Scram uses?

So, assuming the combustion mode was as intended, exactly what use would
there be for a Scramjet?

It seems to me that as it can only function properly at high speeds, you are
still going to need a lower stage to get the engine to its optimum speed and
presumably, altitude to work properly.

As most of the fuel overhead seems to be at lift of, how does having an
engine that can use air as the oxidant at very narrowly defined altitudes
help much?

Brian

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"Brian Gaff" wrote in message
...
So, assuming the combustion mode was as intended, exactly what use would
there be for a Scramjet?

It seems to me that as it can only function properly at high speeds, you
are
still going to need a lower stage to get the engine to its optimum speed
and
presumably, altitude to work properly.

As most of the fuel overhead seems to be at lift of, how does having an
engine that can use air as the oxidant at very narrowly defined altitudes
help much?

Brian

While this engine only works at higher speeds, there is no reason, once it
is proven reliable, that a rocket couldn't be integrated with a scramjet.
This would take care of the lower speeds.


--
Alan Erskine
We can get people to the Moon in five years,
not the fifteen GWB proposes.
Give NASA a real challenge

"Brian Gaff" wrote \
As most of the fuel overhead seems to be at lift of, how does having an
engine that can use air as the oxidant at very narrowly defined altitudes
help much?

Why do you think a lot of aerospace people call it a 'scamjet'?

"Brian Gaff" wrote in
:

So, assuming the combustion mode was as intended, exactly what use
would there be for a Scramjet?

It seems to me that as it can only function properly at high speeds,
you are still going to need a lower stage to get the engine to its
optimum speed and presumably, altitude to work properly.

As most of the fuel overhead seems to be at lift of, how does having
an engine that can use air as the oxidant at very narrowly defined
altitudes help much?

Your question is identical to the question of "Why bother to develop
supersonic flight? It will certainly be less fuel efficient that subsonic."

The answer is devestatingly simple. To get from point A to point B in less
time.

Marvin writes:

"Brian Gaff" wrote in
:
So, assuming the combustion mode was as intended, exactly what use
would there be for a Scramjet?

Your question is identical to the question of "Why bother to develop
supersonic flight? It will certainly be less fuel efficient that subsonic."

The answer is devestatingly simple. To get from point A to point B in less
time.

Then why are there no longer supersonic passenger transports?

The answer isn't so simple. Supersonic aircraft is the realm of the
military. It was only recently that a privately developed aircraft
broke the sound barrier (Spaceship One). Arguably, that was a
"stunt", as the vehicle is currently experimental.

In the context of this group (you do know where you are, don't you),
the question is really more like, "What use would there be for a
scramjet on a launch vehicle?". The answer is, there isn't a good use
for one, considering it only helps you with a narrow range of
velocities while in the atmosphere.

For a launch vehicle, loitering at hypersonic velocities in the
atmosphere is counterproductive, so it's not clear that a scramjet is
useful in this application at all.

In another thread, JimO said they are sometimes referred to as
"scamjets". For launch vehicles, I'd say this is accurate. ;-)

Jeff
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Alan Erskine wrote:
While this engine only works at higher speeds, there is no reason, once it
is proven reliable, that a rocket couldn't be integrated with a scramjet.
This would take care of the lower speeds.

Could a SCRAMJET be started at mach 2.5 ?

If so, then something like the Concorde could take off from airport,
accelerate to mach 2.5 at sufficient altitude, then kick in the scram jets and
do London Sydney in 2 hours.

jeff findley wrote:


The answer isn't so simple. Supersonic aircraft is the realm of the
military. It was only recently that a privately developed aircraft
broke the sound barrier (Spaceship One). Arguably, that was a
"stunt", as the vehicle is currently experimental.


Jeff
--

Ok, Jeff. Argue why Spaceship One is a "stunt".

Just because it is a private project?

I'm all ears...


Richard

"Richard Lamb" wrote in message
...
jeff findley wrote:


The answer isn't so simple. Supersonic aircraft is the realm of the
military. It was only recently that a privately developed aircraft
broke the sound barrier (Spaceship One). Arguably, that was a
"stunt", as the vehicle is currently experimental.


Jeff
--

Ok, Jeff. Argue why Spaceship One is a "stunt".

Just because it is a private project?

Because it's really optimized for one thing: Winning the X-prize.



I'm all ears...


Richard

jeff findley wrote in
:

Marvin writes:

"Brian Gaff" wrote in
:
So, assuming the combustion mode was as intended, exactly what use
would there be for a Scramjet?

Your question is identical to the question of "Why bother to develop
supersonic flight? It will certainly be less fuel efficient that
subsonic."

The answer is devestatingly simple. To get from point A to point B in
less time.

Then why are there no longer supersonic passenger transports?
They dont make economic sense, when used in a context where airport delay
times match or exceed flight times. They dont make economic sense where
legislation prohibits supersonic flight over a quater of the flight
distance needed. And mostly they dont make economic sense when the
technology being used is 42 years out of date(built 1969, on a design from
1962). Concorde was never a practical flight system, it was a stunt flier.
A showoff to the world of just what could be done, not how it should be
done sensibly. A modern-built supersonic plane, with a much reduced sonic
footprint to allow overland use, and with the range needed to do cross-
pacific nonstop flights, might be an economic success. Development costs
are a hindrance, as are the strong anti-supersonic elements in american and
european legislation.



The answer isn't so simple. Supersonic aircraft is the realm of the
military. It was only recently that a privately developed aircraft
broke the sound barrier (Spaceship One). Arguably, that was a
"stunt", as the vehicle is currently experimental.
A *LOT* of the reason for non-development of private supersonic flight is
the fact that it is illegal, in the Usa and Europe.
You try and get a development licence for a manned supersonic vehicle, on
american soil. It is just this side of impossible. The mere technical
difficulty pales compared to the beurocratic difficulties.

In the context of this group (you do know where you are, don't you),
I do. The original poster was comparing subsonic to supersonic flight
though. Maybe you should read his post, to get your context up to date.

the question is really more like, "What use would there be for a
scramjet on a launch vehicle?". The answer is, there isn't a good use
for one, considering it only helps you with a narrow range of
velocities while in the atmosphere.
Absolutely correct. Unless scramjets can demostrate *very* good
accelerations withing their favourable regime, they will never be useful as
a stage in a multi-engine orbital launcer. With a mature and relyable
technology, they *might* be usefull in such applications as serving at the
airborne complement of a rotovator-based launch system. But both scramjets
and rotovators are utterly immature tech at this time, possibly even
dreamware.

"Greg D. Moore (Strider)" wrote:

"Richard Lamb" wrote in message
...
jeff findley wrote:


The answer isn't so simple. Supersonic aircraft is the realm of the
military. It was only recently that a privately developed aircraft
broke the sound barrier (Spaceship One). Arguably, that was a
"stunt", as the vehicle is currently experimental.


Jeff
--

Ok, Jeff. Argue why Spaceship One is a "stunt".

Just because it is a private project?

Because it's really optimized for one thing: Winning the X-prize.



So winning the X prize is just a stunt?