What's new
Van's Air Force

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

Does paint really make a plane faster?

BruceMe

Well Known Member
I've heard that painting makes RVs faster. Is there any real documented data on this? Or is it urban legend?
 
Now that I've had my chance to be a jacka-s, I'll actually give you a worthwhile answer.
Section 13 of the manual covers painting (at least in the RV-7 manual). A paragraph from that states the following:

"The question of whether a painted or bare aluminum airplane goes faster is often raised. Experience with the prototype RVs has not provided a definitive answer, so it would appear that there is little difference in skin friction drag from a typical painted surface to a typical bare aluminum surface."

Ultimately it is a tradeoff from the increased induced drag due to the paint weight, compared to the increased skin friction/parasitic due to a better surface finish (assuming you can paint well). Given that we are running non laminar flow sections, that surface finish may not be so critical.
I think realistically it comes down to other factors, such as... do you mind the glare off the topside of the wings, do you like polishing aluminium on your weekends, do you mind the extra 15-25lbs in paint weight and it's CoG impact (especially on a -7), do you want the best corrosion protection, do you have the right conditions/facilities/$$$ to paint, and what do you want your aircraft to look like? I spent many months sitting on the fence on this one, but I have taken everything into account and decided to paint with a single pack valspar (Wattyl) zinc phosphate epoxy etch primer with a Valspar (Wattyl Colurthane) polyurethane top coat. As a datapoint for Australians out there considering using Colourthane, it turns out that the head office in Sydney will colour match what ever colour you want so long as you send them an sample chip they can match to. I wanted a Federal Standard 595 colour, so I ordered a chip from the States and they will match it free of charge.

Tom.

PS. if you decide not to paint, here's my favourite "no paint" paint job (C-GSMC). It's polished so it's light, but it's also red, so it goes fast!
vr7w4w.jpg
 
When painting the airplane, simply make some adjustments to the airspeed indicator: Change "MPH" to "Kts" and you're 15% faster!
 
The polished ones go fastest... No paint so they're light, and polished so they're smoother than just bare aluminum... :)
 
Can't say for an RV as I only flew our RV9A with paint but can say definitely that our Lancair gained between 5 - 10 kts after the repaint.
 
Not sure about speed impact, but Rejex is the greatest stuff ever for making easy bug removal. I use it on leading edges and all the "buggy" surfaces on the RV, and all my cars. GREAT stuff!:D
 
Paint makes you slower

I have to pull back on the throttle and take fewer flights in order to afford getting mine painted.
 
more data points needed!

So I would expect almost no measurable difference on a flush-riveted polished vs painted surface....surely there are 1932 NACA tests for this?????

my new ride has lots of domed rivets, and I wonder if putting a vinyl wrap over those surfaces wouldn't 'smooth' out the airflow over those heads. yes, they'd all be .002" higher, so not 'hiding' the bump, but perhaps bridging the transitions. ( Yes, it's painted, so can't quantify that effect).

....ok you guys with little wind tunnels in your hangars.....let us know how this all plays out??!?
 
Many years ago I had built a canard style airplane with a very slick paint job my hanger partner had a paint job with heavy orange peel and he had a fast airplane so to make it faster he decided to give it a slick paint job. Well his stall speed went up and top speed went down, he was not happy.
 
I wonder about this....on a off shore race boat they have what they call a stepped hull, it allows air to enter under the bottom to introduce air bubbles between the boat and water surface, to release the suction of the water and go faster. Would micro vortex generators in the paint imperfections do the same?
 
My thinking is that most of the weight of the paint is aft of the CG and as everyone knows, tail heavy planes tend to fly faster.

Just a guess on my part and I could be way off base.
 
I wonder about this....on a off shore race boat they have what they call a stepped hull, it allows air to enter under the bottom to introduce air bubbles between the boat and water surface, to release the suction of the water and go faster. Would micro vortex generators in the paint imperfections do the same?
I always think of the Mythbusters episode where they explored whether dimples such as the ones on golf balls reduced drag; would a dimpled car get better mileage? Turns out, to their surprise, it was confirmed. I'm going to lean heavily on that reasoning if I end up with significant orange peel...
 
Every Top Fuel Dragster I've seen going 300+ MPH was painted.......so......Ok, never mind, might be the 11,000 HP or something :rolleyes:
 
It worked for dozer blades- only in reverse

That works for golf balls, right?

A certain earth moving research department showed that the addition of bumps spaced over a dozer blade actually gave better performance than the smooth blade. The best blade shapes work by shearing off a layer and rolling the collected material. Apparently, the bumps reduced the viscous drag of material. Totally impractical to manufacture, but a an odd success.

Disclosure: air, fluids (water), and regolith do not have the same flow properties.
 
Much faster with paint

My RV-6 is 200+ mph faster with paint. Keep in mind that that is with a really good wax job and that it never flew without paint so the actual speed gain might be a scosh less.
:)
 
Yes

Yes paint makes the plane goes faster.

Without paint, eventually the wings will fall off and the plane will be slower.
 
Back
Top