Don Hillberg.... have a few questions.

Discussion in 'Rotorcraft' started by Blue Chips, Jun 16, 2016.

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  1. Jun 16, 2016 #1

    Blue Chips

    Blue Chips

    Blue Chips

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    You had mentioned a while back that on a Helicom COM II you had soft mounted the main gear box on an aluminum plate. Can/will you detail just how you did that a little, they definitely need it, also what did you do with the Mast support block and struts?

    Ken
     
  2. Jun 16, 2016 #2

    D Hillberg

    D Hillberg

    D Hillberg

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    The struts and supports was mounted to the plate and the plate mounted in rubber mounts to the frame, the fan/clutch pilot bearing kept it aligned and the rubber let the plate float
    on the frame, the derometer of the rubber was stiff, the plate would move vertically about 3/8ths under load, mostly dynamic balancing of the rotor was more critical

    mass balanced, chord balanced removal of that control fly weight system to direct p/c link, inboard chord bob weight, it was a lot of work.

    it was Reads Heli
     
  3. Jun 16, 2016 #3

    Blue Chips

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    How thick was the plate?
    I take it then that the gear box was hard mounted to the plate?
    Rubber bushings at four points ?
    Rubber bushings top and bottom?
    Do you recall or know how many (roughly) hours were put on this setup prior to selling and the crash by the new owner :(
    Did all the work end with the desired result? as far as you know.

    Thanks for the input Don, these should give me enough material to digest for now.
     
  4. Jun 16, 2016 #4

    D Hillberg

    D Hillberg

    D Hillberg

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    plate was 1/2 with triangular relief holes cut into it and web areas for a strong but light assembly, the rubber bushing/mounts where captured by washers sandwiching the plate in the 4 corners , the gearbox lift struts where attached to the plate topside, the main frame carried the loads through the bolts that where going through the rubber bushings and captured washers on top of the plate, all flight controls went unchanged other than better bearings , the set up lasted trouble free from it's first flight till it crashed for no fault of the machine, I have no hours but Read flew the heck out of it for years before he went to the Brantleys Robinsons Hughes & Jet Ranger.
     
  5. Jun 16, 2016 #5

    Blue Chips

    Blue Chips

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    Did you see the air-frame after the crash?
    Wondering where the mast and rotor head ended up and how the soft mount set up did in keeping the gear box/mast in a relatively normal position.

    I've seen first hand one of these where the rotors hit swampy ground, blades went airborne and the mast ended up in the passenger seat, fortunately no passengers.
    Am trying to think of a way to not inhibit normal gear box movement but some method in limiting extreme forward motion in such a case as mentioned, much like seat belts would do.

    Thanks for the added detail, it helped.
     
  6. Jun 17, 2016 #6

    D Hillberg

    D Hillberg

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    the gear box stayed in place the rubber mounts stayed, the frame was torqued and compressed , seat displaced down as designed seat belts held, tail chopped off, engine impact damage from the ground, one fuel tank ripped open but the bladder contained all fuel no leaks, landing gear cross tubes flattened flat (they where separate cross tube and skids like a normal helicopter not welded spuds like safari, the rotors where pretzeled mast bent gear box cracked but because the mounts flexed the energy did not localize when solidly mounted systems would snap at the bolts or hard points. the passenger (pilot?) only had bruising where the seat belts held him. and the bladder kept him from Bar-B-Qing.
     
  7. Jun 17, 2016 #7

    Blue Chips

    Blue Chips

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    By your description it would seem obvious that it was "The End of the story" for that ship and very fortunate for him that the work done was done.

    Did you hear anything on the circumstances that led to the accident?

    I am visualizing a very large chunk of aluminum for the plate in order for the mast support struts to be positioned optimally on it (furthest corners), was the size of it pretty much the same as the top frame work of the main frame?

    The Safari has a 1/2" spacer sandwiched between the upper and lower case halves to accommodate the wider gear which seems like a good place now to put a plate even with out the wider gear, on Reads Heli did the gear box set on the the plate or was it sandwiched?
     
  8. Jun 17, 2016 #8

    D Hillberg

    D Hillberg

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    Accident was all pilot error, he literally flew it into the ground (taxi way cement)

    It's been so long I cant recall the aluminum covered the whole top of the frame , the gear box on top. fan & clutch below. clevis through bolts at the lower end of the struts to the aluminum plate {the webs after milling left a light plate and all hard points and mount areas where the 1/2 plate thickness generous portions around hard points)
     
  9. Jun 18, 2016 #9

    Blue Chips

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    Thanks much for the information Don
     

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