2 servo flaps and ailerons

[oaktree11]

Hi all,
I have just ordered a new fuselage and wing so that I can build my next step Supercub2!

I am wondering about flaps. As I understand it, without flaps, the ailerons could be, say, 12" x 1.75". If inboard flaps were fitted then the ailerons presumably get shorter? If that is the case and they are still effective why do they need to be so long in the first place?

Also, instead of putting servos in the wing (potential weak spot?) what is the disadvantage of using only 2 servos in the center of the wing, one push/pull for the ailerons and one push/push for the flaps all connected by cables embedded in the wing? This would also keep the weight in the center of the aircraft and maybe improve the roll rate? (I just saw the post by Ellis on this - looks good to me and more elegant than wing servos?)

I am currently favouring top hinging as being simple and effective and leaving the top of the wing clean and I like the idea of bevelling the wing not the aileron, there is more "meat" on the wing!

What do you think? Any comments welcome!

[flydiver]

Never done this myself so this is from flying buddies and net feedback.
For a new flier they may be more trouble than they are worth and for small planes they aren't worth much. Mostly they are an exercise in modding and TX programming.

how do i use flaps?
www.wattflyer.com/forums/showthread.php?t=48615

[oaktree11]

Thanks for that Flydiver. I have decided to go with ailerons only at 12" X 1.75".
I am still intrigued to know whether the smaller aileron area when flaps are fitted is less effective than the "normal"size.

I intend to take most of the dihedral out of the wing with a 3.5mm straight brass tube set in to the center section of the wing with 3m carbon fiber rods epoxied into it extending nearly to the wing tip. My only worry is that it might cause the wing to warp around the axis of the tube/rods?

John

[ginginho]

John,
I'm lead to believe that ailerons have more effect the further from the fuse that they are, due to the effect on air flow, and force on the wing. With this in mind, although having shorter ones with flaps at the near fuse areas will not have such effect as a long one, the difference will not be massive and they will work just as well (may have to deflect a tiny bit more).

If you have a programmable radio (E.G. Dx6i) and you use a servo for each wing, you will be able to program these so the ailerons can act as flaps as well (flaperons). Most have mixed opinions on how well this works. I've tried a few times on slow fly-bys and they do work, but do also effect the handling of the plane. I've not used them on a landing for exactly that reason, and prefer to come in a little hotter but have more control.

As for the carbon/brass tube, that's very similar to what I did, except I used 2mm carbon and a corresponding sized piece of brass. The advice I can give on this to make sure any dihedral you want to keep is bent in to the brass and the bends align vertically (i.e. you don't have one carbon rod pointing a bit back/forwards compared to the other). Once you've cut the slot in the wing, tape (or weigh) the wing with the required dihedral down so that it won't change and then trial fit your rods. You may have to play with the angles of the bends in the brass until you are sure it sits in the bottom of the wing slot along the overall length. Only then start thinking about getting the glue out.

If you have a bench saw, this can be helpful for cutting a straight and even depth slot in the wing.

[oaktree11]

Thanks for the tips Ginginho. Now, you raise an interesting point about the dihedral.
Originally I was going to leave it stock with a view to reducing it after tring the aileron setup on a dihedraled wing. however, because I am going to cover the wing I thought I might as well perform the surgery now!
My idea was not to bend the brass tube at all and let it and the carbon rods take out most, if not all, of the dihedral. The question now is should I lose it all or is some beneficial?
BTW I have decided to go for a twin servo installation and I like the look of these servo mountings, seems more elegant than epoxying them? : cgi.ebay.co.uk/WING-SERVO-MOUNT-FOR-MINI-SIZE-SERVOS_W0QQitemZ380134683334QQcmdZViewItem
H

John

[ginginho]

Jul 21, 2009 18:25:50 GMT 1 oaktree11 said:

Thanks for the tips Ginginho. Now, you raise an interesting point about the dihedral.
Originally I was going to leave it stock with a view to reducing it after tring the aileron setup on a dihedraled wing. however, because I am going to cover the wing I thought I might as well perform the surgery now!
My idea was not to bend the brass tube at all and let it and the carbon rods take out most, if not all, of the dihedral. The question now is should I lose it all or is some beneficial? John

It's horses for courses really John. I took out most with mine (less than 1 inch at tips if held in the middle on a flat table) so I still get a bit of "self-righting" when flying a tad off level. Rolls, Cuban 8's etc are well within the birds capability, if not always in mine!
If you make your wing perfectly flat then it won't self level at all but should be more responsive. It really depends on how you fly and how you want it to perform.

If you have some strong tape you could try taking out as much as possible by putting the wing on a table, pushing in the middle to force out some dihedral and then running some tape across the bottom. If it's good stuff it should hold for long enough for you to test fly and see how you feel with that (keep you struts on to be on the safe side). At least that would give you a feel for it before hacking the wing to bits!
Some have just used this method of reinforcing the wing and not bothered with carbon, but I'd be a little wary of sticking with that over a period of time.

Just for info, my ailerons are 12inches long, 2 inches wide, bevelled both aileron and wing underneath. Profilm covering used as the hinges. Some pictures of my setup.