During early 1955, Hiller Aircraft designed a large, tilt-wing VTOL aircraft as an in-house study. In 1956, U.S. Air Force interested this concept and assigned contract to Hiller for the development of a VTOL cargo transport. The test bed was designated X-18. In order to speed the construction process and to conserve available Air Force funding, the X-18 was built from many existing materials, such as the fuselage from Chase C-122, the turboprops engines from XFV-1 and XFY-1, miscellaneous parts from R3Y. The prototype was completed and started to proceed with ground testing in 1958. A year later, it made first flight without any difficult. After a total of 20 flights were completed, the Air Force ended its flight-testing and set aside for ground tests again to develop a database for the upcoming XC-142 transport project. In 1964, the X-18 was disassembled for scrap.

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Experimental tilting wing VTOL transport

To access feasibility of a large tilting wing VTOL aircraft

48ft.

63ft.

24ft.7in.

2x Allison YT40-A-14 turboprop

253 mph

2

None 

The Hiller X-18 is suitable to group with the following collection series.

U.S. X-planes experiment before 2000

Bell X-1

Bell X-2

Douglas X-3 Stiletto

Northrop X-4 Bantam

Bell X-5

Convair X-6

Lockheed X-7

Aerojet X-8 Aerobee

Bell X-9 Shrike

North American X-10

Convair X-11 (XB-65) Altas

Convair X-12 (XB-65) Altas II

Ryan X-13 Vertijet

Bell X-14

Northrop American X-15

Bell X-16 Bald Eagle

Lockheed X-17

Hiller X-18

Curtiss-Wright X-19 (XC-143)

Boeing X-20 Dyna Soar

Northrop X-21A

Bell X-22A

Martin X-23 Prime

Martin X-24

Bensen X-25

Schweizer X-26

Lockheed X-27 Lancer

Pereira X-28 Osprey I

Grumman X-29

Rockwell X-30

Rockwell-M.B.B. X-31

Boeing X-32

Lockheed Martin X-33

Orbital Sciences X-34 RLV

Lockheed Martin X-35 (F-35)

McDonnell Douglas X-36

Boeing X-37 SMV

Scaled Composites X-38 CRV

U.S.A.F. X-39

Boeing X-40 SMV

Boeing X-41 CAV

Orital Scuences X-42 USFEx

Mirco Craft X-43 Hyper-X

Lockheed Martin X-44 Manta

Boeing X-45 UCAV

U.S. Tri-Service VTOL transport competition in 1961

Hiller X-18

Curtiss-Wright X-19 (XC-143)

Bell X-22

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U.S. VTOL experimental aircraft