Dc3Mek

All right, let me start this by saying that I'm an aircraft mechanic for a major airline, been in aviation most of my 50 years in one way or another, and for some reason, I can't figure out why I'm having this reaction when I use flaperons...on two different airframes.......

They are a Cub, and an Extra 300S Gene Soucy.....

The problem is that when I extend the flaperons, the planes nose over. Don't bother to suggest that they are backwards...I know how to rig flight controls. And for the life of me, as I rack my brain and think back to my air sciences classes in college, I can't understand why they are doing this.

I know that flaperons on airframes like Delta wings, flying wings and the like will act to basically curl the wing up if flaperons go up and down when flaperons go down. But here's the thing....they should act like flaps because of the tail feathers right????

I haven't tried mixing in spoilerons to see if they have the opposite effect.

I give up, I'd like to know why this happens. Why would flaperons act completely different from the flaps I have set on my Super Chipmunk for example???? It takes off like a homesick angel when I deploy 10% flaps????

Thanks in advance,

Darrell

Penuts

Check your elevator and see if it moves when you deploy the flaps, it could be you have a mix in the transmitter your not aware of.

Dc3Mek

Yeah, I forgot to mention that I don't have any elevator mix in....

Still don't know what it is!

Thanks

Uncas

My Feedback: (1)

I am not an aeronautical engineer (so I don't really know) but as I understand it, flaps affect different airframes differently, some make the plane nose up, some nose down. I think speed would also makes a difference. When I used flaperons on my UCD (like it needed flaps) it would try to nose over, and never used them. Spoilerons were much better, they force the nose up into a harrier, but when landing, I like the nose level.

Also flaps on a real plane usually do not extent to the wing tips like ailerons do, maybe that explains part of it.

Dc3Mek

Well, I got to work and talked to some buddies and we figured it out.

Basically it has to do with the ratio between CG and CL (center of lift) if the CL is ahead of CG then you'll get a nose up response.
If CL is behind CG then you get a nose down.

The CL will change (move fore and aft) when you mix in the added lift augmentation of the flaps. I guess it depends on the shape of the wing as to how much the relationship changes.

dixielandsbigal

I agree with DC. think of the CG as a pivot point. Now as the air goes past, the tail will go up as it hits the Flaperons. (because it is behing the pivot point.) For the same reason, spoilerons are effective in harrier flight. you are in a sense "trimming" the airplane for a tail down attitude.