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Airspeed Napier Sabre fighters - June 1940

Schneiderman

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The Napier Sabre ran on the bench for the first time in January 1938 and was soon delivering in excess of 2000hp. The Air Ministry had already issued fighter specifications for aircraft to be powered by a high-powered engine, such as the Sabre, and a contract was awarded to Hawker for the Typhoon.
Development of the Sabre was slow, however, and while the problems were being addressed Napier decided to use one engine for an attempt at the World airspeed record and asked Arthur Hagg to design a racer specifically for this engine. Hagg had had a long and successful career with de Havilland where he had designed the Moth family, the DH88 Comet racer and the DH91 Albatross airliner before falling out with management and resigning in 1937. The racer was built by the Heston Aircraft Company as the Napier-Heston Racer in 1940. This was a highly promising design but its potential is regrettably unknown as it was wrecked on its first flight after the cooling system was damaged on take-off. Hagg continued to work with Napier advising them on engine installation issues. In 1942 he joined Airspeed (1934) Ltd as chief designer.
Airspeed had worked hard to obtain orders for advanced aircraft; bombers, fighters and airliners, but had failed to achieve success and seemed stuck building Oxfords and other relatively undemanding aircraft. With the arrival of the Sabre they embarked on another attempt, as described below.

Airspeed Aircraft since 1931, H.A.Taylor, Putnam 1970
Other Sabre-engined fighter projects were also worked upon by the Airspeed team, including one with a well-faired fixed undercarriage and cranked wing. Both this and a retractable-undercarriage version had their radiators aft of the cockpit with cooling air ram-fed into an underside scoop and venting through slots in the tail. A verbal order was given officially at one stage to Airspeed for a day fighter which formed the basis for these undesignated projects, using wooden construction as a means of conserving strategic materials. The order was later revoked under pressure, it is believed, from another sector of the aircraft industry.

This work took place in mid-1940, a turbulent time for Airspeed as de Havilland had become the majority shareholder and had placed their own men on the board, which must surely have distracted Hessell Tiltman, part-owner, director and chief designer, from detailed design work. The design of the above two aircraft is likely the work of one of his subordinates, but judging from the obvious similarity to the Napier-Heston Racer, a secret aircraft that had not yet flown, could it be that Hagg had offered advice?
So……..
 

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Schneiderman

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Two designs from June 1940 powered by a Napier Sabre and housing 12 machine guns. There are a number of differences between the two, other than the fixed undercarriage. The cockpit has been shifted, the inverted gull-wing is modified and it is slightly shorter.
 

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hesham

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Amazing find Schneiderman;

and there experience led to develop Napier Tailless Fighter as I think;

http://www.secretprojects.co.uk/forum/index.php/topic,3461.msg27590.html#msg27590
 

blackkite

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Super!! Thanks for sharing.
 

Schneiderman

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hesham said:
Amazing find Schneiderman;
and there experience led to develop Napier Tailless Fighter as I think;
http://www.secretprojects.co.uk/forum/index.php/topic,3461.msg27590.html#msg27590
I would doubt it, they are very different concepts. Airspeed were looking at ways to produce a quick, cheap fighter using non-strategic material, as Martin Baker and Miles had suggested before, while Napier were simply investigating radical concepts as part of a research programme. Rolls-Royce carried out similar investigations
http://www.secretprojects.co.uk/forum/index.php/topic,3441.msg27421.html#msg27421
 

Hood

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An excellent find.
Do you know what Specification these were designed for or based on? Or where they purely private-venture ideas they were trying to sell to the Air Ministry?
 

Schneiderman

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I suspect that it was a private venture although the fixed undercarriage, wooden construction and twelve guns is very much like that of the Merlin-powered Miles M20, which had specification F.19/40 written around it. If the comments in the Putnam about Airspeed receiving a verbal order for the aircraft are correct then I guess that would have been to F.19/40 too, the timing would be right. Selecting the Napier Sabre was probably a mistake.
 

cluttonfred

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Wonderful finds, thanks for sharing Schneiderman. I was also going to bring up the Miles M.20 for comparison and I agree that the Miles choice f a standardized RR Merlin "power egg" made a lot more sense than the Sabre. Do I undestand correctly that the radiator cooling air would have exited the airframe on either side of the rudder? Ingenious, but it seems to me that the radiator would have Ben very vulnerable in the aft fuselage.
 

Schneiderman

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Yes, the radiator duct system looks remarkably like that on the Napier-Heston Racer, minus the special Gallay radiator. I guess a rear positioned radiator would be slightly more vulnerable in a conventional rear attack than one shielded by the wing or engine.
 

blackkite

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Ummm.......What is the merit of this radiator position compared with Mustang radiator arrangement?
http://www.secretprojects.co.uk/forum/index.php?action=dlattach;topic=27685.0;attach=561245;image
"their radiators aft of the cockpit with cooling air ram-fed into an underside scoop and venting through slots in the tail."

Engine ram air intake is located wing root leading edge.
Armament is very powerful.

Attached drawing shows Napier-Heston Racer and Mustang radiator arrangement.
 

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