A dumb question

[yclui]

I have been flying RC gliders for sometime and I still don¡¦t feel
comfortable with one very trivial thing : just plug the wing panels
in and throw the glider off the slope knowing that the wing panels
are held in place just by the friction between the wing rod and the
tube inside the wing! no bolt, no glue, no ¡K. just nothing.

My new Pike has the tail surfaces attached to the fuselage in the
very same (unsecured) way except that the length of joiner rod going
into the fuselage is just about one inch long ¡V that makes me very
nervous.

Many pilots put tapes over the joints saying that the tape will hold
the panel in place but I remain skeptical about the theory. The tapes
are certainly good for sealing the gap but holding the wing panel in
place ? I doubt. Using tapes on wings with plastic coverings is not a good idea anyway as the covering material will likely be lifted.

Can someone explain a bit about how the wing rod works ? Has there
been any incident of wing panels detaching from model gliders in the
air ? I am yet to witness one. I know it works , just don¡¦t
understand why .


Y C Lui

[Sail 'n Soar]

I'm not sure what would happen if you over-sped the wings and got things fluttering, but otherwise, friction on the rods to hold the wings in place isn't much of a risk. First, there isn't much of an aerodynamic load to pull the wings off the rods (unless you have oversized winglets set up incorectly. Second, the moment due to the load on the wings increases the frictional load on the rods significantly. Starting with the wing flush against the fuselage, the initial flex will tend to move the wings out slightly, but that's about all. Of course, I'm much more at ease with gliders or electrics, where you don't have the vibrations and structural resonances created by an engine.

In terms of your 1 inch tail surface rods, you didn't mention control linkages. If they are connected to the removable surface that will tend to limit how far the surface can shift.

[BMatthews]

As long as there's positive G on the model all should be well. But frankly I don't like relying on friction unless I lightly curve (not kink) the rod or add a small dent into the receiver tube to ensure a consistent and sizable friction fit. Also in rare cases and with meticulous craftmen I've seen wings that slip on with precious little drag as everything is lined up perfectly and dead straight.

On all my slide on wings or tails I've always arranged for some proper locking or tensioning method. Either a pin, small bolt or rubber band. The ways to do it are many and simple. It doesn't take much after all.

At the risk of being pessimistic I'd especially be wary of this on a slope model that tends to do many more aerobatics than a thermal ship.

How often have you flown it? If many does it ever come down with the wings a touch loose from the fuselage? It may be OK now but if you learn to do some fast rolling maneuvers that put more centrifugal forces on the wings......:eek:

As for the tape that's a very effective and surprisingly durable method of retention. Remember that it's under shear and has quite a bit of area. Even a relatively low tack tape that won't bother the covering adhesion will hold quite a force over the length of the chord.

[Sparky Paul]

If you have servos in the panels, then it's a good idea to provide some restraint against the panels skootching out on the rods.
Or if you're into flat spins.. There's really no aerodynamic forces that act out along the span for most flying,as Sail'nSoar mentioned.
A bit of electrical tape if you want.. a #32 gumband between pins in the panels.. a setscrew into the wing rod..
Don't feel you mustn't do something that you antsy about.. Overkill is better than picking up the pieces.
I saw one situation where the panels were held together by a spring, and the anti-rotation rod at the rear of the wing vibrated completely out of one wing in flight.(There was enough room in the other wing for it to fit.) The aileron then changed jobs, and became a full-span boost tab. Which made the airplane respond oppositely to input commands. (Down aileron would rotate the leading edge of the wing down)... The plane was landed successfully, but the odd behavior was atributed to "interference", until I pointed out the loose wing could move about 10 degrees either way around the wing tube.
I've had Nordic gliders which use very short wing fixing tongues without losing wings in flight.
The gumband fix was the suspenders to the belt. :)

[BMatthews]

Originally posted by Sparky Paul
.....Overkill is better than picking up the pieces.


.....anti-rotation rod at the rear of the wing vibrated completely out of one wing in flight.(There was enough room in the other wing for it to fit.) ......


That overkill remark is a goodie.... Words to live by for sure. The bit about the anti rotation rod is an excellent example of another favourite tenet of mine... "Never leave Murphy an opening."

Another point to watch is that while joiner and locator rods may start life with a tight friction fit things have a way of bedding in after a while and suddenly that friction that would hold things together during a fast roll or a tight spin isn't quite enough any more. Pehaps that's what your guy had happen Sparky.