Help! Carbon Fiber Reinforcment

[Om0r A.]

Hello everyone!
I am planning on building and reinforcing an FT Explorer wing. I will cut out a pocket in the spar and install a carbon fiber item. I was wondering what would be more effective: a carbon fiber rod, square tube, or a strip? (Rod, Square, Strip)

 

[Grifflyer]

Personally I would use a feel safest with a rod, because the edge on a square creates a weak point and the strip is only strong when it deals with loads in one direction.

 

[Om0r A.]

Personally I would use a feel safest with a rod, because the edge on a square creates a weak point and the strip is only strong when it deals with loads in one direction.

I was thinking the square would be better because the glue has more surface area connecting it to the foam. Is that not true?

 

[Grifflyer]

I was thinking the square would be better because the glue has more surface area connecting it to the foam. Is that not true?

That is true, but if you made a pocket for the rod it would be about the same.

 

[Headbang]

Round tube is stronger, a rectangle tube is perfect for the job, square will work as well. It will take a lot more glue to hold the round tube. Any reinforcement will work tho, basswood spar is good as well. It does not take much to stop the folding of the wing. Just make sure it is at least 18".

 

[Om0r A.]

That is true, but if you made a pocket for the rod it would be about the same.

Are you saying, the pocket would have to be circular or the glue will just spread to the rest of the rod?

 

[Grifflyer]

Are you saying, the pocket would have to be circular or the glue will just spread to the rest of the rod?

Yes, the pocket should be somewhat circular but I wouldn't spend time trying to get it perfect.

 

[Om0r A.]

Yes, the pocket should be somewhat circular but I wouldn't spend time trying to get it perfect.

How could I achieve this?

 

[Grifflyer]

How could I achieve this?

Just cut a cavity the size of the spar the same way you cut cavities for the A and B folds.

 

[Merv]

what would be more effective: a carbon fiber rod, square tube, or a strip?

All are going to be strong enough to do the job.
Get the cheapest one. Shipping may be your biggest concern.
Bamboo BQS also make great spars. I use 8 in every wing I build. They will hold over 25 pounds.

 

[Om0r A.]

Just cut a cavity the size of the spar the same way you cut cavities for the A and B folds.

But the cavities you make for A and B folds aren't circular. The original plan was to cut a cavity, but how would I make a circular cavity like you are suggesting? Would the circular one be necessary for that small improvement in strength?

 

[Grifflyer]

But the cavities you make for A and B folds aren't circular. The original plan was to cut a cavity, but how would I make a circular cavity like you are suggesting? Would the circular one be necessary for that small improvement in strength?

It doesn't have to be a circular cavity if you cut a square cavity it will still give the spar more points to adhere to the wing, compared if you just glue it straight on.

 

[jross]

I just finished an armin wing for my Explorer. Pretty slick with a carbon fibre arrow shaft to connect both wing halves. The fit is snug and very positive. The armin wing is straight and I expect you could use the pocket/install technique for the polyhedral Explorer wing. Wouldn't work for the poly dihedral wing. Check out this video for ideas. The guy did it after he folded his stock FT wing. You can join wing halves permanently or use velcro or something similar to join them for flight and make transport easier. I'm a greenhorn builder and was surprised how well this wing came together for me.