B-17 Exhaust/Oil Staining

[patricksparks]

I though that I would drop a line on this subject due to the many B-17 models being underway now with the HK kit.  I've noticed over the years that when modelers are weathering their B-17's wings they are putting the stains coming out of the upper wing vents(the 4 vents aft of the nacelle of each engine) if you look at some good quality photos looking down at operational forts you will see that the staining occurs in between the vents, not from out of them. It probably does this because of the disrupted airflow of the depression of the individual vents. I have in the past recreated this effect  by 2 sided taping thin styrene strips into each vent, standing on end that are the width of the vent opening and about a 1/2" tall and then you airbrush your weathering color from the front of each nacelle back, just the same as the real airflow would be and through the styrene "Fence" for lack of better of a better term. Just do a little paint at a time and build the weathering up as desired.

Hope this will help some,

Pat

 

 

 

 

 

 

[geedubelyer]

Hi Pat,

 

Welcome to LSP. Enjoy your stay here.

 

Thanks for the tip.

 

Cheers.

[Bill Cross]

Would love to see a photo illustrating this technique and perhaps on an original plane.

[Guest Nigelr32]

Thanks for posting this info Pat, i too would love to see the effect you achieved.

[patricksparks]

I will try to post some photos. I haven't been successful yet in trying to post photos, I tried the Photobucket route but when I copy and paste the link from the bucket and hit the "OK" button in the post it doesn't do anything. Any tips ?

 

Pat

[patricksparks]

Until I can figure out how to post some photos, I just realized that if you look in some B-17 reference books or on the internet there is the disturbing photo sequence of a B-17 having bombs inadvertently dropped onto it's horizontal stabilizer from a B-17 in the high formation. If you especially pay attention to first photo when the aircraft is nearest to the camera it is a really clear example of the staining on the upper wings, also note that that staining doesn't always travel directly back, I seen many different photos of B-17s and they all have pretty much the same "shaped" staining, my guess would be that the direction path of the stains were created by the direction in which the propellers are turning.

[flounder_al]

Something like this Pat?

 

[Bill Cross]

Thanks, that makes it all more understandable.

 

Would this effect be apparent on other aircraft?

[pzcreations]

thanks for pointing this out..i never really looked at it that closely.

[Silver Dollar]

Thanks Pat for the great tip.  I've also got to do some more research on the stains.  

[patricksparks]

Thanks to flounder_al for posting the overhead photo of the B-17, that's the photo I mentioned in my last post. To Bill Cross, I'm sure that all aircraft have their certain "quirks" with exhaust oil and weathering/staining, to me it's just a lot of photo research, I try to look and look and look again. I'm just a little more aware of the B-17's from being exposed to them all my life, my dad flew 35 missions as a Radio Operator/Gunner on B-17s with the 34th Bomb Group. My first boss who hired me back in 1975 was a Ball Turret Gunner with 25 missions with the 91st Bomb Group, he was a modeler before the war, during the war and after the war(professional) he remembered everything about B-17s, mechanics, weathering,colors inside and outside you name it.

Glad to see that the posting is useful.

Pat

[patricksparks]

Here some photos of  the exhaust/oil staining that I did on a 1:72 scale B-17 some 20 + years ago, my how time flies !!!

[tomprobert]

It's also interesting to notice how the stains don't flow exactly 'backwards' - they canter off the left slightly when viewed from above due to the prop wash/blast.

 

Something not often done very accurately on models - the above post being the exception of course!

 

Tom

[scvrobeson]

Another thing to notice is that the exhaust staining goes between the square vents on the wings, instead of out of them. I've seen a lot of models that have them come out of the vents.

 

 

 

Matt 

[Juggernut]

Yeah, the staining should not eminate from the vents as these were vents for the intercoolers for the engines.  I don't know for sure but I think the stain pattern comes from the direction of airflow over the wing.  The prop blast has an effect but the props turn clockwise and it seems to me that if the prop blast had a major affect on the airflow, the pattern would shift outboard rather than inboard as shown in the photograph above.