Hypersonics Overhype

Allen Thomson wrote:

Pat Flannery wrote



I think it's far more likely to end up as a propulsion system for a
missile rather than a manned bomber- we've probably already done work on
a rocket-boosted silo-launched scramjet cruise missile under the "Teal
Dawn" program.
(whatever "Teal Dawn" was, it was supposed to come out of a Minuteman
silo, be stealthy, have a range of around 6,000 miles, and apparently
worked... it's listed as a "past success" he
http://www.dtic.mil/labman/projects/lqip/dsb/dsb3.html ....it is also
just about impossible to find information on, even though it was
scheduled for operational deployment in the late 1990's)



Could you post the source of the above, please?


In the book "Unguided Weapons"* (Fen Osler Hampson, W.W. Norton &
Company, 1989, ISBN 0-393-02628-0) p.196.
It reads:
"Since 1980, The Defense Department's Advanced Research Projects Agency
(DARPA) has been pushing ahead with "Teal Dawn" , a program to integrate
Stealth radar-evasion techniques into an advanced cruise missile (ACM)
design. The system would be launched vertically from a Minuteman silo or
equivalent and then fly on a horizontal path at supersonic speeds toward
its target where, just before hitting the target it would go into a
ballistic trajectory (37) the air force envisions acquiring about 1,500
advanced cruise missiles, although the final number would depend on
whether the new missile would be available soon enough to interfere with
the existing AGM- 86B program. The ACM would have a range in excess of
6,000 miles, enabling it to be fired from U.S. airspace. The aim is also
to develop a maneuverable system that would be able to evade Soviet air
defenses. In early 1987, Secretary of Defense Casper Weinberger
announced that a site had been chosen for the stealth missile and that
the new missile would begin arriving at the base by 1989, although
deployment would not begin until later in the 1990s (38)"
Citation (37) is to p. 210 of " The Evolution of the Cruise Missile"
(Kenneth P. Werrell, U.S. Government Printing Office, September 1985);
citation (38) is to p.1 of "Current News" (Department of Defense,
January 7, 1987 edition).
There seems to be something odd going on in regards to what is being
discussed here. The first part describes a missile of markedly different
conception than the AGM-129A Advanced Cruise Missile; which is air
launched, subsonic, and has about a third of the range:
http://www.strategic-air-command.com...CM_missile.htm
What the description in the first part sounds like is the Hypersonic
Glide Vehicle: http://www.astronautix.com/craft/hgv.htm
This technology relied on rocket propulsion to get the missile into its
glide path; but under the new HyTech and HyFly programs, scramjets are
being used:
http://www.globalsecurity.org/milita...ons/hytech.htm
http://www.globalsecurity.org/milita...ions/hyfly.htm
....and the program tested a dual mode scramjet driven by conventional
fuels in a wind tunnel test at Mach 6.5 and a simulated 90,000 foot
altitude back in 2002 (above article)....and in fact this program
appears to mirror the NASA X-43 program to such a degree that the
cancellation of the X-43C program seems a wise move so as not to
unnecessarily duplicate research both in the military and civilian spheres.
Here's a painting of a F-15 launching a small X-43 looking scramjet
missile:
http://www.space.com/images/h_hytech missile launch_02.jpg
.....and a photo of the dual mode Pratt and Whitney scramjet:
http://www.space.com/images/h_prattw...ersonic_02.jpg
The military programs use fuel to cool the scramjet and vehicle at
cruising speed, so as to avoid the need for expensive (and fragile)
materials and complex construction techniques such as those used on the
Shuttle's TPS- the test and operational missiles will apparently rely on
titanium and nickel alloy for their airframe construction.

Pat

Pat Flannery wrote:


In the book "Unguided Weapons"* (Fen Osler Hampson, W.W. Norton &
Company, 1989, ISBN 0-393-02628-0) p.196.


Whoops, forgot the *! The book concerns the history of weapons
purchases by the Pentagon during the 70's and 80's, and how politics
affected weapon buying decisions for good or ill.

Pat

"Bill Bonde ( Not the man who knows everything, just the man who knows the
important things )"
[snip]
The ABC thinks it was a success:

http://www.abc.net.au/science/slab/hyshot/default.htm
[snip]

and it was (assuming it operated in SCRAM mode) because the stated purpose
was supersonic (in the engine) ignition and combustion in the engine.
However it was flight only in the barest sense of the word.

The accomplishment of the X-43 is more than just the supersonic ignition
while in the hypersonic flow regime, it was also controlled flight and
computer model validation of the flight models.

All of this is not to minimize the Australian accomplishments, they
are/were worthwhile. Do not however minimize what occured with the X-43.

"Pat Flannery" wrote...
Whoops, forgot the *! The book concerns the history of weapons
purchases by the Pentagon during the 70's and 80's, and how politics
affected weapon buying decisions for good or ill.

Can someone please tell me how something that's broadcasting that much IR
can be called 'stealthy'?

John

John wrote:

Can someone please tell me how something that's broadcasting that much IR
can be called 'stealthy'?


Okay...so it may tend to get a bit warm at those speeds :-) .... I
assume the "stealth" is supposed to be in regards to radar rather than
IR; but it would be interesting to determine how much of the IR would
get to the ground if the emitter's at an altitude of 150,000 feet or
more, as the atmosphere may soak a lot up. The big advantage of
something moving (and maneuvering) at around Mach 5 and those altitudes
is that it's going to be very difficult to hit with a ground launched
missile unless you have a fair degree of warning of its approach, so
that the missile can reach its target's future position when the target
also arrives at it. That's easier to do with radar than IR, and the
fact that the hypersonic missile can maneuver greatly complicates the
intercept problem for the forces trying to intercept it.... you may
launch at a predicted position where you assume it's going to be, then
it turns... and suddenly your interceptor missile finds that it's
heading toward the wrong piece of sky, and that it has too much inertia
and too little fuel and time to change its course to achieve a
successful intercept. At these speeds even slight turns mean miles away
in a matter of a few seconds. If scramjet missiles become widespread,
they are going to be a major incentive to develop directed energy
weapons to deal with them- as that's one of the few things that could
slew around fast enough to target a maneuvering one...otherwise you are
going to need things like super Sprint ABM's just to get to them in time.
And it seems very likely that they are going to be in a _lot_ of
country's inventories around 20 years down the line...even India is
working on one.

Pat

"Bill Bonde ( Not the man who knows everything, just the man who knows
the important things )" wrote:

The ABC thinks it was a success:

http://www.abc.net.au/science/slab/hyshot/default.htm
#begin quote
did the test go?

Well; that's nothing but an account of the test launch, not a summary
of the science. Don't confuse the two.

D.
--
Touch-twice life. Eat. Drink. Laugh.

Pat Flannery wrote:
At these speeds even slight turns mean miles away
in a matter of a few seconds.

Keep in mind that this applies to the cruise missile as well as the
interceptor, the closer the cruise missile comes to it's target, the
less it can maneuver.

Take a notional hypersonic cruise missile taking a path from Soviet
Russia to Offut AFB. While it's still over the Canadian Shield, it
can maneuver practically freely. However, as it approaches the US
border, the 'wedge' it can be in and still strike it's target narrows
pretty rapidly, since even a minimum radius turn can throw it miles
off target. At some point the incoming missile can no longer turn,
but must remain more or less on a direct course.

What this means is that your defense problem changes from a long range
intercept well down range into something close to (but not quite) a
point defense intercept. Difficult, but not perhaps requiring
directed energy weapons.

D.
--
Touch-twice life. Eat. Drink. Laugh.

In article ,
Derek Lyons wrote:
Take a notional hypersonic cruise missile taking a path from Soviet
Russia to Offut AFB. While it's still over the Canadian Shield, it
can maneuver practically freely. However, as it approaches the US
border, the 'wedge' it can be in and still strike it's target narrows
pretty rapidly, since even a minimum radius turn can throw it miles
off target. At some point the incoming missile can no longer turn,
but must remain more or less on a direct course.

This problem can still be compensated for though, with two primary
strategies.

1. The missile can be preprogrammed to make course variations
throughout that would make it appear to be aimed at something that it
is not. Thus, it can be statically pre-programmed to make last-second
course adjustments very close to its target that will throw off the
defenders' predictions of where it's headed. The missile is still
somewhat vulnerable however since, as you point out, there will still
be a point-of-no-evasion some distance from its target.

2. The missile can be preprogrammed with a number of primary and
secondary targets and, assuming it is somehow kept updated on enemy
countermeasures being deployed against it, can keep varying its course
to evade them so long as at least one of its eligible targets is
within the 'wedge'. The missile can then evade counter-measures up to
the very last second since while it might miss its target by doing so,
it will simply allocate a new one. The problem then becomes one of
fuel consumption; how long can it keep up the game before running dry.

Cheers
Bent D
--
Bent Dalager - - http://www.pvv.org/~bcd
powered by emacs

Derek Lyons wrote:

Pat Flannery wrote:


At these speeds even slight turns mean miles away
in a matter of a few seconds.



Keep in mind that this applies to the cruise missile as well as the
interceptor, the closer the cruise missile comes to it's target, the
less it can maneuver.

The trick is to have it's target be at the end of a last violent
maneuver; and hope the enemy doesn't suspect what exactly the target is
until it's too late.


Take a notional hypersonic cruise missile taking a path from Soviet
Russia to Offut AFB. While it's still over the Canadian Shield, it
can maneuver practically freely. However, as it approaches the US
border, the 'wedge' it can be in and still strike it's target narrows
pretty rapidly, since even a minimum radius turn can throw it miles
off target. At some point the incoming missile can no longer turn,
but must remain more or less on a direct course.

What this means is that your defense problem changes from a long range
intercept well down range into something close to (but not quite) a
point defense intercept. Difficult, but not perhaps requiring
directed energy weapons.


It's still going to be a very challenging intercept, especially if the
incoming missile uses stealth; another thing that has been looked into
is have the incoming missile release submunitions as it approaches it's
target, making the task of the defenders more difficult as multiple
submunitions must then be dealt with before they arrive. If that
technique is used, then the parent missile can zig and zag all over the
place as long as it passes at some point close enough to its target or
targets in its trajectory that the maneuver capabilities of its
submunitions allow the objective to be reached. In either case you have
to disperse your ACM (Anti Cruise Missile) interceptor missiles to more
potential target sites so that they can have the time to reach any
incoming missile or sub-warhead as it approaches. And if you put rocket
engines on the submunitions, they may arrive at speeds substantially
higher than their parent missile.

Pat

Bent C Dalager wrote:

2. The missile can be preprogrammed with a number of primary and
secondary targets and, assuming it is somehow kept updated on enemy
countermeasures being deployed against it, can keep varying its course
to evade them so long as at least one of its eligible targets is
within the 'wedge'. The missile can then evade counter-measures up to
the very last second since while it might miss its target by doing so,
it will simply allocate a new one. The problem then becomes one of
fuel consumption; how long can it keep up the game before running dry.




Yeah, if can't hit the ICBM complex at Laputa, it can always head for
Barshaw instead.
(I'm getting of this image of of a hypersonic missile inbound toward a
heavily defended area running into interceptor after interceptor, and
going further and further down it's list of strategic targets to
attack...finally it sets itself on its last target option... and as he
sits in the outhouse of his dacha, the Russian Assistant Undersecretary
for Turnip Pest Control Measures gets the greatest and last surprise of
his Red Turnip Beetle hating life.)

Pat