Twin-engined aircraft
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Twin-engined aircraft
Here's a completely idle and probably futile question that just popped into my mind.
It's sort of natural to assume that on twin-engined aircraft, both engines are of the same type. Symmetry and all that.
But have there ever been any twins designed from the start -- rather than under some testing regime -- to have two significantly different kinds of engines for some weird reason? Maybe some strange push-pull arrangement?
It's sort of natural to assume that on twin-engined aircraft, both engines are of the same type. Symmetry and all that.
But have there ever been any twins designed from the start -- rather than under some testing regime -- to have two significantly different kinds of engines for some weird reason? Maybe some strange push-pull arrangement?
The Rutan Boomerang might qualify, one engine was a Lycoming TIO-360-C1A6D (left hand) rated at 210 horsepower, the other a Lycoming TIO-360-A1B (right hand) rated at 200 horsepower.
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AJI Hustler business aircraft, TPE331 turboprop in the nose, P&W JT-15 turbofan in the rear.
https://en.m.wikipedia.org/wiki/Gulf...erican_Hustler
Never made it beyond prototype stage but was developed into the Peregrine 600 jet trainer sans TPE331, then the Peregrine single engine business jet, neither of which developed beyond prototypes. Thought the Peregine looked great but it had a pretty tiny cabin I think. Predated the Eclipse and so on by some 30 years.
Also Rutan's World circling Voyager had different engines fore and aft.
https://en.m.wikipedia.org/wiki/Gulf...erican_Hustler
Never made it beyond prototype stage but was developed into the Peregrine 600 jet trainer sans TPE331, then the Peregrine single engine business jet, neither of which developed beyond prototypes. Thought the Peregine looked great but it had a pretty tiny cabin I think. Predated the Eclipse and so on by some 30 years.
Also Rutan's World circling Voyager had different engines fore and aft.
Saunders Roe SR 53. Turbojet ( Armstrong Siddeley Viper) plus rocket motor (de Havilland Spectre) Also the SR 177 although this was not completed.
Not "techie" enough to be able to post a photo !!!
Not "techie" enough to be able to post a photo !!!
Last edited by Planemike; 27th Nov 2023 at 14:39.
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I suppose that technically the counter rotating Twin Coms and Navajos have different engines!
Chevv, Mosquito didn`t have c/rot. engines...but the Hornet did....
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The Shackleton MR3 had 2 RR Vipers as well as the 4 Griffons....
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You may well be right. I seem to recall hearing that the handed Allisons in the P-38 were made to rotate in opposite directions,
Wasn't there also a Fairchild Packet which had a jet engine on a pylon above the fuselage roof?
I seem to recall seeing a TWA one years ago in Nairobi. I think it was used for shipping engines about.
I seem to recall seeing a TWA one years ago in Nairobi. I think it was used for shipping engines about.
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I seem to recall hearing that the handed Allisons in the P-38 were made to rotate in opposite direction
The right hand bank as viewed from the distributor end (rear of the engine) must have several spark plug leads interchanged because the cam lobes are backwards. It works out the same for the left-hand bank, somehow ... no left bank changes to the firing order
Basically, to make a left from a right, the engine must be almost disassembled because you must be able to get to the gearcase in front and must split the case and disconnect all the rods to reverse the crankshaft.
However, if you are BUILDING a left or right from parts, the difference in build up is trivial, assuming you have an "H" gear, the new gear, and you know the plugs to interchange (this means rewiring the ignition harness on one side ... so it is MUCH easier to simply build a left or right wiring harness than it is to change one that is already wired).
The "H" gear:
A Standard gear is just a gear with a keyed center. An "H" gear looks like two standard gears joined by a small cylinder in the middle to skip over the gear that was formerly meshed by the standard gear. The new gear you add is to turn the skipped gear in the other direction. All gearcases have the ability to turn either way ... the gear bosses are in all of them, internally.
For both left and right engines, the cams turn the same direction and the crankshaft is reversed and turns backwards.
There is no other engine I know of from WWII that as so easy to make turn in either direction when being built up ... two gears, turn the crankshaft around, and change the right bank firing order ... that's it.
You need a starter that turns the other way, and you need an idler type gear to reverse the direction of the cam towers.
You can see the difference below.