I've been quite interested in hovercraft for a long time (though I've never actually travelled in one).
The idea of a radio control hovercraft has appealed at lease since I was about 10 years old. A few years after that I built a (very semi) semi-scale SR-N1. It was big (a touch over a metre long) and ran on a 3.5cc glow-plug engine. It was free-flight and having proved it could hover, not that interesting. The size of it was such that it wanted lots of space to run (it ran in big circles due to the torque from the engine, which was arranged with the crankshaft vertical). It was also not very sturdy in some areas of detail, and that was its downfall - one day a part of the duct around the propeller broke loose and got sucked into the airstream and through the propeller. The rest of the duct was then unstable, and that got fairly quickly turned inside out and sucked through the propeller too. Some of the stuff on the deck (the control cabin, and ducts taking air from lift to use as propulsion) was supported by the central duct and that too got dragged through the propeller. In a few seconds of ripping and tearing, with chopped-balsa-confetti being ejected from below the deck, it damaged itself bad enough that I didn't bother rebuilding.
I'm not actually that keen on internal combustion engines (smelly, noisy, dirty, generally a pain), so have thought off-and-on about an electric radio control hovercraft. Eventually (some 20 years after the shredded SR-N1) I've got round to actually doing something about it:
I assumed there wouldn't be many people interested in electric radio
control hovercraft - and didn't look very hard for support or advice. I knew
of some toy hovercraft, but didn't think they had the performance I wanted.
Also, designing and building is well over half the fun. Consequently, my Mark
1 was entirely of my own devising:
Before designing my Mark 1, I hadn't seen any model hovercraft, and I find it interesting how closely it resembles the layout of Mark Porter's Griffon design.
There's a separate page with details of the Mark 1 design and build process, including my reasoning behind various design decisions and some photos of the build.
There's also a page about the method I used to
calculate the shape of skirt pieces. It's easily
applicable to any skirt made up from sections of cylinders, and can be applied
to conic sections with a little more care (though you'll have to work out the
extrapolation to conics yourself).
Mark 2A drew on the experience of Mk 1, and also I'd found some stuff on the web by now and some of that (not much, to be honest) fed into the design.
There's also a page for the Mark 2A
design and build process, with more detail of the changes and a few more
build sequence photos.
Mark 2B featured something special in the propulsion department, which I'd never seen on any other hovercraft (full-size or model), but which I subsequently discovered does exist for real. It also had on-board computer fly-by-wire using a microcontroller running my own code. You can read all about the hovercraft on the Mark 2B page and the microcontroller on on its own page.
Mark 2C is the final (to date)
evolution of the mark 2 hull. It has turned
into a bit of a developmental test-bed with assorted nasty bits and pieces
bodged in or on. It does have a nice steering system, with combined
differential thrust and rudders with gyro control.
Mark 3 doesn't exist outside my imagination yet,
but one of the test conclusions from Mark 2C was
that I wanted a new hull. There are some jottings about what it will be...
I have a page about speed trials, which includes my proposals for 'rules' under which speed trials would be run, and results of running my own hovercraft within those rules. I'd like to add results for other hovercraft if anyone else does any.
Probably the best place to look for more information about model hovercraft
on the web is at
www.rc-hovercrafts.com. As well
as links and photo-galleries, there's a reasonably active forum with a number
of experienced model hovercraft builders willing to offer advice.
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