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. I hope this helps. -- Pete Stickney _______________________________________________ Flightgear-devel mailing list [email protected] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
