August 2018

2018 August

Rolls-Royce “The Flying Bedstead”
Thrust-Measuring Rig (TMR) Experimental Research VTOL
First free flight: August 3, 1954

The Flying Bedstead was the first pure Jet (manned and untethered) VTOL machine that successfully took to the air. It was piloted by Captain Ron T. Shepherd, chief test pilot for Rolls-Royce. The 7,196 pounds craft was called the Rolls-Royce Thrust Measuring Rig (or TMR), but it was better known by its unofficial name of The Flying Bedstead (Serial Number XA314). The TMR was the first manned untethered VTOL machine that used Jet Lift for free hover.

The power behind the TMR were two Rolls-Royce Mk4 Nene centrifugal compressor turbo jets, with ducts converging at the center of gravity after a 90 degree turn downward. Controls in all axes were obtained through puffer jets deriving from engine bleed (10% of engine bleed). Landing gear consisted of four caster wheels.

Rolls-Royce built two TMRs. TMR No. 1 crashed during testing at the Royal Aeronautical Establishment, in Farnborough; and TMR No. 2 (Serial Number XA426) suffered the same fate. TMR No. 1 was later rebuilt with parts of the second machine.

There is no question that the Harrier, although not a direct descendant of the Flying Bedstead, benefited from the experiences in controls and jet effects learned on both TMRs. As a minimum, the Bedsteads proved that Jet Lift was possible; what is more, the Bedsteads provided the impetus and support necessary for the successful follow on VTOL programs in Great Britain (namely, the Shorts SC.1 and the Hawker P.1127).

The surviving Flying Bedstead can be seen today displayed at the Science Museum in London.

Photo via Nico Braas and Johan Visschedijk,
Text: Erasmo Piñero Jr.

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