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  • Bi-Rotor Autogyros

    Just curious.I was reading the post by Ben Mullet that was posted in 2006, but it didn"t give many specifics and nobody seemed to comment on it.So, does anyone know what the harsh, cold realities of a twin rotor gyro are?Yes, all accounts seem to be that RC models of such a design work well, and are quite stable/easy to fly.Yes, not all things that work well as a model will scale up to full size with similar performance results.So, does anyone know the what/where/how/why/who/etc of full-size twin rotor gyros?Do they even fly at all, let alone solve any problems of single rotor gyros, or do they have their own set of problems which are so significant that they"re not worth wasting time on?Thanks.

  • #2
    the ELA or the MAGNI

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    • #3
      Thanks for that, but I can"t seem to find anything concrete.All twin-rotor designs appear to be models.Am I correct in that a smaller-span rotor would have a higher loading to that of a longer, more slender rotor?I am correct that a smaller-span rotor would have more difficulty in achieving autorotation than a longer rotor blade?Also, I"m guessing that a small model would have completely different relative weights and loadings compared to a full-scale equivalent (e.g why you can find footage of a model "flying lawn mower" and "flying school bus" whereas a full-sized equivalent wouldn"t do anything of the sort!) This is why I"m wondering if the reason there aren"t any twin-rotor designs is because they tend not to work full-scale with a pilot at the wheel.I"m only new to this, so please feel free to let me know if my understanding of autogyros is completely ****-backwards!Interested to hear what you "seasoned professionals" have to say!

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      • #4
        Im no "seasoned professional", but id recon the extra complexity and sumthn bout resonant stresses between the two discs mean it aint worth the trouble.Besides, youd need a bloody big hanger door.

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        • #5
          Thanks, Birdy.I admire your modesty, but from what I"ve seen here and your various videos on youtube, I reckon you"d qualify as a "seasoned professional" more than most people!Re: Resonant stresses - Hmmm.... I hadn"t considered that but, yes, I guess that"s a factor that would detract from the overall attractiveness of the design. This is sort of the answer to my question that I was expecting/looking for.As for the hangar door issue - well, I guess that is something to think about, but I"d imagine that it probably would be no worse than a whole bunch of high-wing fixed wing aircraft jammed in a hangar together!Cheers.

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          • #6
            Hi ZoinksMost of the twin rotors developed during WW2 were multi blade helicopters fitted with articulating blades. This presents an extra weight problem, and a semirigid 2 blade rotor system such as what we use in gyroplanes would require a complex pre rotator, and control would be a real challange if possible. I feel the rotors would be required to be fixed and all control acheived via elevator, and rudder (like the early Cierva C3). If the twin heads were made to move, then effective control without hitting the fuselage and pilot would be interesting.A twin rotor (one above the other) presents great advantages for helicopters as they counter each others torque affect, so no tail rotor is required. In the case of a gyroplane this does not apply as our rotor creates no torque, so there are no real advantages. This type of design would only present additional complexities, weight, and mechanical challenges for the builder. I would rather a multi blade head instead.

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            • #7
              Hi Sam,That"s a good answer. Thanks for that.Yes, simple is best. I was just doing a "thought experiment".I"m hanging to get into a gyrocopter like I"ve got ants in my pants, but sadly, I am low in the funds department.Also, I"m only a handful of hours off my RA Aus ticket, so I may as well finish that off first. (And again, held up by low funds!)Besides, there are only so many hours in each weekend.Does anyone happen to know tomorrow night"s winning Lotto numbers?

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