Flaperon Flaps

[SuberAvid 617]

I got this idea from looking at some flaps that Randy Apling is developing for cubs.  I decided to try a similar concept by adding a second stage flap to the inboard portion of my flaperons and using electric actuators to drive them.  After searching out what is available that would work and buying the parts and pieces, Jack and I have been drilling, running wires, riveting, etc. to finally reach the prototype ready to test.  I figured I would start small with a 2" wide by 6' long strip on each flaperon and see what happened before trying anything wider.  They deploy up to 50+ degrees in addition to the flaperon travel.  We also set them to reflex about 2.5 degrees.  Attached are the pictures of the system.  I also added to my counterbalances to rebalance the flaperons but these don't show in the pictures since they were not on yet.  

I flew it for a short time today but ceilings were pretty low with clouds and snow so I don't have a whole lot of info on it yet.  What I found was that with the extensions up, there is no noticeable difference in the flight characteristics; it handles the same and I took it to 100 mph and stalled it power off and it felt the same as without. 

With the extensions deployed about 30 degrees and flaps on it definitely adds to the nose down attitude of the plane.  The power off stall is still OK and I could hold stick all the way back and control it with rudder with no wing drop.  I didn't deploy the extensions until I was about 50 mph and then only to about 30 to 40 degrees.  One thing that is very obvious is the aileron control becomes very heavy with them deployed. I flew it around that way and it turns fine but I don't think I would use them in gusty winds.  I also noticed it is very hard to pull flaps with the extension deployed so think it will always be best to pull flaps first and then deploy the extensions, and then  only under 50 mph.  I tried a few landings with them but found it is going to take some practice to use them at the right time and effectively since you have other things going on at the same time with throttle and slips, clearing snow berms, etc. 

I had thought I would immediately go to the 4" extensions once I tried these, but decided I need to fly these for a while and get them figured out.  I think they might be the most advantageous once I get the slats on to allow me to keep a flatter attitude on landing like the fowler type flaps do for the cubs.

Anyway, it is great to have an experimental airplane to play with!

[TJay 1041]

Very cool I like it always making it better. 

Another thing that I have always wanted to try is to shape some pink foam tape it to the bottom of the flaperon to make a symmetrical shape. To me that flap bottom has to create alot of drag.  Maybe I'm wrong but love experimental airplanes.

[ChrisBolkan 130]

Part of me is saying that is the coolest idea I've seen in a ling time and I want to do it to mine. Plus to a small degree it lowers wing loading so should stall some tiny amount slower.

The nervous Nellie part of me is wondering if the addition of the extension changes balance on the flapperons so would the lead counter weight need to be modified in order to prevent potential flutter, and The flapperon hangars are designed for a certain amount of force to be exerted on them before failure and this definitely increases the force so is there a potential problem there?

Another thing that comes to mind is you should not need a flap lever inside the plane with this configuration, since this is essentially a trim tab. So the whole mixer could just go away, right?

 

 

Edited 9 Mar 2020 by ChrisBolkan

[Buckchop 479]

Man Randy, im still Oggiling over how beautiful those shinny aluminum flaperons r!!!!

That is a cool idea, will b interesting to know how it works. 

[SuberAvid 617]

TJay, I think you are right,the later KF have more symmetrical flaperons and that probably is part of what makes them faster.

Chris, I agree with the cautious approach when it comes to flight surfaces.  I made up a mold to fit the OD radius of my counterbalances and used my lead bullet pot to cast up some add on weights to go on the  existing counterbalances and then disconnected the flaperon cables and rebalanced them before I flew it.  I didn't have them on yet in the pictures.  I also added rivets to the flaperon torque tubes every 6" to distribute the added torque along the tube.  I decided to deploy them at 50 mph and below and after using them I think that is definitely the limit I need to adhere to or it could overload the system.  That is another reason I think this might be the size limit and the 4" would just be too much; The aileron control becomes much heavier so even though they could be used to trim the plane, it is just not as light and easy to fly with them deployed, so I think they are really only of use when you are landing.  I need to spend some time playing with them at different deflection amounts in ground effect to see what they can do.  They do seem to act  sort of like a speed brake from my first impression.  They deploy at a rate of about 10 degrees per second so I found that it makes things a little busy on landing to get it slow, pull flaps, deploy extensions (that act like brakes) and adjust the throttle as needed to keep from dropping it in too soon.  I need to get it slowed down and get the flap extensions in with enough room to control the landing with just throttle, and I wasn't there yet with the few landings I got in yesterday.  Shuck, just have to fly it some more.

Thanks Bucky, they were in pretty good shape so I figured I might as well polish them instead of painting them.

Edited 10 Mar 2020 by SuberAvid

[ChrisBolkan 130]

This is fascinating. So lets assume the system you have come up with is balanced so no flutter under any conditions and the flapperon hangars can withstand any force the system can apply. This leaves two really interesting approaches to consider in deployment of the flapperons and extensions.

1) apply flaps with the lever in the plane, and then from there apply the extensions for even more droop.

2) use the extensions to apply the flapperons. The internal flap handle would become unnecessary as an upward deflection of the extensions would force the flaps to deploy, more like the action of a trim tab on an elevator. 

Either way, you gain the benefit of additional wing surface area so lower wing loading, but in #1 you are changing the airfoil shape to add more under camber and in #2 you are just adding surface area to the wing and removing the need for the flapperon mixer because the extensions would control flap deployment.

Is this the way you see it? It would be so much fun to experiment around and see how it would behave in different scenarios!

Hopefully you can play with both and let us know the performance differences.

 

[Av8r3400 1179]

Related idea:  VGs on the flapperons...

[SuberAvid 617]

It will be fun to try different scenarios.  I basically tried it in #1 and I think it might be of value (I hope) when I get the slats on to allow me to keep a flatter angle of attack on landing.  I know the split Fowler type flaps on the Supercubs really work well for that.  On #2, we set them up to reflex a max of 2.5 degrees, just to get best cruise speed, but you could set them with a lot more reflex and see what that would do.  It is pretty easy to build different brackets for the piston position, so could reflex 25 degrees and deploy 25 degrees or more. That is interesting.  VG's on the flaperons could make a difference especially with this set up.

[SuberAvid 617]

I got a chance to play with these a bit more this weekend and as I get used to them a bit I think they will be pretty good.  I flew them in ground affect compared to just flap on full (26 degrees for my plane).  With full flaps, my plane would fly along at 36 to 37 mph but felt a little mushy.  With flaps on and the extensions deployed about 30 to 40 degrees, it actually felt more solid and would fly at 31 to 32 mph.  When the extensions are initially deployed at 40 to 50 mph it does give the plane some more nose down attitude but at 31 to 32 MPH it is still at a pretty high angle of attack. The response to the throttle at that speed is still good and didn't seem to want to fall off.  I could still easily control it with power and climb out whenever needed.

[ChrisBolkan 130]

That's a huge change in minimum controllable airspeed

[SuberAvid 617]

I'm not too  savvy on this, how do I attach a video in here.  I got some short clips of the slow flight with the extension deployed.

[saskavid 47]

I think when you reply to the thread there will be a paper clip thing that says drag or choose files. if you hit the choose files it will prompt your computer and you then can attach the video that way or if it is a video already on utube there is the insert other media at the bottom to stick that on here. 

[marksires 484]

You are much better off to post the video to youtube, and then just paste a link here.  Youtube has a lot more bandwidth than this site.

[SuberAvid 617]

 

Edited 28 Mar 2020 by SuberAvid

[STOLpacer20 6]

WoW!

[ChrisBolkan 130]

That's pretty slow!