Recently, Larry Dighera posted:

On Tue, 07 Aug 2007 17:51:27 GMT, "Neil Gould"
wrote in
:

Recently, Larry Dighera posted:
[...]
I'm thinking there would be necessity for some means of conducting
the heat from the engine to a remote heat exchanger, and the
resulting complexity and weight increase would negatively impact
the potential advantages of a Stirling aviation engine. In any
event, in addition to the Stirling engine and its fuel, a heat
exchanger of some type needs to factored into the weight, cost,
performance, and efficiency equations.

Of course, but I don't see a lot of reason why that couldn't be
incorporated into the overall design. My point is that heat
exchangers need not be heavy, and could probably double as
structural and/or aerodynamic components, further reducing (and
possibly enhancing) their impact.

How would you get the heat from the Stirling engine to the heat sink?
If you use liquid coolant, it would be heavy and prone to leaks.

I'm not a Stirling engine designer, so I can't answer that factually. I
have been reading up on it a bit since the article was referenced in this
thread, but I haven't seen such things as the required rate of dissipation
for the engine to work efficiently. If the heat sink needs to be large and
close to the engine, perhaps a design where the engine is mounted on or
even incorporated into the wing is a way to go.

There might be one advantage to using Sterling external combustion
engines for aviation: the use of atomic energy as a fuel source if
the weight of the lead shielding were not too great. Imagine an
aircraft that effectively never runs out of fuel! There'd be no
more fuel exhaustion mishaps.

One downside would be the hazardous materials that could be
dispersed in a crash.

There are a lot of down sides to atomic power, but NASA uses it to
power Stirling engines in space.

Understandable, but their expectation is that catastrophic
destruction would disperse the nuclear material harmlessly. That
can't be presumed for light aircraft.

If the rocket detonated in the atmosphere, it might not be so
harmless.

I don't see why it would be nearly as bad as a "dirty bomb" would be, as
the material would be dispersed over a pretty large area.

I would guess the reactor is jacketed with sufficient
strength to preclude its destruction.

My guess is that NASA et al are just hoping for good fortune. Having a
reactor land from orbit intact in the middle of a city wouldn't be all
that desirable. ;-) So, my bet is on there being no good plan for
dealing with such a catastrophe *other* than wide dispersal of the nuclear
material or the luck of landing in the ocean. Not that *that* outcome is
desirable either...

Neil