On 5/4/2011 7:56 PM, Frank Whiteley wrote:
On May 4, 4:47 pm, Bob wrote:
On May 4, 3:34 pm, Reed von wrote:

Trust me, it's not repairable. Even if it was, you would end up
spending years and 30k dollars plus fixing the thing.

I've seen some pretty clever repairs on about this magnitude, so I
respectfully disagree. For example, there was the Genesis where JJ
basically created about six feet of wing from scratch. It took him a
winter of on-and-off work, and turned out so nice you could not tell
the wing had been repaired.

Thanks, Bob K.http://www.hpaircraft.com

I once knew a BGA senior inspector that rebuilt an absolutely
shattered DG-300 (that he flew into some wires). The repair was at
least this complex. The rebuild weighed within 10oz of the original
weight. That was craftsmanship.

Frank Whiteley

George Applebay once (chucklingly, once he realized how little I then knew
about composite repairs), said to me, "Oh no, Bob. That's not a major repair.
To us, a major repair might be something like splicing a main spar within 3
feet of the root."

As JJ and others have previously shared, fiberglass-based composites are
conceptually (as distinct from 'craftsmanly') easy to repair, and definitely
simpler if enough of the broken bits remain from which to make (if no unbroken
bits exist from which to pull) female molds in which to create/splice things
back together.

Carbon is not fundamentally more difficult to repair, though arguably more
'persnickety' due to lower strength margins (thanks to its relatively higher
stiffness compared to fiberglass) in the final product, and increased
difficulty visually verifying proper/complete 'wetting-out' of dry hand layups.

Kevlar is in a different league, due (not entirely) to cutting difficulties.

I know of a Nimbus II that was shattered (fatally, unfortunately) on an OFL
attempt, and - unlike Humpty Dumpty - the fuselage (& canopy) was (were)
pieced back together to make a male mold/plug, around which a female mold was
formed, in which a new cockpit area was made, then grafted back onto the
spliced-together tailboom. Major wing repairs were also required. All done by
two guys with previously little fiberglass experience, one of whom later
opened an FAA-approved composite repair station.

If the repairs are properly done, no detectable weight gain due to the repairs
need occur.

As always, the devil is in the details, so...kids, don't try this at home
without professional input.

Bob W.

P.S. Anyone who takes the above as sufficient guidance and knowledge to begin
crafting their own structural composite repairs might want to reflect upon
their place in the gene pool beforehand, so please - no flames on any basis of
the information being incomplete. Of COURSE it is. My major conceptual point
is that when assking the question, "Can [this collection of composite shards]
be repaired?" the answers is almost always, "Yes," when we're talking 'glass
gliders'. Insert the word 'economically' directly ahead of 'repaired' and the
answer become much more complex.