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Hugh Lorimer's creations freed from the shackles?

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  • Hugh Lorimer's creations freed from the shackles?

    Hugh Lorimer built aircraft, he was an ex aerospace and teaching chap, who had battles royal with G and the system.

    SSDR came too late for Hughie but he still has the two machines, one of which secretly flew

    Here's an email I received from another, perhaps if it suits all he will pop up and continue this:-

    ---Quote---
    Hi *****, My Sgian Dubh has been taken to the taxying stage but I removed the Rotax447 and installed it in my Quaich. Both these single seaters could fit ssdr. Do you know of anyone who would like to continue the development of these two projects? as I am medicalled out...............Hughie.
    ---End Quote---

    Hugh has early Parkinsons, although his mind is as sharp as ever when I visited him a while ago; brilliant bloke, even though Scottish..;-)

    Hope someone takes him up and flies them again, Hughie used to load test everything to Section S

    Cheers
    G-KEVA
    BMAA 5696

    "If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: it's all balls."

    R.J. Mitchell :- Designer of the Supermarine Spitfire

  • #2
    Hugh Lorimer's creations freed from the shackles?

    Such a shame that the timing didn't work out for Hughie. The Sian Dubh looks like the TP might earn his metaphorical money, but a perfect example of something that can be experimented with in a deregulated system, that might just result in something the regulated system would struggle to produce.

    Paul

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    • #3
      Hugh Lorimer's creations freed from the shackles?

      By chance, I have recently been in touch with Hugh and am now in the process of modifying his Sgian Dubh design to take an 'on the heavy side' pilot. My mods are an up-sized motor, a 1600cc Jabiru has been offered to me at a very low price, a slightly widened cockpit with a bit more head room as well. Retractable nose wheel and possibly mains as well but weight will define that later on. It is possible I will need to increase the total wing area as well but for the time being, I'm concentrating on getting the build method clear in my head. Hugh plans, unfortunately, are not as complete as they need to be for any one else to consider building another plane.
      It is indeed a pity that Hugh had his run in with the authorities and that he is now in less than perfect health. His mind is a sharp as ever though and he has been very helpful to me. Time will tell if I ever build this version of Hugh's plane but the plan is for it to happen before I gain my feathered wings :lol:

      Attached files

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      • #4
        Hugh Lorimer's creations freed from the shackles?

        Doug,

        I'd be very careful with a Jab engine in pusher config. I remember Medway tried using one, but it wasn't very successful. Cooling was a problem with the engine at the back. It needs the prop wash to help keep it within proper operating temps range.

        Best regards,

        Bob Hood
        XL's forever! Well, one of them anyway. It's all I can afford, not to mention the Raven and the Mini-Max. Oh, and I almost forgot the Spectrum as well :-)

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        • #5
          Hugh Lorimer's creations freed from the shackles?

          Hi Doug,

          Is it an amphibian, or are those wing floats actually fuel tanks?

          What are the fuselage and flying surface skins made from?

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          • #6
            Hugh Lorimer's creations freed from the shackles?

            Hi guys, sorry for the delay in answering. I'd forgotten to tick the notification box.

            Re my version of Hugh's design. Yes I am aware of the cooling issues but I'm trying to avoid water cooled engines due to weight problems. I've also got to think of where I'm going to put the oil cooler without causing extra drag. Perhaps a couple of NACA ducts will provide sufficient through-flow for that purpose. Only testing will provide the answers. The reason for choosing the Jabiru engine is that I have one available to me at an affordable price. I'm a cousin to the original 'penniless flyer', don't cha know.

            As for those 'tanks/floats' under the wings, well I get carried away at times and there are fanciful luggage containers needed for weekends away. Just big enough to carry a one person tent and swag. When Hugh put his plane on view, he hung model Sidewinders from the same positions.

            The skins are T290 twill glass and epoxy. A single layer id all that's needed but with some overlap in places. Can't tell you any more as I'm new to the world of composite builds.

            Happy to hear your comments and answer more questions. All for now from a cold (17*)winters day in sunny South Australia. Yep, got the heating on.

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            • #7
              Hugh Lorimer's creations freed from the shackles?

              Doug, I hope you don't mind if I point out that from the images that you posted there seems to be a major spar cap discontinuity at the root of the outer wing panels. The spar cap reduces to one third of its thickness as it enters the centre wing section.

              Also the Jabiru will need to be moved forward quite a bit because of its much higher weight. You will probably need a prop shaft. Otherwise some wing sweepback will be required to get the centre of lift in the same place as the CG. You will then need reflex on the wingtips to avoid tip stalling and to give longitudinal stability. The rearward shift of the CG would mean that your fin arm is then reduced and the aircraft would loose some directional stability.

              Flying wings tend to be twitchy in pitch due to the short effective tail arm and thus low pitch stability and damping.

              It all starts to get a bit complex.

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              • #8
                Hugh Lorimer's creations freed from the shackles?

                Hi Adrian. Yes I'm aware of your spar concerns and had the same doubts at first. Hugh load test the wings to 6g before he mounted them onto the fuselage. In mounting them, they become homogenous with the fuselage skin, not that that is the final answer. To put my mind at rest, I've decided to add plywood former between the spars and the wooded floor, see attached graphic.
                As to the weight of the Jabiru engine, this is a benefit in that I weigh 100kg, some-what heavier than the 'assumed' 85kg pilot in most designs. Hopefully we will balance each other out. New weights and balance calcs yet to be done. As for the total extra weigh, I've said previously that I may have to increase the wing area(lengthen the outer panels)
                As for pitch sensitivity, Hugh has reflexed the inner wing 25% from 80% cord line to the T.E. I am having this tested by having a friend build a 4ft span r/c model with interchangable inner wing sections. One will be plain, the other reflexed. Wool tufts on the wings will be videoed in flight to see the differences.

                Happy to answer any more questions, Cheers, Doug

                Attached files

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                • #9
                  Hugh Lorimer's creations freed from the shackles?

                  Hi Hugh, It was the outer wings that I was concerned about. Assuming that the spar caps are sized to take the g loads, they then reduce to one third of their required strength as they pass into the centre wing section.

                  Also I wouldn't bother flying a model with no added reflex as it will be unstable in pitch. That is unless the wing section already contains reflex in its design. All non reflexed aerofoils have their aerodynamic centre in front of the centre of lift, and are thus unstable. This is why either a tailplane or reflex is needed, to move the aerodynamic centre behind the centre of lift.

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                  • #10
                    Hugh Lorimer's creations freed from the shackles?

                    OOPS, you addressed your last comments to Hugh and I'm not sure if he's following this conversation.

                    Sorry I missed your reference to the outer wing panels. I take you point but those panels passed the test as they are. Top and bottom caps could be taken full length without adding too much weight though. I doubt that a fully composite wing spar would be much stronger than the foam with ply-wood cheeks anyway., without the caps that is. what I intend to do is put a single layer of f/g tape along the top of the spars and down the sides about 1". I want this so that the final skin adheres to f/g and not wood or foam. Just feel it will be stronger.

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                    • #11
                      Hugh Lorimer's creations freed from the shackles?

                      Not too dissimilar to this little french tail-less glider seen doing loops and rolls at the Old Warden Show last sunday.

                      Alan

                      Attached files

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                      • #12
                        Hugh Lorimer's creations freed from the shackles?

                        And another couple of pics

                        Alan

                        Attached files

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                        • #13
                          Hugh Lorimer's creations freed from the shackles?

                          Sorry Doug, senior moment.

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                          • #14
                            Hugh Lorimer's creations freed from the shackles?

                            G'day Alan. Thanks for your input. A very similar aircraft indeed. I don't intend to do aerobatics as they're illegal under our basic rules, ie, special certificate required. That's not to say that I might not find myself up-side-down whether intention or not. :nono:

                            Looking at the elevators on that Flavel, it looks like it uses the tabs for pitch stability rather than a reflexed wing. Just my guess though. I will research for more info. Thanks for the link.

                            Have a nice day now guys.

                            Doug

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                            • #15
                              Hugh Lorimer's creations freed from the shackles?

                              If you look carefully at the outer wing section of the Fauvel, where it meets the fin, there is a reflex curve at the trailing edge. There are signs of a similar feature on the second image of your version of Hugh's design, the 3/4 aft view. It looks like you have reduced the chord of the outer wing section and removed the reflex, making it unstable in pitch.

                              The centre section cannot be used alone for reflex because the elevators are there. With down elevator applied the reflex would disappear and so would any longitudinal stability. The aircraft would immediately tuck in and the negative g would probably tear the wings off.

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