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        Discussion High Alpha Flight

#1 Air Head Nov 29, 2010 06:14 PM

High Alpha Flight
 
While all you guys are trying to break 200 miles per hour ( or is it up to 210 now).

What about something like this.....How about a high alpha slow speed ducted fan model.

What sort of thrust to weight would I need to do some slow speed high alpha flight maneuvers....????

#2 Richie Simpson Nov 29, 2010 06:38 PM

If you have to ask....<g>
 
Without a variable exhaust nozzle it is not possible with a jet. No airflow over control surfaces.
That said delta wings are more forgiving, search for sapac Saab gripen for the best I have seen.

#3 DanSavage Nov 29, 2010 06:54 PM

Any modern jet is capable of high-alpha flight without TVN.

TVN is only required if you want to hover your jet at zero-airspeed, which is otherwise known as 3D flying.

#4 iron eagle Nov 29, 2010 09:12 PM

Quote:

Originally Posted by Air Head (Post 16683952)
While all you guys are trying to break 200 miles per hour ( or is it up to 210 now).

What about something like this.....How about a high alpha slow speed ducted fan model.

What sort of thrust to weight would I need to do some slow speed high alpha flight maneuvers....????

thrust to weight ratio would have to be 1 to 1.

#5 turbonut Nov 29, 2010 10:14 PM

Not really 1 to 1 but it helps to maintain alt. if your too slow..My old Kyosho Mirage would high alfa but if you got to slow and low you could not recover to level flight easy

#6 Bob Reynolds Nov 29, 2010 10:22 PM

Many, many years ago, My son, David, won the slow flying award at the Denver Jet rally at 16.4 mph. He was flying his own design "U-Who" with his own designed 4" fan. A picture of this plane appeared in RC Jet International, May 2001.

#7 crypto666 Nov 29, 2010 10:50 PM

http://lh3.ggpht.com/_m7VQ1uRXqMc/TP...h%20A%20FB.jpg

#8 Neil Guildford Nov 30, 2010 05:36 AM

My Tamjets F-16 1:8 will do a slow high alpha pass at its current weight of 20.5lb.

#9 aero1960 Nov 30, 2010 12:55 PM

It's been done. Here is my video of my own design.
360 Thrust vectoring with 64mm EDF RC F-22 Foamy (2 min 42 sec)


I modified it even more and am practicing on slow inverted high alphas.

#10 Erik v. Schaik Nov 30, 2010 01:09 PM

I have seen the Lubach F16 in 80 degrees high alpha. One needs vertical climbout to recover from this angle. Lightweight and critical CG is the only option. He used minifan,16/15/3 and 4s1800mAh.

#11 Erik v. Schaik Nov 30, 2010 01:14 PM

4 Attachment(s)
Quote:

Originally Posted by Richie Simpson (Post 16684168)
Without a variable exhaust nozzle it is not possible with a jet. No airflow over control surfaces.
That said delta wings are more forgiving, search for sapac Saab gripen for the best I have seen.

I think that is feasable;) A variable exhaust nozzle is a nogo IMO. The gain is in the intake design.

#12 marcelo3d Nov 30, 2010 01:34 PM

As said before, detla wings are the most forgiving. Jets with little taper (think L-39) may want to snap.
The main requirement is to have a rudder and use it to correct the trajectory as the nose starts to drop to the side. Ailerons cause adverse yaw: the wing that you are trying to lift gets more drag, so the plane yaws to that side.
You can do a nice high-alpha with not a lot of power. A pretty decent high-alpha will require lots more, but not 1:1. 1:1 (or a little more) is nice to get out of high-alpha: punch the throttle and release elevator. With less thrust, you have to let the nose drop and regain airspeed, losing some altitude in the process.
It is a fun manuver and very useful to know.
M.-

#13 Erik v. Schaik Nov 30, 2010 01:38 PM

What angle do you consider high alpha?

#14 DominicM Nov 30, 2010 02:15 PM

My GWS J-10 with working canards is awesome at high alpha.

F16s are great for high alpha slow flight. Don't understand why though. Very tempting to catch rather than land. Doesn't always end well.

High Alpha Disaster (0 min 55 sec)

#15 George-Styria Nov 30, 2010 04:03 PM

1 Attachment(s)
Here is my build TWM J10B with TV from rc-lander.
Works fine!!:D

http://www.youtube.com/watch?feature...&v=69CdmOd5KGo

Regards
George


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