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Old Apr 12, 2003, 10:16 PM
Registered User
Oak Ridge, TN
Joined Nov 2002
13 Posts
F4U Corsair, Left wing drop, flap mod

I took my corsair on its maiden flight today... wow. I had heard about some serious left turn/left wing stall problems. I did not expect the problem I encountered. With the rudder at full right, it still turned left and nosed down. The elevator was still functional throughout the crash, but I did not have the skill to use it to my advantage. Second hand launch I had the rudder trimed extremely right. No help though, it flew well but the slow (because I had full right rudder again) roll to the left brought it down.

It seems my options are:
To twist the wings slightly to cause a right roll effect, but that would mean I have to redesign all my wing mounts and supports.

Or

If I cut a piece of styro like the picture below, and attached it to the bottom of the wing about midway, it might act as a flap to reduce the stall characteristic and as a slight aileron down to rotate the plane right to counteract the torque of the motor...

Could anyone give me any feedback on the second mod? or possibly another alternative.


Thanks,
Tom

BTW this is the Flying Styro Corsair, a light foam plane with a ~28" wingspan.
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Old Apr 12, 2003, 11:44 PM
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Sparky Paul's Avatar
Palmdale, CA
Joined Oct 2000
13,499 Posts
A manuver like you describe is generally a result of a tip stall. At launch, it's because the plane is going too slowly.
Throw it faster.
Use a bungee..
Twist washout into the left wing with a heat gun on the covering.
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Old Apr 14, 2003, 03:20 AM
Registered User
Oak Ridge, TN
Joined Nov 2002
13 Posts
on to plan C!

Thanks for the response. I can't heat up or twist the wing due to its construction. (Two molded pieces of foam glued together, hollow in the middle)

But you have got me wondering about the launch speed. I'm going to go with plan C putting ailerons on the wings. I had originally wanted ailerons anyway, so it will be a welcome improvement.

I've been flying slow parkflyers for a couple years now. I have mostly stuck with very forgiving aircraft. This tip stall is a new phenomena to me. I had read about it, but it is another thing all together to try to recover from it at 10' up!

Thanks,
Tom
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Old Apr 15, 2003, 08:12 AM
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Houston, Texas
Joined Oct 2000
1,030 Posts
I tested a fellow club members Top flite Corsair for him, I knew I had to keep the speed up on landing. On every landing that day it would drop the left wing inches before touchdown right as I flaired and the left wheel would make contact first. I told him the importance of keeping the speed up, well the next week when I asked where it was he said he let someone elese fly it and it snap rolled into the dirt. I don't know for sure but it seems to me the Corsair is the worst in this respect, I have flown 3 different Corsairs and they all had this problem, I have also watched several take a dive too.
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Old Jun 24, 2003, 01:00 AM
Registered User
Oak Ridge, TN
Joined Nov 2002
13 Posts
Just an update.

I finally got around to making some changes to my Corsair. I took it to the field today and had some surprises. First off, wow, it flew great as long as I kept the speed up. ...but... after about 5 minutes the left wing got heavy and didn't free up when I added speed. I landed quickly and found the front of the cowling had rotated. I assume it came off and the hub of the prop was hitting it. A quick fix and back in the air.

Second time I took it up really high and experimented with the stall. It actually looks really cool when the left wing and nose drop together into a dive. I think I can somewhat see the warning signs before the wing actually stalls.

Something interesting happened just as I was starting to get comfortable stressing the plane thru a few aerobatic manuvers. At about 5 mistakes high, it fell out of the sky. I rotated the throttle, went with the dive, tried several different methods to regain level flight but no luck, a 4 second spinning dive to the ground. I expected to see some sort of major structural failure. What I found was a perfectly intact aircraft with no damage. There was just a little grass stuck in the cowling. (A good reason to fly over 5' grass) The battery was secure. The only problem I can find after taking it apart is the front motor mount came loose.

It's amazing just how much effect the prop angle can have on a light plane. BTW I corrected the problem in my first post by changing the angle of the prop more down and right, and by using a lighter prop.

I thought someone might find that interesting. I am going to try positioning the battery towards the right side of the plane to see if I can slow it down a little more without stalling. If anyone has any comments on that, I'd appreciate it.

Later,
Tom

Attached is a poorly lit pic of the plane with the scale prop on it.
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