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History of Gyros

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  • History of Gyros

    Hello gyronuts
    I am writing a piece about gyros, just passing the Bensen years, need some info about
    How Bensen created his gliders? Thought process
    Who configured the CLT gyros, in special the Air Command?
    thanks in advance
    Moving on! :)

  • #2
    last year I went to a "Mini Maker" fair at Vanderbilt University ; and had my dominator and a Kolb ultralight on display. There was a elderly gentleman there, which had a display also. He had a Bensen clone that was podded up to lool like "Little Nellie". He had a lot of articles and historical information with him. He was a Colonel in rank.
    I had a very lengthy conversation with him that day. As I recall his story, it went something like this.
    I am assuming after the fall of Germany in WWII.
    He said they were on a beach and about 1/3 of a mile away was a concrete bunker. Housed within the bunker was a German Submarine, and a few gyro gliders. He said that Dr. Bensen was there as an employee of General Electric and was designing water "turbines" propellers. I assume to be used in hydro electric dams. He said Dr. Bensen was really intrigued with the gyro housed on and in the Submarine.
    We know from Dr. Bensens story, that he brought the gyro glider back to the USA for testing. General Electric say no practical application or the ability to produce a profit so the entire project was aborted. Dr. Bensen took the remnants of the program and started building and testing on his own. There was the birth of "Bensen Aircraft Co." and we know most of that history.
    You mention CLT.
    The B7m and B8m models were designed around a McCulloch or Volkswagen engine. Using his plans and either of these engines, and the gyro was very very close to CLT.
    These designs did not have a functioning horizontal stabilizer either. Flown properly by an average skilled pilot, they are quite safe and fairly pitch stable.
    The McCulloch "Mac" engine developed a fairly nasty reputation for quitting. Builders started using the Rotax engines and wanted larger diameter propellers. The standard Bensen frame with a VW or Mac accommodated a 50 inch prop. To accept the larger diameter props on a Rotax, the builders would just raise the engine mounting location on the mast and get the distance they needed for the propeller clearance to the keel. Not realizing they were building a HIGH thrust line, pitch unstable machine. I believe that is where the bad reputation got started on the Bensen B8 design.
    Last edited by Gyro28866; 10-22-2018, 05:37 AM.
    David McCutchen
    Bensen B7m, 90 hp Mac
    Dominator Tandem, 100 hp Hirth
    Kolb Mark III Classic, 80 hp Verner
    Certified - Advanced Master Beef Producer
    EAA Member #0511805
    PRA Member #28866
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    President / Sylvia - Yellow Creek Volunteer Fire Dept.
    Chairmen - Dickson County Veteran's Day Committee
    Volunteer - Dickson County Airport Aviation Day Committee
    2 busy 2 No!


    • #3
      Thank you very much, that's the missing link for me!
      Moving on! :)


      • #4
        Thank you very much, that's the missing link for me!
        Moving on! :)


        • #5
          This account combines a few details.

          The German-submarine gyroglider was a Focke -- the same company that produced the first controllable helicopter, famously demonstrated by flying it in an indoor arena around 1938. The Focke gyroglider had a 3-blade rotor.

          Igor Bensen may have been intrigued by the Focke, but his gyros were derived not from that model, but from the free-flying Rotachute developed on the Allied side by Raoul Hafner. Its intended military function was to substitute for a parachute in infantry air-drops. Igor's earliest gyros were very, very close to Hafner's in design, right down to the overhead stick.

          Bensen's B-7 was designed around the 40 hp Nelson engine. The B-7 had quite a substantial H-stab; the B-8 had almost none.

          The B-8M proved to be a prolific killer of unwary amateurs. It had fast, light rotorblades and its short-coupled little H-stab made no handling difference (that I could notice anyway).

          Ken Brock's version of the B-8M, with light wheels and a seat tank, may have been close to CLT, but the stock Bensen wasn't. It had very heavy, iron-hubbed industrial wheels and a steel outboard-motor gas tank mounted low. There was some degree of HTL which combined with very low rotor damping to make a machine that was very prone to pilot-induced oscillation a/k/a porpoising.

          Once you learned to under-control and let the machine catch up to you, you were largely safe from porpoising. Many died before they could get this straight, however. Arguably a machine marketed in Popular Mechanics to non-pilots should have been more beginner-friendly.

          At one point in the late 60's, the B-8M was killing about one pilot a month. We have yet to live down the horrible reputation that this disgraceful situation earned for gyros.

          The introduction of offset redrives around 1980 made the HTL situation much worse for awhile, of course.

          We've turned the stability problem around with CLT, H-stabs and much heavier, slower rotors than Bensen used. We'll see if the reputation problem likewise turns around. We've had quite a deep hole to dig out of.


          • #6
            Iíve seen photos of Dr. Bensen flying the Rotachute at GEís Schenectady flight test center.
            Hereís Bensenís patent for landing gear controlled by the pilotís feet. Thatís sorta duh but what is interesting is the accompanying drawings showing his water pipe version of the Rotachute with overhead stick and non underslung seesaw rotor. A jackhammer ride for sure.