Peter Stickney wrote: > An addition/correction to my previous posting. > On Sunday 17 July 2005 18:29, Peter Stickney wrote: > >>On Friday 15 July 2005 06:45, Vivian Meazza wrote: >> >>>6. Copies of the relevant pages of the Pilot's Manual. Post these >> >>somewhere >> >>>that I can access/fetch. Particularly any description of the >> >>variable boost >> >>>control. >> >>That was the FE's job. The supercharger system of a B-29, or any >>other turbosupercharged airplane worked like this: (Well, was >>supposed to work like this - Early B-17s and B-24s with the >>mechanical oil pressure driven turboregulators required more >>fiddling, but the electronic turboregulators used on later -17s, > > 24s, > >>P-38s, P-47s, B-29s and subsequent airplanes did work like this) >> >>There was a potentiometer dial on the turboregulator control box > > that > >>was calibrated from "0" to "10". This selected the amount of > > output. > >>from the turbo system as a whole, "0" being no output. The turbos >>supplied air to the inlet of the engine's mechanical supercharger at >>slightly over sea level ambient (29.92" on a Standard Day). This > > was > >>done to keep the turbo moving, so that it didn't freeze up due to >>poor lubrication at Sea Level. The engine's throttle was set to >>provide whatever power conditions were required, and as the airplane >>climbed, the turbo's "Volume Control" was tweaked to keep providing >>its sea level conditions to the engine's supercharger. The >>Turboregulator governed on the selected pressure rise (The "Volume" >>and turbo RPM and, often, bearing temperature. The Pilot of Flight >>Engineer had no indication, or control over the turbo except the >>potentiometer. As far as the engine was concerned, it was sitting >>happily at Sea Level the whole time. Once it had reached the point >>where the turbosupercharger/mechanical blow couldn't supply the >>proper power conditions any more, power dropped off normally. > > > As it turns out, the B-29's turboregulator control was a little bit > different from what I described. The "Volume Control" governed off > total system MAP. If you set the potentiometer to , say, '*8", it > maintained the overall MAP until the turbo reached its limits. So, > for example, you set the engines to Max Continuous, you wouldn't need > to twiddle the turbos as you climbed from Sea Level to 25,000'+. > Sorry if I cased some confusion, there. > > "Zeno's Warbirds" has, IIRC, a Realplayer movie on flying the B-29. > That's a pretty good resource.
True, though for some reason I have not checked it out. I do have the .ram file that points to the stream though. Also, note that to go past 8 on the turbo dial required opening a safety latch and per the pilot's handbook was not to be done for more than 2 min. which I think is the equivalent of the RAF WEP. I'm not sure what bearing this has on the engine modeling but at some point I should put in a nasal script to blow up the turbos after some extended period at settings above 8. I'll have to figure out what conditions would actually cause a failure though. Josh _______________________________________________ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
