Vivian Meazza wrote: > Peter Stickney > > >>On Friday 15 July 2005 06:45, Vivian Meazza wrote: >> >>>Josh Babcock >>> >>> >>>>Vivian Meazza wrote: >>>> >>>> >>>>>Josh Babcock ought to be asking for the turbo charger for the >> >>B29 now, >> >>>>but >>>> >>>>>hasn't yet (perhaps he's now using JSBSim?). I've been unable to >> >>find >> >>>>much >>>> >>>>>available on the web for the Wright R-3350. I'm doing some work >> >>on the >> >>>>>aircraft carrier right now, but I've done some preparation for >> >>the turbo >> >>>>>simulation. >>>> >>>>Nope, I've just been busy with animations and other non-fgfs >> >>stuff. I >> >>>>don't have much data on the R-3350-23, but I do have the pilot's >> >>manual >> >>>>and a lot of web sites. If someone is offering to help with the >> >>engines >> >>>>I would love it. I am available to give all the info I have. I >> >>don't >> >>>>really feel I know enough about engines to do this properly >> >>myself. >> >>>If by 'someone' you mean me, then I guess I should help here. I need >> >>some >> >>>thing to test my putative modifications to YASim on anyway. >>> >>>I need a few hard numbers, which perhaps you could give me or point >> >>me at a >> >>>suitable web site/s: >> >>From a variety of sources, including the FAA Type Certificate Data >>Sheet E-218 (Wright Double Cyclone C18BA series) and the 1950 edition >>of "Model Designations of USAF Aircraft Engines". >> >> >>>1. propeller gearing. >> >>0.35:1 >> >> >>>2. max manifold pressure. >> >>Now - that will depend on the specific rating. Exceeding the >>allowable boost for an RPM/Mixture combination is Very, Very Bad. (As >>in, as the P2V Manual puts it, "Trouble is indicated by internal >>engine parts exiting teh exhaust stacks." >> >> >>>3. full throttle altitude which may also be described as the >> >>critical >> >>>altitude. >> >>Military Power - 2200 HP/2800 RPM/ 44" Hg / SL-25,000' 15 Minute >>limit >>For the engine and turbosupercharger combination. >>Without the turbo - (Mechanical blower only), the ratings were: >>2200 HP/2800 RPM/ 44" Hg /Sea Level >>2200 HP/2800 RPM/ 42" Hg / 7,000'. >> >>Note the decrease in MAP as altitude increses. Wright Engines from >>teh late 1930s on were rated to a constant power, not a constnat >>Manifold Pressure. As altitude increased, Temperature and Back >>Pressure (Not relevant for the turbo) decreased, giving more power >>for a given MAP. MAP was decreased to hold constant power. >> >> >> >>>4. the rated HP and the rated altitude. >> >>Normal Power - 2000 HP/2400R RPM/ 42" Hg/ SL-25,000' Continuous >>(Turbo) >>2000 HP/2400 RPM/42" Hg/ Sea Level >>2000 HP/2400 ROM/41" Hg/ 4200' on the Mechanical blower only. >> >> >>>5. take-off HP. >> >>2200 HP/2800 RPM / 44" Hg >> >> >>>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 tubo'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. >> >>I don't know, but it sound like you could be making things a bit more >>complicated than they were. The Turbos were basically Black Boxes. >>There wasn't anything more to do with them but set them to the >>appropriate pressure rise & let them go. >> > > > Very helpful. I think you will find that the turbo pressure was controlled > by the pilot, at least at critical point of the flight. While the pilot can > regard the turbo as a black box, we need to know a little more about it so > that the FDM can be set up correctly. > > This is the first reference that I have seen to a turbo/mechanical blower > combination. I would be interested in seeing your source. This is for the > R-3350-23? > > Thanks > > Vivian > > > > > > _______________________________________________ > Flightgear-devel mailing list > [email protected] > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > 2f585eeea02e2c79d7b1d8c4963bae2d >
All the 3350s had this turbo/super setup. You can see it in some of these images: http://www.enginehistory.org/G&jJBrossett/RAFCosford/Wright%20Cyclone%20R-3350%20cutaway.JPG http://www.enginehistory.org/G&jJBrossett/RAFCosford/Wright%20Cyclone%20R-3350%20cutaway%20view.JPG http://www.saunalahti.fi/sariri/Img/UKRAFC05/Eng/slides/P2060078.html http://www.midwaysailor.com/eddiemiller/eddiemiller-761b.jpg Josh _______________________________________________ Flightgear-devel mailing list [email protected] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
