(Iain McClatchie) wrote in message . com...
(Arthur Hansen) wrote in message om...
http://www.popsci.com/popsci/aviatio...3272-1,00.html

Is pulse detonation applicable for rocket technology? Considering
"loud" isn't really that big an issue for a rocket. And considering
rockets carry their own fuel and oxidizer, it would seem that pulse
detonation technology would be something that would be easier to use
and develop instead of trying to make into an advance jet engine
first.

Arthur Hansen

P.S. Thanks, Slashdot.org for noticing this neat article!

The article is enthusiastic but not informative. Here's a basic
question: why would a pulse detonation engine be any more efficient
than a fanjet?

The basic premise is that "exploding" fuel is more energetic and
efficient than just burning it, isn't it?

I can imagine that the detonation wave compresses the unburned fuel-
air to much higher pressures before burning than the compressor in a
turbojet core would. And I know that burning at higher compression
is good because when you expand the gas back down to ambient pressure
you recover more of the heat added as work and less ends up as
residual exhaust temperature.

It seems that PD technology seems to hold higher fuel efficiencies by
more perfectly combusting fuel and oxidizer because of very highly
defined pulsed explosions. Ergo, more efficient thrusters. IIRC,
aren't they hoping for a 500% increase in fuel efficiency?

But how do you get the detonation wave to accelerate lots of unburned
air out the back of the tube? Puffs of fuel detonated between long
stretches of unburned air? [This would have the advantage of a
variable "bypass" ratio -- just change the ratio of puff to unburned
air.]

I'm not sure there is "un-burned" air at that point, but I could be
very wrong. I'm just an enthusiast, after all.

Arthur Hansen