[ExI] Where's the jetpack that the future promised me?

BillK pharos at gmail.com
Mon May 30 09:33:52 UTC 2011


2011/5/30 spike wrote:
> Thanks Max, cool.  Ducted fan is the wrong answer for this application
> however.  The power consumption from having such short rotors makes the
> whole idea a no-go.  If they used tandem unducted rotors, even eight feet
> long, that would work better, and would give the pilot a reasonable chance
> of survival in a power-out event.
>
> This Martin craft is an impressive feat from a controls engineering
> perspective however.
>


This Martin device has attracted some controversy.
Namely, it is too big and heavy to be a backpack device and it is not
driven by jet or rocket power.
Most people would probably call it a small ducted-fan helicopter that
you strap yourself into.

The ultralight helicopter market has some examples that are light
enough to carry around, but the rotor diameter is wider (and more
efficient, as Spike said) than the ducted fan device. The Martin
machine's ducted fans have a (somewhat) smaller footprint than rotors,
but there's a heavy price to pay in increased weight and fuel
consumption, as there always is when you shrink the thrust disc area.

Autogyros or gyroplanes seem much more fun and cost about the same as
a motorcycle.
<http://www.sportcopter.com/Gyroplanes/tabid/124/Default.aspx>

Yves Rossy's backpack jetplane flies pretty well, but the present
version cannot takeoff from the ground.
<https://secure.wikimedia.org/wikipedia/en/wiki/Yves_Rossy>


BillK




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