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? |
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.
https://cimg7.ibsrv.net/gimg/pprune....547534a73.jpeg |
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. |
Piston in the nose, jet in tail.
Curtiss XF15C-1, only three built https://cimg0.ibsrv.net/gimg/pprune....6504269cc2.jpg Ryan FR Fireball, 71 built, entered service March 1945 but never saw combat. https://cimg1.ibsrv.net/gimg/pprune....cc2c515002.jpg |
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 !!! |
I suppose that technically the counter rotating Twin Coms and Navajos have different engines! :}
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Originally Posted by treadigraph
(Post 11546144)
I suppose that technically the counter rotating Twin Coms and Navajos have different engines! :}
I mentioned it once but I thnk I got away with it. |
Chevv, Mosquito didn`t have c/rot. engines...but the Hornet did....
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Originally Posted by treadigraph
(Post 11546144)
I suppose that technically the counter rotating Twin Coms and Navajos have different engines! :}
But if we're allowing C/R props, the A400M is another candidate. |
The Shackleton MR3 had 2 RR Vipers as well as the 4 Griffons....
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The OP did say "Twin Engined".
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Originally Posted by dixi188
(Post 11546343)
The OP did say "Twin Engined".
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Originally Posted by dixi188
(Post 11546343)
The OP did say "Twin Engined".
Lockheed P2 Neptune Twin piston & twin jet |
Originally Posted by treadigraph
(Post 11546144)
I suppose that technically the counter rotating Twin Coms and Navajos have different engines!
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If we've wandered off from the original twin idea, I'll see your Shackleton MR3 and raise you the Convair B36, Six Turning and Four Burning.
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Originally Posted by WHBM
(Post 11546375)
Are the engines not the same, rotating the same way, but it's the gearbox that reverses the rotation of one of them (rather like having one half of a contra-rotating gearbox) ?
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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. |
Originally Posted by BSD
(Post 11546407)
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. https://cimg3.ibsrv.net/gimg/pprune....60656cabd3.jpg https://cimg6.ibsrv.net/gimg/pprune....332ae6d444.jpg |
The He177 was a four engine, twin prop aircraft.
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Originally Posted by WHBM
(Post 11546375)
Are the engines not the same, rotating the same way, but it's the gearbox that reverses the rotation of one of them (rather like having one half of a contra-rotating gearbox) ?
The standard engine, like most American powerplants, has what is termed Right-Hand Rotation (clockwise, upper propeller blade moving to the right, as seen from behind). Of course, when the airframe designer decides to equip contra-rotating engines, usually to address the problems of "critical" engine failure, it is the right-installed engine which undergoes the change. Hence, the left-side engine of a Chieftain has right-hand rotation, and the right-side engine has left rotation, and a left-hand prop. |
Thank you very much to all responders. And thread drifts are welcome -- they're what bring forth other interesting topics and tidbits.
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Originally Posted by DuncanDoenitz
(Post 11546460)
Of course, when the airframe designer decides to equip contra-rotating engines, usually to address the problems of "critical" engine failure, it is the right-installed engine which undergoes the change. Hence, the left-side engine of a Chieftain has right-hand rotation, and the right-side engine has left rotation, and a left-hand prop.
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Using criteria previously mentioned, the Westland Whirlwind must count.
The Rolls-Royce Peregrines were designed from the outset to be handed. Not just with an idler gear, the whole engine rotated in the opposite direction. Having it tried with the Peregrine, Rolls-Royce concluded it was a b***** stupid idea and never did it again. |
With the A400 isn't it something like the inboard props rotate top blade outwards and the outboard props rotate top blade inwards? Noisy bugger whatever...
Good thread indeed and educational! |
A400M props are "CACA" ie. Clockwise, Anticlockwise, Clockwise, Anticlockwise, when viewed from behind.
In French caca means pooh! |
If you can include the B36, then you can also include The Avro Lancastrian
https://planehistoria.com/wp-content...018a6ef1_o.jpg |
Originally Posted by DuncanDoenitz
(Post 11546460)
Of course, when the airframe designer decides to equip contra-rotating engines, usually to address the problems of "critical" engine failure, it is the right-installed engine which undergoes the change.
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Originally Posted by Sue Vêtements
(Post 11546824)
Didn't the P38 have two critical engines?
Both engines turning outward gives the stronger “P-factor” slipstream on the side of the rudder deflection in case of an engine out. As far as I recall. |
Originally Posted by Sue Vêtements
(Post 11546821)
If you can include the B36, then you can also include The Avro Lancastrian
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Originally Posted by Sue Vêtements
(Post 11546824)
Didn't the P38 have two critical engines?
FAA definition - "Critical engine means the engine whose failure would most adversely affect the performance or handling qualities of an aircraft." The definintion requires loss of one engine to have a more adverse effect than loss of the other. |
The C-123K and KC-97L also carried a pair of turbojets to boost take off performance.
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There's a piccie of an Indian Air Force C-119G sporting a dorsal Orpheus on the cover of Air Pictorial, August '63.
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Medic 022 and Nord 1500 Griffon II both powered with turbo jet and ram jet.
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No end of types with auxiliary jets, and then there's JATO/RATO ...
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Trident 3
3 proper engines and an oversize and unbelievably noisy APU boost engine or must t be a mix of jet and prop. Also from the real past the Fairey Rotadyne, another fuel to noise unit Two RR Tynes on the wings-such as theywere- and ducted air sinning the monster rotor |
Originally Posted by pax britanica
(Post 11546981)
Trident 3
3 proper engines and an oversize and unbelievably noisy APU boost engine |
Originally Posted by DaveReidUK
(Post 11547062)
If you're going to count APUs as well, then the T3 had 5 engines (as did most 4-holers).
B707/720, DC-8, CV880/990, VC-10, DH Comet, didn't have APUs. 4 holers with APUs - B747, A340, any others? OK, the RAF VC-10s did and I saw a VIP 707 with one. There was a 5 engined Vulcan. |
I believe the TWA Fairchild was called “Ontos”.
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I flew the A340-200 and -300. These aircraft were considered to have four hair driers and one APU.
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