Exhausts

[robertandy]

Obviously one should not make aircraft exhausts rusted out like an old car or on a tank, but how oxidized should they be? I am working on the engine my 1/32 Mustang from Dragon and oxidized the exhausts (seen in WIP), maybe a little heavy handed, but a couple of folks on Hyperscale said no rust at all. So anyone have an idea. We are also talking wartime examples which I went off a picture of, not a warbird since those are a bit more babied than a front line fighter.

Rob

[LSP_K2]

My guess would be not all that much. The tremendous heat would probably roast a lot of the oxidation off I'd think. Just a guess mind you. I'm surprised none of the Mustang fanatics have lept on this.

[csavaglio]

Actually it's sort of the opposite.....the heat doesn't cook off the oxidation, it actually speeds it up.

 

The reason ceramic coatings on welded tubular steel exhaust headers for cars are so popular, is that it prevents them from rusting.

 

Bare steel or iron exhausts rust extremely fast, especially cool, humid invironments since the heat draws the moisture to them as they cool. If you take a look at a car that has uncoated headers, they begin to rust after only a few times of being heat cycled. This is why exhausts are the first component on a car to rust out.

 

I paint them steel and use pastels to light dust them with a tannish grey, or go over lightly with a dark rust color, then go back over with a grey.

 

 

 

C

[robertandy]

Actually it's sort of the opposite.....the heat doesn't cook off the oxidation, it actually speeds it up.

 

The reason ceramic coatings on welded tubular steel exhaust headers for cars are so popular, is that it prevents them from rusting.

 

Bare steel or iron exhausts rust extremely fast, especially cool, humid invironments since the heat draws the moisture to them as they cool. If you take a look at a car that has uncoated headers, they begin to rust after only a few times of being heat cycled. This is why exhausts are the first component on a car to rust out.

 

I paint them steel and use pastels to light dust them with a tannish grey, or go over lightly with a dark rust color, then go back over with a grey.

C

Thanks, that is my feeling and what I have seen is some pictures. Most..well All my experience is with modern USN Jets and turbo props so I can't say from personal experience, I toned my rust down a tad with a black wash, but I'm sticking by a more rather than less rust especially on Iwo Jima (VLR Mustang). I HAVE been there a few times in my career and it is hot humid and just plain wet!

Rob

[Edgar Brooks]

[Shawn M]

That ^ would appear to be a modern/restored spitfire.

 

Wartime birds would have more hours in a month then that plane has in a year.

 

Good shot for exhaust flow though, you can see where it hits.

 

Modern restored mustang:

 

 

 

image from flickr user: Chop49

[robertandy]

That ^ would appear to be a modern/restored spitfire.

 

Wartime birds would have more hours in a month then that plane has in a year.

 

Good shot for exhaust flow though, you can see where it hits.

 

Modern restored mustang:

 

image from flickr user: Chop49

Good point on hours flown also, the guy on Hyperscale who felt I was wrong with weathering my exhaust (and it was a bit heavy handed) used a very nice Mustang restoration as an example. I did point out warbirds are babied by their owners and justifiably so!

Rob

[LSP_K2]

There was a WIP on a 1:24 Hurricane some time back that had the best depiction of exhausts I've ever seen, but I'll be darned if I can find it. Perhaps someone else here can provide a link?

[Derek B]

There was a WIP on a 1:24 Hurricane some time back that had the best depiction of exhausts I've ever seen, but I'll be darned if I can find it. Perhaps someone else here can provide a link?

 

Hi Rob,

 

A few thoughts on the subject from my perspective...Most (piston engined) aircraft have stainless steel exhausts (although this could have contained a much higher degree of carbon and iron in WW II exhausts for cheapness and ease of production reasons). The subject of how much weathering, or rust, these would have seen in theatres of operation is a mute point, as it really depends a great deal on climate.

 

My motorcycle (a BMW R1150RT) has a stainless stell exhaust system as standard. I ride it every dat in all weathers and because it is mostly hidden behind a full fairing, never really gets cleaned. I expect that the type of corrosion and weathering my motorcycle exhaust experiences is not that far removed from what aircraft exhaust systems would also experience.

 

I agree that the full 'tank exhaust' rust treatment would not look right on aircraft exahusts, but where they operated is important. In hot climates, the exhausts would turn more of a powdery light tan (in some cases, almost pure white - especially if the engines were run very lean!). Rust appreared to be more prevalant in coastal and damp conditions. In all cases, there appears to be a graduation of colouring from the engine end to the open end (as evidenced in Edgar's photograph), with the rearmost pipes suffering more than the front pipes.

 

HTH

 

Derek

[Juggernut]

As Derek has stated, most piston engine exhausts are stainless steel (18-8 stainless I do believe), they do not rust (some modern ones are inconel). They do discolor and will crack from expansion and contraction over time. As you can see by the posted photos, the discoloration takes on a dark tan-ish hue with off white highlights. You'll also notice that the insides of the stacks are not black but a darker version of the tan (from the lighting, or lack thererof) There will be some lead deposits which may or may not be visible as dark grey metallic spots/streaks within the pipes but I would not overdo that in any way, shape or form. A black interior of an exhaust pipe is an indicator that the cylinder is running either very rich or has an oil leak, either way, not a real nice thing to have. I will stick my hand up first and say I am guilty of painting the insides of the exhausts of my aircraft black...but they really shouldn't be.

[robertandy]

Well I tried to not get a "rust" color, but a tanish grey, kinda failed in that respect. The black wash helped, I plan on using some graphite rubbed on them then maybe a slight grey/tan pastel. My big problem now is even though I pre-fit and re-did the firewall......Once I added the truss and engine....I STILL HAVE A FREAKIN GAP! The whole "display the engine on a stand" next to the model is looking better each day. But how to attach the exhausts and the spinner if the engine is not in? I did a bunch of detailing and I think it would look good....but I digresssssssssssss.......Still I am enjoying this "unbuildable atrocity" For which Dragon should be flogged!!! LOL!!!

Thanks for the help guys! I'll put a pic on wip later this week when I get a chance to do some more.

Rob

[Shawn M]

on really worn pipes I start with flat black, lightly drybrush gunmetal, followed by an even lighter drybrush of alum or steel (we're talking reallllly light here) then I use testors bottle paint "dark tan" and drybrush/stipple the pipes until im happy with the decay. The layers give it some depth. For the mustang pipes I would start with a base coat of steel, then gunmetal, then light light light treatment of black at both ends, followed by the "rust"

[Cajun Two One]

Rob,

 

I have done mine in a base of terra cotta and used washes and pastel chaulks to taste. Light to dark and stop when it looks good.

 

Cheers

Itch

[robertandy]

Rob,

 

I have done mine in a base of terra cotta and used washes and pastel chaulks to taste. Light to dark and stop when it looks good.

 

Cheers

Itch

Sounds good, I may start over on them, and try your technique

Rob

[MikeMaben]

There was a WIP on a 1:24 Hurricane some time back that had the best depiction of exhausts I've ever seen, but I'll be darned if I can find it. Perhaps someone else here can provide a link?

 

http://forum.largescaleplanes.com/index.ph...mp;hl=hurricane