Author Topic: Diesel Exhaust outlet (rectangular) questions  (Read 326 times)

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Offline Bob Tomlin

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Diesel Exhaust outlet (rectangular) questions
« on: 21 Sep , 2016, 08:46 »
Hi Gents,
As I'm arriving at different parts of my model, various questions arise for me, so I hope you don't mind me posting questions on here to try to tap into some of your knowledge and in the spirit of discussion all things type IX (I'm throwing this open to everyone here as opposed to just asking on Mr Tores mailbox).


One of the mods to convert from Revell's U-505 kit to a IXC/40 was to change the type of exhaust outlet to the rectangular type widely seen on type IXs.
There's a very similar design on the type VII (Type 4 in Dougie's modelling article), which has this rectangular large aperture sat above two smaller rectangular 'drainage slots'.
I can see what this looks like on the outside, but not what's just inside this larger aperture and with it being large enough to have a bit of a look in, I'm keen to try and replicate something of what's in there.
My main question here then is does anyone please know what's just inside this exhaust aperture?
Here's a very rough sketch to show the limits of what I know:



It would be very simple for me if it's just a rectangular 'duct' as hinted at in the above sketch, but I've a sneaking suspicion that there might be more to it than that?
Opinions are therefore also invited as to what you gents think/know is in there please.


My suspicions (probably wrong but I have to ask) are based on a few photos and a couple of bits of film.
I was wondering what was the point of adding the smaller twin drainage holes below the main exhaust outlet and whether they were connected. In other words, is there a drainage slot in the base of the main exhaust duct which would allow water to fall down and out of the smaller twin drainage holes below? .....or not?


Reasons for thinking this:-
If you have a look at around 00.40 in this film, you'll see the swell rise up into the exhaust outlet hole but very little water flows out of this as compared to the twin holes below.
It does the same later in the film.
http://footage.framepool.com/en/shot/678512935-corvette-ship-royal-canadian-navy-surrendering-naval-warfare


There's a bit of a look into the main exhaust outlet of U-802 at 01.37 to 01.40 in this film. I can see a lighter rectangle in the middle of this outlet with dark lines above and below.
Is the dark line at the bottom a slot going the width of the 'duct' or just a shadow. If the lighter rectangle is the base of the duct, why doesn't it extend to the edge of the outlet?


https://www.youtube.com/watch?v=EHIxJfWaqXI


Here's an IWM photo A28897 taken at Lisahally. Note the water streak markings from the twin smaller drainage slots as opposed to the main exhaust outlet.


http://www.iwm.org.uk/collections/item/object/205187578


The same effect is in the photo of the Type 4 exhaust in Dougie's modelling article on type VIIs.


I'd be very grateful if anyone knows the answer and would like to share it please, but I'd also be grateful for opinions/discussion in the absence of the answer.
Thanks very much.
Cheers Bob.