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I had hoped the carbon pile would have been a practical soft start resistor, but it looks like it isn't a runner. Peter Barsden [Assistant Technical Manager in Western Australia] can supply a proven electronic device using Pulse Width Modulation, it has damping for the large back EMF spikes developed by the rapid switching involved.If cheap, light, simple and effective is your thing go to Dick Smith and buy 2 packs of Nichrome wire, twist the two strands together with an electric drill and wind them like strings on a harp on two pieces of brass threaded rod about 4 inches apart, one spring loaded, this gives you about 80 strands in parallel. It works well.There does not seem to be any need for being able to vary the resistance.John EvansThink logically and do things well, think laterally and do things better.
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quote:Originally posted by telfNot really feasible.One of the biggest issues with gyros is weight.The tank would be a big weight penalty, you would need to keep it charged up.All in all, there are much lighter ways.That said, its good to see a new idea being thrown around.We are all open to suggestions.Thanks Telf. I realised, when I thought about it further, that to get the required fifteen seconds or so run time, you'd only need a tank a metre long and twelve (?!!) metres in diameter at ten atmospheres pressure. Not too practical in that way, but what would happen if you ran the air motor on hydrogen peroxide? The motor would have to withstand temperatures of 650 degrees, but if it could, Hyd.Peroxide would make a nice compact fuel. ie About two to three litres of the stuff per start. Of course you could also buy Bengt Whatsisname's tip jet system, too. The greenies would love it, too, with all that waste oxygen floating about, not to mention water vapour for this parched old continent.Flying - The knack lies in learning how to throw yourself at the ground and miss. (Douglas Adams-The Hitch-Hiker's Guide to the Galaxy)R.J.W.S.
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Verry interesting discussuin here ! I love brain storming ideas ! tiz the best way I know of to come up with a great soulition !... My gyro has a mechanical drive to the pre-rotator , it drives off a v-belt pully behind the prop turning another pully to turn the 90 degree gear box ... from there a drive shaft of simple design ( 2 swivle/universal joints fron the tool box to a slip joint of 2 square toobs one inside the other ) this turns the one way clutch v-belt pully that turns the 12" v belt pully on the rotor head . why not use the v belt arrangement as your SOFT start arrangement instead of gears ? the v belts do slip to a certain extent and that would take the shock out of the starter motor kicking in ..... though the starter would no doubt try to burn the belt off belts are cheep to replace. I dunno if you would need a lever to tighten the v belt or not in this senerio...perhaps a tension spring would be all thats needed ? the results would be , simply hit the starter button the blades would start to spin up ... without alot of shock... once spun up release the button and the one way clutch on the pully kicks in and the starter stops ,alowing the belt to continue turning .... granted there is resistance to the rotor turning by useing a v-belt this way , but it works on the bumble bee so why not modify it to use elsewhere ? so whats wrong with this idea ?Bob......" Momm'a alwayse told me , Son the impossable is only a little bit Harder... and ya know I do believe She was RIGHT ! "
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