This page describes design evolution from the Mark 2B design, which itself evolved from the Mark 2A.
As for from 2A to 2B, the changes to the design from 2B to 2C are fairly minor - it's built on the same hull.
2C has itself been through a few variants, but I'm not going to describe
them individually. Effectively, it's been using the mark 2 hull as a test-bed platform.
I played with some control systems. The final scheme uses a combination of differential thrust from the two fans, plus gyro-stabilised rudders.
The arrangement is a little tricky, and relies on a custom mix on the transmitter. Steering at the transmitter sends full steering signal on one channel, and 30% of the signal on another channel (I have a 6-channel transmitter which can do this sort of thing). At the hovercraft the 'full signal' channel is fed through a V-tail mixer, combined with the speed channel, and hence to the fans. The 30% channel is fed through a gyro and to the rudders.
When running, most of the steering is done by the differential thrust, but at the start and end of turns, the rudders tend to give an extra kick to start a turn, and a reverse kick at the end.
It actually makes for a nicely controllable craft, though possibly more by
luck than judgement.
I built a very nasty centrifugal lift fan, and bodged it into the craft
(sticky tape, black cardboard, bicarb&cyano, very nasty). Surprisingly, it
gives better performance (in terms of current to achieve a hover) than my
fancy four-blade electric prop. This is the main reason for building
Mark 3...
Mark 2C is also the first of my hovercraft where I've set about measuring the
speed (about 20kph). There's a separate page
about that.
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