Black Paint on fiberglass

[wawrzynskivp]

Hello All,

An A&P advised me that black paint will cause my fiberglass to go past its Tg and distort. I have used black paint on boats, and see other RVs with black paint so I thought I might find someone here who has done this and can share experience with hot sun conditions.

As a mental aside: wouldn't shutting down a fully warmed engine with the stock Van's baffling provide more temp than sun/black paint? (of course I am talking about the average core temperature of the glass matrix and not what we feel on the outer skin)


Cheers
Vince

[rv7charlie]

Back when EZs were much more common, it was common knowledge that you shouldn't use anything but white or very light colors on them. Newer epoxies might tolerate heat better, but I'd want the epoxy mfgr's blessing before putting black on structural stuff.

I doubt that cowl temps after shutdown could come anywhere neat the temps of a black surface exposed to sunlight for hours.

Having said all that, there are black & dark colored RVs out there. They do have the advantage that the closest thing to real 'structure' is the cowl itself (except the -10, of course).

Charlie

[snopercod]

Back in the olden days, Lancair did a study on the temperature effects of different paint colors. From memory, the darker colors (including red) raised the temperature of the fiberglass to over 200F. So their advice was "light colors only". But then they went and painted their demo plane N320L red. Go figure...

[penguin]

Yep, dark surfaces often get to 200* in the sun. But don't worry much for your RV parts.

The Tg depends on the resin used and the post-cure heat treatment applied. Not all resins can take a post-cure, and not many moulders would apply a post-cure to fairings. The post cure is typically 140 to 180* for between 8 and 16 hours (so expensive to carry out), all depends on the resin in use. For structural parts it is essential, for fairings probably too much bother.

West 105 doesn't take a post-cure. Tg for room temperature cured parts (or make that 100* post cure, but it has little effect) is around 120* and depends on the hardener used - slow hardener gives better properties. Tg is not an all-of-a-sudden property, the resin will often gradually over about 15*. Above Tg the resin just becomes soft - it won't all run away!

Thin fairings will cool down quickly once flying, so are unlikely to deform much unless they are under stress to start with.

Anyone know what type of resin Van's uses for cowlings & wheel fairings?

Pete

[Mel]

Originally Posted by snopercod

Back in the olden days, Lancair did a study on the temperature effects of different paint colors. From memory, the darker colors (including red) raised the temperature of the fiberglass to over 200F. So their advice was "light colors only". But then they went and painted their demo plane N320L red. Go figure...

Actually the red plane WAS the test aircraft. They imbedded thermistors into the structure while building with the intent of testing.

[wawrzynskivp]

Thanks for weighing in, still hoping to hear from someone who has gone with black?


Cheers
Vince

[broken1234]

Lancair proceeded with an abundance of caution. They proved that there was more to it than just adhering to the glass transition temperature number.
I have done partial black birds a few times, but never a whole plane.
I have never seen any detrimental effects to the aircraft structure. But I have seen a lot of visible weave due to the obviously hotter surface temps shrinking and baking the primer, but the same poor bodywork was not evident in nearby areas painted in a lighter color.
So, proceed at your own risk... that's the beauty of experimental aviation!

[Tom Martin]

My RV4 was painted black. I owned it for three years, and the next owner had it for many more. While I had the plane I experienced no problems. I do live in southern Canada. If I was in Arizona I might consider another colour option. Also if the plane was tied down outside I would not paint it black. Consider the number of actual outside hours a year your plane sees if it normally rests in a hangar.
I hear lots of bad things about black paint on airplanes but is never from some one who has actually owned on.
Numerous pilots told me that it was the easiest plane to spot in the sky.

[wawrzynskivp]

Thanks for the feedback!

[paul330]

In the UK, the authorities promulgated a mandatory mod for the RV10 stating ?no dark colors? for the canopy as it is structural.