Reinforcing Foam Wing?

The classic solution is to slit a channel in the wing and epoxy in a carbon fibre rod.

On Wed, 05 Sep 2007 04:38:34 GMT, "mjc13" wrote in :

The combat Gremlins use strapping tape as a spar.

Strapping tape has strands of fiberglass in it running lengthwise. Tape like this provides more resistance to stretching than ordinary packing tape.

Unstressed. You don't want to distort the wing

I would wrap the tape around both the top and bottom of the wing. It's pretty light and having the extra tape will provide extra stickiness.

I'm having a failure of imagination here. I can't see how a length of tape acting like a spar is going to make the wing more slippery. My guess is "no", but I'm not sure I understand your question.

Marty

wrote in

Sounds like a good idea. I'll see if I can find some. Thanks.

I didn't plan to wrap the wing at all. I just wanted to add a length of tape on the underside, to stop the wing from being stretched upwards to the breaking point.

I think the tape may be more slick than the foam wing, and the way it attaches, it's wing surface against hard, slick plastic fuselage. I wanted to put the soft tape at that interface, to stop the wing from shifting.

On Wed, 05 Sep 2007 21:03:37 GMT, "mjc13" wrote in :

I'm talking about a strapping-tape "spar" that runs the length of the wing about 25% back of the leading edge.

By making a continuous loop around the wing (underside of left wing, top of left wing, top of right wing, bottom of right wing, back to where you started, overlapping a bit), you pretty much guarantee that the tape won't come unstuck and will help resist bending and breaking the wings along the long axis.

If you're talking about reinforcing the center of the wing from front to back, that's a different kettle of fish. The strapping tape won't help there. For strengthening the center section of wings, we usually use some fiberglass and epoxy. If you get real light fiberglass (~.75 oz per yard) and apply the epoxy really carefully, you won't add a lot of weight and you will add some strength.

I've used ... thin strips of adhesive-backed foam ... (don't know the trade name) to create a soft interface between wing and fuselage on large planes. The strips are designed as insulation for doors and windows, I think, and cost a few bucks at a hardware store. Maybe 5/16" wide?

Moleskin might work, too, although it would probably be more expensive. It's an adhesive-backed felt that folks use to prevent or care for blisters.

Marty

wrote in :

Now I understand you. This plane is supposed to be a bit underpowered; do I have to worry about the extra weight of about 2.25 times as much tape as I'd planned? I didn't think it would come loose, but I have no experience with this kind of foam wing...

I know what you mean. I'm concerned though about using something too thick, at a joint that wasn't designed for more than just the wing. I read somewhere about someone using a strip of electrical tape to make that friction fit, and figured that would be thin enough. Thanks for the advice.

On Thu, 06 Sep 2007 03:37:06 GMT, "mjc13" wrote in :

Not if you use the 3/4" strapping tape.

I imagine that the added weight would be within the error bar of any ordinary scale you could use to weigh the plane.

You are imagining that the wings will flap a bit in flight.

The only thing underside tape offers as resistance to the flapping motion is the adhesive.

The adhesive on tape is relatively light. If it was super-stick, you'd never be able to get the tape off the roll.

If you create a tape spar, then you've got 2.25 times as much adhesive working in your favor, along with the friction around the wing tip that will resist letting the tape get pulled away from the foam.

Marty

The message from "Martin X. Moleski, SJ" contains these words:

Hi, plasterers in the construction industry use a fibre glass mesh tape about 2'' wide and tacky to run down the joints of wall boards used for dry lining houses, it is quite cheap and very strong and if you apply it then paint over the top with a coat of PVA it is very strong for very little weight,

regards, Terry

wrote in

I'll try something of the sort, anyway. Thanks.

Thanks, but I'd rather keep the chemical use to a 'bare' minimum. ;-)