What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Polyester wingtips.. heat tolerance?

LAL

Active Member
A little help with my low fiberglass IQ would be appreciated (would that make it a low FQ??): A good portion of my wingtips will be gloss black in current, primarily red, paint scheme. I'll be tied down outside on many trips and wonder if this will this present a heat problem with the polyester tips in bright sunshine on those 90 or 95 degree summer days?
Regards,
Len
N72ML, OSH with much, much luck.
 
Shouldn't be a problem

Should not be a problem. You might want to add a couple of chordwise bands of glass cloth when you build them to provide a little more structure.
 
It is getting hot in here

There is a scientific answer but the short answer is the wingtips are not structural so it does not matter. However over time you may get some warp/distortion.

Just to throw some numbers at it, between white & black *surface temp you might typically see a 50F degree difference between the colors. On a hot (100F) day black might be hot as 170F. The polyester will be "soft" at 170F.

The worry is the bubble canopy, direct sunlight, will give some magnification, the cockpit gets hot enough to distort plastic bezel on radios. Polished RV's can reflect sunlight off the wing on to the canopy, actually melting it. I did not believe it, but it has happened. Put a cover on your plane it will thank you. G

*PSFactoid - Interiors of White car are about 10F cooler than black.
 
Last edited:
poyester is the cheapest and lowest grade of resin. It is not a good structural or high temp resin. Some additional stiffners are good up to a point , in that the unsupported areas will still sag a bit and you will then see the "ribs" showing thru. I am leaving mine per plans, so when it does sag it will still be a flatish surface.
Also some aerobatic mounts made of resin are G rated only up to a certain temp. So if it gets too hot, say in a dessert you may have a problem.

As far as painting them black I feel its a bad move from a heat sag angle. I wouldnt think its a structural issue though. Check with Vans.
 
Last edited:
So soft

Polyester resins have a very low heat tolerance (low glass transition temperature and heat deflection temperture around 120 to 140F). If you have any doubt, put a heat gun on it to heat it up to a temperature where you can still tolerably touch it with your hands, and it will be very pliable and soft.

Polyester resins are worse than the vinylester resins used on many glass homebuilts that are painted mostly white.

I had the same question about the wing tips. They are changing shape just sitting on edge in my garage in the Seattle area where it does not get very hot. I am thinking about adding some additional foam ribs to keep the shape better.

The worst case is sitting on a hot tarmac in the sun where temperatures. Once the airspeed picks up, the tips should cool quickly.
 
Vinelester is actually a brilliant resin. Personally I think its a nicer resin than epoxy to work with. It also cures quicker and can be fuel resistant. Some grades have incredibly high deformation temperatures. Epoxy advantage is the lack of smell.
 
polyester wingtip heat tolerance

Thanks to all for your thoughts. Bottom line sounds like the wingtips should have a bit of reinforcement in that they will soften some in any case. As I think about it, I suspect that the black will be somewhat hotter than if I kept it the overall red of the airplane, but also in either case it will get hot. As for vinylester: I have already plumbed my main tanks and wings for tiptanks and installed filler caps in the tips. That has added little weight and keeps open my options, considerably easing the way should I decide to go forward with it after flying. I would plan on making the tanks themselves by building up the tips with vinylester layups (that has been fairly widely recommended to me because of vinylester/polyester compatibility and vinylester's fuel resistance).
All continuing thoughts welcome, including tip tank comments.
Regards,
Len
N72ML.. OSH with much, much luck
 
Back
Top