paint/wax airspeed

ebykowsky

ebykowsky

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Seeing a shiny newly painted aircraft next to an old faded one and feeling the difference in texture makes it apparent that there is some drag induced by the old rough paint job. Personally, we wax the hulls of our boats every year and it makes them plane more easily and they get a higher speed and lower fuel consumption, but the effects are still relatively small. Seeing the pics of Charlene (looks beautiful by the way!) made me wonder just how much of an improvement in performance a new coat of paint or wax will give an airplane... or does it make the plane heavier and perform worse? I'd assume they strip the old paint first though.
 
My current ride is polished aluminum. At one time (probably just after polishing it) I considered painting it and researched the speed gain/loss that might be expected. Everything I read seemed to suggest that the painted planes were a tiny bit faster than my polished version.

ebykowsky said:
Seeing a shiny newly painted aircraft next to an old faded one and feeling the difference in texture makes it apparent that there is some drag induced by the old rough paint job. Personally, we wax the hulls of our boats every year and it makes them plane more easily and they get a higher speed and lower fuel consumption, but the effects are still relatively small. Seeing the pics of Charlene (looks beautiful by the way!) made me wonder just how much of an improvement in performance a new coat of paint or wax will give an airplane... or does it make the plane heavier and perform worse? I'd assume they strip the old paint first though.
Click to expand...
 
In most cases, old the paint is stripped first, so other than the diffence in the weight of the paint (many aftermarket paint jobs use thicker or more coats) is minimal. How much speed you get by clean paint or a wax job is anybody's guess, and would depend a lot on the condition of the surface before, but I'm guessing a few knots in a light single.
 
I don't think it's going to make a measurable difference in small aircraft. In airliners they've looked at this. The effect from weight of the paint is typically more than the drag reduction.

Back when I was in the fire department we'd be out waxing the fire engines. Someone asked why we spent so much time doing so, and I told them it cut down on the wind resistance (the front of our pumpers were pretty much the the proverbial flat plate).
 
Ron Levy said:
In most cases, old the paint is stripped first, so other than the diffence in the weight of the paint (many aftermarket paint jobs use thicker or more coats) is minimal. How much speed you get by clean paint or a wax job is anybody's guess, and would depend a lot on the condition of the surface before, but I'm guessing a few knots in a light single.
Click to expand...
Actually the new ura type paints will cover better and will shine better with a thiner coat. typically a 3 mil thickness.

the old Imron catalyzed enamel was about 12 mil thickness and lasted around 15 years with care, the new ura types will go 50 years with care .. (that's a prediction from Randolph)
 
If I have my dates that Imron was used it should be what's on my plane, 30 years old.
 
I remember reading an article on the CAFE foundation website in which they tested a Mooney before and after waxing and it was 3kts faster after waxing. So, wax on...
 
On this topic, I clay bar my airplane about once a year, followed by waxing it.

The clay bar process involved rubbing the skin with (literally) a clay bar which shears off irregularities. The paint is much, much smoother after that. With the RV, it probably takes 2-3 hours to clay bar the whole airframe. Waxing it takes a similar amount of time.

I don't know if the process makes the airplane any faster, but the bugs sure clean off easier...
 
A smooth glass ball has more drag in the wind tunnel than a glass ball with a circular area of sand glued onto the front.
 
So the consensus seems to be $1000/KT... I'd stick with the bar of clay.
 
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