Returning builder

[Frank Day]

Recently back in the hobby and looking for some build advice,  I have a part finished traditional build to complete and another short kit to build at a later date when the skill level has improved.

 

Both kits use a whole bunch of 1/4 sq balsa in the fuselage and wings and I was wondering about the pros and cons of using carbon fibre box instead, ie weight, strength, bonding etc

 

All advice welcome

[Simon Chaddock]

Frank

You really need to establish the weight per unit length of the carbon fibre section you intend to use and then compare it with the equivalent balsa.  Then you have to establish if the additional strength is actually required and finally whether the rest of the structure around the carbon fibre will benefit from its strength.

Yes, carbon fibre can be stronger and lighter than steel but not many models use that as a structural material! ?

Balsa glues very well to balsa and many other fibrous materials giving a joint strength broadly equivalent to the material. A carbon fibre to balsa joint is only as strong as the balsa, say 1/20 that of the carbon fibre.

Of course it you are loading the structure well above its original design capability then reinforcing may well be required but carbon may not be the best solution.

 

I am always a bit concerned that 'carbon' is seen as a universal strength salvation. It can be but it is only really effective when it is made to 'work for its keep' and that takes careful structural integration.