enginehistory.org

[gryan]

I just watched a BBC programme about the Battle of Britain. I've seen it before but it was still worth the time to see.

During the discussion one commentator mentioned that the DB engine in the Me109 had a variable speed supercharger. He reported the drive was infinately variable, not discretely geared. Now that's interesting.

I've been meaning to find out more about this device for some time. Does anyone have any information? I'm interested in explanation of how it operated and some pictures/illustrations. How efficient was it at part load? What about when the aircraft was operating at low altitude and the supercharger could not be run at high speed? That would imply high slippage or a larger gear ratio. How efficient then?

regards

Gerald

[jwells]

Re info on this device, I think that probably the best is the S.A.E. paper by F.M. Kincaid, Jr called "Two-speed Supercharger Drives" March, 1942.
You can get it from the SAE or I'd be happy to send you a photocopy.
The paper is reproduced in the book, "Supercharging the Internal Combustion Engine" by E.T. Vincent, 1948 p156 but this is a very rare book.
The basic problem with the DB 601 system was that ALL the torque to drive the impeller went through the fluid coupling resulting in a lot of heat due to slippage.
In all the other WWII designs (mostly American) involving fluid couplings, most of the transfer torque was via mechanical devices with the couplings only being involved at certain times.
Cheers, Jerry Wells.