#1226: Jetrims

I was inspired by this guy‘s tip-jet helicopter to apply the principle to terrestrial vehicles.

Today’s invention is a new form of motor in which each wheel has a number of jets fitted on the periphery of its rim. These jets are designed to maintain a horizontal, rearwards pointing orientation as the wheel turns.

Each jet is supplied with a gas at a pressure which is regulated to increase as its height above the road increases.

Since each wheel turns instantaneously about the road contact point (assuming good grip) this distribution of force provides a near-maximal torque characteristic.

This would require a tank of highly compressed gas (eg air) to be carried, but is much less ‘lossy’ than supplying the gas to a conventional car engine to drive pistons etc. Drive to each wheel could be optimised by the use of electronic control valves in each wheel.


  1. Two issues:
    1) What happens when you go around a corner? Differentials deal with this quite nicely in shaft-driven transmissions, but this idea might require some very careful control systems to stop you from drifting.
    2) It would need a very well sealed manifold to supply compressed air to the jets as the wheel rotates.

    Who knows, it might be workable though.

  2. It’s true that there would need to be multiple, high pressure, rotating seals. At least these could be based on a standard design…economies of scale etc. Failure would be pretty graceful in that sealing would mostly degrade gradually. I guess failsafes would cut in, so that if pressure went below a safety threshold, the whole system could be lowered in pressure allowing a driver to park and seek assistance.

    Actually differentials have lots of inherent problems such as complexity, weight, performance with one wheel on ice…etc so I reckon programmable gas jets would provide an extremely high level of performance flexibility and responsiveness…they might actually outperform multi-diff 4wd systems (if any wheel began to slip, the lowermost jets might be fired in retro mode, until grip could be established. Also, the other jets could be briefly fired downwards to boost grip!)

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