Hi Kurfurst
interesting post
but I'm not seeing any by-pass duct for the boundary layer over the radiator
Do you have any more on this? I've not read any claims by German designers to have harnessed Meredith Effect. Do you have any figures for available thrust?
The bypass duct is there, the small arrows show the path of the airflow.
There is also a good description in the US evaluation report of the 109F (which is based on British reports). Also note the seperate duct clearly visible on the photos of the 109F exit flaps - note the seperate ducting on the upper exit flap.
The opening of radiator flaps were controlled automatically by a thermostat measuring coolant temperature but could be overridden manually by the pilot. A good illustration of how it opens and closes during a climb can be seen on this graph from an 1942 test report involving a Bf 109G-1, WNr. 14 026:
As for the actual thrust figures from this system, I have not seen any yet, but the principle of operation is clearly the same as on the Mustang (variable outlet flaps, and in addition, the inlet flaps are also variable). The system on the 109E OTOH is very much the same as on the Spitfire (though the exit flaps were variable in exit area, there was no variable inlet flaps yet, and the opening was set manually). Junkers I believe was using such systems already in the 1920s (or was it early 1930s..?) IIRC.
Thanks
that's alot clearer
As a system, it has all the hallmarks of Teutonic engineering thoroughness but it seems (to me) to be a clever way of cooling, not a method for harnessing Meredith Effect.
I would postulate that Atwood's theory that other attempts failed because of incorrect exhaust aperture would apply here - the exit seems too large and not of the correct shape for an efficient aperture, for a radiator that is too small to build up enough back pressure.
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