The Hiller X-18, begun in February 1957, used various components from existing aircraft. The fuselage was that of a Chase YC-122C transport. The two wing-mounted 7,100 eshp Allison T40-A-14 turboshafts came from the XFY-1/XFV-1 tailsitter (#23 and #24) program and could not be cross-linked. It had three engines, the two turboprops drove the 16 ft diameter counter-rotating three-bladed propellers and a 3,400 lb thrust Westinghouse J34 turbojet which produced pitch control thrust.

 

The 33,000 lb loaded X-18 underwent extensive ground tests beginning in December 1958, and made its first conventional flight on 24 November 1959. It made partial conversions with wing angles of up to 33° (relative to the fuselage) -- with a 17° nose-up attitude, the wings had an effective 50° degrees of tilt (relative to the flight path). The turboprop engines had electric pitch controls and were too slow to provide adequate response in hover. On the 20th flight it had a propeller pitch control problem at 10,000 ft and went into a spin. It was recovered before impact, but was grounded, having never achieved hover. It continued to test ground effects before it was damaged by a test stand failure.

 

 Source: AHS V/STOL Wheel

Overview

Data on design, manufacture and status

Design authority: Hiller Aircraft Corporation

Primary manufacturer: Hiller Aircraft Corporation

Parent type: No type defined

Aircraft status: No longer flying

Configuration

Primary flight and mechanical characteristics

VTOL type: Convertiplane

Compound type: N/A

Lift configuration: Tilt wing (x4)

Dedicated control device: Thruster

Crew required: 2

Crew seating: Side-by-side

Landing gear: Wheels (non-retractable)

Overall Dimensions

Data on aircraft size

Engine Details

Aircraft powerplant (lift and/or propulsion)

Total number of engines: 3

Weights and Performance

Data on aircraft weight and flight characteristics

Max Gross Weight (ground): 14969 kg (33000 lb)

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