Repair hollow molded wings for escape

[planefun]

I had the misfortune to step on my escape wing, about 8 to 10 inches from the center of the wing. There was a slight crunch when my boot hit the wing. There seems to be a slight indentation on the top of the wing just forward of the wing rod. Any suggestions on how to repair the dent?

[solo6796]

Box everything up carefully and send it to me. I'll be happy to rapair it for you....................

HAHA

AJ

[Ollie]

Does the Escape have balsa or rhoacel foam as the middle layer of the wing skin sandwich?

Put a straight edge spanwise over the deepest part of the dent and measure how deep the dent is. Also measure the width and length of the dent. That will help us understand the extent of the damage.

How do you fly the escape? Do you push it near the limits of its speed and strength? How important are the cosmetic aspects of the repair to you?

Also, what is your skill working with light glass cloth and laminating epoxy?

[sventek]

dang ollie,....your a tremendous help to some of us on this board!!! Using your time and all. Its like talking to an aero engineer/mechanic!
Your detailed questions for a diagnosis are very impressive!

[planefun]

Thanks for the reply. The Escape has rhoacel foam as the middle layer of wing skin. You can see the dent only if you press on the section where it's located. When you press on it you can feel the rhoacel foam give way. The dent is about 7 inches long and when you press about 2 inches wide. I fly the Escape to the limits. Cosmetic are not important, performance is. I have bagged foam core wings in the past and have worked with carbon, kevlar and glass cloth. I'm not an expert but can manage pretty good. I found an article on the Charles River Web site about fixing molded wings,http://www.charlesriverrc.org/_vti_bin/shtml.dll/search.htm
What's you take on this.
Planefun

Originally posted by Ollie
Does the Escape have balsa or rhoacel foam as the middle layer of the wing skin sandwich?

Put a straight edge spanwise over the deepest part of the dent and measure how deep the dent is. Also measure the width and length of the dent. That will help us understand the extent of the damage.

How do you fly the escape? Do you push it near the limits of its speed and strength? How important are the cosmetic aspects of the repair to you?

Also, what is your skill working with light glass cloth and laminating epoxy?

[Ollie]

I can't disagree with the article at the CRRC web site since I wrote it.

From your description, it seems that the outer skin is not damaged but the rhoacel and inner glass skin are broken over a wide area. If only the top of the airfoil is affected, then the soft spot can be repaired with a minimum of disturbance to the undamaged skin. Cut a piece of 1/64 inch thick plywood to the outline of the damaged area but a little bigger all around to over lap the undamaged area. The grain of the plywood to run spanwise. Cut a 1/4 inch wide, chord wise slit in the middle of the damaged area that is big enough to slip the ply piece into the inside of the wing. Place the ply piece over the damaged area and mark the location of the the slit under the ply. Thread a needle with sturdy thread and pierce the ply in the middle of its width at the location of the slit. Then pierce the ply again from below and sew the thread in a loop through the center of the ply. tie off the loop of thread so that it is as long as the ply piece. The loop of thread will be used to pull the ply against the inside curve of the top wing skin (through the slit) after the ply is loaded into the hollow wing. Do a dry run to see that the ply can be pulled snuggly into place without the damaged material inside the wing interfering. (If you can't get the ply to snug up against the inside of the wing skin in the dry run, then abandon the rest of this method, cut away the rest of the damaged area and apply the repair technique outlined in the Charlles River R/C article. ) Check to see that the ply can be held in place without causing the skin to bulge. Fish the ply piece out of the wing. Mask off the area around the slit to protect it from stray epoxy. Mix up a batch of micro balloons and laminating epoxy to the consistency of sour cream. Slather a thick coat of micro balloons and epoxy onto the top of the ply piece. Load the ply back into the hollow wing being careful not to scrape the epoxy mixture off at the slit. Pull the ply into position and then up against the inside of the wing skin. Turn the wing upside down and weight the thread loop enough to keep the ply in place while the epoxy cures. Don't put so much weight on the thread that it causes the skin at the repair to bulge. Apply the tension on the thread slowly so that the epoxy mixture has a chance to flow into the damaged area. After the epoxy has cured contour the epoxy at the slit, remove the masking tape and feather the edges of glass skin around the slit. Fill any low spots at the slit with more micro balloons and epoxy. When you have reestablished the original contour, cover the slit with several layers of 3/4 ounce cloth in epoxy overlapping the original skin and staggering the edges. Feather the edges of the patch, prime and paint.

[planefun]

Thanks for the information and your help.

PFun