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Has there ever been an aircraft that can fly using at least two different type of engines? For example, a piston engine and a turbine engine, or a piston engine and a electric motor.

To clarify the question:

  • It is not necessary to operate both engines at the same time. However the pilot must have the ability to switch from one engine to another engine while in the air.
  • The engines must generate power using completely different mechanisms.
  • VTOL/STOL aircraft (e.g. V-22, F-35) does not quality because the aircraft is simply directing thrust from the same engine elsewhere.
  • The question is not asking about variants of an aircraft model where each variant is fitted with a different kind of engine. Both engines has to be fitted on the same airframe and operable at the same time.
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  • $\begingroup$ The answer that Peter linked includes the aircraft that immediately came to mind, the Rutan Voyager. Different engine in the front than in the back. Both used for takeoff, then one shut down for cruise. $\endgroup$
    – Ralph J
    May 4, 2018 at 22:52
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    $\begingroup$ You might want to clarify about whether aircraft whose purpose is to test new engine designs and have old engines as a backup are included. $\endgroup$
    – chrylis -cautiouslyoptimistic-
    May 4, 2018 at 23:08
  • $\begingroup$ @PeterSchilling That's exactly what the comment by Peter Kämpf said … :-) $\endgroup$
    – can-ned_food
    May 5, 2018 at 4:20
  • $\begingroup$ @Ralph J: But (AFAIK, anyway) the Voyager's two engines were both of the same kind - standard 4-cylinder Continental aircraft engines. $\endgroup$
    – jamesqf
    May 5, 2018 at 17:46
  • $\begingroup$ Engines: Teledyne Continental, Front Engine: Type O-240, 130 hp, Rear Engine: Type IOL-200, 110 hp $\endgroup$
    – Ralph J
    May 5, 2018 at 19:19

6 Answers 6

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The Convair B-36 Peacemaker had six Pratt and Whitney radial piston engine propellers and four GE turbojets. The turbojets were used during takeoff and shut down during flight.

enter image description here image source Wikimedia Commons

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    $\begingroup$ The turbojets were also meant to increase speed while flying in hostile airspace. $\endgroup$
    – Peter Kämpf
    May 4, 2018 at 20:07
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Wikipedia lists 27 "mixed-power aircraft". Most were prototypes or were never even built, the only ones I can see that made it to double digits in their production runs were:

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  • $\begingroup$ It looks like only two prototype Destroyers were built with the mixed propulsion. $\endgroup$
    – Todd
    May 4, 2018 at 20:23
  • $\begingroup$ @Todd Good catch, thanks! I didn't read the full details; updated. $\endgroup$
    – Pondlife
    May 4, 2018 at 20:39
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    $\begingroup$ That list is incomplete: there's also en.wikipedia.org/wiki/…, which lists the Convair B-36, some variants of the Avro Shackleton, a civilian modification of the Fairchild C-119, the Fairchild C-123, the Lockheed P-2, the North American A-2, the Martin P4M, and a whole bunch of prototypes. $\endgroup$
    – Mark
    May 4, 2018 at 22:23
  • $\begingroup$ @Mark: Don't forget the Boeing KB-50 (112 converted from various versions of B-50) and KC-97L (81 modified from earlier KC-97Gs) tankers, both of which were equipped with dual turbojet pods to allow them to refuel fighter jets without the latter falling below their stall speed. $\endgroup$
    – Vikki
    Sep 5, 2018 at 3:16
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I would say that any aircraft equipped with JATO capabilities fits into your description. The only point it may not subscribe to is the first one, the pilot can not really switch between power sources although they can ignite the JATO rockets on command.

The space shuttle (if you want to include that as an aircraft) was powered by both liquid fuel rockets and solid fuel rockets.

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The Screaming Sasquatch is a 1929 Taperwing (bi-plane) with a P&W 985 Radial Engine that they strapped a GE J85 with 3,000lb-thrust to the bottom of:

enter image description here Source: EAA Vintage.org

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The B-36 Peacemaker quickly comes to mind, using 4 turbojet engines to augments it’s six diesel radial engines.

A number of proposed aircraft made use of multiple, different types of power plants. The X-30 National Aerospace Plane, a reusable runway to orbit vehicle, used turbojet, scramjet and rocket engines at various stages of its proposed flight into space. The new SR-72 hypersonic reconnaissance airplane is rumored to use a proprietary turbojet and scramjet powerplant built by Rocketdyne. an experimental French fighter called the Nord 1500 Griffon, making use of a hybrid turbojet and ramjet for high speed flight. Even business aircraft attempted with hybrid propulsion. The ill fated Gulfstream American Hustler, used a PT-6 turboprop engine at low altitudes and a jet engine at high altitudes in an attempt to conserve fuel.

During the postwar era, hybrid turboprops and jets did make a debut, particularly as a solution for the problems early jet aircraft had recovering aboard aircraft carriers. The Ryan Aircraft FR-1 Fireball was a hybrid powered fighter, looking much like a conventional WWII era piston powered fighter but had an additional jet engine in the tail of the aircraft to be used in high speed flight.

Some types of aircraft have used multiple types of jet engines. This has been a popular solution for VTOL capable fixed wing aircraft. The Yakolev Yak-38 Forger made use of a single R-28 engine for forward flight and combined that with a pair of RD-38 lift engines for VTOL operations. Another impressive design was the Dornier DO 31 prototype V/STOL cargo aircraft which made use of a pair of Rolls Royce Pegasus turbofan engines combined with no less than eight Rolls Royce RB162-4D turbojets mounted in the twin wingtip pods for control during hover.

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The engines must generate power using completely different mechanisms.

If you allow your two engines to be to be built stacked one after the other, then fast jets such as Lockheed SR-71 Blackbird switch between the turbojet and afterburner as speed increases. Either could be considered an engine in their own right - a turbojet and a ramjet.

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    $\begingroup$ I think that "ramjet" would be a better word for both "afterburner" and "air breathing rocket". $\endgroup$
    – Agent_L
    May 5, 2018 at 9:48
  • $\begingroup$ @Agent_L The SR71's J58 engine is often called a "turboramjet" for that reason. Regardless of what you call it, though, it is very clearly designed and operated as a single engine, not as two separate engines. $\endgroup$
    – StephenS
    Feb 15, 2019 at 18:50
  • $\begingroup$ @StephenS I think you've meant to direct your comment to the author of this answer, not to me. $\endgroup$
    – Agent_L
    Feb 17, 2019 at 22:36

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