speed record set by scramjet - fair?

"gatt" wrote in message ...
"Don French" wrote in message

Regardless, it seems to me that the rocket's speed has to be
subtracted from the jet's speed to arrive at the actual jet speed when
you talk about the world's record for speed of a jet plane.

Hmm. Would you say the same for Yeager and the X-1, it having been dropped
from the belly of another aircraft, or is your particular question related
just to the rocket?

In the same vein, many early airplanes needed a catapult to get up to
flying speed, including the Wrights' planes away from Kitty Hawk's
winds. Doesn't make them any less amazing.

Wikipedia makes an interesting point as well... that high-speed jets
taking off from an aircraft carrier need a catapult launcher to get
them up to flying speed. (Obviously the jets can also take off with a
long enough runway, but the similarity is that an assist to get to
speed shouldn't negate the accomplishment, in many people's opinions.)

Best, Kev

Kevin Darling wrote:

Wikipedia makes an interesting point as well... that high-speed jets
taking off from an aircraft carrier need a catapult launcher to get
them up to flying speed. (Obviously the jets can also take off with a
long enough runway, but the similarity is that an assist to get to
speed shouldn't negate the accomplishment, in many people's opinions.)

The assistance doesn't *negate* the accomplishment.

However, if the assistance is *necessary* then the accomplishment
is of something slightly different.

Recently, Robert Briggs posted:

Kevin Darling wrote:

Wikipedia makes an interesting point as well... that high-speed jets
taking off from an aircraft carrier need a catapult launcher to get
them up to flying speed. (Obviously the jets can also take off with
a long enough runway, but the similarity is that an assist to get to
speed shouldn't negate the accomplishment, in many people's
opinions.)

The assistance doesn't *negate* the accomplishment.

However, if the assistance is *necessary* then the accomplishment
is of something slightly different.

Perhaps the question at hand is the nature of the accomplishment; as I see
it, the accomplishment is getting a scramjet to work in the real world.
That is pretty amazing, IMO. Another accomplishment is that the _jet_ was
operating at Mach 10; equally amazing, as no other jet can do so, AFAIK.
The launch method would seem to be pretty much irrelevant to those
accomplishments.

Regards,

Neil

The press report I read said that the scramjet wouldn't even start below
Mach 4.0.

Bob Gardner

"Don French" wrote in message
om...
How fast was the rocket going when it released the record-setting
scramjet? If the rocket was going Mach 9 in the thin atmosphere at
100,000 feet and released a stone, for example, the stone would travel
several seconds at close to Mach 9. I assume that the rocket was not
going Mach 9, but I haven't seen any information on how fast it was
going.

Regardless, it seems to me that the rocket's speed has to be
subtracted from the jet's speed to arrive at the actual jet speed when
you talk about the world's record for speed of a jet plane.

-- Don French

Don French wrote:

How fast was the rocket going when it released the record-setting
scramjet? If the rocket was going Mach 9 in the thin atmosphere at
100,000 feet and released a stone, for example, the stone would travel
several seconds at close to Mach 9. I assume that the rocket was not
going Mach 9, but I haven't seen any information on how fast it was
going.

Regardless, it seems to me that the rocket's speed has to be
subtracted from the jet's speed to arrive at the actual jet speed when
you talk about the world's record for speed of a jet plane.

-- Don French
Quoted from some web site.

"The telemetry showed the X-43A was set free by the booster at a speed
well in excess of Mach 9 but was able to maintain its cruising velocity
under the thrust from its scramjet.

Engineers followed the X-43A as it travelled more than 1,000km (620
miles), eventually losing speed and plunging into the Pacific. "

Now if the rock went 620 miles after release

On Wed, 17 Nov 2004 18:22:14 -0500, Aardvark
wrote:

Don French wrote:

How fast was the rocket going when it released the record-setting
scramjet? If the rocket was going Mach 9 in the thin atmosphere at
100,000 feet and released a stone, for example, the stone would travel
several seconds at close to Mach 9. I assume that the rocket was not
going Mach 9, but I haven't seen any information on how fast it was
going.

Regardless, it seems to me that the rocket's speed has to be
subtracted from the jet's speed to arrive at the actual jet speed when
you talk about the world's record for speed of a jet plane.

-- Don French
Quoted from some web site.

"The telemetry showed the X-43A was set free by the booster at a speed
well in excess of Mach 9 but was able to maintain its cruising velocity
under the thrust from its scramjet.

Engineers followed the X-43A as it travelled more than 1,000km (620
miles), eventually losing speed and plunging into the Pacific. "

Now if the rock went 620 miles after release

That's interesting. I wonder how far it would have glided without
lighting the scramjet. At mach 9, the miles go by pretty quickly...

With so little air friction at 100,000 feet, a stone would go quite
far. Give it an aerodynamic shape and it would go even further. I
would only be guessing, but maybe it would go a few hundred miles.

The point is that almost any craft with a propulsion system capable of
moving it at 700 miles per hour would make it to Mach 10 when dropped
from a rocket going Mach 9, provided it was structurally sound enough.
It just sounds to me like an accomplishment that was not in
proportion to the media it got. But I am not an aeronautical engineer
by any stretch of the imagination. So, maybe it really was an
incredible accomplishment and I just don't understand why.

Aardvark wrote in message ...
Don French wrote:

How fast was the rocket going when it released the record-setting
scramjet? If the rocket was going Mach 9 in the thin atmosphere at
100,000 feet and released a stone, for example, the stone would travel
several seconds at close to Mach 9. I assume that the rocket was not
going Mach 9, but I haven't seen any information on how fast it was
going.

Regardless, it seems to me that the rocket's speed has to be
subtracted from the jet's speed to arrive at the actual jet speed when
you talk about the world's record for speed of a jet plane.

-- Don French
Quoted from some web site.

"The telemetry showed the X-43A was set free by the booster at a speed
well in excess of Mach 9 but was able to maintain its cruising velocity
under the thrust from its scramjet.

Engineers followed the X-43A as it travelled more than 1,000km (620
miles), eventually losing speed and plunging into the Pacific. "

Now if the rock went 620 miles after release

"Don French" wrote in message
om...
With so little air friction at 100,000 feet, a stone would go quite
far. Give it an aerodynamic shape and it would go even further. I
would only be guessing, but maybe it would go a few hundred miles.

The point is that almost any craft with a propulsion system capable of
moving it at 700 miles per hour would make it to Mach 10 when dropped
from a rocket going Mach 9, provided it was structurally sound enough.

This thread is hilarious. A bunch of armchair propulsion engineers
pooh-poohing a significant accomplishment in engine technology, none of whom
actually could design a scramjet if their lives depended on it.

Anyway, I certainly think NASA is well within their rights to tout the
success of actually operating a scramjet in flight. It's as revolutionary
as successful operation of the first turbine engine was. What makes the
speed interesting is that no other engine is capable of operating at that
speed. Even if the test vehicle didn't wind up ANY faster than it was when
the engine was started, as long as the engine continued to operate as
designed, it would have been a successful test.

Pete

I never said it wasn't a successful test, but the only thing touted in
the media was the speed it achieved and the world record it set for
speed, and attributed that speed to the scramjet, not the rocket.
That was just wrong. The speed was almost entirely a result of the
rocket's velocity and had nothing to do with the scramjet. Seriously,
they could have dropped a Piper cub off that rocket and it could have
maintained Mach 9 for hundreds of miles. Should it get the world's
speed record for prop-driven planes? I think not. And I think that
giving the X-43A a worlds speed record is just as fraudulent.

With so little air friction at 100,000 feet, a stone would go quite
far. Give it an aerodynamic shape and it would go even further. I
would only be guessing, but maybe it would go a few hundred miles.

The point is that almost any craft with a propulsion system capable of
moving it at 700 miles per hour would make it to Mach 10 when dropped
from a rocket going Mach 9, provided it was structurally sound enough.

This thread is hilarious. A bunch of armchair propulsion engineers
pooh-poohing a significant accomplishment in engine technology, none of whom
actually could design a scramjet if their lives depended on it.

Anyway, I certainly think NASA is well within their rights to tout the
success of actually operating a scramjet in flight. It's as revolutionary
as successful operation of the first turbine engine was. What makes the
speed interesting is that no other engine is capable of operating at that
speed. Even if the test vehicle didn't wind up ANY faster than it was when
the engine was started, as long as the engine continued to operate as
designed, it would have been a successful test.

Pete

"Don French" wrote in message
om...
I never said it wasn't a successful test, but the only thing touted in
the media was the speed it achieved and the world record it set for
speed

Who cares what the media says? If you know anything about aviation, you
know as well as the rest of us that the media does a pretty poor job of
getting facts straight, especially for technical issues like this one.

and attributed that speed to the scramjet, not the rocket.
That was just wrong. The speed was almost entirely a result of the
rocket's velocity and had nothing to do with the scramjet.

Todd already pointed out the fallacy of that statement. The fact that the
scramjet *accelerated* to the maximum speed clearly shows that the scramjet
is, in fact, the *entire* source of the speed. It produced enough thrust to
maintain Mach 10.

Your statement is like saying that if you towed a Y*go behind a Porsche and
got it up to 150 mph, that you'd be able to then simply disconnect from the
Porsche and still maintain 150 mph in the Y*go. That's simply not true. A
vehicle that can accelerate to Mach 10 from *any* speed and maintain that
speed is capable, all by itself, of that speed. It's just plain incorrect
to claim that "only the last Mach was due to the scramjet" (or however you'd
like to word it).

Seriously,
they could have dropped a Piper cub off that rocket and it could have
maintained Mach 9 for hundreds of miles.

Hundreds? I doubt it. But more importantly, it would NOT have accelerated
to Mach 10.

Should it get the world's
speed record for prop-driven planes?

In your example, the Piper Cub at no point *maintained* a record-breaking
speed.

I think not. And I think that
giving the X-43A a worlds speed record is just as fraudulent.

Well, I'm sorry your incomplete grasp of the facts makes you think that.
Fortunately, those who have a say in the matter have a better understanding
of the situation.

Pete