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Subject: Rocket sled ride
The proposal is to build a rocket sled ride on a desert site in Western Australia. The ride will be
aimed at wealthy tourists, and will allow them to experience supersonic speeds. We envisage
carrying two passengers at a time, seated behind the pilot. The idea is inspired by the Sonic Wind
experiments, which I’m sure you’re familiar with. However, it goes without saying that safety
will be the number one priority, which means that extremes of acceleration and deceleration
must be avoided. For instance, a water brake, like the one used in the Sonic Wind tests, is clearly
out of the question.
The site is large enough to accommodate a track up to 16 km long, though I reckon 10 km would
be adequate. According to my rough calculations, that would be sufficient to allow progressive
acceleration up to and through the sound barrier to about 350 m/s, and progressive deceleration
to a standstill without exceeding 2 G (20 m/s2), while still leaving three to four kilometres of
track as a safety margin. However, I'm not an engineer, so would appreciate your professional
opinion on that.
In terms of basic technology, I assume the most suitable vehicle would be a rail-mounted sled,
with steel skids that grip the track, above and below the rails, to prevent derailing, and avoid
problems with aerodynamic lift. I assume wheels wouldn’t be feasible given the speeds involved,
though I’m not 100% sure about that. Perhaps you can advise. Propulsion would be provided by
a rocket or aircraft jet.
I already have a consultant sourcing a suitable engine, however, so that angle is being looked
into.
As far as your input is concerned, the main area where I need your expertise is on the braking
system. As I said, violent braking is out of the question. As I see it, suitably gentle options
include systems that apply friction to the rails, aerodynamic flaps, parachutes, or reversed engine
thrust. But, again, I’m not an engineer, so I look forward to discussing your thoughts on these
issues.

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