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Old Dec 24, 2012, 07:49 AM
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Cougar429's Avatar
Canada, ON, Windsor
Joined Apr 2008
972 Posts
Winters here, it's Christmas Eve and with family coming down I've had to "Grandson Proof" the build room. The Bear and the other big warbirds will likely now sit till spring.

On the note of surface mods, this brings up another question. Just picked up an Eflite BAE Hawk and it's reported that without significant aileron reflex the stall can happen way before expected. Once free to pull out my "Stuff" again, (no pun intended) I intend to check if there is any washout at all as I suspect little to none. One other trick was to add diamond cut sandpaper to the leading edge areas to simulate "Glider Tape". I've read about this as the resultant turbulation enhances laminar flow, but found no pics to describe how or where it's applied.

Happy Holidays everyone and thanks for the help.
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Old Jan 01, 2013, 05:11 PM
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stuntflyr's Avatar
Los Angeles
Joined Jun 2010
1,305 Posts
Hi Cougar,
Remember that T-6's have high aspect ratio wing planforms and are much more critical to cg location.
The Bearcat on the other hand is very low aspect ratio, especially if the wings are clipped, and handles in a more forgiving manner.
The story of the heavy Bearcat needing more washout accomplished by raising the ailerons means to me it just needed more washout for it's weight because it needed more AOA on approach than it was designed for. The idea that flaps make a wing need more washout is totally the opposite of fact. RC experts are often wrong, the reality is that flaps enhance wash out. If the wing is straight and the flaps are lowered, it automatically makes the wing have washed out tips enhancing low speed stability. It delays the stall to the wingtips.
Check that Harvard's cg location carefully, and raise the ailerons a smidgen. It always helps.
Chris...
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Old Jan 01, 2013, 05:52 PM
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Canada, ON, Windsor
Joined Apr 2008
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I may have been a bit confusing. It is the D/F BAE Hawk that many report requires raising the aileron trailing edges to prevent tip stall. I have none with either the Harvard or Rare Bear.

I too understand your point regarding washout, but it is a bit irrelevant here. Each Harvard takeoff where it exhibited the snaps occurred with NO flap deployment at all.
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Old Jan 04, 2013, 09:26 AM
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LesUyeda's Avatar
San Diego, California
Joined Dec 2004
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"I've had to "Grandson Proof" the build room. "

I just keep a rice paddle handy. Works fine:-)))))))))))))))))))))

Les
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Old Jan 04, 2013, 04:36 PM
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Canada, ON, Windsor
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I should have also done the same to the Christmas Tree! Nice dent in the side now.
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Old Jan 06, 2013, 02:40 PM
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Los Angeles
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Quote:
Originally Posted by Cougar429 View Post
I may have been a bit confusing. It is the D/F BAE Hawk that many report requires raising the aileron trailing edges to prevent tip stall. I have none with either the Harvard or Rare Bear.

I too understand your point regarding washout, but it is a bit irrelevant here. Each Harvard takeoff where it exhibited the snaps occurred with NO flap deployment at all.

Split flaps do not really change the incidence of the inboard section of the wing so it doesn't really matter. If the wing is stalling on takeoff there are three things happening;
The model is not going fast enough.
The model is too aft loaded.
The wing does not have enough washout to fly in a partially stalled condition in a stable manner.

Raising the wingtips a smidgen can help, but the real difference with a Harvard/SNJ/T-6 wing is to ensure proper CG because of it's high aspect ratio.

Hope this helps, even the real T-6 has nasty low speed handling.

Chris...
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Old Jan 06, 2013, 02:51 PM
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Canada, ON, Windsor
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I brought up several behavioral tendencies with this one to a friend who instructed on Harvards for many years. He countered the rumors of nasty stalls and although they are many, I have to believe him. He had nothing to contribute to my observation the split flaps had little or no pitch effects at all.
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