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Re: Inverted Merlin.....possible to do ???

Posted by Christer on Wed Oct 10, 2001 07:50:02 AM

In reply top Re: Inverted Merlin.....possible to do ??? posted by Paul McMillan on Wed Oct 10, 2001 06:50:13 AM

Guys,
it?s true that fuel injection finally solved the negative G conditions on the Merlin.
There is a difference though between the DB 600 series and the Merlin, the DB injected fuel directly into the cylinders whereas the Merlin had an injection carburettor which injected fuel into the eye of the supercharger. To my knowledge the Merlin never had direct fuel injection since RR considered the charge cooling of injection into the supercharger important for performance. Some german engines could temorarily feed fuel to the supercharger inlet to cool the charge as a means of power boost.
The last versions of the Merlin had injection pumps but they still injected the fuel into the supercharger. The same applies to the Griffon, this is the difference between the Griffon 87 and 88 fitted to the Seafire 47.

The major problem would be the lubrication system. A Merlin subjected to sustained negative G burps through the crank-case ventilation tube. In addition to that the oil return system would have to be inverted with the scavenge pums in the top side, which becomes the bottom side, of the engine. Also scavenge pumps in the rocker covers would be neccesary.

There is a good book on this subject (the Merlin, not the possibilities of inverting): "Rolls-Royce Piston Aero Engines" written by A.A. Rubbra. It is #16 in the historical series from Rolls-Royce Heritage Trust.

Regards,
Christer

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