Wing rod rotates in Compulsion

[jacksoar]

I have a bent wing rod in my Compulsion to achieve proper Dihedral. After several landings I notice the wingrod has rotated slightly and the wings are angled foreward. Any solutions to preventing the wing rod from rotating?

Thanks in advance

Jack P

[Andy W]

It the wings are secured to the fuselage, and the fuselage cannot compress at the leading edge, they should stay put.. do you have a brace at the leading edge? That's what I have on the one model I have that also uses a bent joiner..
..a

[kablair]

The Houston Hawk uses the same design - angled wing joiner through the fuse - and it will rotate as well. During construction, this rod is held in place with an epoxy/filler mixture but it can come loose. When Jack came to a local contest, I asked him what he thought and his suggestion was to run some CA down the rod to secure it.

Another Houston Hawk member doesn't worry about his rotating when it's on the ground since it gets aligned when he puts it together and tapes the wing to the fuse. It does make a good anti-crush device by letting the wing rod rotate during those 100 point dork landings.

Bottom line - if you tape the wing to the fuse, it's not a big problem.

-Keith

[glderguy]

Just run a piece of tape span wise across wing /fuse/ wing towards rear of wing root.
You see this done all the time at contests to keep wing/rod from rotating forward
during spot landings.
Walter

[glderguy]

By tape I mean something more substantial than vinyl type electrical tape.

[allanp]

Thin CA around the fuse hole with the rod inserted,let it set then break it free.Flip it over and do the same to the other side. You don't want it too tight though as it will absorb excess energy if you "dork" one.
Allan

[terry.cx]

1" strapping tape works for me. One piece in the back, one piece midway. Then vinyl tape around the root.

Terry


By tape I mean something more substantial than vinyl type electrical tape.

[kablair]

Personal preference is to use a quality (3M) vinyl electrical tape. I've never had it fail in flight and it has always failed at just the right time during an aggressive landing.

If you're worried about the structural integrity of the tape during flight, consider the vertical reaction forces being applied to a joiner during flight. As soon as it's flying and the wing is lifting - there's alot of force keeping that rod in whatever position you put it in. The tape is really in shear to keep the wing from rocking fore and aft while it's unloaded (on the ground).

Anyhow - that's been my experience. I'd be very interested to learn from someone else whose had a quality electrical tape failure in flight that caused the loss of a wing panel.

Thanks,
-Keith

[kzimmerm]

Personal preference is to use a quality (3M) vinyl electrical tape. I've never had it fail in flight and it has always failed at just the right time during an aggressive landing.

If you're worried about the structural integrity of the tape during flight, consider the vertical reaction forces being applied to a joiner during flight. As soon as it's flying and the wing is lifting - there's alot of force keeping that rod in whatever position you put it in. The tape is really in shear to keep the wing from rocking fore and aft while it's unloaded (on the ground).

Anyhow - that's been my experience. I'd be very interested to learn from someone else whose had a quality electrical tape failure in flight that caused the loss of a wing panel.

Thanks,
-Keith


I second the use of good quality vinal tape. I also use 3M because it comes in white. Some additional notes. I also use a good quality box tabe strip about 1 1/2" wide along the top and bottom of the root. This is done so that when you lift the vinal tape you don't lift the covering/paint.

I've also heard of some guys devising a block that mounts in the fuse and "pinches" the joiner rod to prevent it from rotating. It is a very good idea but I think it is somewhat overkill for our application.

Kurt

[nuevo]

More wisdom here.

Bent CF wing rod rotation problem (http://www.rcgroups.com/forums/showthread.php?t=227081)

[kzimmerm]

Another trick I remembered from a friend of mine was to very carefully drill a hole into the rod 45 degrees from the top (he claimed to be a lower stress area". This hole was drilled so that an "L" shaped pin was placed in it that fit into a notch in the fuse locking the joiner rod into place. This worked but I would be concerned about creating a weak point in the joiner rod. I've done this and it does work. The joiner rod sheered as a result of the plane flew through a pine tree, not from a hard landing.


Kurt.

[glderguy]

I use the same stuff Terry.
Walter

[O.L. Adcock]

The best trick is to build the dihedral into the spar and leave the joiner straight. I've had/built a couple using bent joiners and at the very least they are a nuisance.....O.L.

[OVSS Boss]

Bent rods are the best fuse/wing saver in the world, if you have an anit-compression piece at the LE of the wing where it meets the fuse. I had friends that this wierded them out, and that little bit of rotation is a saver on a hard landing at times when you need it. Ya, the tape may bust, but not the plane. Yes, have your joiner rod holes pretty tight in the fuse, but by all means, do not glue the rod in or stop it from rotating if forces are substational enough.

Marc

[davidjensen]

I have the same problem on my Thermal Dancer. Using good strapping tape helps but is not the cure all. I agree it is a good thing that the rod can rotate and take some of the landing (crashing) loads off of the wing itself.

[kzimmerm]

On my very first bent joiner rod plane I chose using a piece of tape parallel to the flaps about 1/8" ahead of the flaps. This tape was about 6" long and would be put down first. After that was in place I'd tape the wings to the fuse chord wise. I found this to be overkill and resorted to the the cord wise tape.

One other thing I did was install a 3/8" dowel inside the fuse at the leading edge. This dowel would keep the fuse from compressing if there was wing rotation.

Kurt

[nuevo]

Yes, have your joiner rod holes pretty tight in the fuse, but by all means, do not glue the rod in or stop it from rotating if forces are substational enough.
very wise advice

[glderguy]

With the Compulsion, of which I have had several, you need the anti crush brace. But if the wings are left to rotate forward enough times what usually happens is you end up slowly crushing/damaging the wing LE at the root. At first it looks like minor delam but in reality the foam core is slowly crushing away in that area. In time it turns into a semi major repair.
Walter