Re: UV damage

Mike Dwyer

Hi Richard,

For the standard Q's (not Tri-Q)... If I remember my calculations of 20 years ago, when a wing develops 1G of lift it is doing so with the lift distribution over the entire wing surface. If you lift a plane by only the wing tips that is basically equivalent to a distributed 2G load. If you have 2 wings and lift the plane with only one of them (the canard) then you have the equivalent of 4G on that one wing. If you bounce up and down a bit while getting in the plane (we all do) then the loaded G equivalent is probably more like 6G on the canard. Nobody use the Q as a trampolene please!

The Q200 canard I heard was good for 30G and the main wing 15G,,, tho never tested anywhere near this. The most the plane can pull in flight is about 4G, but I suppose a fast updraft could put more load on the plane?

No correctly built airplane has ever come apart in flight to my knowledge. I say it that way because one main wing broke after an incorrect repair job.

UV to my knowlege doesn't penetrate very far, kinda breaks down the first molecule it hits.

As for your paint theory try a different thought. No idea if this is right or not. I understand fiberglass resins outgass for their entire life. If you seal over it with a super non-porus sealant then when it outgasses it will blow the paint off. My theory is use cheap paint cause we're all going to be repainting in 15 years! My paint bubbled right off as you described. Darn, I got 15 years on the first paint job and now have 11 on the second. Don't tell me that I'll have to do it again in 4 more years! see:

Mike Q200 N3QP


To: Q-LIST@...
From: richard@...
Date: Sun, 17 Jul 2011 20:49:24 +0100
Subject: [Q-LIST] Re: UV damage

Hi Mike.

Can you explain your statement

I calculated that the Q200 canard has the equivalent of 4G on it when
loaded to gross on the ground, plus it is supported by the wing tips. ?

It's a few years since I have played with Aero loads, but to have G do
you not need to have movement or acceleration ? So at Design gross
weight is it not still 1G loading ?

Do we know what Burt and successors originally stressed the spars to
take ( on the Long eze he said it was 17 G ) ?

Also has there been any main wing or Canard failures in flight ? I only
remember 1 problem which was elevator mount failure wasn't it ?

How much damage is caused to the spar caps when the outer layers are
not or become no longer painted ?
Can the UV penetrate the outer plies to that depth and damage the spar
? What testing has been done to prove this ?

Not a problem for you hot climate boys, but from my experience I noted
that the old style UV layer will unfortuanately absorb moisture if
there are any pinhloes in the paint layer, which softens it and then it
sheers under the outer paint layer, the paint can then be locally
stripped in sheets, yet under the remaing black the weave surface is
just like new with no damp or UV damage.
That's why I have used good quality 2 pack epoxy primer and 2 pack
polyurathne top coat to refinish, as it's specification states it is a
UV barrier and its protected from virtually everything including salt

Richard Thomson

Getting closer every week.


Join to automatically receive all group messages.