Twin-engined aircraft
Thank you, I've learned something there (you'll be glad to know I'm not a licenced powerplant engineer for the relevant types !). It does seem however the more surprising and complex approach, different spares needed for each side, ever the risk of some procedure being applied wrongly, etc.
Surprised no-one has mentioned the Rutan Model 76 Voyager yet. Push-pull design with an O-240 at the front and an IOL-200 aft. It was initially flown with two O-235s that had received a 'dirty rag overhaul' as in, a quick wipe before bolting them on. For the world flight they needed two slightly different designs. The IOL-200 was supposed to run for the entire flight, with the O-240 only used for take-off and the first couple of days until the weight had gone down enough to shut it down and maintain altitude on the rear engine only.
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. Only in passing though...
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I remember seeing a 4 engined Catalina parked on the `civvy` terminal at Albuquerque..Looked like big Lycoming 6`s outboard of each P& W....
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DHfan (post 24, 27th November) states that the RR Peregrine was designed to have "handed" versions for the Westland Whirlwind fighter. This may well have been the case, but by the time these aircraft entered front-line service in about mid-1940, Peregrines were all of one kind, with all engines rotating in same direction - see the close up views in the Pathe movie "Whirlwind Fighter Squadron" (1943). Pilots' notes make no mention of handed engines/propellers. Don't know how authentic the sound on latter part of this movie is, but it is very exciting!
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The interesting answers to the original question are types where the two different engines have two differing specifications because of a quirk in operation or the role envisioned for it. Mixed-powerplant types such as the Ryan Fireball and Saunders-Roe SR.53 have been mentioned before. Most of the times, having more than one powerplant is because you want redundancy and in that case having two similar engines makes sense from a spares/handling/economy point of view. Having 'handed' engines is just a way of dealing with less-than-ideal one engine out performance and is not related to the mission or role if you ask me.
Looking at civil types, the two Rutan models discussed are the only ones I can think of that started with two different engine types. Looking a bit beyond that, the airshow performers such as the Screaming Sasquatch (https://eaavintage.org/the-screamin-sasquatch/), the Yak-110 (https://www.fargoairsho.com/yak-110) and the Rich Goodwin Pitts (https://www.richgoodwinairshows.com/) are conversions (the last two are three-engined types if we're being picky) that use two different engine types.
DHfan (post 24, 27th November) states that the RR Peregrine was designed to have "handed" versions for the Westland Whirlwind fighter. This may well have been the case, but by the time these aircraft entered front-line service in about mid-1940, Peregrines were all of one kind, with all engines rotating in same direction - see the close up views in the Pathe movie "Whirlwind Fighter Squadron" (1943). Pilots' notes make no mention of handed engines/propellers. Don't know how authentic the sound on latter part of this movie is, but it is very exciting!
The reason I often see mentioned for the cancellation of the handed Peregrine was the doubling up of some spares, no doubt the handling issue noted by DHfan, was the prime reason, the Whirlwind being the engines only application.
The handed Peregrines were installed in one of the two Gloster F9/37prototypes.
The handed Peregrines were installed in one of the two Gloster F9/37prototypes.
Originally Posted by Sue Vêtements
Didn't the P38 have two critical engines?
Didn't the P38 have two critical engines?
As with many of the high powered twins of the day (Mosquito) the safety speed was far higher than the take off speed so an engine failure during the period of airborne acceleration to the safety speed required a power reduction on the good engine in order to maintain directional control.
Back when Pratt was developing the PW4000/94" (767/747-400), they used the very first 767 (VA001) as a flying test bed - PW4000 on one side, JT9D-7R4 on the other.
Very nearly ended in tears during an early test flight - at about 50 ft. during TO, the PW4000 surged big time - the PF calmly reached over and pulled both thrust levers to idle
The other pilot quickly slammed the levers back up - the JT9D slowly pulling the aircraft skyward while the PW4000 kept surging away.
The PF is question was later removed from "Experimental Flight Test"...
Very nearly ended in tears during an early test flight - at about 50 ft. during TO, the PW4000 surged big time - the PF calmly reached over and pulled both thrust levers to idle
The other pilot quickly slammed the levers back up - the JT9D slowly pulling the aircraft skyward while the PW4000 kept surging away.
The PF is question was later removed from "Experimental Flight Test"...
Bristol Brabazon did have all the same engines but twinned in an unusual setup of 4x 2 engine each under 32degree angle of the axle of the counter rotating propellers.
