Paint vs polished aluminum. Does this affect flight characteristics?

Pi1otguy

Pi1otguy

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Recent I stumbled upon the theory that some airlines polished the aluminum skins instead of full paint jobs to save weight. This is pre-composite of course.

Do the same logic apply to light singles? While I can imagine ~20lb lower empty weight, are there any meaningful differences? Does a smooth polishing get an extra 2 knots similar to adding pants?
Is it actually lighter or do owners of bare metal planes as layers of polish over time?
 
Paint added 20 lbs. to my small taildragger. I didn't notice any change in airspeed but I do keep it clean and wipe it with spray wax after flights. I read years ago that keeping the surfaces clean and waxed does help with a small increase in speed.

I had a polished plane a few moons ago and I recommend that every should own one ... once. It was a low wing and IIRC the hottest metal I've ever touched against my skin that wasn't being cut or welded was that shiny wing surface in the 100ºF sunshine at a fly-in. I crawled up on the wing in my shorts and learned a valuable lesson that day ... so now I understand why most planes are painted white. :biggrin:
 
Pi1otguy said:
Do the same logic apply to light singles?
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Not really. The paint weight is not that great. Now if you were flying a weight challenged aircraft then if you needed another 20-30lbs of empty weigh to make it work, then maybe. However, your preventive care hours will definitely go up a lot. Regardless, cleaning and waxing any aircraft on a regular basis will give you some extra speed.
 
This is a VERY complex topic, and it can go both ways depending on the application and the airframe. The P-51 Mustang, for instance, greatly benefitted from having a filled, smoothed, and painted with to maintain the laminar flow. Other planes may be better off with less weight from the paint. So, you'd almost have to pick an airframe to discuss for this to be very meaningful.
 
I have instructed my neighbors that if they ever see a bare metal plane in my hangar, to go ahead, pick up that nine-pound sledgehammer in the corner and just start hitting me over the head with it.
 
Back in my racing days I knew someone that refused to put a drop of paint on any part of his car. He claimed it was faster without the extra weight.
 
Zeldman said:
Back in my racing days I knew someone that refused to put a drop of paint on any part of his car. He claimed it was faster without the extra weight.
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The racing guys around here say ... "chrome's faster"
 
A WW2 USAAF study of B-17s in the ETO found that painting one added 1% or so ro its weight, and increased top speed by 1-2%. Because the paint, although less smooth than polished aluminum, "smoothed" the airflow at panel edges and over rivets. YMMV.
 
Zeldman said:
Back in my racing days I knew someone that refused to put a drop of paint on any part of his car. He claimed it was faster without the extra weight.
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I raced a bare chrome moly chassis not because it was lighter, it was so we could see cracks better and weld repairs were easier. And why cover up those beautiful tig welds.
 
Daleandee said:
The racing guys around here say ... "chrome's faster"
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What about "Wisconsin Chrome?" (Duct tape)

I was one of the only cars that would run chrome rims.
 
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