Performance cost of paint job

[mussie]

I was just looking at the P38k artical on widewings site and read the following

the elimination of the heavy coat of paint would have gained even more performance.

I am wondering just how much a coat of paint could effect an aircrafts performance.....

[MORAY37]

Originally posted by mussie
I was just looking at the P38k artical on widewings site and read the following
 

I am wondering just how much a coat of paint could effect an aircrafts performance.....

For every pound... you lose performance.  Climb, turn, AoA performance all change.  I don't know about WW2 weights, as far as paint... but USN F-18's carry about 800 pounds of paint.

I've read that 737's carry around 1,100 pounds of exterior paint.

Probably why most late war US fighters, and cold war fighters were polished aluminun, until thrust output caught up with weight.

[Anaxogoras]

I still find it much more difficult to see Spitfires and other aircraft with paint against the land than the late war USAAF stuff (polished aluminum).  The camouflage might be worth the weight in some cases.

[ridley1]

well, by the time the USAAF went to polished aluminum they had air superiority, if not supremecy... camoflage really didn't matter

[fjaloma]

Originally posted by MORAY37
For every pound... you lose performance.  Climb, turn, AoA performance all change.  I don't know about WW2 weights, as far as paint... but USN F-18's carry about 800 pounds of paint.

I've read that 737's carry around 1,100 pounds of exterior paint.

Probably why most late war US fighters, and cold war fighters were polished aluminun, until thrust output caught up with weight.

*** What you said above is true.  That's why American Airlines have polished aluminum. The benefit of 1000+ pounds of weight helped performance and also saved fuel.

My dad owned an F4U (retired Naval Aviator) in Seattle. During a restoration project 15 years ago in Arizona, he performed some tests on performance. Seems that bare skin netted  him an additional 10 knts as sea level and  almost 17 knts at 20k. It may not sound like much, but with a bandit on your six, there are times you'd kill for just 10 more knots of speed.

So it pays not to paint, but you're REAL easy to spot from 15 miles away.

[CMC Airboss]

Originally posted by MORAY37
For every pound... you lose performance.  Climb, turn, AoA performance all change.  I don't know about WW2 weights, as far as paint... but USN F-18's carry about 800 pounds of paint.

I've read that 737's carry around 1,100 pounds of exterior paint.

A recent 747 that I worked on took 76 gallons of high-solid paint which comes in at ~12 pounds per gallon.  That is a total of 912 pounds.  It only took 6 gallons to completely cover both sides the vertical fin.  Given that the coverage area of a 747 more than 4x that of a 737, 1100 pounds is unlikely.  Coverage that thick would start eroding on the first flight.

[Sled]

Are those weights of wet paint or dry paint?

Obviously paint in the bucket before application if FAR heaver than dry applied paint.

[ImMoreBetter]

There are several reasons not to paint a plane.


-Shiny aluminum draws attention away from other things... like the bombers you're escorting.

-Cheaper and faster production, probably the most important reason.

-By the time the Americans started with the bare metal look, they had most taken control of the air. There was a much smaller risk of the planes from getting strafed while on the ground, where camo was most effective.

-Intimidation, like painting the nose of a 109 yellow. When you see a shiny spec floating above a bomber formation, you know you're going to need to watch your back.

-Reduced drag.

-Reduced weight.

[bozon]

When looking at planes from below on the background of the skies, the under sides tends to look darker than the background (because they are not directly illuminated by the sun). As long as the plane is not in such orientation as to directly reflect sun light to the observer's eye, a bright color (white, silver) would help it blend in the background from a distance.

I guess that by the time USAAF was using the metal finish, they were only seen from below by AA or bomber hunters.

I've read about experiments that tried to illuminate the under side of planes in order to help with sky camouflage. Eventually it was not worth the effort and almost all paint schemes today settle for a white / light-gray color.

[CMC Airboss]

Originally posted by SLED
Are those weights of wet paint or dry paint?
Obviously paint in the bucket before application if FAR heaver than dry applied paint.

That is the weight after the paint has been applied and fully dried.

[kozhedub]

I had always assumed the Americans stopped using full coats of paint to help with performance.

What I never understood was why the other airforces didn't also follow this if the advantage in weight was obvious, especially needing all the fuel savings they could in Germany/Japan.

The "already had air superiority" makes sense but certainly this was also the case in the Eastern front from most of 43 onwards and I'm not sure the standard greys made for good ground camo. Could be they didn't see that significant savings in weight.

Edit : Does anyone have images/stories/evidence of VVS fighters operating with metal finishes?

[Motherland]

Originally posted by kozhedub

What I never understood was why the other airforces didn't also follow this if the advantage in weight was obvious, especially needing all the fuel savings they could in Germany/Japan.
 

In the Blond Knight of Germany, Hartmann describes his first contact with Mustangs as 'I saw the glints of silver in the sky, and knew they had to be American as the Luftwaffe had abandoned polished silver in the Spanish Civil War' or something to that effect. I guess they figured it wasnt worth having your planes standing out like sore thumbs.

[2bighorn]

Originally posted by kozhedub
What I never understood was why the other airforces didn't also follow this if the advantage in weight was obvious, especially needing all the fuel savings they could in Germany/Japan.

Advantage in weight wasn't as obvious. Added weight was roughly 60-80lbs for an average sized fighter.

Not all planes were built 100% out of metal. They had wooden parts, fabric covered parts, etc. You had to protect those.

[Gunston]

A big reason for the non-painted American fighters late in the war was part of a pre-invasion (D-Day) strategy to destroy as much of the remaining Luftwaffe fighter force as possible. It was an invitation to come up and fight.

[Overlag]

americans have no style, so couldnt paint there planes.