X-43 - Has anyone else done it?

Henry J Cobb wrote in message ...
Eunometic wrote:
X43 is trying to do a few other things. It is trying to integrate the
forbody of the vehicle as part of the scramjet intake i.e
precompression and the afterbody of the vehicle as the engine nozzle
while also making the body a lifting body. It's all tall order to
integrate all three but they have to be integrated because scramjets
just don't work well enough on their own. The wedge shapped nose has
to be agressively cooled by hydrogen.

The problem with hydrogen is that it isn't very dense so you can't carry
much fuel and the problem with hydrocarbons is that the air flows
through the scramjet engine too quickly for these fuels to burn.

The X-43C will use hydrocarbon fuel for cooling and the heat breaks the
fuel down so it can burn quickly enough to provide thrust in the engine.

-HJC

Thanks, presumably that was the X-43A we just saw. What I don't
understand is how they will prevent coking and pyrolising of the fuel.
I can understand hydrocarbones breaking down into hydrogen but carbon
vapour?

The concept is a little reminiscent of an inductor ramjet the Germans
tested in the 1930s/40s which instead of using a central rocket engine
to induce the airflow in the main body of the ramjet used a heat
exchanger wrapped around the body of the ramjet to produce a high
pressure vapour. The high pressure vapour was injected to provide
stationary thrust and induce and airfow:- it was hot enought to self
ignite. ( a fired vaporiser was used to start the process up)

The X-43C seems similar however it recovers the heat not of combustion
but of hypersonic heating the forebody of the vehicle

Henry J Cobb wrote in message
...
Eunometic wrote:
X43 is trying to do a few other things. It is trying to integrate the
forbody of the vehicle as part of the scramjet intake i.e
precompression and the afterbody of the vehicle as the engine nozzle
while also making the body a lifting body. It's all tall order to
integrate all three but they have to be integrated because scramjets
just don't work well enough on their own. The wedge shapped nose has
to be agressively cooled by hydrogen.

The problem with hydrogen is that it isn't very dense so you can't carry
much fuel and the problem with hydrocarbons is that the air flows
through the scramjet engine too quickly for these fuels to burn.

The X-43C will use hydrocarbon fuel for cooling and the heat breaks the
fuel down so it can burn quickly enough to provide thrust in the engine.

Unfortunately, the X-43C was recently cancelled.

Steve Hix wrote:
Henry J Cobb wrote in message
The X-43C will use hydrocarbon fuel for cooling and the heat breaks the
fuel down so it can burn quickly enough to provide thrust in the engine.

Unfortunately, the X-43C was recently cancelled.

Ouch, just last month.

http://www.aviationnow.com/avnow/new...s/eng03194.xml

-HJC