U.S.
Xplanes experiment before 2000
Bell X1
Bell X2
Douglas X3 Stiletto
Northrop X4 Bantam
Bell X5
Convair X6
Lockheed X7
Aerojet X8 Aerobee
Bell X9 Shrike
North American X10
Convair X11 (XB65) Altas
Convair X12 (XB65) Altas II
Ryan X13 Vertijet
Bell X14
Northrop American X15
Bell X16 Bald Eagle
Lockheed X17
Hiller X18
CurtissWright X19 (XC143)
Boeing X20 Dyna Soar
Northrop X21A
Bell X22A
Martin X23 Prime
Martin X24
Bensen X25
Schweizer X26
Lockheed X27 Lancer
Pereira X28 Osprey I
Grumman X29
Rockwell X30
RockwellM.B.B. X31
Boeing X32
Lockheed Martin X33
Orbital Sciences X34 RLV
Lockheed Martin X35 (F35)
McDonnell Douglas X36
Boeing X37 SMV
Scaled Composites X38 CRV
U.S.A.F. X39
Boeing X40 SMV
Boeing X41 CAV
Orital Scuences X42 USFEx
Mirco Craft X43 HyperX
Lockheed Martin X44 Manta
Boeing X45 UCAV 
U.S. TriService VTOL
transport competition in 1961
Hiller X18
CurtissWright X19 (XC143)
Bell X22
¡@
U.S. VTOL experimental aircraft
