Krenn wrote:With any sort of steam-powered variant of a famous bomber or cargo plane, there's no reason why the steam engines would need to be the same size of, or in the same place as, the original historical engines.
Doing the math here....The current generation Praigyr produced about 0.13 Old Terran horsepower per pound, whereas Hindenburg’s diesels had produced 0.3 horsepower per pound.
Looking up a wide range of large, WW1-WWII aircraft...
and there's bad news. About half the aircraft I can think of COULD have replaced their engines with a heavier, steam-powered equivalent... if they had been willing to dedicate their ENTIRE cargo bay, and payload weight, to carrying replacement steam engines.
The DO X flying boat is one of the better examples...
DO X1a
Empty weight 28 metric tons
payload+ fuel 28 metric tons
top speed 131 mph
Engines 12
total power: 7320 hp
Frame: Aluminum
7320 hp, at .13 HP per pound, works out as ...
21 metric tons worth of steam engines and boilers.
We can save 4 metric tons by taking out the 12 ORIGINAL engines, which we won't be using...
But that still gives us this:
DO X1a (steam version)
Empty weight 45 metric tons
payload+ fuel 11 metric tons
top speed 131 mph
Engines (1 boiler, 12 driven engines)
total power: 7320 hp
Frame: Aluminum
11 tons for an aircraft that size is pretty much just enough for fuel and crew. and 10 tons of fuel is actually a little low, for what an aircraft of that size would normally want to carry. And we would still need to replace the aluminum frame with a steel one.
In order for this to work, you would basically wind up replacing the entire cargo bay of a DX1a with a single giant boiler/ flame-box /moisture recuperator, and then running steam pipes to the 6 engine naccelles, which contained two engines each. Those engines would actually run on the external supply of steam from the cargo bay, and send used steam back via a return pipe, to be recycled.
Most other aircraft I could find would actually be in WORSE shape... they'd barely have any weight left over for fuel at ALL, or else would exceed their maximum takeoff weight entirely.
A wellington would be about 3 tons overweight with a replacement steam engine and no fuel. a Mosquito would be about 8 tons over, likewise. A C-47 skytrain would be about 1 ton over, same.
Some of the WWII-era, planes which were custom-built to set the flight distance record could probably make the conversion... if you replaced about half of their enormous fuel resorvior in for a steam engine, instead. and didn't carry any cargo, other than the flight crew.
of course, that would cut the range in half, too. and the only purpose the aircraft could serve would be either single-person VIP transport, recon, or MAYBE carrying a few light machineguns as armanents.
The Gasuden Koken or the Bleriot 110 would be good candidates.
Hi,
The National Air and Space Museum has full size reproduction Besler Steam Engine and lists the following physical description:
"Type: Reciprocating, two-cylinder compound double acting, V-type, steam engine, reproduction
Power rating: 112 kW (150 hp) at 1,625 rpm, 1,200 psi boiler pressure
Displacement: 1.41 L (86.1 cu in)
Bore and Stroke: 76.2 mm (3 in.) x 76.2 mm (3 in.) high-pressure cylinder, 133 mm (5.25 in.) x 76.2 mm (3 in.) low pressure cylinder
Weight: 82 kg (180 lb) engine, 136 kg (300 lb) boilers and condensers"
That works out to 150hp / 480lb or .3125 hp/lb.
7320 hp would require 23,434 lb for 12 engines, boilers, and condensers. Each complete power plant would have to be 4 times more powerful than the Besler steam engine.
I would think that Owl needs to work on the efficency of the Praigyrs.