Clarification on X-43A flight profile sought

I've been seeing some contradictory and/or misleading
information in various reports about the X-43A flight
and just what was achieved. Specifically, what speed
the vehicle was released from the rocket and how much
acceleration the vehicle achieved on its own. There
are some sources, including quotes from NASA and others
involved with the project, that say the separation
occured at Mach 7, with the scramjet power merely
maintaining that speed or very slightly increasing it.
There are other reports, some from the same sources,
that seem to say the separation occured at Mach 5 and
the scramjet boosted the X-43A up to Mach 7.

I haven't had much luck digging up facts on the X-43A
itself that would help resolve this quandry.
Specifically I can't find any mention of the amount of
thrust the scramjet is supposed to generate, which
would help determine the potential acceleration
capabilities of the vehicle during its 10 second flight.


If anyone has access to reliable sources I'd really
like to know what the X-43A actually did.

On 28 Mar 2004 17:31:53 -0800, (Christopher M.
Jones) wrote:

I've been seeing some contradictory and/or misleading
information in various reports about the X-43A flight
and just what was achieved. Specifically, what speed
the vehicle was released from the rocket and how much
acceleration the vehicle achieved on its own. There
are some sources, including quotes from NASA and others
involved with the project, that say the separation
occured at Mach 7, with the scramjet power merely
maintaining that speed or very slightly increasing it.
There are other reports, some from the same sources,
that seem to say the separation occured at Mach 5 and
the scramjet boosted the X-43A up to Mach 7.

No. Pegasus got it to Mach 7. The scramjet should have sped it up
somewhat, kept it from slowing, or at least kept it from slowing too
fast. The scramjet is fairly small.

I haven't had much luck digging up facts on the X-43A
itself that would help resolve this quandry.
Specifically I can't find any mention of the amount of
thrust the scramjet is supposed to generate, which
would help determine the potential acceleration
capabilities of the vehicle during its 10 second flight.

That's probably ITAR and you won't.

If anyone has access to reliable sources I'd really
like to know what the X-43A actually did.

Didn't they say on www.dfrc.nasa.gov ? I know I read some of this
somewhere and I haven't been looking very many places. If not AvWeek,
it must have been Dryden's web page.

Mary

--
Mary Shafer Retired aerospace research engineer

While you are all on the topic I wonder if someone can explain what is so difficult about building a scramjet.
With all the supercomputers and physicists around it should be rather straightforward.

Does the thing have significant moving parts? My understanding is that the speed of the ship and the inlet
geometry does the compression...

Is the complexity of the task so great that the private sector is not doing research on its own?

Some engine info

http://hapb-www.larc.nasa.gov/Public...-2000-3605.pdf

Publications list
http://hapb-www.larc.nasa.gov/Public...edpublications

"postit" wrote in message
...
While you are all on the topic I wonder if someone can explain what is so
difficult about building a scramjet.
With all the supercomputers and physicists around it should be rather
straightforward.

Well, it ain't.


Does the thing have significant moving parts? My understanding is that
the speed of the ship and the inlet
geometry does the compression...

No moving part and you're right about the geometry.


Is the complexity of the task so great that the private sector is not
doing research on its own?


The private sector isn't interested which should be obvious in light of the
fact that Concorde (which flies much slower) has been cancelled.

My prediction: supersonic flight for the masses won't occur until we've
solved the energy problem (i.e. it's too expensive currently to fly a
supersonic airplane, technology isn't the problem).

"Uddo Graaf" wrote in message
...

My prediction: supersonic flight for the masses won't occur until we've
solved the energy problem (i.e. it's too expensive currently to fly a
supersonic airplane, technology isn't the problem).

I suspect the boom problem is a bigger issue. It severely limits the areas
in which such a jet can fly. At least in the US.

"Dale" wrote in message
...
On Mon, 29 Mar 2004 12:45:52 GMT, "Greg D. Moore \(Strider\)"
wrote:

"Uddo Graaf" wrote in message
. ..

My prediction: supersonic flight for the masses won't occur until we've
solved the energy problem (i.e. it's too expensive currently to fly a
supersonic airplane, technology isn't the problem).

I suspect the boom problem is a bigger issue. It severely limits the
areas
in which such a jet can fly. At least in the US.

I think the trans-Pacific market alone could support such a plane, with
minimal "boom problems"- but as Uddo suggests, it's too expensive at
present to attract much interest.

"maybe"

Remember, a lot of folks who want to go to Pacifica are from the East Coast.
Which makes overland flight an issue again.



Although it would be cool to fly to Narita on a JAL flight that starts out
under the wing of a B-52

:-)



Dale

On Mon, 29 Mar 2004 12:45:52 GMT, "Greg D. Moore \(Strider\)"
wrote:

"Uddo Graaf" wrote in message
. ..

My prediction: supersonic flight for the masses won't occur until we've
solved the energy problem (i.e. it's too expensive currently to fly a
supersonic airplane, technology isn't the problem).

I suspect the boom problem is a bigger issue. It severely limits the areas
in which such a jet can fly. At least in the US.

I think the trans-Pacific market alone could support such a plane, with
minimal "boom problems"- but as Uddo suggests, it's too expensive at
present to attract much interest.

Although it would be cool to fly to Narita on a JAL flight that starts out
under the wing of a B-52

Dale

On Mon, 29 Mar 2004 13:18:26 GMT, "Greg D. Moore \(Strider\)"
wrote:

I think the trans-Pacific market alone could support such a plane, with
minimal "boom problems"- but as Uddo suggests, it's too expensive at
present to attract much interest.

"maybe"

Remember, a lot of folks who want to go to Pacifica are from the East Coast.
Which makes overland flight an issue again.

Well, they could always cross the continent by train... ;-)

I live near Seattle, and it's about a 10 hour flight to Japan. Much longer to
Australia. If there were economical supersonic flights, I'm sure the time
saved would be appreciated even by those who have to make a subsonic
leg to the west coast first. But to fly "the masses", I think Uddo is right-
the cost is the biggest obstacle.

Dale

Maybe we just need to learn to love the boom

In article , postit wrote:
While you are all on the topic I wonder if someone can explain what is
so difficult about building a scramjet. With all the supercomputers
and physicists around it should be rather straightforward.

It's not. Supercomputers don't help much if you don't know what to
program them to do; feed them the wrong inputs and they will happily
generate plausible-looking nonsense outputs. The guys who simulate
aerodynamics on supercomputers spend far more time on "validation" --
trying to decide whether the programs' output has any relation to
reality -- than they do on the actual programming.

Does the thing have significant moving parts? My understanding is that
the speed of the ship and the inlet geometry does the compression...

Depends on how wide a range of speeds you want it to work over. At any
given speed, no moving parts are needed. But the exact shape required
changes as the speed changes, so a wide speed range requires variable
geometry.

Is the complexity of the task so great that the private sector is not
doing research on its own?

The complexity is high and there is no obvious market, so there is little
private interest in the topic.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |