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Hoskins, and Wallis, Wood Rotor Blade -

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  • Hoskins, and Wallis, Wood Rotor Blade -

    Hi Folks:

    When looking at the history of autogyros, Monte(y) Hoskins and the 3DRV Gyrotor , and the WCdr Wallis WA-116/117 come to mind. From what I understand, Monte and Wing Cdr Wallace used plywood blades and I have seen pics of them or shall I say, cut sections of the WAllis blade.
    WCdr Wallis (IIRC) sold plans for the WA-116 and Monte sold plans for the 3DRV and Gyrotor blades at least I remember them in the EAA Plans book showing the Wallis in a picture from 1980 or thereabouts. I have also seen a non-plan illustration of how it was done.

    Not being able to find Monte on the net, at least a contact number or email addy, I must ask if Monte is still with us. More recently I understand WCdr Wallis has hung up his wings.

    I would like to find anyone with an email address, a web site, for Monte and / or locations of the Gyrotor book, and the rotor blade construction items. OR links to anyone that has information on said WA series gyros (gyro plans or blade plans.)

    I owned a set of full size Bensen B7 plans with the wood blades and early spherical bearing controls that I got from Vortech in the early 90's and was short sighted enough to throw all my rotorcraft/airplane plans away once I was diagnosed with a medical revoking heart problem and lost hope. But then there is the ultralight and the UL Gyro and a few Gyro instructors west of here.....hope floats once more. And the B19/20 and B7 style wood blades plans are out there. Steel Straps and all on the B7, and a douglas fir plank on the B19.

    Does anyone out there have any information I can start on? ADDED - IF not Hoskins/Wallis Plans how about a reference or source for Hoskins "GYROTOR " book? IF anyone still has one.

    I have been reading 'A Dream of Flight" by Bensen and a more descriptive than technical Smithsonian style book by Peter Brooks "Cierva Autogiros". I have yet to read any Peter Bergen Abbott on the gyroplane. Martin Hollman's work on the Bumblebee and the derivatives by Taggart (Taggert?) show good insight, but not as far as the blades and the math (except for Hollman's work on the Blade Resonance) and the design of the blade, a combination of extrusion, foam and fiberglass....

    I have the Helicopter Experimenter book from Vortech and need more.

    Chuck Beaty? Are you on this list? ADDED - From what I have been reading on this forum is that the BENSEN blades did not have a proper SPAR, and thus the steel strap. What would you consider a proper spar? I saw the picture of your full length wood blade of glued up sections...Birch...Your input would be appreciated. I have been taking advantage of the search feature on this forum to supplement my research.

    I do expect the questioning responses as to my mental state, but this is a mind exercise no longer. Research helps one learn.

    Thanks in advance.

    Curtis Scholl
    Last edited by curtisscholl; 05-03-2017, 05:25 AM.

  • #2
    Thank you for opening this thread, Curtis. I have always taken great interest in the question of wooden rotor blades and it would be great if someone came up with instructions on how to build Wallis blades. I had dug up an information regarding the glue that Ken has used (see below) but apart from that I can only try to answer your question regarding a "proper spar"
    the BENSEN blades did not have a proper SPAR
    Leishman writes in "Principles of Helicopter Design "
    In the United States, Charles Kaman adopted Anton Flettner's synchropter rotor design. One of Kaman's innovations was the use of torsionally compliant solid spar spruce rotor blades with servo flaps.
    from here:

    i.e. a proper spar may well consist of wood, it just has to be properly designed, thus the Bensen and Wallis blades had wooden spars which were incorporated into the blade nose. As far as I know the steel strap in the Bensen blades were just balancing the blade chord wise. If they were used as spars they would have to be attached to the rotor hub to transfer the load, which was not the case to the best of my knowledge.

    I do hope that someone can turn up more on building especially the time honoured Wallis blades because wooden blades marvelously stand the test of time, as post #47 in the thread below shows.

    Since Ken was too busy flying for writing stuff down we will probably have to pray for a little miracle...;-)
    Last edited by kolibri282; 04-19-2017, 12:13 PM.


    ..Il semble que la perfection soit atteinte..
    ....non quand il n'y a plus rien à ajouter,...
    ...mais quand il n'y a plus rien à retrancher...
    - Antoine de Saint-Exupéry -


    • #3

      In this forum, there is a wealth of information about wood rotor blades between the posts of Chuck Beaty and all the other contributors. I have gathered a lot of data here.

      With regard to the Bensen steel spar attachment to the hub, on the B7/B8 versions, and the B19/20, yes,it was attached to the hub. On the built up plywood version (B7 for sure) there was the steel spar itself on the bottom of the blade screw attached with wood screws, (glued too?) and it extended out past the blade root, and there was a steel strap on top that was mated to the spar by bolt holes that were match drilled to complete the blade assembly. This formed mounting "ears" for the attachment of the blade to the hub bar and load transfer from the spar/blade. (edited to correct misconception). But the B19/B20 Douglas fir blade had not only the spar, but TWO mounting straps on the drawings....

      The balance was accomplished on a Bensen wood blade by an assembly attached nearer the tip of the blade, and extending forward of the blade. It was not the spar that was doing the balancing.

      The Wallis and Hoskins (assumed) use the steel strap more toward the nose of the blade in the interior of the blade as balance, but I saw a pic with Wallis next to his Nellie and there was a balance attachment on the blade as well.

      Chuck Beaty put a picture of a blade he built with birch, with a flat nose to attach a shaped lead weight, and the flat vertical unshaped rear side where the vertical grain balsa would go as a trailing edge. I counted 6 separate plys horizontally of solid birch. The whole assembly was glassed according to him. The thing is I do not know the width of the blade front to back to tell how thick the individual plys were. If I assume a 7" blade that an 8H12 foil, the 12%thickness of an 8H12 for 7" is .84 but that depends on chord length.

      Kaman and Bell used wood. Bell used vertical birch plies for the nose then other woods for mid section and balsa for the trailing edge. Kaman took a wood spar but added different kinds of glass and roving to build it up the rest of the way. That should be sufficient enough a testimony.

      The thing here is the math to go with the design of the blade assembly. This is not for guessing. Engineering a blade is not copy and paste. While Aluminum (6061 T6) has a 45K psi yield, wood has maybe 15K psi to 17.5 K psi yields depending on the species. And vertical grain "straight grain" or however you want to designate it is expensive in the longer boards. Grade A and B plywood (no voids and exterior glue) would be good if you could get it in 1/8", 1/4" for top an bottom skins, or do what Jean Claude DeBreyer did for his Tractor design in wood, or the shaped plywood out of Argentina (?) that picture as well. If you want, smaller lengths could be scarfed together where the scarfs are distributed at different locations in the blade assembly.

      Seeing a blade cutout, knowing how it was assembled, knowing what wood was used, and knowing there are better "glues" these days, I would say it was doable and would last longer than an experimental run before implementing the foil in aluminum. If Ken can do it, so can we.

      Gougen Brothers were the subject of a fine tech report workup on the site for wood blades, built up with epoxy, but it was for lonnnng turbine blades. Epoxy and wood and some glass. But it seems that epoxy loses strength at higher temperatures. Back to WeldWood?

      Juan De La Cierva used steel spars of 20Ga (.035 wall) high strength steel (for that time) on the C19 and following and there is a Spanish Youtube video of an old Cierva bird that was rebuilt...steel spar, wood ribs, plywood covering not just LE and cloth. It worked, a bird strike could ruin your airfoil but the spar would maintain. His C17 and C18 used "planked" mahogany. 90 degree grain orientation on successive plys.

      I am STILL looking for the plans for the Wallis or Hoskins blades. And for the Hoskins Book "GYROTOR An Experience in Wood Rotorblades" as stated before.
      I have the plans for Monte Hoskins 3D-RV gyro. I just want a set of his plans for the blades.

      Curtis Scholl
      Last edited by curtisscholl; 04-26-2017, 11:08 AM.


      • #4
        You are right, Curtis, that with the Bensen blades the steel straps were used for load transfer, I had mistaken them for the Wallis blades.
        I keep me fingers crossed that something will turn up. If so, please let us know!




        ..Il semble que la perfection soit atteinte..
        ....non quand il n'y a plus rien à ajouter,...
        ...mais quand il n'y a plus rien à retrancher...
        - Antoine de Saint-Exupéry -


        • #5


          I recall Jean Claude DeBreyer, is using wood. In the "Wood. Seriously!" thread on this forum I found the below graphic (second graphic). It is basically a Bensen style blade (see first graphic) with a solid wood spar rather than plywood (assumed since the graphic only indicates plywood for the skins). Steel Strap under a wood spar, with a pine/spruce nose cap and plywood skins. You commented on it in that thread. Jean Claude used a different rotor head style. I am wondering if it ever flew?

          Curtis S.

          Click image for larger version  Name:	BENSENPATENTAIRFOILPIC.JPG Views:	1 Size:	98.5 KB ID:	1119366

          Click image for larger version  Name:	wood blade wood fuselage sans-titre-43d710c.png Views:	1 Size:	725.1 KB ID:	1119339

          Last edited by curtisscholl; 04-26-2017, 10:54 AM.


          • #6
            Jean Claude's project is indeed very interesting and I think I had asked him back then to share some details with us. Unfortunately he did not reply. This year I will go to the French autogyro meeting at "Bois de la Pierre" 3&4 of June (I have already bought the train tickets, it's very exciting to think of it....;-). Perhaps I will meet someone there who could give me a status on the project or even better share some details of the design. I will definitely post a few picture when I'm back.

            Last edited by kolibri282; 04-29-2017, 08:27 AM.


            ..Il semble que la perfection soit atteinte..
            ....non quand il n'y a plus rien à ajouter,...
            ...mais quand il n'y a plus rien à retrancher...
            - Antoine de Saint-Exupéry -


            • #7
              Sorry, Juergen. I not read your request. My building progress is slow. Now, it is the cover of engine and the internal cooling circuit.

              Curtis Scholl,
              The dimensions are shown in your post # 5
              Identical from the root to the tip.
              Leading edge and spar are an exotic wood, density 0.65
              Trailing edge is an plywood Okoumé 3 mm , density 0.5
              The lead fused in the holes gives GC at 26% of chord.
              Airfoil is not Naca 8H12. It is an airfoil designed with JavaFoil for good efficiency of flat surfaces and Cm0 > + 0.02 Not tested yet.
              Last edited by Jean - Claude; 05-03-2017, 01:58 AM.


              • #8

                Merci d'avoir pris le temps de répondre à ma question. C'est la grande information. (computer translation).

                Many thanks for responding to my question. This is great information. The G12-2 javafoil predictions look good, better than 8H12. I hope that you have good results with the design.

                Curtis Scholl


                • #9
                  UPDATE - Wood Rotor Blades of Ken Wallis

                  I wrote to the Norfolk and Suffolk Air Museum about the estate of WCdr Wallis and the future of his Autogyro and wood rotor blades. I wanted to see if I could get a message in to the estate and discuss the gyros. I got a response:

                  ""Thank you for your enquiry but we cannot be of much help as Ken's Estate is still in the hands of solicitors as grant of Probate is awaited.
                  I can tell you that the rotor blades were made by Ken in wood and steel with the pusher propeller in carved wood, although he did try
                  other methods with varying success, such as extruded aluminium. Consequently, the blades on his autogyros are often of different construction
                  and dimensions as he tended to "borrow" them when required following a mishap for example as he did not always have sufficient time to build
                  new ones. He preferred a steel core, surrounded by Hidulignum (a high density plywood) and an outer skin of aviation plywood. He employed other
                  "tricks of the trade" to perfect their performance and found that a small deviation could alter performance quite dramatically. He preferred not
                  to document the procedures too closely to protect his invention and never disclosed details or provided plans. He often said that he would not wish
                  to be responsible for somebody's injuries owing to them being tempted not to follow his instructions to the letter; best therefore not to encourage
                  others to copy his design."

                  So Probate is just as long over there as here for important persons and heirs.

                  The important point here is that WCdr Wallis was not going to sell plans for fear of someone not following instructions and damaging themselves. He was not willing to take that risk.

                  So the search for Monte Hoskins' wood rotor plans continues. Monte sold plans and the blades were successful, just labor intensive. And so were the Bensen wood variants.

                  Curtis Scholl
                  Last edited by curtisscholl; 05-08-2017, 06:24 AM.