On Monday 18 July 2005 18:25, Josh Babcock wrote: > All the 3350s had this turbo/super setup. You can see it in some of > these images: > > <URL's snipped>
No, actually, those are the turbocompounded TC18s used on later Lockheed Constellations, DC-7s, Most P-2 Neptunes, and most C-119s. The turbines that you see in the back are geared directly (Well, though a shock-dampening clutch) to the crankshaft, and contribute directly to the shaft horsepower available. There were 3 turbines, each fed by 6 cylinders. They contributed, at full power, 150 Shaft HP each, for a total gain of 450 Shaft HP.) They were completely independent of the supercharger, which was a normal gear-diven 2-speed single stage blower. In terms of running the engines, they were the same as any other mechanically supercharged big recip. There were 3 flavors of the R3350. One was the engine used on the B-29. It had a single-speed gear driven blower. The turbosuperchargers (The B-29 used 2 per engine - basically the same model used on the B-17 and B-24 - with twice the displacement, and about the same RPM, it needed twice the mass flow, and using the paired turbosuperchargers meant that they could deliver a working system without having to interrupt production) fed air at what were essentially sea level conditions to the engine's mechanical blower. The production versions peaked out at about 2200 HP, and a useful Full Throttle Height of around 25,000'. The second was a similar engine, with a 2-speed mechanical blower. This was mainly used on Navy Attack airplanes like the AD/A-1 Skyraider, and early models of the P2V/P-2 Neptune and the Constellation. They had a FTH in high blower of around 15,000'. The third model were the turbocompounds described above. They ended up being the ultimate in exacting teh maximum amount of power (In cruise) from an amount of fuel, with Specific Fuel Consumption down in the range of 0.3 lbs/Hp/hr. (A typical large recip would be around 0.5 lbs/Hp/Hr.) The Turbo Cyclones were Curtiss-Wright's shining moment, and their downfall. Turbo Cyclones powered nearly all of the successful 1950s airliners, and the Navy's patrol airplane inventory, and the Air Force's Troop Carriers. They sold a _lot_ of engines. But, in doing so, they completely buggered up their jet engine development, and when jets took over in the late 1950s, Curtiss-Wright had nothing to offer. Pratt & Whitney, and later, GE, filled the need. During the 1930s and into the 1950s, turbosupercharged engines were really 2-stage supercharged engines. The engine itself always had a mechanical blower as its main stage, and the turbo fed air to that. It was an add-on that required a bit more ducting and plumbing, but didn't change the basic engine. But that's not the only way to do it. I've been preparing a series of articles on supercharging reciprocating engines. Is there any interest for me to pull some of it out and present it here? -- Pete Stickney _______________________________________________ Flightgear-devel mailing list [email protected] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
