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Old Nov 14, 2012, 12:28 PM
310mph Kolibri T25 Swist
henke's Avatar
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Quote:
Originally Posted by Chuchuf View Post
henke, this project must be edf. While I would like to build it with a P200, that is just not an option.

I like your ideas too, I just want to shuf in my experiences. Reading only on rcgroups leaves you lonely with the electric fanboys and you might loose the whole perspective.

Check out Andys T38 above(close in size and weight of the L39), an awsome project but badly needs more power if you ask me. 12kW sounds like alot, but for a big plane like this it's still marginal for aerobatic flights.
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Old Nov 14, 2012, 06:06 PM
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Quote:
Originally Posted by falcon5 View Post
For planning and to get an idea of large EDF possabilities here is a twin Stumax 100mm EDF powered 12 foot long T-38 that flew decent on 6000 watts per fan for about 28 pounds of thrust. The plane weighed 44 pounds AUW and with onboard GPS reported 135 mph on a flat pass, calm wind.

http://www.youtube.com/watch?v=1SS2cD69wAI
Falcon.
I'm pretty impressed with the performance of your plane and would be pleased with performance like that.
Do a straight interpretation, if I hit 60 lbs, I'll need 8000+ W per fan to achieve results like yours assuming the air frames are equal (which they aren't)
So some quick math says on 14S I would be looking at 143A at 4V/cell call it 150A. Thats reasonable. Comes out to 266W/lb but I'm sure there will be a certain inefficiency of the twin so lets say 230W/lb. I'm still pretty happy with that.

Falcon, how did you construct your thrust tube arrangement?

Thanks,

Terry
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Old Nov 14, 2012, 06:11 PM
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Quote:
Originally Posted by henke View Post
Check out Andys T38 above(close in size and weight of the L39), an awsome project but badly needs more power if you ask me. 12kW sounds like alot, but for a big plane like this it's still marginal for aerobatic flights.
henke, you know from other groups that you and I are in that I like to go fast. Maybe not quite as fast as you but fast none the less.
If I build this plane it will be for someone else who would be very happy with performance like Andy's T38.
So I think that is a goal to shoot for.

Terry
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Old Nov 15, 2012, 01:14 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
Joined Jan 2001
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Quote:
Originally Posted by Chuchuf View Post
henke, you know from other groups that you and I are in that I like to go fast. Maybe not quite as fast as you but fast none the less.
If I build this plane it will be for someone else who would be very happy with performance like Andy's T38.
So I think that is a goal to shoot for.

Terry
If that's the case all is fine All is not about going fast, next years project will go slow but still with great performance.
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Old Nov 15, 2012, 06:07 AM
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Speed of sound

True Steve, But the Speed of Sound we are used to is at Std temp and Sea level. See what happens to it when to go up to altitude, and temperature, and preassure changes, because of compression. LIke I said before, EDF's are air pumps, not turbines. There is no "Gain" like you have in a turbine. Also the XF-88B and XF-84H use laminer flow airfoils. EDF blades are nowhere close to that.
Bottom line, there is a limit to All EDF's as far as maximum RPM. If you want more thrust, the swept area has to get bigger.

My 2 cents worth

Larry E.




Quote:
Originally Posted by Steve C View Post
Why would this have to be true? Wouldn't every fighter jet fall out of the sky then because the wing would stall at supersonic speeds?

A prop or fan can be made to run supersonic as long as the airfoils and angle of attack are under control. This was tested by NACA with a 6,000 hp prop dyno/windtunnel and the XF-88B and XF-84H

It is however unlikely that the ET fan was designed for this or that they ever ran one near 100k rpm.
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