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Simply put, all the information I've found about autogyros/gyrocopters has been about very small single-engine sport aircraft that can carry the pilot and maybe one passenger.

Why aren't there any larger autogyros, with a scale along the lines of the larger helicopters or twin-engine GA airplanes? Is there a fundamental physical problem stopping you from ripping the wings off a twin-engine light aircraft and sticking on the helicopter blades of an equivalently-sized helicopter to build a gyrocopter that can carry a dozen or so people?

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    $\begingroup$ Check out the en.wikipedia.org/wiki/Fairey_Rotodyne $\endgroup$ Commented May 2 at 16:40
  • $\begingroup$ The Fairey Rotodyne's history suggests that the problem isn't mechanical or physical, but convincing someone to pay for it. When it's that big, it's not a fun toy anymore, it must earn its keep. $\endgroup$ Commented May 2 at 20:29

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Why aren't there any larger autogiros?

Because you would basically have a machine with the same limitations of a helicopter (in terms of speed and maintenance) but, since the rotor of an autogyro produces only lift, you'd need to add one (or more) propeller for forward propulsion, a tailplane for stability and controllability and a wing to offload the rotor at higher speeds.

Or vice versa, because you would basically have an airplane with the addition of a free-spinning rotor that would add further weight, complexity and speed limitations to it.

And if you would go for a gyroplane instead, like the (in)famous Fairey Rotodyne, then the matter would be even more complicated since the rotor wouldn't be free-spinning like in an autogyro rather powered and controlled like in a helicopter... the apotheosis of the complexity is served.

In the end an autogyro makes sense if you want to add safety to an aircraft that doesn't need to be fast or big: should the engine stop, it can autorotate till zero speed, while a conventional aircraft couldn't fly slower than its stall speed.

If you need to go fast and/or big then a tiltrotor like the Valor or a rigid coaxial rotor like the Raider is definitely more efficient design.

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    $\begingroup$ What about passenger service to bush airports with runways too short for larger GA aircraft? I remember a bit of controversy last year here in Australia when CASA stopped flights to a few islands because the runways were too short for the larger aeroplanes that were now being flown and then someone drowned on a boat ride to them. $\endgroup$
    – nick012000
    Commented May 3 at 2:25
  • $\begingroup$ How far are those islands from the mainland? And how many passengers should be served? I suppose that something like a Super Puma might do the job (?) $\endgroup$
    – sophit
    Commented May 3 at 2:59
  • $\begingroup$ I think the comparison to helicopters / airplanes is a bit faulty: in fact when compared to a helicopter you trade tail rotor to a forward propulsion propeller. You have the benefit of not needing main rotor gearbox, which is a major weight/ maintenance benefit. In comparison to an airplane, you trade main wings to the rotor, which I imagine is a pretty equal trade. $\endgroup$
    – Jpe61
    Commented May 3 at 11:50
  • $\begingroup$ "In comparison to an airplane, you trade main wings to the rotor, which I imagine is a pretty equal trade" It's not: a rotor is a much more complicated part, it needs flapping and lead-leg hinges (read: maintenance), its structure must be resonance-free for all the rpms at which it can rotate (read: complicated design and more weight) and it... rotates (read: vibrations, which might set in resonance the airframe, so again more complicated design and weight) ... $\endgroup$
    – sophit
    Commented May 3 at 12:08
  • $\begingroup$ ... "when compared to a helicopter you trade tail rotor to a forward propulsion propeller" It depends: on the Fairey Rotodyne the tail rotor was substituted for a quite complex and noisy system ejecting fast and hot gases from the blade tips (and this system was actually the reason that commercially killed this aircraft). Furthermore the tail rotor in an helicopter is used also for manoeuvring around the yaw axis so it actually substitutes also the vertical tailplane. $\endgroup$
    – sophit
    Commented May 3 at 12:08
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Simple supply and demand. There just aren't that many people interested in large autogiros to justify the costs of producing and supporting a certified aircraft.

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