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NA Harvard Mk.1- Do any survive?

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  • Mark_pilkington
    Rank 9999 Registered User
    • Jun 2004
    • 1791

    #21
    Originally posted by Beermat View Post
    I would be extremely wary of going back to the earliest of the breed. Recreating a non-washed-out, straight-winged, short-tailed, round-ruddered NA trainer.would mean reversing all the amends made to make a frankly dangerous aeroplane acceptable. There is a story in there, and as is often the case it's not the one told by the manufacturer.
    We built and flew 750 2 deg washed-out, straight-winged, short-tailed, round-ruddered CAC Wirraway licence built NA trainers down under and coped with the wing stall characteristics, and have a number still flying today, although one restored example did succumb to those un-forgiving wing stall characteristics when the pilot was performing steep turns at an Airshow, but the same characteristics were also in the CAC Boomerang and CAC Ceres and those also flew successfully, with restored examples flying today, the characteristics were improved through the fitting of leading edge wedges to the centre-section as well as wing slats on the Ceres.


    Click image for larger version  Name:	Wirraway_A20_109a.jpg Views:	0 Size:	55.5 KB ID:	3865146



    However If someone did want to recreate a Harvard I with a full steel tube (short) fuselage, and with its squared rather than rounded or triangular rudder, I personally would avoid the costs and issues with building new examples of the straight trailing edge wing and simply use the more modern T6/SNJ tapered wing, inclusive of its Centre-section and simply put round wing tips on it, what ever you build is only ever going to be a reproduction, not a restored and authentic original.

    In fact the first post war airworthy restoration of a Boomerang by Guido Zuccoli flew with a clipped T-6 tapered wing until the first new straight trailing edge Boomerang wings were built Matt Denning.


    Here is the description of the Wirraway wing from the Overhaul and Repair Manual

    l. Description. ' The wing assembly consists essentially of a centre section, two outer panels, two wing tips, two ailerons, two aileron booster tabs and five flap panels. The centre section. is of constant chord design and is set at a 2 angle of incidence. Each outer panel is twisted 2', thus resulting in, an angle of 0'at the tips, The outer panels have a sweep back of 12 5' at their leading edges and have, relative to the centre section, a dihedral angle of 5' measured along the upper surface. The entire trailing edge of the wing is straight.


    2. Centre Section. The wing centre section is of aluminium alloy construction consisting of two spars with channel type flanges and flat sheet webs, flanged channel type intermediate ribs between the spars, two end plates and a corrugated sheet riveted to the spar flanges and intermediate ribs between the spars at the top. The entire assembly is covered with aluminium alloy sheet, with access doors and openings provided in the upper surface to accommodate the fuel co*k extension shaft, aileron control cables, flap and hydraulic brake pipes, fuel tank filler necks, . A large door, extending the whole length of the centre section between the spars,- gives access to the fuel tanks. When bolted into position between the outer wing panels this - door forms an integral part of the wing centre
    section. Incorporated in the assembly of this fuel tank cover is the manual bomb release mechanism. The removal of this cover gives access to both fuel tanks. The landing gear supports and lock-pin mechanisms are installed at the outboard ends of the centre section _on ,the front spar. Wheel wells are provided in the leading edge to accommodate the landing gear wheels in the fully retracted position. On the rear bottom surface of the centre section are installed electro-magnetic -bomb release mechanisms.

    3. Outer Panels. A twist of 2' (wash-out) is incorporated in each outer wing panel, which is of aluminium alloy construction throughout. The basic construction of each- outer panel consists of a single spar, pressed flanged ribs and aluminium alloy sheet covering. Access doors are provided on the upper and lower surfaces to facilitate inspection, servicing, replacement, - The outer -panels are attached to the centre section by means of eight (8) bolts through angles riveted to end plates of the centre section and screwing in-o anchor nuts on the spar of the outer panel, also by numerous bolts through bolt angles which are riveted to the centre section and outer panels about their respective root profiles. Two universal type bomb carriers are built into each wing panel. These carriers are so arranged that the-.slip and .electro-magnetic releases are- entirely within the wing. The necessary bomb steadies and rails for the fusing units are incorporated as part of the wing assembly.

    For Pat's inquiry above I have added a photo of the Wirraway wing outer panel and the repair drawing of the wing from the manual, showing the straight trailing edge in common with the NA-16 and Harvard I, and the 13 rib positions.


    Regards

    Mark Pilkington
    Attached Files
    Last edited by Mark_pilkington; 13th June 2019, 00:23.
    "Never has a Country so Big!, owed so Much!, to those who Flew!"

    Comment

    • J Boyle
      With malice towards none
      • Oct 2004
      • 9728

      #22
      Since several have indicated interest in the surprisingly diverse history of the North American trainers serirs, I can recommend this book...

      https://www.amazon.com/North-America...s=books&sr=1-2

      There are sever curved rudder SNJ-2s flying in the U.S., and several Yales...including projects as well.

      The NA trainers (note I avoid using the T-6 or Harvard designation since there are many other members of the family) are a bit like the DC-3 family...a lot of variations and even otherwise knowledgeable enthusiasts don't appreciate the differences in the variants.

      There are two sides to every story. The truth is usually somewhere between the two.

      Comment

      • Beermat
        1 Registered Rank Loser
        • Oct 2009
        • 3617

        #23
        Hi Mark

        I note these examples were 2 degree washed-out. Without the washout things would be - indeed were - beyond marginal.

        Do you know the story of an attempt made to shortcut introduction of washout, so urgent was it? A wing was put in a jig by NAA with rivets drilled out, literally twisted and then re-riveted. As soon as it was removed from the jig, it sprang back, throwing rivets all over. I will dig out my source for that later.

        Matt
        www.whirlwindfighterproject.org
        It's all good. Probably.

        Comment

        • Mark_pilkington
          Rank 9999 Registered User
          • Jun 2004
          • 1791

          #24
          Originally posted by Beermat View Post
          Hi Mark

          I note these examples were 2 degree washed-out. Without the washout things would be - indeed were - beyond marginal.

          Do you know the story of an attempt made to shortcut introduction of washout, so urgent was it? A wing was put in a jig by NAA with rivets drilled out, literally twisted and then re-riveted. As soon as it was removed from the jig, it sprang back, throwing rivets all over. I will dig out my source for that later.

          Matt
          .
          I would be keen to see that information as I have an ongoing interest in the NA-16 family of aircraft, - I have recently been collecting original NAA Trainer manuals and am currently waiting for a rare NAA Harvard I manual to arrive from Canada.


          I would agree that the original zero-wash-out wings would not be a good idea to replicate, and the BT-9 had a number of mods to improve its wing, and the CAC Wirraway seemingly benefited from those lessons, - my earlier post was simply to suggest that a Harvard Mk I "could be replicated" through using the Wirraway wing design as the basis of new Harvard I wings given both are NA-16 derivatives, and that the ongoing operation of Wirraways in Australia suggests they can be flown safely by experienced pilots.

          However, again as per my earlier post, if I was trying to create a flying Harvard I reproduction, I personally wouldn't bother making new straight trailing edge wings and would instead use the later T6/SNJ taper wing for its ease of obtaining, its ongoing parts support and of course its better flying characteristics, and that a fabric covered full steel tube frame with short length rear fuselage, and flat bottomed rudder, would deliver most of the obvious visual aspects of the Harvard I compared to the Harvard II to IV, and most would not be aware of, and notice that its wing was a taper wing and hence incorrect for the type.

          I am not sure what Pat's objective was in converting a set of Harvard II taper wing outers to Harvard I straight trailing edge wing outers, as changing the wing outers is probably the least recognisable element of a Harvard I, and hence a Harvard II with Harvard I wing outers would still be hard to identify on a flight line, and would be a poor reproduction of a Harvard I if it retained the metal skinned fuselage etc, and fitting the flat bottomed rudder would simply make it look like an SNJ-2.

          Where as the fabric covered fuselage, and flat bottomed rudder of a Harvard I would make it stand out as "different" on a flight line of T6's, SNJ's and Harvard II to IV's , regardless of the paint schemes.

          Regards

          Mark Pilkington

          "Never has a Country so Big!, owed so Much!, to those who Flew!"

          Comment

          • Mustang51
            Rank 5 Registered User
            • Sep 2008
            • 269

            #25
            Here, Here Beermat............... Wirraway with no wash-out is not a friendly aircraft. Totally different handling to the BC.2/ T.6/Later Harvards. Nasty stall characteristics that resulted in many accidents/losses when low and slow. My friend Ed Field, whose company rebuilt two Wirraways and a Mustang, said to me that the best way to learn to fly a Wirraway was to start on the Tiger Moth, graduate straight to the P.51 then go to the Wirraway.........

            Comment

            • Mark_pilkington
              Rank 9999 Registered User
              • Jun 2004
              • 1791

              #26
              I purchased a rare original North American Harvard I (NA-16-1E) manual from Canada (they only ever had 30 examples of the type) via Ebay a few months ago - it has just arrived.

              Its very easy to see the family resemblance with its NA-16 sibling the CAC Wirraway

              regards

              Mark Pilkington
              Attached Files
              Last edited by Mark_pilkington; 18th June 2019, 05:52.
              "Never has a Country so Big!, owed so Much!, to those who Flew!"

              Comment

              • Mark_pilkington
                Rank 9999 Registered User
                • Jun 2004
                • 1791

                #27
                Here are some equivalent pages out of the CAC Wirraway manual, to show the similarities, between it (a licence built NA-16-2K / NA-33) and the Harvard I (an NAA built NA-16-1E / NA49)

                (and a "side on" modern photo as a comparison to the Harvard I in the previous post)


                Regards

                Mark Pilkington

                Attached Files
                Last edited by Mark_pilkington; 18th June 2019, 11:57.
                "Never has a Country so Big!, owed so Much!, to those who Flew!"

                Comment

                • Mark_pilkington
                  Rank 9999 Registered User
                  • Jun 2004
                  • 1791

                  #28
                  Here some various modern photos from the net, of Wirraways flying with their younger T6/SNJ cousins to contrast the shorter rear fuselage, fabric covered metal tube front and rear fuselage, round rudder and straight trailing edge wing (copyright as per any branding)

                  Regards

                  Mark Pilkington

                  Attached Files
                  "Never has a Country so Big!, owed so Much!, to those who Flew!"

                  Comment

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