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Thread: new aluminium hovercraft

  1. #9
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    Default Re: new aluminium hovercraft

    sorry here is my email

    gregoryandy@hotmail.com

  2. #10
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    Default Re: new aluminium hovercraft

    It may worth looking into getting rid of the gearbox from the BM engine and using a belt reduction drive upto the fan/prop. This would enable you to keep the engine down low in the craft so helping with the centre of gravity.



    The Universal craft are very good at what they do which, IMHO, is go quickly in a straight line on flat calm water. And the WIG version works.


  3. #11
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    Default Re: new aluminium hovercraft

    Richard Evans succesfully built an aluminium hovercraft adapted from the constructors guide so it is possible



    http://www.rhevans.co.uk/



    it ended up a little heavy but was very well constructed



    good luck with it



    Tony








  4. #12
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    Default Re: new aluminium hovercraft

    That BMW R100 will deliver around 65 to 70hp maximum, rather than 90hp, although I would have thought that this should be enough power for a fair sized cruising craft. I know of the conversion you have and know the chap, David Howell, that was hawking this engine around the microlight world a few years ago, and as far as I know it works OK. Curiously, I have a completely re-built R100, fitted with a Rotax C type gearbox and centrifugal clutch drive, sat unused in my workshop.



    As has been already mentioned, that's a heavy lump of engine to have sat up in the air directly driving the fan/prop. I'd thought about using mine in my project but concluded that it was not ideal because of the weight/C of G issue.



    Using a belt drive to the fan/prop would allow the engine to be fitted lower down, but would also mean doing some re-engineering to the conversion. It should be possible to fit a pulley to the Rotax prop flange easily enough. The gearbox is most probably a 2.62:1 reduction, which will give an output rpm of around 2500 at the engine max speed.



    If opting to fit the engine lower down, then it will need some form of fan cooling, I think. When used in aircraft, these BMW R100 engines usually need a fairly nifty bit of air ducting to get enough air flowing over the heads. They are a bit fussy about air flow direction as well, they like the cooler incoming air to be directed at the exhaust port side of the heads. I fitted a reverse profile camshaft to mine so that I could change the heads from side to side and get the exhaust ports at the front, whilst also having the output shaft at the front (the opposite way around from when the engine is in the motorcycle).



    Overall these engines are very reliable, even when run at high rpm for hours on end. I checked with BMW when converting mine, who confirmed that the engine would run continuously at 7000 rpm without having any reliability issues.



    Good luck with this project, sounds interesting.



    Jeremy

  5. #13
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    Default Re: new aluminium hovercraft

    Thanks jeremy!

    every bit of info is needed i realise theres alot to do your right it is a heavy lump but as bike engines go its not that bad i can lift it so it has some good points ,whence i get into the workshop and have a proper look ill know more ! ive thought about making new components for the prop and fitting with a belt thus moving everything skyward but as you say cooling will be paramount, dont worry i have no intention of putting it up in the air its an engine not a keel after all lol.

    Im pleased you have seen this engine and gear box before the bhp was not made clear when i picked it up but you have narrowed it down for me, an email or two to scriminger should get everything in focus then ill know def what im looking at , as for aluminium you have to work with what you know! i could of course work with foam board and fibre glass resin resin resin but im a metal worker and it will be a challenge to get the superstructure

    both very light and very tough (if they can build wings fill them with aviation fuel and take to the sky im sure i can get my poxy craft to hover ha ha ha )as for making it to 53 mph to get into ground effect will have to see but thats why we do it isnt it ?long slog = failure drawing board more long slog and it might just come true you never know .

    andy

  6. #14
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    Default Re: new aluminium hovercraft

    the ali is ordered laser cutters at the ready !!!!!!! theres no going back now .


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    Default Re: new aluminium hovercraft

    well ive been in touch with scriminger !!!

    i spoke to steve scriminger about my lovelly tender engine

    and he remebers building the two units for the effects people personally he says its basically a new engine now apart from the obvious ie shell and you were right 72hp running peak 7250rpm ! had a great chat with him and very helpful he was too .so the engines going on her holidays to newark !!! and shes gunna have a lovelly time with steve and team ah blessss on her return she will have twin spark skimmed heads new coils and a happy happy just over ten hp more!!!!! bit more fiddling and im told she will be running at 6500rpm and giving me the power i need !!!! praise the lord sorry steve lord steve yep!!

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    Default Re: new aluminium hovercraft

    Quote Originally Posted by alpha3
    ...if they can build wings fill them with aviation fuel and take to the sky im sure i can get my poxy craft to hover ha ha ha...


    Quoted for posterity.



    I would strongly recommend getting a ride in a fast craft before you go too much further in order for you to experience what it is like. You need to ask yourself some questions. What would happen at 50mph if you came across floating debris? A craft cannot turn as quick as a boat to avoid it. If the debris ripped off your skirt at 50mph you will stop very very quickly and probably very very painfully!



    What experience of hovercraft have you got? Please note this is not meant to be a patronising question in any way, it is only asked to serve as a way to judge how to answer any further questions you have.



    Please do not take this a being discouraging in any way, I am only trying to point out some issues you may come across.



    Look forward to seeing your initial design.

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