British F.7/30 fighter specification.

[blackkite]

Hi!

F.7/30 Fighter capable of at least 250 mph and armed with four machine guns
Blackburn F.3, Bristol Type 123, Bristol Type 133, Gloster Gladiator, Gloster SS.19, Hawker P.V.3, Supermarine Type 224, Westland F.7/30

Specification F.7/30
https://www.alternatehistory.com/forum/threads/specification-f-7-30.368722/

Hi! Bristol type 123.

http://alternathistory.com/chetyrekhpulemetnye-istrebiteli-bristol-aeroplane-company-chast-1-bristol-type-123

Wikipedia.
https://en.wikipedia.org/wiki/Bristol_Type_123
"The aircraft was powered by a Goshawk III loaned by the Air Ministry, which used condensers in the lower wing leading edge for cooling, coupled to a forward-mounted ventral condenser. Engine cooling problems delayed the first flight, made by Cyril Uwins on 12 June 1934. Testing revealed serious lateral instability that a series of modifications to fin, rudder and the inner slots failed to cure, and which may have been structural. Development was therefore abandoned."

 

[blackkite]

Hi! Bristol type 133.

https://books.google.co.jp/books?id=glJgAwAAQBAJ&pg=PA77&lpg=PA77&dq=Bristol+Type+155&source=bl&ots=mwYMq-OqM-&sig=7GbLzEbD_ZG423sGUpijDB53lSY&hl=ja&sa=X&ved=0ahUKEwixjYjM6OrWAhUIUbwKHQp0A6oQ6AEIVzAI#v=onepage&q=Bristol%20Type%20155&f=false

http://alternathistory.com/chetyrekhpulemetnye-istrebiteli-bristol-aeroplane-company-chast-2-bristol-type-133?mini=calendar%2F2017-05

Wikipedia.
https://en.wikipedia.org/wiki/Bristol_Type_133
"The main wheels of the Type 133 retracted fully into bath-type fairings under the wings; this was done hydraulically, using a handpump."

"The Type 133 first flew carrying the experimental marking R-10 on 8 June 1934 piloted by Cyril Uwins, who was impressed. Testing over the next eight months produced some modifications including the addition of a sliding canopy and a crash pylon, better brakes, an enlarged rudder and the replacement of the tailskid with a castoring tailwheel. Engine exhaust and cooling were also improved. The long-span ailerons were shortened and combined with centre section split flaps. The aircraft was almost ready to attend the competitive tests at RAF Martlesham Heath when W.T. Campbell entered a spin with the undercarriage unintentionally down. An irrecoverable flat spin developed and Campbell had to abandon the aircraft. This ended Bristol's interest in the specification F.7/30 competition, which was won by the Gloster Gladiator."

 

[blackkite]

Blackburn F.3
http://www.airwar.ru/enc/fww1/blackf3.html
Wikipedia
https://en.wikipedia.org/wiki/Blackburn_F.3

"Following the release of Air Ministry Specification F.7/30 for a single-seat day and night fighter, eight different companies proposed 12 different designs and three, including Blackburn Aircraft, received contracts to produce a prototype. Blackburn's design, the F.3, was a single-bay biplane of unequal wingspan and with an unusual configuration, the upper wing being mounted approximately halfway up the stressed-skin fuselage and the lower wing about two feet below it, the gap being occupied by an enclosure for the condenser of the evaporatively-cooled Goshawk III engine. The undercarriage was attached to the lower wing's front spar, with diagonal struts transmitting the landing loads to the fuselage longerons. Initially the wheels were fitted with spats, but these were later removed. The four Vickers machine guns were fuselage mounted, two in mid-position on the fuselage and the other two on either side of the top of the condenser housing."

 

[Schneiderman]

F.7/30 Fighter capable of at least 250 mph ....

No, no, no and no. This is a myth, F7/30 did not specify a minimum top speed of 250mph, all it said was 'not less than 195mph at 15000ft'

 

[blackkite]

Indeed.

Westland F.7/30.
https://www.rcgroups.com/forums/showthread.php?2105916-Westland-F-7-30-%28or-Westland-PV-4%29
Wikipedia
https://en.wikipedia.org/wiki/Westland_F.7/30
"The Westland F.7/30 was designed in response to Air Ministry Specification F.7/30, which was formally issued in October 1931 and subsequently amended many times. It called for a day and night fighter with an armament of four .303-in (7.7-mm) machine guns, a top speed of at least 195 mph (314 km/hr), a high rate of climb, and a low landing speed. Although the specification did not request the use of the Rolls-Royce Goshawk evaporatively-cooled engine, the Air Ministry informally expressed a strong preference for its use and all of the design proposals selected by them for building as prototypes used it. The specification stressed the importance of a good "fighting view" from the cockpit and suggested a low-wing monoplane design as one possible solution to this problem. Another idea suggested was a pusher configuration."

"The engine was a Rolls-Royce Goshawk III or IIS, cooled by a radiator that was installed ventrally, aft of the legs of the fixed undercarriage. The position of the engine put the exhausts between the wings, behind and below the cockpit."

Rolls-Royce_Goshawk
https://en.wikipedia.org/wiki/Rolls-Royce_Goshawk

Russian site
http://www.airwar.ru/enc/fww1/f7-30.html

 

[blackkite]

Hi! Hawker P.V.3.
https://en.wikipedia.org/wiki/Hawker_P.V.3

"To meet this requirement, Hawker Aircraft submitted two designs, one a monoplane and the other a biplane, but both were rejected by the Air Ministry when contracts were awarded for prototypes in 1932, orders going to Blackburn Aircraft (for its F.3 and Westland Aircraft (the Westland F.7/30). Despite this rejection, Hawker decided to construct a single example of its biplane design, the Hawker P.V.3 as a Private Venture without an Air Ministry order. The P.V.3, design of which was led by Hawker's Chief Designer Sidney Camm, was an enlarged development of Hawker's Fury fighter, powered by the preferred Goshawk. Like the Fury, it had an all-metal structure with fabric covered wings (which unlike the Fury were swept back), tail and aft fuselage, with a metal skinned forward fuselage. Steam condensers for the Goshawk engine were fitted in the upper wing, supplemented by a smaller retractable condenser under the fuselage. It had a fixed tailwheel undercarriage with spats covering the mainwheels to reduce drag. Two machine guns were mounted at the top of the nose cowling, with two more machine guns mounted one on each side of the nose."

 

[blackkite]

Hi! Supermarine type 224.

https://twitter.com/spitfire_bot/status/837574335497818112

Wikipedia.
https://en.wikipedia.org/wiki/Supermarine_Type_224
"The evaporative cooling system used by the Goshawk involved allowing the cooling water to reach a temperature greater than 100 °C without boiling by keeping it under pressure while circulating through the engine: this superheated water was then allowed to boil off by releasing the pressure, the resulting steam then being cooled in a condenser, collected as water and then recirculated through the engine.

The system had been experimentally flown in other aircraft, but these were all biplanes, and the condensers and collector tank for the condensed water were all mounted in the upper wing. In the Type 224 the collector tanks were in the undercarriage fairings, and, as the condensed water was nearly at boiling point, it was liable to turn to steam under any slight change of pressure; this frequently occurred in the water pumps and would cause them to stop working."

 

[Schneiderman]

There is also this Hawker design, almost certainly an early concept associated with F.7/30 and remarkably similar to Bristol's Type 129.

http://www.kingstonaviation.org/js/plugins/filemanager/files/Brief_History_Banner__12B_Layout_1.pdf

The drawing seems to be available in the Kingston aviation groups archive or possibly at Brooklands. If anyone has access it would be nice to know more about it

 

[blackkite]

Oh!! Thanks a lot. I hope that your future work also include clear image of this design.

 

[Schneiderman]

Although F.7/30 said that any engine could be used that had received British type approval there was not actually much choice. The Hawker Fury that had just entered service could reach a little over 200mph with a Kestrel engine, and the new projects would have to at least match that while carrying twice as many guns, a radio and other 'extras'. The only engines available at the time that could deliver the necessary horsepower were the Goshawk, which was still under development, and the Bristol Mercury, that had been giving trouble for several years and had yet to meet its true potential. In the circumstances its not surprising that the Air Ministry favoured the Goshawk and most designers selected it for their projects.

 

[Schneiderman]

Oh!! Thanks a lot. I hope that your future work also include clear image of this design.

We need to see if there is a Hawker specialist on this forum, I'm sure there will be one.

 

[Schneiderman]

Then we have Boulton Paul's P67. They decided that the best solution to the visibility issue was to have two engine, in this case Napier Rapier air-cooled inline engines. It was an interesting design that featured a retractable undercarriage but let down by a rather basic monoplane wing with extensive wire-bracing. It may have been worth building to see how it compared with the single engine types.
3-view from the Putnam volume on B-P aircraft

 

[Schneiderman]

Early Bristol designs here

https://www.secretprojects.co.uk/forum/index.php/topic,4345.msg316419/topicseen.html#msg316419

 

[Schneiderman]

Armstrong Whitworth submitted the AW21 with either the A-S Hyena air-cooled 15-cylinder engine (just a project at this stage) or the conventional A-S Panther radial. Although it is a cantilever monoplane with a retractable undercarriage and looks advanced it actually had a conventional metal-frame fuselage with fabric cover and corrugated wing skinning. It was not built.
The Hyena engine was flight tested but ran into cooling problems. The Panther was not sufficiently powerful to meet F.7/30 requirements.
From the Putnam volume on A-W aircraft

 

[Schneiderman]

Vickers had been playing around with the Type 151 Jockey, a 1927 design, for a few years and had slowly improved its performance. Both Mercury and Jupiter engines had been trialled. The aircraft now sported a Townend ring around the engine and spats on the wheels. The cantilever wing was of Wibault corrugated construction and the weak rear fuselage had been redesigned by Barnes Wallis, but was still of conventional metal frame construction with non-loading bearing metal covering. It met F.7/30 requirements except for still having just two guns as flown, but the design was looking dated.
The aircraft entered a flat spin and was destroyed in July 1932 before it could be assessed for the competition.

 

[blackkite]

Hi!

 

[riggerrob]

At first glance, Bristol 123 has similar proportions to the (post-WW2) Pitts Special. They both have unusually short tail moment arms.
Pitts are great for aerobatics but so neutrally stable that they are tiresome for long cross-country flights. Pitts also have dismal forward visibility for landing.

In comparison, Bristol 123 has an even smaller vertical fin than Pitts: reducing directional stability.
Bristol 123's huge wheel spats/trousers/hawks' leg fairings also add a lot of lateral area forward of the centre of gravity, even further reducing directional stability.

 

[riggerrob]

Bristol 133 also has unusually large main wheel spats. They add even more lateral area (forward of the C. of G.) when extended, further reducing lateral stability. No wonder it could not recover from a spin. Note that later airplanes (Curtiss P-40, Douglas Skyraider, etc.) only use small leg strut fairings.

 

[Schneiderman]

The current issue of Aeroplane includes a short article about Specification F.7/30 that unfortunately repeats the errors - top speed 250mph, requirement for Goshawk etc - that were demonstrated to be incorrect at least twenty-five years ago, probably earlier. So, in an attempt to stop these errors spreading further here is the full text of the specification.