Telemaster Has Me Confused!

[noodle]

Yes, a Telemaster. I'm indignant. A TRAINER has me confused! :eek:

A flying buddy showed up at the field with a Telemaster .40 the other day. I'd heard about the lifting stab, but I hadn't heard about an interesting feature it contains. Instead of the elevator going all the way to the end of the stabilizer, it stops about 1/4" short on each end. The carved Horner wingtips (stabtips?) then extend all of the way back, covering the end of the elevator. Can anyone visualize this? :rolleyes: As far as I can tell, the only reason that these are in existence is to provide yet another thing on a model airplane that is easily broken. Does anybody know of a real aerodynamic reason for these tips to be there?

[Tom Harper]

The idea is to leave the tip clean so that you don't have a moveable surface in the tip vortex. I'm not sure it is of benefit because you create two tip vortices - one at the tip and another at the end of the elevator.

The lifting stab puzzles me. The only way it can contribute is when it is loaded. This would require the CG to be near the trailing edge of the wing. My Sr. Telemaster will fly tail heavy but I do not feel that is a safe rigging. I assume others feel the same. So we all rig our Telemasters with a forward CG and haul around that draggy lifting stab just because it's there.

One of these days I'm going to replace the kit stab with a symmetrical section.

[slipstick]

I don't know if those tips do anything very useful for a stab/elevator on a fairly slow model but they certainly help on wings with full span ailerons. Several times now I've seen really bad aileron flutter cured simply by cutting an inch or two off the outside ends of the ailerons and fixing it to the wing. It's almost like magic ;).

Steve

[Tom Harper]

Slip,

That makes sense. I have avoided running control surfaces to tips but never had any real rationalization for it.

Thanks for giving me a reason.

Tom

[noodle]

Thanks for the replies, guys.

Yeah, it does seem to indicate that you would get two vortices- at least when the elevator is deflected. Doesn't make a whole lot of sense. Especially when you figure in that this only helps when the elevator is deflected. It doesn't seem to be worth the extra complexity.

As far as the lifting stab, I always just assumed that the Telemaster was balanced tail heavy to compensate for it- in a properly designed plane this shouldn't be a problem. Do the plans recommend a fairly normal CG placement?

Unusual, if you ask me. But nevertheless, everyone I've talked to so far seems to agree with the ads- Nothing flies like a Telemaster! :D

I had fixed tips on the ailerons of my Q500 (RIP). Never had any trouble with flutter. Can anyone tell me how these tips reduce it? I always thought that flutter was caused by excess hinge gap, flimsy control surfaces, slop in the linkages, etc. (i.e., things that allow the control surface to move around). I guess I'm wrong. So, does anybody feel like educating me on what causes flutter? :confused:

[Sparky Paul]

You're not wrong about the causes of flutter.. it's all of those things.
Terminating the ailerons before the tip -may- contribute to less flutter, but all by itself, isn't THE fix. It's everything.. surface weight, good hinges, connection to the servo in the right spot, a stiff connection to the servo..

[skymind]

This is all interesting, I didn't realize. Maybe what I did to my ailerons have this same benefit. They run out to the wingtips but the ends are trimmed back at about 45 degrees.. I did it to keep the end corners from being hit.

[noodle]

Hmmm... Makes sense, but I still don't understand how using "dead" tips reduces flutter. Has it got something to do with the tip vortex hitting the aileron?

[rebell]

The lifting stab has much to do with trimming at different speeds. There is a discussion on a thread somewhere on this forum. Having " dead tips" as you say is giving less stress on the ailerons, thus less flutter. On elevator it is more cosmetic than anything else. You don't get 2 vortexes per wing tip, but it does increase drag. It is a compromise situation.