Shear Webs in Extra 300
 

I am building a GP Extra 300 .60 kit. When building the wings, the instructions called for shear webs on only one side (front or back). However, upon examination later, the plans indicated two shear webs (front and back) for the first three bays. Unfortunately I found this after sheeting the wings.

Looking for recommendations. Do I need cut the sheeting and put in the extra shear webs in those three inner rib bays?

Thanks in advance for your guidance.

RE: Shear Webs in Extra 300
 

Built / flown lots of aerobtic planes - -never seen dual shear webs in a single rib bay on a wing.
Can't imagine the difference between one set of properly installed shear webs and two sets would be critical...
But if you decide you have to put them in, wouldn't it be stronger/ easier / prettier to cut out the existing shear webs, install the new inner webs, then reinstall new outer shear webs?

-Rick

RE: Shear Webs in Extra 300
 

In high stress areas, it's very common to web both sided of the spar. Even if the plans don't call for it, I've made it a habit and have NEVER (30Years) had a wing failure. Rather than damage what you have already completed, cut some pieces of lite ply to fit over the existing webs. It won't be quite as good as the webbing on both sides, but I don't believe you're going to have any problems. 1/16" lite ply should do it.

Make sure that the additional webs fit tight from rib to rib.

RE: Shear Webs in Extra 300
 

All i can say is I sheared both sides of the spars. I have always read the kit's manual 3 or more times through and found that exact thing out the 2nd time through. The Extra .60 is a great kit but dont install Ca hinges, and when you go to make the trailing edges of the kit use a thick piece of balsa for the hinge mounts and install hinge points. I just had Ca hinges fail and I emailed Gp and told me to Send them to their Tech department for examination. Strange but you might have a bad batch too. Get a good set of robart hinge points or nylon hinges. Go with the dual elevator setup and make sure you have a strong elevator setup, Mine without me even looking came with defective wood and half my elevator flew off in a base leg turn. Beware, build light but also build it strong. You might even guy wire the tail section. Since your already at the wing, you must have already done the elvator and rudder, I was hoping I could tell you to make aerodynamic counterbalaces like the rudder already has. They really cut down on Vib. Good Luck and hope you dont go through any trouble with the kit. Its a great kit, take your time. my 2 cents:D

RE: Shear Webs in Extra 300
 

Thanks for the great info. As I looked again, you are right. I should be able to cut out the inner web, install the outer and then place a new inner web on. That isn't much work so I'll go the safe route and add it.

Thanks for the advise on the CA hinges. I had heard that those represented a good technology. You scared me about the "bad batch." Are the Robarts easy to install? I have only installed the CA hinges before. Maybe I should just buy some Sig CA Hinge material at the LHS.

RE: Shear Webs in Extra 300
 

If you are a DIE HARD CA fan, go ahead with some Ca hinges. But along with many others i would recommend the robarts. Just drill a hole(bit and key included with the hinges, 12 buck at hobbytown:D and 15 hinges) and put some epoxy in it and stick it in. Prit-tea easy.........You arent going to run into trouble here. also if you go with any hinge but a clear peice of monocote or trim sealent on the TE and The control surface. Just in case it fails( you cant see it and its like insurance for you 200+ hour Kit:D) Good luck with the kit!