Bizarre Question
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From: New York & California
Bizarre Question
I was wondering that during the 1930's and 1940's when the United States had no supersonic wind-tunnels; was it possible to test a model at supersonic speed by mounting the model on a huge propeller and spinning it at a sufficient RPM?
You got the speed fast enough you'd get supersonic tip-velocities and if you were doing this for test purposes, thrust wouldn't be a desired goal.
You got the speed fast enough you'd get supersonic tip-velocities and if you were doing this for test purposes, thrust wouldn't be a desired goal.
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From: Sale, Australia
What they did and how they did it.
Research in Supersonic Flight and the Breaking of the Sound Barrier
Research in Supersonic Flight and the Breaking of the Sound Barrier
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From: Wor Yerm
Thanks Brian, that was a really good read. What was really eye-opening was that this research was either corporately or officially sponsored. You can't help but wonder if this sort of research is done nowadays?
PM
PM
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From: Manchester
I don't quite know why you would mount it on a prop. You'd have all manner of other forces acting, centripetal etc plus the prop itself would ruin any chance of any kind of analysis.
A supersonic wind tunnel isn't a difficult thing to achieve theoretically, it just requires high pressure gas, and a control of pressure. Realistically it's a right pain, because you need a very high pressure to get the necessary gas velocity.
A supersonic wind tunnel isn't a difficult thing to achieve theoretically, it just requires high pressure gas, and a control of pressure. Realistically it's a right pain, because you need a very high pressure to get the necessary gas velocity.
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From: New York & California
Ex Cargo Clown
The idea would be in days that a supersonic wind-tunnel didn't exist you could still get a supersonic tip velocity by spinning a sufficiently large diameter prop fast enough with a model on the tip
The prop would produce interference effects? Would the model need to be curved (to form the shape of the edge of the prop disc to deal with the fact that it would be spinning rather than going straight) or not?
To some extent I understand how a supersonic wind-tunnel works. Convergent/Divergent with slots in the area where the model is to avoid shockwaves from bouncing off the walls of the tunnel and messing up the readings.
I don't quite know why you would mount it on a prop.
You'd have all manner of other forces acting, centripetal etc plus the prop itself would ruin any chance of any kind of analysis.
A supersonic wind tunnel isn't a difficult thing to achieve theoretically, it just requires high pressure gas, and a control of pressure. Realistically it's a right pain, because you need a very high pressure to get the necessary gas velocity.
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From: New York & California
DERG
Well, when I was a kid I wanted to be an astronaut, but otherwise, no.
What things do I see that others don't?
Ever considered a job with NASA?
you can see things that others can't.
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From: Canada
During the early days of the CF105 Arrow {Canadas TSR2} They fired rockets across one of our large lakes with models of the aircraft mounted on the pointy end, using then state of the art transmitters data was collected by the base station . These models are now the subject of several searches by various SCUBA dives, dont think they have found one yet.
Last edited by clunckdriver; 19th February 2011 at 12:53.
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From: On the lake
During the early days of the CF105 Arrow {Canadas TSR2} They fired rockets across one of our large lakes with models of the aircraft mounted on the pointy end, using then state of the art transmitters data was collected by the base station
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From: Jungles of SW London
Never mind supersonic research, that DeHavilland can only be designed to fly sloooooooooowwwwwwwwwwly. 
Wow! The 'barn door' flaps on big airliners always amaze me, but those jokers are huuuuge! 
Would all that be an experimental rig for blown flaps? With prop wash it would practically be VTOL.
ROger.
Wow! The 'barn door' flaps on big airliners always amaze me, but those jokers are huuuuge! Would all that be an experimental rig for blown flaps? With prop wash it would practically be VTOL.
ROger.
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From: On the lake
At this point, the flap was only blown by prop wash, I believe!
I presume the purpose of the rig was to confirm actual pitching moments, pre-first flight. I'll try to find out from somebody who knows later this week.
I presume the purpose of the rig was to confirm actual pitching moments, pre-first flight. I'll try to find out from somebody who knows later this week.
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From: Escapee from Ultima Thule
Jeez, with flaps that size I wonder if it would need a larger tailplane volume to handle pitching moments &/or reduced IAS? I wonder if it could even maintain level flight. The drag would be enormous!
Last edited by Tinstaafl; 22nd February 2011 at 18:27.