WOT 4 Foam-E cracked spine

[Martin 0]

 

In the last funfly (Skittles), my WOT 4 Foam-E had an "arrival" which cracked the rear fuselage. Upon closer inspection, the carbon tube spine has also split (lengthways like bamboo - it hasn't actually broken the fibres).

 

I'm considering my options for repairing this.

 

Firstly, I could take the rear section right off (the foam is broken on one side, but I could break the other side too), and try to replace the spine with a fresh piece of tube. The issues I see with this are:

 

• there's no guarantee I'll actually be able to get the old tube out of the rear section without damaging everything further.

• getting the pushrods back where they're supposed to be would be hard (I have another fuselage that broke more drastically in the same place, and trying to slot it all back together is difficult as the pushrods want to go through the foam rather than through the holes).

 

I could try to just get a narrower new tube that would fit inside, and glue this into the cracked tube. This would solve the problem of trying to get the spine out, but wouldn't solve the problem of getting it all back together again!

 

Alternatively, I could leave the existing spine where it is. I could maybe get some cyano to it (via a long flexible nozzle) to hold it back together a bit better. If I did this, I'd look to reinforce somewhere else to reduce the need for the spine. I could cut slots in the outside of the fuselage and let in some carbon strips to provide stiffness. Another thing I was considering is just gluing the foam together and using fibreglass reinforcing tape to pull it together, so the foam is all in compression.

 

To be honest, I'm not sure how much impact the carbon spine actually has, and so how important it is to repair it.

 

Any ideas or opinions?

 

[Trevor 25]

 

Martin,

Cyano usually holds carbon fibre together quite well. I would have a go at repairing the carbon tube with cyano first, being careful not to get the cyano on the foam. Then repair the fuselage with epoxy, uhu por or something.

 

Edited May 19, 2015 by Guest

[Geoff.L 0]

first I remove the fin and tailplane then I cut the fus top and bottom along the join with a long blade, you then see where everything goes and repair damage internally, then I join the broken side when dry (with all rods etc. in place) I join the 2 sides with UHO por and some thin ply on the outside. make sure it is straight/inline before adding the ply (I didn't and had to redo!!!!) if looks bent then steam it and it will straighten. don't look new but flies OK. Geoff L

[Bravedan 106]

 

Don't know if its possible in this case but a lengthwise splintered carbon tube can be repaired by inserting a smaller tube (or rod if so small the strength isn't good enough) and flooding it with wicking thin cyano as you say.

 

Can you "guide" the pushrods by temp extending them with a rod and something to grab their end to avoid it digging in?

 

[Martin 0]

 

Thanks for all the tips. I think I'll practice on the one that's really broken before I commit to anything on the one that still has hope!

 

The idea of attaching some sort of extension (I'm thinking of taping on bamboo barbeque skewers) to the pushrods is a good one. If I can cover the wire ends with tape then hopefully they won't stick through the foam.

 

[Trevor 25]

If you have some bourdon tubing you can push it through and over the end of the pushrods to guide them through the fus

[Peter Royall 47]

 

replacing the carbon tube without ruining the fus would be next to impossible in my opinion. I have cut up several now, and the carbon tube is well fixed!

If all else fails, a new fus is available from Ripmax for around £30.

Also, it is near Wings and Wheels time, and there is no telling what I shall return with!

The Cynao should work, along with the epoxy for the foam.

Good luck

Oily

 

[Peter Royall 47]

 

Martin,

I left a tatty foamy fuz for you with Rod on Sunday.

Its been repaired a few times, but I wondered if you could use it?

I don't want anything for it.

It has a claim to fame as from the "RC model flyer" magazine review model.

That is all,

Oily