The weight of paint?

[az_gila]

Originally Posted by Mel

Filling rivets adds weight and lots of labor. I did it on one airplane. It really looks nice but I would never do it again.

I have a rivet filling Q for experienced painters too....

One builder mentioned not exactly filling rivets, but just adding one or two extra passes with a narrow spray fan along all of the lines of rivets during the primer application.

It seems this might somewhat fill the rivets but with little added weight or extra sanding work.

For the experienced painters, does this make sense?

[OneCharlieKilo]

Just another data point, but I weighed my RV-6A right before and after paint with same scales and result was 16 lbs for scheme in picture shown below. That was at T&P AeroRefinishers in Salinas and Juan pays a lot of attention to weight.
White coat went on everywhere, then black trim stripe added, then red. Clear coat on only the black and red areas.



paint data:

Base color: 570-535 Mattehorn white Jet Glo - Sherwin Williams
Red: RS911F Red - DuPont
Black: G9009S Black - DuPont
Clear coat (only applied to red and black): G2-7779S - DuPont

weight data:

Before: EW = 1,087 lbs, empty CG = 67.2"
After: EW = 1,103 lbs, empty CG = 68.1"

web page showing my paint process:

http://rv6aproject.ckhand.com/PaintJob/PaintJobPg1.htm

And prior thread I posted when I got it out of paint shop:

http://www.vansairforce.com/communit...ad.php?t=68189

Good luck, and post pics!

[bret]

Originally Posted by Bob Axsom

You already know the weight will increase 30 to 40 pounds with a beautiful paint job so you have the basic answer to your question I think. Perhaps surprisingly the weight is not that big a factor in cruise - maybe you know that. Dave Anders if a very famous RV-4 builder with extreme attention to detail including weight. He built his RV-4 with natural aluminum finish and red paint trim stripes and spinner. He flew it for years this way but now the aluminim is covered with white. The plane is described in a decades old Sport Aviation article - I can look it up if necessary - I still remember reading about him temperature controlling the rivets until installation in a dentist oven - detail!!! He set the RV Gold class record 240.58 mph in the AirVenture Cup race in 2010 painted.

When I worked at McDonnell Aircraft in St. Louis starting in 1958 the F-101 had a natural aluminum finish, The F-4 Phantom II was painted with epoyx, and the F-15 was painted with polyurethane. When I built our RV-6A I flew it for a year with no paint except for a thined epoxy resin brush on coat of the fiberglass cowl and fairings. I loved to fly it that way as it seemed very military utilitarian with no polish. I experienced no deterioration so either way works. I am sure in my own mind that the protection and appearance benefits of the weight are worth the sacrifice.

I know that is not directly responding to your original question but I think it is relevent to the bigger question.

Bob Axsom

P.S. The rule of thumb on the effect of weight on cruise speed is 1 kt per 100 lbs.

OK OK, So....even if I am heavy on the paint I will only lose 1/2 a kt. I can live with that, I am 230 Lbs so I gues I can go on a diet if need be. I like painted.

[Mel]

Originally Posted by az_gila

One builder mentioned not exactly filling rivets, but just adding one or two extra passes with a narrow spray fan along all of the lines of rivets during the primer application.
It seems this might somewhat fill the rivets but with little added weight or extra sanding work.
For the experienced painters, does this make sense?

The problem that I've seen using this method is that some rivets will fill more than others and it will look "non-uniform".
I think it's better to either fill completely or leave them.

[RV6_flyer]

IF you want to go back 14-years, my RV-6 picked up 8 pounds after painting. Yes EIGHT pounds. It was weighed both before and after on CALIBRATED electronic scales that were used to weight other aircraft.

Paint used was DuPont ChromaOne Acrylic Urethane. It is an automotive paint and yes the airplane was primed with DuPont acid etching primer that was the big thing at the time. Aircraft was painted by a friend that had only painted a couple of airplanes before.

Paint does not weight that much after the liquid evaporates.

Looks like I am the only data point so far in this thread that did not pick up a substantial amount of weight.

[GusBiz]

So your saying Dry it was something like

Dry
2lbs = Primer
2lbs = Base COat
2lbs = Clear coat layer one
2lbs = Clear coat layer two

Lets say that its a mostly solvent solution so

Wet
10lbs = Primer
10lbs = Base Coat
10lbs = Clear coat layer one
10lbs = Clear coat layer two

I do not see 10lbs of wet anything covering a whole plane.

I think that you may have gone thin on some coats or just didn't include all of them.

[smokyray]

When I finally painted my RV4 in 1999 (after 4 years of flying) I very carefully weighed it on digital race car scales. I etched and alodined it, 1 coat grey primer 1 coat base color single stage PPG DGHS fleet cement truck paint. I chose to not paint stripes, rather paint control surfaces and cowling a different color, thus not having more than 1 coat.
End result was a 12 lb weight gain carefully checked on the exact same spot and scales. I know the paint is no longer used as it is considered hazmat. When we painted the X last year we repeated the process, exactly with a modern single stage sprayed with HVLP. Weight gain? 18 lbs.

For a unpainted RV in my neck of the woods, "rust never sleeps"...


FYI
Smokey

[videobobk]

This thread got me thinking--I went with vinyl for my second and third colors. I knew it was a big money savings, but what about weight? I just went down and weighed a square foot of Oracal 951 Premium Cast Vinyl in black. 951 is the best (IMHO) vinyl, and the only thing I put on airplanes. I weighed it on an accurate powder measure scale, and it weighed 158 grains. There are 7000 grains to the pound. That means that it would take a little over 44 square feet to equal one pound. I used about half that much on my 9A and I don't think I have added a pound to anything I have ever decorated; another argument for vinyl.

I would guess that using vinyl instead of paint on the average RV would increase the weight by about 1.476 ounces, give or take. CG shift would be exactly 0.0002" aft. I didn't figure it in knots

Bob

[Bob Axsom]

Originally Posted by bret

OK OK, So....even if I am heavy on the paint I will only lose 1/2 a kt. I can live with that, I am 230 Lbs so I gues I can go on a diet if need be. I like painted.

That is what Dave Anders did for maximum performance - I don't remember the exact weight loss - but I think the greatest benefit was in the climb performance. Aside from aircraft performance the weight loss may have other benefits. I weighed 228 pounds in 1956 when I started conciously trying to get it down. I think I had it down to 197 by the time I left Korea. Yesterday morning I weighed 196.2 I think. I have had it as low as the high 170s and I made a new Year's resolution yesterday to get it back under 185 pounds in 2012 when I have my next third class medical coming up in November.

Bob Axsom