Rolls-Royce Mustang Mk.X

Mustang Mk.X
Mustang Mk X AM203 in the third configuration tested with a high-speed paint finish applied by Sanderson and Holmes, the coachbuilders in Derby, UK.
Role Experimental aircraft
Manufacturer Rolls-Royce
First flight 13 October 1942
Introduction experimental
Primary users Royal Air Force
United States Army Air Forces
Number built 5
Developed from P-51 Mustang
Early Allison-powered P-51, October 1942

The North American Mustang Mk.X (as in "Mark.10"; also known as the "Rolls-Royce Mustang") was a British variant of the US North American P-51 Mustang using a Rolls-Royce Merlin engine in an experimental program established by the Rolls-Royce company in 1942.

Design and development

In April 1942, the Royal Air Force's Air Fighting Development Unit (AFDU) tested the Allison V-1710-engined Mustang at higher altitudes and found it wanting, but their Commanding Officer, Wing Commander Ian Campbell-Orde was so impressed with its maneuverability and low-altitude speed that he invited Ronald Harker from Rolls-Royce's Flight Test establishment to fly it.

It was quickly evident that performance, although exceptional up to 15,000 ft (4,572 m), was inadequate at higher altitudes. This deficiency was due largely to the single-stage supercharged Allison engine, which lacked power at higher altitudes. Still, the Mustang's advanced aerodynamics showed to advantage, as the Mustang Mk.I (P-51A) was about 30 mph (48 km/h) faster than contemporary Curtiss P-40 fighters using the same Allison powerplant. The Mustang Mk.I was 30 mph (48 km/h) faster than the Spitfire Mk VC at 5,000 ft (1,524 m) and 35 mph (56 km/h) faster at 15,000 ft (4,572 m), despite the latter having a significantly more powerful engine than the Mustang's Allison.[1]

Rolls-Royce engineers rapidly concluded that the Mustang powered by a two-stage Merlin 61 would result in a significant improvement in performance and started converting five Mustangs to Merlin power as the "Mustang Mk.X" (i.e., Mk.10) With a minimum of modification to the engine bay, the Merlin engine neatly fitted into the adapted engine formers. A smooth engine cowling with a "chin" radiator was tried out in various configurations. The Merlin 65 series engine was utilized in all the prototypes as it was identical to the Merlin 66 powering the Spitfire Mk IX, allowing for a closer comparison. Due to the speed of the conversions, engines were often swapped from aircraft to aircraft as well as being replaced by newer units.

Testing

The high-altitude performance was a major advance over the Mustang I, with the Mustang X serial AM208 reaching 433 mph (697 km/h) at 22,000 ft (6,506 m) and AL975 tested at an absolute ceiling of 40,600 ft (12,375 m). Air Ministry official, Air Chief Marshal Sir Wilfrid Freeman (Chief Executive at the Ministry of Aircraft Production) lobbied vociferously for Merlin-powered Mustangs, insisting two of the five experimental Mustang Mk Xs be handed over to Carl Spaatz for trials and evaluation by the U.S. Eighth Air Force in Britain. After sustained lobbying at the highest level, American production started in early 1943 of a North American-designed Mustang patterned after a P-51 Mustang prototype originally designated the XP-78 that utilized the Packard V-1650-3 Merlin engine replacing the Allison engine.

The pairing of the P-51 airframe and Merlin engine was later designated P-51B for the model NA-102 (manufactured at Inglewood, California) or P-51C for the model NA-103 (manufactured at a new plant in Dallas, Texas from summer 1943). The RAF named both these models Mustang Mk.III. In performance tests, the P-51B achieved 441 mph (710 km/h) at 25,000 ft (7,620 m) and subsequent extended range with the use of drop tanks enabled the Merlin-powered Mustang version to be introduced as a bomber escort.

Variants

Mustang Mk.X conversions:
Artist's concept drawing of the Rolls-Royce F.T.B.

Advanced developments

In June 1943, Rolls-Royce proposed to re-engine the Mustang with a Griffon 65, although the resultant "Flying Test Bed" (F.T.B.) would involve a dramatic redesign. Three surplus Mustang I airframes were allotted by the Ministry of Air Production and were dismantled in order to provide the major components for a mid-amidships installation of the more powerful Griffon engine, somewhat like the V-1710 Allison installation in both the American Bell P-39 Airacobra and Bell P-63 Kingcobra. The project culminated in a mock-up, albeit with a Merlin 61 temporarily installed, serialed as AL960, that was examined by representatives from the Ministry in 1944, but was not given priority status. Further studies involving more powerful engines or turboprops were not given approval and the development contract was cancelled in 1945 with the mock-up being destroyed.[2]

Operators

 United Kingdom
 United States

See also

Related development
Aircraft of comparable role, configuration and era
Related lists

References

Notes

  1. Birch 1987, p. 11.
  2. Birch 1987, pp. 96–98.

Bibliography

  • Birch, David. Rolls-Royce and the Mustang. Derby, UK: Rolls-Royce Heritage Trust, 1987. ISBN 0-9511710-0-3.
  • Delve, Ken. The Mustang Story. London: Cassell & Co., 1999. ISBN 1-85409-259-6.
  • Gruenhagen, Robert W. Mustang: The Story of the P-51 Mustang. New York: Arco Publishing Company, Inc., 1969. ISBN 0-668-03912-4.

External links

Wikimedia Commons has media related to Rolls-Royce Mustang Mk.X.
This article is issued from Wikipedia - version of the Wednesday, June 24, 2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.