I'm going to be building a Great Planes P-51 mustang kit. I was thinking of adding flaps to it. To accomplish this I was thinking of cutting the strip aileron in half, using the inside half as flaps and the outside half as the ailerons.

Anybody have any thoughts on this? Would this model benefit from flaps?

I was also thinking of extending the inside of the wing back and making split flaps?

Would this be worth the extra effort?

Mike

Mike:

You want flaps? Do it.

Split the ailerons as you had thought, just be sure to mix them in as flaperons, then you lose nothing except the added weight of two servos and the linkage.

Yes, you could extend the upper surface to make split (scale) flaps, and it probably wouldn't make any difference in the way the plane flies, but it is NOT a scale plane, and it's a lot more trouble.

Bill.

Mike,

I have done this mod to My GP P-51 as well as a few others. You have the right idea, but don't cut the ailerons in half. You only need flaps that are abot 5" long. They will work very well, and won't take anything away from the ailerons, so there's no need to mix flapperons.

I have a pic of the setup at my office, I'll post it Monday.

Mike:

Another advantage of Minn's way is needing only one servo for the flaps. Good idea.

Bill.

Besides, Mustangs did not have split flaps.

Bruiser:

Sorry, thought the Mustangs were like the C-47/DC-3.

Bill.

Do 5" flaps make a significant difference when landing? Minn, what is the width (chord length?) of your flaps?

I have a WM P-51 Mustang (.46) that has long and narrow ailerons. They stop 4-1/2" from the wing root. 4.5" flaps are kind of tiny, but it would be cool to have.

Juice

4 1/2" flaps will work. You'd be surprised at how effective those things are when they're in the prop wash.

Minn...

What is the chord length of your flaps? I've read that typical flaps have a chord length of about 20-25% of the chord length of the wing. Is this an acceptable guideline for 5" flaps? If you don't mind, I'd really like to see that pic your mentioned.

Thanks,
Juice

MinnFlyer, I would also like to see that picture, as I am going to do flaps on my GP P-51. It might help me avoid a costly mistake because I was thinking of cutting my ailerons down to 60% of their original length and leaving the other 40% for the flaps.

Thanks,

Doug

Ooops, sorry, it completely slipped my mind. Here is the pic. The cord length is simply the width of the original strip aileron. Mine are about 8" long, and are actuated with a two position switch. If I drop the switch fully, I can't land the plane because it will continue to float at idle (It's almost comical to see)

MinnFlyer, thanks for posting the drawing on your flaps. I had a question based on a problem I'm running into with mine. I am using the torque rods for the flaps like you did.

The problem is that the torque rods spread apart when the flaps go down and when they are raised, the torque rods move close together. What did you use to connect the torque rods to the servo that would allow for the spreading action?

Thanks for your help!

Doug

Doug,

Here's a more accurate drawing of the push rods. They join each other near the servo. This allows for any flex that might be needed.

Thanks for posting a more detailed drawing. I'll give that a try. Thanks again for your help!

Doug