Hub Bars and Starter Motors

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Yeah, I remember those big dry cells - used in phone systgems. I doubt if theyre still available. I didn't realise they had a negative temp coefficent. I do have some carbon electrodes for a carbon arc torch.John EvansThink logically and do things well, think laterally and do things better.

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John,They were called a N0 6 Cell. all the bestPete Barsden

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Hi guysDont forget standard lockwire makes a nice resistor as does a strip of stainless steel albeit a bit crude. The batteries you speak of are available at "Tates Toy Kingdom"Shannon Ave Geelong Ph 52224201/03. they sell them for the toy glow motor cars. I prefere a single cell nicad myself but they still sell em, I believe thay are imported from china or somewhwere like that. You could also try the welding shop for some "gouging rods" RJ Jeffries in Duro st Geelong also sell these in small lots at resonable prices, ranging from about 6 mm to 20 mm. I have never puled a 9 volt battery appart but I have been lead to believe they have a nice little block in each cell just great for making carbon piles out of.cheers.Gyro Gearloose

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Interesting that our views on that coincide Chuck! Peter Barsden has done a lot of work on this , he has developed a very nice unit using P channel FETs. He mentions this in earlier posts.When I put my suggestions for the 'Harp' resistor soft start on Norm's old forum about 3 years ago I recieved information from someone in the US about his pulse width modulation unit, but he went silent when I asked what he did to snub back EMF spikes. Peter assures me he has looked after that.Right now I feel that car starters are overkill. My Red Monster uses a motorcycle starter driving through bicycle chains and sprockets. The motorcycle battery seems able to support this with the help of the alternator, making a system that is signifigantly lighter.John EvansThink logically and do things well, think laterally and do things better.

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Peter,Would you be so kind as to forward details of your rig to me at neast@tac.com.au?Thank you,Nick.

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cabeaty@att.net

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Thanks Pete, makes a resistor sound like a good idea[]John EvansThink logically and do things well, think laterally and do things better.

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John,No it dosn't, it just explains how simple it is, every person to his/her trade, all the bestPete Barsden

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This message was deleted and reposted to update the topic by admin Gee, sorry Pete, I didn't mean to intrude! Anyway I'm starting to wonder if we're barking up the wrong tree.Are we really looking at a combination of forces, starter motor impacts simply being one of them.Where a hub bar has the teeter block bolt holes near the edge it has a stress raiser in a bad place. I wonder if the 'two per rev' shake intrinsic to these rotors is a major contributor to failure. We know that Courtney was fortunate to lose the second blade in his crsh that lead Cierva to reluctanly fit 'lead/lag' hinges. So it sounds as though all four blades were close to departure!I understand that one of our members experimenting with a four blade rotor experienced cracking at the trailing edge of his blades, which he attributed to this force.Machines that have the rotor head mounted to a mast structure that is not free to flex would appear to be putting extra stress on the hub bar.Does anyone know of any investigation of this area?Does the doubling of the frequency,i.e. four blader, lead to a harmonic that is destructive?Is the Magni arrangement designed to let the structure that replaces the hub bar flex to alleviate this force?I guess any mug can ask the questions. John EvansThink logically and do things well, think laterally and do things better.

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Doc,Give Gerry Goodwin a ring, (029) 525-9451, all the best.Pete Barsden

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