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General Forums => Aces High General Discussion => Topic started by: mussie on January 19, 2008, 02:45:52 PM

Title: Performance cost of paint job
Post by: mussie on January 19, 2008, 02:45:52 PM
I was just looking at the P38k artical on widewings site and read the following
Quote
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.....
Title: Re: Performance cost of paint job
Post by: MORAY37 on January 19, 2008, 03:02:54 PM
Quote
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.
Title: Performance cost of paint job
Post by: Anaxogoras on January 19, 2008, 03:24:26 PM
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.
Title: Performance cost of paint job
Post by: ridley1 on January 19, 2008, 05:09:46 PM
well, by the time the USAAF went to polished aluminum they had air superiority, if not supremecy... camoflage really didn't matter
Title: Re: Re: Performance cost of paint job
Post by: fjaloma on January 19, 2008, 06:12:08 PM
Quote
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.
Title: Re: Re: Performance cost of paint job
Post by: CMC Airboss on January 19, 2008, 07:36:45 PM
Quote
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.
Title: Performance cost of paint job
Post by: Sled on January 19, 2008, 07:40:22 PM
Are those weights of wet paint or dry paint?

Obviously paint in the bucket before application if FAR heaver than dry applied paint.
Title: Performance cost of paint job
Post by: ImMoreBetter on January 19, 2008, 08:42:14 PM
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.
Title: Performance cost of paint job
Post by: bozon on January 20, 2008, 04:19:54 AM
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.
Title: Performance cost of paint job
Post by: CMC Airboss on January 20, 2008, 06:10:05 PM
Quote
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.
Title: Performance cost of paint job
Post by: kozhedub on January 20, 2008, 06:30:39 PM
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?
Title: Performance cost of paint job
Post by: Motherland on January 20, 2008, 06:34:15 PM
Quote
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.
Title: Performance cost of paint job
Post by: 2bighorn on January 20, 2008, 06:41:51 PM
Quote
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.
Title: Performance cost of paint job
Post by: Gunston on January 20, 2008, 06:59:04 PM
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.
Title: Performance cost of paint job
Post by: Overlag on January 20, 2008, 09:46:30 PM
americans have no style, so couldnt paint there planes.

:noid
Title: Performance cost of paint job
Post by: Sled on January 20, 2008, 10:21:45 PM
Quote
Originally posted by Overlag
americans have no style, so couldnt paint there planes.

:noid


Oh get serious, :huh

we had the best looking nose art of the war. :aok
Title: Performance cost of paint job
Post by: Roscoroo on January 21, 2008, 02:04:32 AM
actually Aluminum is more work to keep in tune for the liter weight ...

it has to be buffed and polished on a weekly- monthly  basis to keep from oxidizing and dirt pitting .(this can cause as much drag as a unwaxed paint job)
Title: Performance cost of paint job
Post by: Overlag on January 21, 2008, 06:57:01 AM
Quote
Originally posted by SLED
Oh get serious, :huh

we had the best looking nose art of the war. :aok


i was joking :D:t
Title: Performance cost of paint job
Post by: rabbidrabbit on January 21, 2008, 07:45:28 AM
Back then they did not have big enough gold chains to hang around the noses, cool enough lighting or spinny rims so they made due.  There was a war going on ya know!  I always admired them for making the best of what precious little resources they had.
Title: Performance cost of paint job
Post by: kozhedub on January 21, 2008, 08:54:27 AM
Quote
Originally posted by 2bighorn
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.


Good points, especially the non metal bit.
Title: Space shuttle
Post by: zilla on January 21, 2008, 09:39:12 PM
The original space shuttle external fuel tanks were painted white to help protect them from UV rays while sitting on the launch pad for long periods of time. When NASA found out that there was no danger from the UV they stopped using the paint. Here is a quote about the weight savings.

"Subsequent tests found that the paint wasn't vital for shuttle launches and it was abandoned to free up weight - about 600 pounds (272 kilograms) - for additional payload, NASA officials said. "
Title: Shuttle payload
Post by: zilla on January 21, 2008, 09:42:20 PM
Additional pay load could just mean more Ho's an beer. Maybe one of those shiatsu massager cushions for the pilot.