Re: Be careful what you ask for

Martha Adams <mhada@[EMAIL PROTECTED]
> wrote:
> It's an interesting topic but as I scout down the thread my spidey,
> oops, reality sense keeps saying, oops, oops, oops: a little
> something missing here.  What is missing is *numbers* to establish
> scale and magnitude.  *I very much doubt* what I see here, as it
> stands today.  These are things used in childrens toys.  For adults
> application, you cannot keep pumping the thing up: *thermodynamics*
> is at the bottom of it here.

I don't know of any children's toys that use liquid nitrogen.  I do
know of some that use gasoline.

Gasoline engines result in peak temperatures of about 1500 K.
Ambient temperature is about 300 K.  Liquid nitrogen is 77 K.  The
temeperature difference from ambient is about five times greater for a
gasoline engine.  So as a very rough estimate, I'd expect mileage from
liquid nitrogen to be about one fifth the mileage from gasoline.  I
think such a vehicle is practical.
-- 
Keith F. Lynch - http://keithlynch.net/
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