Deskpilot

Hi Hildy. It appears that I'm not the only one who's curious about 'who you are'. 20 visits to your profile so far.When a newbie appears on the forums, the first thing I look at is where they're from and what they fly. Care to update anything? Good to hear that your training is going so well. Like they say 'if you can fly an LSA55, you can fly anything'. I've only tried a Sportstar and a Crafter's SportCub for comparision and they are both boringly simple although the cab, being a tail-dragger had it's moments, on the ground. Stay safe, Doug

G'day mate, I wonder if you'd care to help this guy in America with answers to his Vampire V2 questions. I put in a link to Rec/flying but I think I cocked up a bit. Anyway, your choice. Sadler Vampire Cheers, Doug

[Guess I'm going to have to look at this 95.10 in detail and then see if I can design something that comes within the weight limit but without being too small. I was looking at about 65/70% scale or even bigger but that seems to be going out the window. I'm 6ft and really don't want just my head under the canopy. Some W.A.R. replica's look way too small. I wonder if there'll be any changes to the rule in the upcoming release? Two-strokes in a war plane, yuk, but might be the only way to go if I can get them cheap enough. Perhaps the props will modify the sound sufficiently bearing in mind that the original was a turbo. Thanks for the tip on the thrust bearing. I'd completely forgotten that. Shouldn't be too hard to fit. Flex coupling are already on my list and hopefully, the concentric part of the system will be short enough not to have worry about harmonic/torsional vibrations. Nice work with your SR-71 photo. Would be great if you could get sufficient lift with a modified wing section and some extra horses from your engines. Don't forget to look at the yaw oscillation thing that occurs with swept wings (this kept me away from experimenting with a Hawker Hunter T7) BTW, whats the go with wheel retracts and experiment category? Are they allowed with RAA cert. I seem to be seeing conflicting reports. If you need to move these posts to a different area, go ahead. I'm sure I'll find it eventually. Cheers, Doug

[Guess I'm going to have to look at this 95.10 in detail and then see if I can design something that comes within the weight limit but without being too small. I was looking at about 65/70% scale or even bigger but that seems to be going out the window. I'm 6ft and really don't want just my head under the canopy. Some W.A.R. replica's look way too small. I wonder if there'll be any changes to the rule in the upcoming release? Two-strokes in a war plane, yuk, but might be the only way to go if I can get them cheap enough. Perhaps the props will modify the sound sufficiently bearing in mind that the original was a turbo. Thanks for the tip on the thrust bearing. I'd completely forgotten that. Shouldn't be too hard to fit. Flex coupling are already on my list and hopefully, the concentric part of the system will be short enough not to have worry about harmonic/torsional vibrations. Nice work with your SR-71 photo. Would be great if you could get sufficient lift with a modified wing section and some extra horses from your engines. Don't forget to look at the yaw oscillation thing that occurs with swept wings (this kept me away from experimenting with a Hawker Hunter T7) BTW, whats the go with wheel retracts and experiment category? Are they allowed with RAA cert. I seem to be seeing conflicting reports. If you need to move these posts to a different area, go ahead. I'm sure I'll find it eventually. Cheers, Doug

G'day Arthur. So you did get my pm. I was expecting some form of notification that you'd answered but didn't receive any. I found your reply by chance after I'd had the thought that I might have saved my pm somewhere. Anyway, thanks for you response. If my memory serves me correctly, your comments many months ago were along the lines that you liked the long nose, good for C of G etc. That's all I can remember. Getting back to your reply. I have stayed away from differential drives because of the weight being so far forward, besides which, I can't visualize the setup. I am aware of the Cozy side by side engines and have taken that as a start point. My idea to mechanically join the two blocks was to circumvent the 'no 2 engines' rule. On this point, how does the 95.10 rule apply? I've looked but the RAA site just confuse me. I also have worries about 2 engines, running at different rpms and the resultant effects on both props and airframe. Choice of engine really comes down to cheap experimental items, besides which, the VW is low revving and therefore no weight penalties for reduction gearing. Inlet and outlet manifolds shouldn't be a problem as I used to work in the auto exhaust industry and still have contacts to get new headers etc professionally made. I agree that cooling might be a problem due to the small cooling air intake area. Additional intereior cooling fans may be needed but power losses would have to be minimal. Heat build up at the 'flywheels' is a problem but I thought an oil bath below the lower engine could be utilised (both flywheels fully enclosed) Extension shaft bearings are also of concern. I know there are many high speed, prepacked bearings available. How would they last at lower speeds but with the loads that the props would add. How do I work that out? So many questions in my head but I won't bother you with them at the mo. Any help/advice you can give me is really appreciated. Cheers my friend, Doug PS You didn't answer an earlier question re the SR-71 Blackbird. Did it fly?

G'day Arthur. So you did get my pm. I was expecting some form of notification that you'd answered but didn't receive any. I found your reply by chance after I'd had the thought that I might have saved my pm somewhere. Anyway, thanks for you response. If my memory serves me correctly, your comments many months ago were along the lines that you liked the long nose, good for C of G etc. That's all I can remember. Getting back to your reply. I have stayed away from differential drives because of the weight being so far forward, besides which, I can't visualize the setup. I am aware of the Cozy side by side engines and have taken that as a start point. My idea to mechanically join the two blocks was to circumvent the 'no 2 engines' rule. On this point, how does the 95.10 rule apply? I've looked but the RAA site just confuse me. I also have worries about 2 engines, running at different rpms and the resultant effects on both props and airframe. Choice of engine really comes down to cheap experimental items, besides which, the VW is low revving and therefore no weight penalties for reduction gearing. Inlet and outlet manifolds shouldn't be a problem as I used to work in the auto exhaust industry and still have contacts to get new headers etc professionally made. I agree that cooling might be a problem due to the small cooling air intake area. Additional intereior cooling fans may be needed but power losses would have to be minimal. Heat build up at the 'flywheels' is a problem but I thought an oil bath below the lower engine could be utilised (both flywheels fully enclosed) Extension shaft bearings are also of concern. I know there are many high speed, prepacked bearings available. How would they last at lower speeds but with the loads that the props would add. How do I work that out? So many questions in my head but I won't bother you with them at the mo. Any help/advice you can give me is really appreciated. Cheers my friend, Doug PS You didn't answer an earlier question re the SR-71 Blackbird. Did it fly?

Hi Arthur, hope you don?t mind but the only areo? engineer that I know and I want to pick your brains, so to speak. I have a dream to build an aircraft with a difference and in doing so, bend the rules slightly. As I usually fly alone, I hanker for a warbird replica and have long had a ?love affair? with the Westland Wyvern S4. http://picasaweb.google.com/dg.mansfield/WestlandWyvernS4/photo?authkey=aKFdUoqGyS0#5218240547659938002 As you can see, it?s a contra rotating prop setup and although it goes against the single engine, single prop rule of RAA.Aus, I want to do some experimental work to see if my ideas work, prior to approaching the rule makers, and CASA if necessary, to allow me dispensation to fly my dream. The Power Plant: (1off) What I envisage is 2 VW (or similar if cheap enough) blocks mounted one above the other and offset, facing in opposite directions so that their starter ring gears intermesh. Fuel will be fed via a common carbie system with single throttle and carbie heat controls, fired by a single distributor modified to 8 cylinders, and exhausted via a common collector box, then out through twin mufflers below the cockpit as per the real thing. The Propulsion System: (1 off) 2 direct drive shafts with suitable support bearings and flexi couplings are taken from the front of one block and the rear of the other. A belt drive with a 1:1 ratio couple the shafts to a concentric configuration on which the props are fixed. Sounds simple but I realize there are many potential pitfalls. Heat at the ring gears and prop shaft bearings lubrication being the most obvious. Ignition timing will also need some form of variable setup so that the two blocks work without vibration between each other. I think a variance of flywheel rotational position might sort that out. Taking weight out of the equation for now, what do you think? Will it work? Is there some great factor I have not seen? Looking forward to your reply, Cheers, Doug (Deskpilot) Mansfield.

Hi Arthur, hope you don?t mind but the only areo? engineer that I know and I want to pick your brains, so to speak. I have a dream to build an aircraft with a difference and in doing so, bend the rules slightly. As I usually fly alone, I hanker for a warbird replica and have long had a ?love affair? with the Westland Wyvern S4. http://picasaweb.google.com/dg.mansfield/WestlandWyvernS4/photo?authkey=aKFdUoqGyS0#5218240547659938002 As you can see, it?s a contra rotating prop setup and although it goes against the single engine, single prop rule of RAA.Aus, I want to do some experimental work to see if my ideas work, prior to approaching the rule makers, and CASA if necessary, to allow me dispensation to fly my dream. The Power Plant: (1off) What I envisage is 2 VW (or similar if cheap enough) blocks mounted one above the other and offset, facing in opposite directions so that their starter ring gears intermesh. Fuel will be fed via a common carbie system with single throttle and carbie heat controls, fired by a single distributor modified to 8 cylinders, and exhausted via a common collector box, then out through twin mufflers below the cockpit as per the real thing. The Propulsion System: (1 off) 2 direct drive shafts with suitable support bearings and flexi couplings are taken from the front of one block and the rear of the other. A belt drive with a 1:1 ratio couple the shafts to a concentric configuration on which the props are fixed. Sounds simple but I realize there are many potential pitfalls. Heat at the ring gears and prop shaft bearings lubrication being the most obvious. Ignition timing will also need some form of variable setup so that the two blocks work without vibration between each other. I think a variance of flywheel rotational position might sort that out. Taking weight out of the equation for now, what do you think? Will it work? Is there some great factor I have not seen? Looking forward to your reply, Cheers, Doug (Deskpilot) Mansfield.