FIXING WINGS AND TAILS
By Ed Anderson
aeajr on the forums
Repairing a low cost foam wing, typicak of the HobbyZone and similar planes
is not hard. However trying it fix a creased or folded wing with packing
tape alone doesn't really work very well. It works better on the tail
because it encounters different forces, but what I am about to explain works
MUCH better on both the wing and tail and is easy to do. It should also
apply to the Xtreme, Sky Fly, the Firebirds, and all similar planes that use
a foam core wing.
A creased taped wing might fly, but at the first real stress, its going to
fold and you are going to crash. Tape alone has no body or stiffness of its
own to resist a fold since the wing's internal foam is compressed. Net Net,
there
is nothing to resist the next fold. You need to stiffen and support the
wing. Here are things I have used for wings and the V tail with pretty good
results.
Take a hobby knife or razor blade and open the vinyl covering at the crease
or stressed area. Get the wing set in the proper position, even bend it
slightly the other way to open up the gap.
Basic repair
Fill the folded area with Elmer's white glue or titebond yellow glue. The
white and yellow glues will seep into the foam and bond with it and stiffen
it.
It is best if you let it dry overnight, but give it at least 3 hours to seep
into the foam. Now, fill it again. The second coat will fill the gap. Let
it dry 24 hours then check it. If it is fully dried, apply a little clear
packing tape to help it resist pulling open.
Stronger repair approaches
If your repair is in the center area of the wing, say within 6 inches of
where the rubber bands cross, or if you tend to fly hard, do lots of loops,
fly in wind and the like, then you probably want to take this next step.
For a wing, I add thin but somewhat stiff strip of 1/32 ply, to the top of
the wing to bridge and support the area. Typically this is 8-16 inches
long and 1/2-1 inch wide. Regardless of where the repair is, you always
center this wood strip on the wing so that the wing is balanced and the
impact on the air foil is uniform. This will resist flexing in both
directions but is not so stiff that it encourages the wing to fold at the
end of the ply. Also 1/32 ply is light and flexible so it will shape to the
curve of the wing so as to minimize the extra drag the repair will cause.
To get it to more closely align with the wing I use thin double sided carpet
tape on the strip. Try to get the ply in complete contact with the wing.
It is stiff enough to resist the next fold, but will still flex with the
wing. When it is set, cover it with clear packing tape. Don't tuck it in
tight around the ply, stretch it out so that it forms a smooth air flow
surface.
Another method to support a deep fold or a break is to slit the vinyl along
the length of the wing and embed a spar, a piece of wood or wood dowel, that
will act as a support. If you look at the T-Hawk, or the Aerobird Xtreme,
you will see an embedded dowel that provides some stiffness to the wing.
Again, glue this in using the procedure above, then close the gap with
packing tape.
If you are fixing a tail, use the same process, but use 1/64 ply or a
thinner towel to keep it light. Be sure to do the left and right the same
to keep the tail balanced. Now cover it with clear packing tape stretched
so that it forms a smooth finish with no sharp edges so the air can flow
nicely over the wing. The repair does effect the shape of the wing so it
does impact how the plane flies, but not enough to matter if you fly under
power most of the time. If you like to glide and thermal, I find these
wings are not as good as a new wing but they are very useable.
When repairing the tail, any added weight on the tail will make the plane
tail heavy. If you are flying with the 6 cell battery and tend to leave the
landing gear off, this could tend to make the plane a bit "twitchy" or
sensitive. Some people like this because it becomes very responsive.
However if you like your plane stable, you might have to add a dime to the
battery area to rebalance it. Fly it and see what you need.
I have never had one of these fold.
While Epoxy is strong, it doesn't move with the foam the way Elmer's or
Titebond will. I have seen a tendency for epoxy to pull away from the foam
as the wing flexes. However give it a try and let us know your experience.
.
Reinforcing new wings
If you look at the T-Hawk or the Aerobird Xtreme, they have a support rod
embedded into it when you buy it. This gives you a stiffer wing which will
resist bending under pressure of aerobatics. You can follow the procedure
outlined above for repairs, but you can do this when you get he wing new.
This is a Recommended wing reinforcement posted by by mdp17681 for the Sky
Fly. Might work well on the aerobird too.
http://www.wattflyer.com/forums/show...8&postcount=16
Don't Depend on Tape
Give it a try. The key message here is don't depend on tape to keep the
crease from folding again. Tape is good for closing up damage on the front
or
rear edges of the wing and for reinforcement of a new wing by the prop area,
but it can't keep a creased wing from folding up again.