Pheonix rc glider question

I recently scored two sets of Phoenix wings and plans. The plans do not mention what the weight for the fiberglass tape. Any help here would be appreciated. Thanks.

Hi Ken,

I remember it as being pretty light stuff - maybe 2oz or 4oz.

I assume that the FG tape is for the spar? If so, you can replace it with light weight unidirectional carbon fiber if so desired.

TheAviator said:

I assume that the FG tape is for the spar? If so, you can replace it with light weight unidirectional carbon fiber if so desired.

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It is for the spar and reinforcement in wing. Is unidirectional better than woven? I plan on bagging the wing. Should I use kevlar for the aileron hinges?

schke said:

It is for the spar and reinforcement in wing. Is unidirectional better than woven? I plan on bagging the wing. Should I use kevlar for the aileron hinges?

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It depends on what the "reinforcement" is. The spar is designed to take primarily bending stresses which are compressive on the top and tensile on the bottom (unless you pull an outside loop, then reverse it). These stresses point span-wise along the wing, so it makes sense to align the fibers with the wing. The chord-wise fibers in a woven cloth provide no strength because they are not stressed, so they are not needed. Long story short, use unidirectional on the spar, a little wider on top because of the lower compressive strength (~25-35%). The 3oz HM uni that CST sells would be a good choice.

For other reinforcements, you need to decide what the primary loading is and choose a fabric for that. Uni is good for the trailing edge because its primary purpose is to resist dings.

For the hinge, Kevlar(R) (or Aramid, to use the general term) is definitely more durable than fiberglass. 1.0 or 1.7 oz works and is available from CST. When using it as a hinge, you want to "bias cut" the kevlar; i.e. cut 45* from the axis of the fibers. Then "shear" the fabric to +/-20* or so (about as far as you can get it). This will make the fabric wider but shorter, so don't cut your hinges out before you do this. Then cut your hinges and place as per the instructions.

One caveat to using Kevlar: you need a pair of Kevlar shears or a sharp rolling wheel fabric cutter and a good arm. Regular scissors just kinda slip around the Kevlar.

EDIT: I found a copy of the Phoenix manual on Aerotech's website. It seems that the ailerons are cut free from the wing, edged in balsa, and reattached. I would follow the instructions and just substitute CA hinges and foam-safe CA if the material included in the kit is not present.