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  • nibb100
    Rank 5 Registered User
    • Sep 2006
    • 345

    Hydulignum props

    a friend of mine has a mounted blade and a cabinet that were presented to her Grandfather in 1942 in recognition of his money raising activities for aircraft, the plaque on the blade says it is a Hydulignum prototype Spitfire prop,
    as I understand it Horden Richmond invented the process of laminating the wood with the heat activated glue, were their props ever used on Spitfires, it would appear that the cabinet was also made of the same material

    has anybody got any thoughts
    Last edited by nibb100; 16th September 2013, 16:17.
  • Edgar Brooks
    Rank 5 Registered User
    • Apr 2009
    • 966

    #2
    According to his book, "Rotol," Bruce Stait says that Hydulignum was used, and a Rotol book lists propellers, with a green disc on their front face, as being constructed of Hydulignum.

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    • nibb100
      Rank 5 Registered User
      • Sep 2006
      • 345

      #3
      thanks
      so people other than Horden Richmond made props using Hydulignum, what we are trying to do is to find out who would have made the blade and the cabinet

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      • Edgar Brooks
        Rank 5 Registered User
        • Apr 2009
        • 966

        #4
        According to a post-war report, up to 1940, Hordern-Richmond had factories in Chesham, Haddenham, and Princes Risborough, producing fixed-pitch props (but doesn't specifically name customers, other than the M.A.P.,) with another, in High Wycombe, from October 1942. The report also says that Hordern-Richmond worked under the supervision of Rotol.

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        • nibb100
          Rank 5 Registered User
          • Sep 2006
          • 345

          #5
          thanks very interesting, I've read a Flight article from 42 that mentions P40s but not Spitfires, so any props would be under Rotol's name,I wonder if they actually ever made spitfire props
          thinking about it it seems likely that any presentation would have been from H-R

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          • antoni
            Rank 5 Registered User
            • Dec 2005
            • 698

            #6




            There is a drawing of tghe construction of a Rotol Hydulignum blade here:

            http://www.enginehistory.org/Propell...ol/rotol.shtml

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            • Edgar Brooks
              Rank 5 Registered User
              • Apr 2009
              • 966

              #7
              Supermarine, in a 1976 symposium, on the Spitfire, stated that the Mk. VII & P.R.XI used 4-blade Rotol Hydulignum props. According to "Spitfire, the History," Hydulignum blades were an option on the VIII, IX, X, XI, XVI & XIX.

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              • nibb100
                Rank 5 Registered User
                • Sep 2006
                • 345

                #8
                the Grandfather's name was A O Bluth he must have had a fairly high profile in WW2 he had a strong connection with Churchill and was involved in fund raising, his main occupation was a Banker,
                Has anybody come across his name ?

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                • low'n'slow
                  Rank 5 Registered User
                  • Sep 2006
                  • 1436

                  #9
                  Hydulignum was the name given by Horden Richmond to a process where they bonded a fabric covering onto wooden propeller blades then baked them at high pressure and temperature in an autoclave before painting. The result was apparently a stronger blade for the same thickness of material and equally importantly in the war years, it meant they could use British woods like beech and ash (of which there is plenty in Bucks) rather than imported woods such as mahogany.

                  The British woods normally pose problems with more variable moisture content affecting balance and longevity, something which the Hordern Richmond propellers avoided. Blades were certainly made for Rotol variable pitch units, while the majority of wartime Tiger Moth propeller were also of Hordern-Richmond manufacture.

                  In about 1942 (I think), Hordern Richmond moved from Chesham to a brand-new factory at Haddenham and in turn, later became part of the de Havilland group.

                  As to longevity. We've got a wartime Tiger Moth propeller, still in good order and after an overhaul last year, the 1939 H-R prop on my Tipsy Trainer is still giving good service!
                  Attached Files
                  Last edited by low'n'slow; 17th September 2013, 15:52.
                  www.lightaircraftassociation.co.uk

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                  • nibb100
                    Rank 5 Registered User
                    • Sep 2006
                    • 345

                    #10
                    amazing longevity, obviously the use of the process of heating plastic glue was ahead of it's time!!!

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                    • antoni
                      Rank 5 Registered User
                      • Dec 2005
                      • 698

                      #11
                      Hordern Richmond were bought by Permali in 1954 and Hydulignum is still manufactured by them today along with other resin/wood products. Beech is certainly used today but as far as I know birch was used in WW II. The Use Of Wood For Aircraft In The United Kingdom Report of the forest Products Mission June 1944 lists the types of wood being used in aircraft production:

                      “Aside from birch, the principal veneer used in plywood for aircraft frames and in propellers, the following species are used in plywood: Gaboon, English beech, hard maple, yellow poplar, and red gum. Large quantities of birch, a part of which is cut in England and a part in America, and small quantities of hard maple go into aircraft frame plywood and propellers. Small amounts of American-cut yellow poplar and red gum are made into plywood for lightly stressed aircraft parts. Gaboon and beech are used chiefly for boats and War Office supplies.”

                      No fabric was involved. Weybridge Blade, made by the the Airscrew Company Ltd, were covered with Hessian, Jabo blades with cellulose acetate or cellulose nitrate, Hudulignum with Cristofin. Cristofin was developed by Hordern Richmond but I cannot find out exactly what it was. As far as I can work out it seems to have been a type of Formvar. Late in the war Jablo blades switched to using Cristofin.

                      The types of blades used by modern WW II aircraft such as Spitfires were made from thin veneers of wood such as Canadian Birch, Douglas Fir etc., not blocks of hardwood such a Mahogany as in the WW I types of propellers.

                      Hydulignum

                      One 1/36 inch birch veneer was coated with approximately 20 percent of Formvar by weight. After the solvent (trichlorethylene and alcohol) had evaporated, the veneer was pressed into panels with a specific gravity 0.95 at an elevated temperature and then cooled in the press. Two corners of the board were trimmed off and that end was then further compressed sidewise to a specific gravity of 1.3. This was carried out with the top and bottom also under compression. The resulting final board had a high-density double-compressed root, a transition zone, and a medium-density blade and tip. After rough patterning, several boards were assembled into a blank with a cold-setting urea formaldehyde glue and the blank rough-carved by machine, and then finish carved and balanced by hand. Jablo and Weybridge blades were balanced against masters, but Hydulignum blades were furnished only in matched sets and were not interchangeable.

                      After several coats of primer containing chlorinated rubber, and of Formvar varnish, had been applied, a brass leading-edge strip was riveted and screwed in place. About 14 additional coats of Formvar completed the blade.

                      The normal choice of bonding resin for compressed and non-compressed wood laminates would be phenol formaldehyde better known as Bakelite (hence the name sometimes used – Bakelised wood) . This because, unlike other synthetic resins, Bakelite bonds with the cellulose in the wood. It this that which provides the strength. Bakelite is thermosetting plastic, which does not mean that is requires heat to harden it as many people think (Bakelite will harden quite happily at ambient temperatures but takes a longer time. Brief heating to a high temperature is used to hasten the hardening process, the condensation reaction.) , it means that once fully hardened it will not soften again when heated. This is because the cross-linking is in three dimensions. Thermoplastics can be re-softened many times by heating because the cross-linking is only in two-dimensions.

                      In the case of Hydulignum Bakelite could not be used because of the requirement to compress the wood twice. Another, thermoplastic, had to be found. After researching various vinyl resins Formvar was chosen as having the most suitable properties. Formvar was registered trade name for polyvinyl formal produced by the Monsanto Chemical Company, which is a family of polymers formed from polyvinyl alcohol and formaldehyde as copolymers with polyvinyl acetate. They are also called modified polyvinyl acetal resins.

                      A particular advantage claimed for the Hydulignum propeller was that the equalized shear strength in the root, in the two planes parallel and perpendicular to the glue surfaces, permitted the use of smaller diameter hub fittings. Practical considerations requiring the use of a standard hub for all-wood blades, however, precluded the use of a smaller hub for the Hydulignum blade. A contemporary article in Flight Journal describes how, in order to demonstrate the feasibility, of making wooden blades with narrow roots, some damaged blades from Curtiss hollow steel electric
                      airscrews, which had very small diameter roots were obtained. The steel shanks were sawn off, heat treated, and pressed into a conical shape. They were then used as an adaptor into which the wooden blade root was screwed. After ground testing a full set of blades were made and flight tested on an American aircraft. This seems to explain the role of the P-40.

                      References

                      The Use Of Wood For Aircraft In The United Kingdom Report of the Forest Products Mission June 1944

                      Flight: http://www.flightglobal.com/pdfarchi...0-%202476.html

                      Comment

                      • Sedbergh
                        Rank 5 Registered User
                        • Aug 2010
                        • 21

                        #12
                        nibb100
                        See this page on my website about Haddenham airfield, home of Hordern-Richmond propellers. Sorry I'm hopeless at the technical side of prop manufacture but there are a couple of nice photos - including one on Hordern's own Tipsy!

                        http://www.haddenhamairfieldhistory....propellers.htm

                        Peter

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                        • antoni
                          Rank 5 Registered User
                          • Dec 2005
                          • 698

                          #13
                          Interesting set of photographs that confirm that it was a P-40 that was used to test the Hydulignum narrow root blades.

                          Interesting article here about Wallis Autogyros and that mentions the use of Hydulignum in the manufacture of the blades:

                          http://www.flightglobal.com/pdfarchi...0-%200896.html
                          Last edited by antoni; 21st September 2013, 16:17.

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