Guest TOSGcentral Posted October 30, 2008 Share Posted October 30, 2008 A bit of a progress report on the Swift Prototype development. This has been a bad year for myself. Progress has been like wading through waist deep treacle â€“ a lot of effort and not much headway. The key factor has been the Angle of Incidence bracket which has to be right before surrounding and/or consequential modifications are made. This turned out to be totally impractical and unsatisfactory. The prototype bracket came out well and looked nice but it was difficult to make, almost impossible to drill out the face plates at the correct angle and would have been far too expensive even if we could have got it right. So it never flew! A key factor was that the new bracket was also intended to get around some major assembly/disassembly hassles with the Thruster. On top of that we wanted simple â€˜at homeâ€™ fitting so virtually anyone could do the work themselves. That did not work either! What really stopped me in my tracks was what you have to do to the root end of the wing front spar in order to allow the wing to connect with the bracket. Far too much material had to be taken out of the spar and extra good cutting equipment/skills are required. This (in my opinion) was beyond reasonable expectancy for the â€˜at homeâ€™ guy to do, plus there was a real chance of stuffing the wing spar completely â€“ or a defective job put back into the air. So I went back to the drawing board and built the concept up from grass roots again using the original objective parameters that I had set. It now looks as though we have it right and part of that process was getting the engineer, fabricator and myself together in my workshop with the Prototype. That was a torrid experience but nobody lost their tempers. This is how the new design turned out and the Mk2 prototype is currently being built: The bracket returns to the original design intent of being in four pieces. The enables the bracket to be put in or taken out without dismantling most of the aircraftâ€™s front end. An owner will have to do this on initial installation but only have to do it the once. The â€˜legsâ€™ of the bracket bolt in to the front A frame struts and boom mounting point as per normal â€“ no change at all. The front and back plates of the bracket are now symmetrical and parallel drilled. The angle of incidence of the wing is achieved by the welding angle of the plate assembly. This is very easy to do in a simple jig at manufacture and far cheaper. The two plates are bolted together and clamped to the â€˜legsâ€™ via 8 AN bolts and are along the lines of the Gemini and T600 front brackets. To avoid the requirement for metal â€˜carvingâ€™ on the wing spar roots the bracket span has been increased to accommodate the roots fully as per original design. The only real â€˜technicalâ€™ work the new owner will have to do is lop off, with a drop saw, a measured amount of spar root length and re-drill the mounting holes from a template that will be supplied with the kit. This preserves the overall wing planform geometry of the aircraft. The existing internal spar sleeving stays in place and there is no change in that area. If this works as intended and calculated then we will have a much tamer Thruster in the landing configuration that will be easier for students and instructors alike to deal with in the 3 Point landing. I called a halt at 4 degrees A of I reduction. I could go further but I wanted to retain 1.5 degrees of declage to remain totally safe and not invoke challenges in other areas. On the other hand I will be writing into the Engineering Order that tail unit formers MUST be fitted as part of the modification. These are as cheap as chips and provide about 30% more elevator power. This will drive the aircraft into full 3 point rotation through the high pre stall sink on the Thruster much more easily than what we currently have to put up with. Other Swift news is in the fibre glass area. I have just brought in the full cockpit assembly and the Mk3 pod that I am already having some final touches done to. I will add some photos later. I had intended to fly the Prototype in â€˜standardâ€™ T300 configuration for the A of I bracket but I have lost too much time. So while I have her in the workshop Lois and I will complete the new nose assembly. I will also probably put in the full span wing sleeving for the 450 kg MTOW mod. This should not affect the aerodynamics other than raise the stall speed one or two knots. The roof panels will have to be changed later for the new design incorporating the flap and trim actuating lever housings and the upper ventilation system but I guess that I can live with that. More later as it happens. Aye Tony Link to comment Share on other sites More sharing options...
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