SCRAM, Baby !.... X51A flies over 3 minutes at Mach 6+

[Ted King]

Could a scramjet missle survive the heating from "friction" that would happen at Mach 6 in the lower atmosphere?

[freeradical]

Ted King wrote:
Could a scramjet missle survive the heating from "friction" that would happen at Mach 6 in the lower atmosphere?

I don't see why not. The physics package of an ICBM is able to survive much greater velocities during the descent phase of it's travel.

[Racer X]

SDGuy wrote:
[quote=Racer X]
[quote=raz]
[quote=freeradical]
It's funny that we still have carrier battle groups.

Well, not funny in a humorous sense.

An attack with mach 6+ cruise missiles would ruin the battle group commanders day.

Possibly. However, I'd expect the Phalanx to have a pretty good shot at terminating the missile. Reaction time, target lock delay and cyclic rate of the CIWS are pretty small for a target that fast.
CIWS is a last-ditch line of defense. The Navy has other things they go to when there are incoming missiles...
hitting a "bullet" with a "bullet" is still tough, even these days.

[Will Collier]

Impressive. All kinds of weird stuff happens above Mach 5; maintaining air-breathing powered flight at those speeds is quite a feat.

[Carnos Jax]

Ted King wrote:
Could a scramjet missle survive the heating from "friction" that would happen at Mach 6 in the lower atmosphere?

I was about to respond until I read Ted's post. His answer alludes to another issue.

My guess would be the purpose of this research is not a hypersonic scramjet cruise missile. I'm pretty sure a scramjet engine is not powerful enough to overcome the huge drag an air vehicle would encounter in the lower atmosphere (particularly on the 'deck').

Even if you wanted to develop a weapons system that could streak to its target in the upper atmosphere, you'd ultimately have to descend to the thick air of sea level, which would require some kind of rocket motor to maintain hypersonic velocities, and even then you probably won't get much past Mach 4 (again, due to the tremendous drag at sea level). Even this scenario is unlikely due to the need of the rocket motor to maintain a powered descent for too many miles.

[Paul F.]

Carnos;

All plausible...
However, I think that if later vehicles (remember, this is an experimental unit, not a production model...) can reach Mach 10+, even with a burnout altitude of 100,000 feet, I suspect a hardened kinetic "kill vehicle" could reach the surface PLENTY fast enough to do damage without a warhead. Just shuck the hypersonic engined stage and dive into the target. Granted, easier said than done at high mach numbers!

In fact, I think there were plans or experiments done from ORBIT (or high sub-orbit) with kinetic impact vehicles in the 80's... but I think their accuracy was lacking at the time.

[Carnos Jax]

Yeah, I remember those orbital telephone pole size rods of tungsten often referred to as "rods from god". Never knew why they weren't pursued.

And you may be right (the U.S. military was thinking of a hypersonic missile that would launch to 300,000 feet and glide the rest of the way to target...it was supposed to hit the target at Mach 4), but the only thing I can think of is that in orbit you have a lot more energy to start with (both in kinetic energy and gravitational potential energy).

[Paul F.]

Hmm..
Well, here's a mostly unedumacated scenario;
Hypersonic air-breather stage for high mach long distance cruise, then the "penetrator" detaches with it's own solid rocket motor as a speed sustainer...

Now you have intercontinental range, high speed, high altitude cruise, and high speed 'warhead' impact... so the hypersonic stage doesn't have to operate in thicker atmosphere.

And once the hypersonic engines are more fully developed, there are LOTS of things to do with them that don't involve breaking stuff! :-)

[Will Collier]

Carnos Jax wrote:
Yeah, I remember those orbital telephone pole size rods of tungsten often referred to as "rods from god". Never knew why they weren't pursued.

They were too cheap. Seriously.

[Bill in NC]

Hypersonic missiles are just one of the many ways to cheaply kill carriers:

http://fredoneverything.net/DeadCarriers.shtml

cbelt3 wrote:
[quote=raz]
[quote=freeradical]
It's funny that we still have carrier battle groups.

Well, not funny in a humorous sense.

An attack with mach 6+ cruise missiles would ruin the battle group commanders day.

Possibly. However, I'd expect the Phalanx to have a pretty good shot at terminating the missile.
I don't if the missile has any kind of guidance flexibility. CIWS response time against a 2,000 m/sec maneuvering target means that the weapons system has perhaps 0.5 seconds to identify and take down the target. While the 'wall of lead' solution is a known high velocity target solution, and the Aegis radar system should be capable of guiding intercept solutions, the probability of success when multiple hypersonic weapons are fired at the same target increases rapidly.

The tactical goal is to saturate the defenses and then overcome them. Keep in mind that at Mach 6, the resultant impact is referred to as a 'kinetic kill', and thus the missile really becomes a control system on an airframe with no need for a warhead. So it's a cheaper kaboom, and you can fire a whole bunch of them when compared to the cost of a naval vessel. Mate them with a UCAV carrier vehicle, or even a standoff BUFF, and you have a coastline denial weapon that makes surface navies obsolete.