1 – Augumented lift
• DFS 194 1940 – Tailless rocket aircraft used in development of Me 163
• DFS 346 1948 – Supersonic reconnaissance aircraft used for research
• Dassault/Dornier Alpha Jet TransSonische Tragflügel (TST) – Transonic supercritical wing research^[4]
• Dornier Do 29 – Tilt rotor STOL

Heinkel He 178 pioneering turbojet-powered aircraft

• Dornier Do 31 – Experimental VTOL transport
• EWR VJ 101 – Experimental tiltjet VTOL fighter
• Fieseler Fi 158 – Testbed for radio control system
• Flettner airplane – Magnus effect test vehicle
• Flettner Fl 185 – Gyrodyne
• Focke-Wulf F 19 – Multi-engined canard demonstrator
• Fokker V.1 – Structures and aerodynamics testbed
• Göppingen Gö 8 – Development aircraft for Do 214
• Göppingen Gö 9 – Pusher (behind tail) aerodynamic testbed for Dornier Do 335 development
• Gotha Go 147 – Tailless research aircraft

Opel RAK.1 rocket engine research aircraft

• Heinkel He 119 – High-performance research aircraft
• Heinkel He 176 – Rocket research aircraft
• Heinkel He 178 – Jet engine research aircraft
• Horten H.III – Flying wing
• Horten H.IV – Flying wing
• Horten Ho VI – Flying wing
• Junkers J 1 – Pioneering all-metal cantilever monoplane (1915)
• Junkers EF 61 – Pressurization
• Junkers Ju 49 – High-altitude test aircraft
• Lippisch Delta IV – Delta wing
• Lippisch DM-1 1944 – Delta wing glider
• Lippisch Ente – Rocket-powered canard technology demonstrator
• Lippisch P.13a – Coal-powered delta wing
• Messerschmitt Me P.1101 – Variable geometry (swing-wing) jet
• Opel RAK.1 – Rocket propulsion technology demonstrator
• RFB X-113 – Wing in ground effect vehicle
• RFB X-114 – Wing in ground effect vehicle
• Sack AS-6 – Disk wing technology demonstrator
• Schmeidler SN.2 – Wing flaps
• VFW VAK 191B – VTOL fighter
• Zeppelin-Lindau V I – All-metal stressed skin construction

Italy

Caproni-Campini N.1/CC.2 experimental motorjet and second jet aircraft to fly

• Ambrosini Sagittario 1953 – Swept wing research aircraft
• Bossi-Bonomi Pedaliante 1936 – Human-powered aircraft
• Caproni Campini N.1 1940 – Jet engine research
• Jona J-6 – Tilting wing stabilisation system
• Lualdi-Tassotti ES 53 – Gyro stabilized helicopter
• Piaggio P.111 – High-altitude research
• S.C.A. SS.2 – Experimental canard
• S.C.A. SS.3 Anitra – Experimental canard
• Stipa-Caproni – Ducted prop research
• Sandro Simoncini - Experimental helicopter

Poland

• Flugtechnische Fertigungsgemeinschaft Prag FGP 227 – Scale proof of concept for German BV 238
• Lala-1 – Jet biplane testbed for PZL M-15 Belphegor

Japan

Gasuden Koken

• 

  NAL Asuka

  Gasuden Koken 1937 – Long range experimental aircraft
• Honda MH02 1993 – Over wing engines, forward swept wing
• Kawasaki Ki-78 1942 – High speed research aircraft
• Kayaba Ku-2 1940 – Tailless glider
• Kayaba Ku-3 – Tailless glider
• Kayaba Ku-4 – Tailless research aircraft
• Kimura HK-1 – Tailless glider
• Mitsubishi RP-1 – Experimental helicopter
• MXY-6 – Canard scale testbed for Kyushu J7W
• X1G – High-lift device based on Saab 91 Safir
• National Aerospace Laboratory (NAL) Asuka – STOL
• Shin Meiwa UF-XS – Proof of concept demonstrator for Shin Meiwa US-1A
• Mitsubishi T-2CCV - Experimental aircraft for CCV technology
• Mitsubishi X-2 Shinshin – Advanced stealth technology demonstrator

Russia/Soviet Union

Antonov A-40 tank glider

Bartini Beriev VVA-14 Ekranoplan

• Alexeyev – Ekranoplans
• Antonov A-40 1942 – Tank glider
• Antonov 181 – Blown channel wing demonstrator
• Bartini Beriev VVA-14 1972 – Ekranoplan ground effect vehicle
• Bartini Stal-6 – High speed aircraft
• Chyeranovskii BICh-3 – Tailless delta research aircraft
• Chyeranovskii BICh-11 – Flying wing to test wingtip rudders
• Chyeranovskii BICh-16 – Human-powered ornithopter
• Chyeranovskii BICh-18 – Human-powered ornithopter
• Chizhevski BOK-1 – High-altitude research aircraft
• Chizhevski BOK-5 – Tailless research aircraft
• Grigorovich I-Z – Recoilless cannon evaluation
• Grushin Octyabrenok – Tandem wing
• Ilyushin Il-76LL – Engine testbeds (5)
• Kozlov PS – Visibility (covered in transparent material)
• MAI EMAI – Magnesium construction
• Mikoyan-Gurevich MiG-8 Utka – Pusher canard proof of concept (1945)
• Mikoyan-Gurevich MiG-105 – Lifting body
• Mikoyan Project 1.44 – Technology demonstrator
• Mikoyan-Gurevich N – Mixed propulsion system

Yakovlev Yak-36 VTOL research vehicle

• Moskalyev SAM-9 Strela – Delta wing
• NIAI RK – Telescopic wings
• NIAI RK-I – Telescopic wings
• Nikitin PSN-2 – Glider bombers
• Sukhanov Diskoplan – Disk wings
• Sukhoi T-10 – Technology demonstrator
• Sukhoi T-58VD – VTOL research aircraft
• Sukhoi Su-47 – Technology demonstrator
• Thermoplan – Heavy lift lenticular-shaped hybrid airship technology demonstrator
• Tsybin LL – Forward swept wing
• Tsybin NM-1 – Proof of concept
• Tupolev Tu-95LAL – Nuclear-powered aircraft
• Ushakov – Flying submarines
• Yakovlev Yak-36 – VTOL technology demonstrator
• Yakovlev Yak-42LL – Progress D-236 propfan engine testbed
• Yakovlev Yak-1000 – Supersonic technology demonstrator
• Zveno project – Parasite fighters

Spain

Cierva C.6 autogiro

• Cierva C.4 1923 – Experimental autogyro, first to fly
• Cierva C.6 1924 – Experimental autogyro

Sweden

• Saab 201 - Aerodynamic testbed for Saab 29 Tunnan
• Saab 202 – Aerodynamic testbed for Saab 32 Lansen
• Saab 210 1952 – Aerodynamic testbed for double delta concept for Saab 35 Draken

Switzerland

• Solar Impulse Project – Solar power technology demonstrator

United Kingdom

Avro 707 research aircraft in formation with Avro Vulcan bomber prototypes

Fairey Delta 2 research aircraft

Gloster E.28/39 jet engine research aircraft

Miles M.35 Libellula canard research aircraft

• Armstrong Whitworth Ape 1926 – Variable configuration aerodynamic test vehicle
• Armstrong Whitworth A.W.52 1947 – Jet powered flying wing
• Avro 707 1949 – Aerodynamic proof of concept for Avro Vulcan delta wing bomber
• Avro Ashton – Jet engine research vehicle based on Avro Tudor
• BAC 221 – High speed delta wing research
• Baynes Bat – Experimental tailless glider
• Blackburn B-20 – Retractable hull seaplane
• Boulton Paul P.6 – Wing research
• Boulton Paul P.92 – Half-scale proof of concept for turret fighter
• Boulton Paul P.111 – Delta-wing research aircraft
• Boulton Paul P.120 – Delta-wing research aircraft
• Bristol 138 – High-altitude research aircraft
• Bristol 188 – High speed flight research
• British Aerospace EAP – Technology demonstrator
• Cierva W.9 – Experimental helicopter with anti-torque jet efflux
• de Havilland DH 108 Swallow – Swept wing tailless transsonic research aircraft
• English Electric P.1A – Supersonic research aircraft
• modified Fairey Battle – Engine testbed for Rolls-Royce Exe, Fairey Prince (H-16) and Napier Dagger.
• Fairey Delta 1 – Delta-wing research aircraft
• Fairey Delta 2 – Delta-wing research aircraft
• Fairey Jet Gyrodyne – Jet-powered rotor technology demonstrator
• Folland Fo.108 – Engine test bed
• General Aircraft GAL.56 – Tailless swept wing glider
• Gloster E.28/39 – Jet engine research
• Gloster Meteor F8 "Prone Pilot" – Prone position flight control research
• Gloster Trent Meteor – Turboprop propulsion
• Hafner A.R.III Gyroplane – Experimental autogyro
• Handley Page H.P.17 – Aerodynamic slot research
• Handley Page H.P.20 – Aerodynamic slot research
• Handley Page H.P.75 Manx – Tailless flight research
• Handley Page HP.88 – Handley Page Victor aerodynamic testbed
• Handley Page HP.115 – Low speed delta-wing research
• Hawker P.1052 – Swept wing testbed
• Hawker P.1072 – Armstrong Siddeley Snarler rocket booster testbed
• Hawker P.1127 – V/STOL technology demonstrator, led to Hawker Harrier
• Hillson Bi-mono – Slip-wing research
• Hunting H.126 – Blown flap research
• Miles M.3E Gillette Falcon – High speed flight research
• Miles M.30 – Blended wing body design
• Miles M.35 Libellula – Tandem-wing fighter testbed
• Miles M.39B Libellula – Tandem-wing research
• Miles M.52 – Supersonic flight research
• Parnall Parasol – Wing pressure and aileron testing
• Parnall Peto – Experimental submarine-launched aircraft
• Parnall Prawn – Flying boat testing buried engine with variable-angle thrust line
• Reid and Sigrist R.S.4 Bobsleigh – Prone-pilot research
• Rolls-Royce Thrust Measuring Rig – Low speed VTOL control test rig

Rolls-Royce thrust measuring rig VTOL testbed

• Saro Shrimp – Experimental half-scale flying boat for development of cancelled Saunders-Roe S.38
• Saunders-Roe SR.53 – Mixed rocket/jet propulsion development aircraft for cancelled Saunders-Roe SR.177
• Short Cockle – Metal construction technology demonstrator for flying boats
• Short Mussel – Testing metal construction techniques for aircraft floats
• Short S.6 Sturgeon – Tested aluminium construction techniques for aircraft
• Short S.31 – Half-scale model for Short Stirling development
• Short SB.1 – Tailless glider for isoclinic wing research
• Short SB.4 Sherpa – Powered isoclinic wing research
• Short SB.5 – English Electric Lightning wing research
• Short SC.1 – VTOL research
• Short Silver Streak – Stressed skin construction, developed into Short Springbok
• Supermarine 508 – Development aircraft with vee tail
• Supermarine 525 – Swept wing development aircraft for Supermarine Scimitar program
• Vickers Type 618 Nene-Viking – Jet engine testbed
• Vickers Type 470 and Type 486 Wellington – Whittle jet engine testbeds
• Vickers Type 602 Wellington Mark X – Rolls-Royce Dart turboprop testbed
• Westland-Hill Pterodactyl – Tailless monoplane testbeds
• Youngman-Baynes High Lift – Youngman flap testbed

United States

Bell X-1 supersonic research aircraft

Bell X-5 variable-sweep wing testbed

North American X-15 hypersonic rocket-powered research aircraft

X-planes

Main article: List of X-planes

• Bell X-1 – Supersonic flight and sound barrier
• Bell X-2 – Mach 2–3 supersonic flight
• Douglas X-3 Stiletto – Sustained supersonic flight
• Northrop X-4 Bantam – Tailless aircraft
• Bell X-5 – Variable-sweep wing
• Convair X-6 – Nuclear reactor test aircraft (for nuclear-powered aircraft)
• Lockheed X-7 – Unmanned ramjet and guidance test missile
• Aerojet General X-8 – Sounding rocket (became Aerobee)
• Bell X-9 Shrike – Guided missile
• North American X-10 – Unmanned missile technology demonstrator
• Convair X-11 – Single engine missile testbed for Atlas
• Convair X-12 – Three engine missile testbed for Atlas
• Ryan X-13 Vertijet – Tail sitter VTOL jet
• Bell X-14 – Thrust vectoring VTOL jet
• North American X-15 – Hypersonic rocket-powered research aircraft (Mach 6)
• Bell X-16 - High-altitude reconnaissance jet
• Lockheed X-17 – Research rocket testing high mach re-entry
• Hiller X-18 – Tiltwing STOVL cargo aircraft
• Curtiss-Wright X-19 – VTOL tiltrotor
• Boeing X-20 Dyna-Soar – Spaceplane program
• Northrop X-21 – Laminar flow wing
• Bell X-22 – Ducted fan V/STOL
• Martin X-23 PRIME – Lifting body reentry vehicle testbed
• Martin Marietta X-24 – Lifting body test aircraft
• Bensen X-25 – Single-seat autogyro
• Schweizer X-26 Frigate – Sailplane
• Lockheed X-27 Lancer – high-performance technology demonstrator based on Lockheed CL-1200
• Pereira X-28A Sea Skimmer – Single-seat flying boat for US Navy

Grumman X-29 forward swept wing and stability research aircraft

• Grumman X-29 – Forward-swept wing test aircraft
• Rockwell X-30 – Single-stage-to-orbit spacecraft
• Rockwell-MBB X-31 – Extreme angle of attack test aircraft
• Boeing X-32 – Joint Strike Fighter Program technology demonstrator
• Lockheed Martin X-33 – Unmanned scale demonstrator for VentureStar single stage to orbit spacecraft
• Orbital Sciences X-34 – Reusable launch vehicle testbed
• Lockheed Martin X-35 – Joint Strike Fighter Program technology demonstrator, developed into F-35 Lightning II
• McDonnell Douglas X-36 – Tailless fighter research agility aircraft
• Boeing X-37 – Reusable unmanned spacecraft
• NASA X-38 – Crew return vehicle for International Space Station (cancelled after tests)
• X-39 – Reserved for USAF/DARPA program use
• Boeing X-40 Space Maneuver Vehicle – Testbed for X-37 guidance and flight characteristics
• X-41 Common Aero Vehicle – Classified DARPA/NASA maneuvering re-entry vehicle
• X-42 Pop-Up Upper Stage – Classified rocket upper stage
• NASA X-43 Hyper-X – Hypersonic scramjet
• Lockheed Martin X-44 MANTA – Multi-axis tailless aircraft concept
• Boeing X-45 – Unmanned combat air vehicle
• Boeing X-46 – Unmanned combat air vehicle (proposal only)
• Northrop Grumman X-47A Pegasus – Unmanned combat air vehicle
• Northrop Grumman X-47B Iron Raven^[5] – Aircraft carrier capable unmanned combat air vehicle technology demonstrator
• Boeing X-48 – Blended wing aircraft
• Piasecki X-49 – Compound helicopter technology demonstrator
• Boeing X-50 Dragonfly – Gyrodyne unmanned aerial vehicle
• Boeing X-51 Waverider – Mach 5+ scramjet missile demonstrator
• Boeing X-53 Active Aeroelastic Wing – Wing warping flight demonstrator
• Gulfstream X-54 – Supersonic boom intensity research and demonstration aircraft
• Lockheed Martin X-55 – Advanced composites technology demonstrator
• Lockheed Martin X-56 – Flutter suppression and gust load testing unmanned testbed
• NASA X-57 Maxwell - Electric-powered light aircraft
• Lockheed Martin X-59 QueSST - Low-boom supersonic aircraft
• Generation Orbit X-60 - Air-launched single stage suborbital rocket vehicle
• Dynetics X-61 Gremlins - Unmanned aerial vehicle
• General Dynamics X-62 VISTA - Variable stability, thrust vectoring (formerly known as NF-16D VISTA)
• ABL Space Systems X-63 - Aerospike variant of RS1 rocket booster
• Invocon X-64 - Recoverable suborbital rocket
• Aurora X-65 CRANE - active flow control demonstrator
• Boeing X-66 - Truss-Based Wing demonstrator

Other experimental types

US Army Bell 533 high speed helicopter research aircraft

XFV-12A on ramp at NAA in Columbus, Ohio

Scaled Composites Proteus in flight during 2002 for US Department of Energy ARM-UAV program

• Acme Sierra 1959 – Technology demonstrator
• AstroFlight Sunrise 1974 – Solar powered drone
• Ball-Bartoe Jetwing 1977 – Blown wing research
• Bell D-292 1985 – Advanced Composite Airframe Program
• Bell L-39 1946 – Swept wing research
• Bell Model 65 1954 – Tiltjet VTOL
• Bell XV-15 1977 – Tiltrotor VTOL, precursor to V-22 Osprey
• Bell 533 1962 – US Army high speed helicopter experiments
• Boeing ecoDemonstrator 2012 – Airliner fuel efficiency and noise reduction technologies
• Budd BB-1 Pioneer 1931 – Stainless steel construction
• Burnelli RB-1 1921 – Lifting body proof of concept vehicle
• Carlson-Lynch Vertipactor 1923 – Wingless VTOL aircraft
• Chrysler VZ-6 1959 – Ducted fan
• Convair NB-36 1955 – Nuclear propelled aircraft testbed
• Convair XFY Pogo 1954 – Fixed propeller VTOL
• Curtiss-Wright VZ-7 1958 – Quadcopter
• Curtiss-Wright X-100 1963 – Tilt rotor VTOL (developed into X-200 and X-19)
• Custer Channel Wings 1953 – Blown half-barrel wings
• Doak VZ-4 1958 – Tilt-fan VTOL
• Douglas D-558-I Skystreak 1947 – Supersonic research
• Douglas D-558-II Skyrocket 1948 – Supersonic research
• Fairchild VZ-5 1959 – Deflected air VTOL
• Farrar LSG-1 Bird Flight Machine 1969 – Glider to research bird flight

Lockheed Vega Winnie Mae high-altitude research aircraft – confirmed existence of jet stream

• General Dynamics F-16XL 1982 – Relaxed stability delta wing, boundary layer suction laminar flow
• General Dynamics F-16 VISTA 1992 – Variable stability, thrust vectoring (Redesignated X-62 Vista in 2021)
• General Electric GE36 testbed 1986 – Propfan engine testbed on a modified Boeing 727
• Goodyear Inflatoplane 1956 – Inflatable rescue aircraft technology demonstrator
• Gossamer Albatross 1979 – Human-powered flight
• Gossamer Condor 1977 – Human-powered flight
• modified Grumman Gulfstream II – Engine testbed for the NASA Propfan Test Assessment (PTA)
• Hiller VZ-1 Pawnee 1955 – Direct lift rotor platform
• Hypersonic Technology Vehicle 2 2010 – Hypersonic glider
• Kaman K-125 1947 – Intermesh twin rotor helicopter, servo-flap control
• Kaman K-16 – Modified Grumman Goose for tiltwing V/STOL research
• Lockheed Altair 1938 – Twinned engine testbed (both engines were in a single cowl)
• NASA Dryden Lockheed C-140 Jetstar 1964 – Electronic variable stability, propfan engine (1981) and laminar flow wing testbed (1985)^[6]
• Lockheed Have Blue – Stealth technology demonstrator
• Lockheed Vega Winnie Mae – high-altitude research – confirmed existence of jet stream
• Lockheed QT-2 – Quiet Thruster noise suppression experiments
• Lockheed XC-35 – Pressurized cabin development

Lifting body research aircraft – from left to right, X-24A, M2-F3 and HL-10

• Lockheed XV-4 Hummingbird – Jetlift VTOL
• LTV XC-142 – VTOL transport technology demonstrator
• Martin 162A Tadpole Clipper – Proof of concept aircraft
• Martin XB-26H Marauder – Tandem undercarriage
• McDonnell Douglas MD-81 UHB – General Electric GE36 and PW-Allison 578-DX propfan engine testbed
• NASA AD-1 – Oblique Wing
• NASA Environmental Research Aircraft and Sensor Technology experimental aircraft – ALTUS, Pathfinder and Helios
• NASA Hyper III – Lifting body remotely piloted vehicle
• NASA M2-F1 – Lifting body/re-entry vehicle
• NASA Pathfinder – Solar-powered aircraft
• Northrop F-5 Shaped Sonic Boom Demonstrator – Shockwave reduction

Northrop N-9M flying wing

• Northrop HL-10 – Lifting body/re-entry vehicle research
• Northrop M2-F2 – Lifting body/re-entry vehicle research
• Northrop M2-F3 – Lifting body/re-entry vehicle research
• Northrop N-1M – Flying wing research
• Northrop N-9M – Flying wing proof of concept aircraft for Northrop YB-35
• Northrop Tacit Blue – Stealth technology demonstrator
• Piasecki PV-2 – Helicopter technology demonstrator
• Piasecki VZ-8 Airgeep – Liftfan VTOL research
• Piasecki PA-97 1980 – Heavy lifter
• Republic XF-84H "Thunderscreech" – Supersonic propeller testbed
• Republic XF-91 Thunderceptor – Inversely tapered swept wing
• Rockwell HiMAT – Maneuverability and control research
• Rockwell XFV-12 – Augmented wing vectored thrust VTOL
• Rotary Rocket Roton 1999 – Single stage to orbit helicopter rocket
• Ryan VZ-3 Vertiplane 1958 – Blown flap VTOL research
• Ryan XV-5 Vertifan 1964 – Fan lift VTOL research
• Sawyer Skyjacker II – Low aspect ratio research aircraft

Vought V-173 disk wing research aircraft

• Scaled Composites Proteus 1998 – Telecommunication relay testbed
• Schweizer SGS 1-29 1958 – Laminar flow research on wings made of metal
• Sikorsky S-69 1981 – Compound co-axial research
• Sikorsky S-72 1976 – Helicopter/aircraft hybrid research
• Sikorsky S-75 1984 – Advanced Composite Aircraft Program
• Sikorsky S-76 SHADOW 1985 – Sikorsky Helicopter Advanced Demonstrator and Operator Workload
• Stinson L-1 Vigilant – One example modified for boundary layer experiments
• Travel Air 2000 – One modified for Besler steam powered aircraft
• Vertol VZ-2 – tilt wing VTOL research
• Vought V-173 – Disk wing research for Vought XF5U
• Vought V-326^[7] – High-altitude test aircraft
• Vought-Sikorsky VS-300 – Helicopter

See also

• List of German WW II prototypes and projects