British Full-Scale Wind-Tunnel & Turbulence (i.e. why they thought the Beaufighter could do 370 mph)

[wuzak]

I never noticed that the Tornado and Typhoon had different wing spans. I assume this has to do with the mounting differences between the engines?

 

[wuzak]

Not all data is to be had, but... this at least shows you that the estimates were heavily driven by power estimates. Look at the difference just projected from two engine choices.

You can also see at this point its a 12 x .303 gun aircraft.

(pencil scribbes are original)

Regarding the size originally envisaged I dont know, but I suspect from reading the file that this early speed esimate was little more than a rough
figure Hawker proposed based on the hoped for Sabre power in an updated fighter of approximate Spitfire/Hurricane size using more modern
design techniques. I think this was proposed before the air ministry specification was issued, and hence I think it is little more than Camm
saying "I can make a plane that goes that fast with that engine and has some guns".
View attachment 666650

The performance of the Vulture version wasn't too far off - 428mph vs ~400mph for the actual aircraft. Though I am not sure about the speed being achieved at 190,000ft!

There was a change in the radiator design of the Tornado early in the testing program. Might that have something to do with performance overestimation too? Was the initial Typhoon design also with a ventral radiator?

Calum, do you have the estimated engine power for those performance estimates?

 

[Admiral Beez]

the Beaufighter would manage 370 mph,

I wonder if this Bristol Beaufighter Mk IV with four blade props and Rolls Royce Griffon engines could do it.

Bristol Beaufighter Mk IV T3177 with Rolls Royce Griffon engines | World War Photos

Beaufighter Mk IV T3177 at Hucknall in 1943

www.worldwarphotos.info

https://rclibrary.co.uk/files_titles/2532/Profile_137_Bristol_Beaufighter_IandII.pdf

 

[Simon Thomas]

I found this interesting paper, which had the answer I was looking for:

The second question is why was not the tunnel made bigger and why was the speed limited to 115 m.p.h. A tunnel to test even the smaller of the best service aircraft under maximum speed conditions would require twice the cross section and at least three times the speed, so that instead of the present 2,000 h.p. for the fan, 100,000 h.p. would be required. Increase of size leads to reduction in sensitivity of balances and increased time on rigging and repair. The tunnel built represents a very convenient compromise for the type of work for which it is intended.​

COOLING PROBLEMS, WITH PARTICULAR REFERENCE TO THE WORK OF THE 24ft. R.A.E. TUNNEL
BY G. P. DOUGLAS, M.C., D.Sc., A.F.R.Ae.S.
Royal Aeronautical Society Proceedings Lecture November 18th, 1935.

 

[ThomasP]

Interesting.

 

[elbmc1969]

A tunnel to test even the smaller of the best service aircraft under maximum speed conditions would require twice the cross section and at least three times the speed, so that instead of the present 2,000 h.p. for the fan, 100,000 h.p. would be required.

This is why the German built wind tunnels in the Austrian Alps next to dams. IIRC, at least one was a direct, physical drive like a watermill. No generators.

 

[GregP]

@DarrenW , & @pbehn

I actually don't have a specific source (and I could be wrong), but I remember hearing something like this before. From what I remember, Supermarine didn't seem to be affected because they got most of their research data on race-planes they built and didn't listen to claims that a thick wing was desirable at high speeds. If I recall a Canadian guy named Beverly Shenstone (I'd have hated to be a guy with the name Beverly...) who also noted that Supermarine's data was correct.

One of the best aerobatic demo ever senn was by one Bevo (Beverly) Howard in a 1949 V-tail Bonanza. Beverly used to be a semi-popular boy's name.