Speed Kills: The Case For Hypersonic Weapons

[popcorn]

The potential threat from hypersonic glide weapons spurring interest in THAAD ER but only as a stop-gap. Would love to see what a railgun with a fragmenting round performs.



http://m.aviationweek.com/defense/thaad ... ch-mission

However, Lockheed is restarting its Thaad-ER campaign now, in an attempt to exploit this narrow window of opportunity. Although Thaad-ER would provide some capability against a rudimentary hypersonic threat, it is not an optimal solution, the industry source says. Ideally, the Pentagon hopes to have matured other technologies —such as railguns or directed energy—to counter the threat. But those are not expected until the mid-to-late 2020s. Until then, Thaad-ER could fill a gap.

[eskodas]

Other documents with X-51.

http://www.dtic.mil/ndia/2014SET/Wilcox.pdf

http://www.dtic.mil/ndia/2012set/Leugers.pdf

https://info.aiaa.org/Regions/Western/O ... t_Test.pdf

http://aviationweek.com/awin/high-speed ... -51-flight

On reaching the launch point south of the Channel Islands and northwest of San Nicholas island, the X-51A was dropped at Mach 0.8. The Atacms ignited and propelled the entire 25-ft.-long stack—including the booster, inter-stage and X-51A cruiser—for 29 sec. until it reached 63,000 ft. and Mach 4.9. The cruiser separated and coasted to Mach 4.8 before the scramjet was started using ethylene. The scramjet then transitioned to JP-7 hydrocarbon fuel, successfully overcoming the point at which the second flight failed in June 2011, when “we unstarted the engine and we lost control of inlet dynamics,” says Brink. The X-51A flew for another 210 sec. under scramjet power, climbing to 64,000 ft. with a constant dynamic pressure (q) trajectory of 2,200-2,350 lb. per square foot. Peak acceleration was over 0.2g, notes Brink.

[archeman]

Other documents with X-51.

http://www.dtic.mil/ndia/2014SET/Wilcox.pdf

http://www.dtic.mil/ndia/2012set/Leugers.pdf

https://info.aiaa.org/Regions/Western/O ... t_Test.pdf

http://aviationweek.com/awin/high-speed ... -51-flight

On reaching the launch point south of the Channel Islands and northwest of San Nicholas island, the X-51A was dropped at Mach 0.8. The Atacms ignited and propelled the entire 25-ft.-long stack—including the booster, inter-stage and X-51A cruiser—for 29 sec. until it reached 63,000 ft. and Mach 4.9. The cruiser separated and coasted to Mach 4.8 before the scramjet was started using ethylene. The scramjet then transitioned to JP-7 hydrocarbon fuel, successfully overcoming the point at which the second flight failed in June 2011, when “we unstarted the engine and we lost control of inlet dynamics,” says Brink. The X-51A flew for another 210 sec. under scramjet power, climbing to 64,000 ft. with a constant dynamic pressure (q) trajectory of 2,200-2,350 lb. per square foot. Peak acceleration was over 0.2g, notes Brink.

So how much better is this 210 seconds of dual fuel Hypersonic Ramjet than just extending the burn of the rocket booster a little longer, or 2nd stage smaller rocket? I assume despite different propulsion systems, either could perform the 'glide/coast phase' equally well.

Is there a table or graph that shows the fantastic advantage that an F-35 weapon with Hypersonic Ramjet has over a very similar weapon powered by conventional Rockets?
There certainly seems to be a fantastic development and engineering cost difference.

[eskodas]

You won't get 210 seconds of burn of the same intensity in a normal rocket, normal rockets need an oxidising agent, due to the hypersonic speed of this rocket it's taking in a sh*t ton of air each second and uses that instead as oxygen which gives much more room for fuel which means more range. The fuel this scramjet uses is simple old JP-7.

http://upload.wikimedia.org/wikipedia/c ... 090105.png

[sprstdlyscottsmn]

So a solid rocket boost phase and a JP-7 powered steady Mach 4 cruise for 200 miles?

[eskodas]

Boosted to Mach 4.8 then scramjet to Mach 5.1 for 210 seconds or 195 miles, they plan to extend that range to ~600nm

For reference, this is about .93 miles a second, an M-16 bullet when leaving the barrel is 0.58 miles per second.

[archeman]

Boosted to Mach 4.8 then scramjet to Mach 5.1 for 210 seconds or 195 miles, they plan to extend that range to ~600nm

For reference, this is about .93 miles a second, an M-16 bullet when leaving the barrel is 0.58 miles per second.

But what has been tested in the samples above used a rather large ex-Army ground rocket booster to reach that Mach 4.8, not something that would fit on an F-35.
So that means the missile for our aircraft would have to push a much smaller package up to that Mach number where the magic can begin.

Thanks eskodas, for that chart, but what would make the comparison really meaningful and explain the real value of this Hypersonic Ramjet is if there was a chart showing:
* absolute range comparison
* approximate cost comparison (including this protracted research & development period) for:
** fixed Payload weight
** fixed Total Weapon weight

pure rocket vs rocket/scramjet.

[bring_it_on]

The HSSW is the missile project for the USAF. I am not sure whether that would be an F-35 weapons system solution (size) but that has been hinted in the past. They are spending 600 Million $ on this project split between the AFRL and DARPA. If they really decide to push the range which seems the logical thing to do given the Pacific (Tyranny of distance as the USAF charecterizes the theater) it could become a system for the bomber fleet.

[eskodas]

This isn't the working model that will be on the F-35, this is a maturity/prototype.

Guided by results from the X-51A, Brink says researchers have a hit list of potential enhancements and improvements that will be used to develop the concept into a tactically relevant hypersonic weapon. The baseline speed and approximate size of the X-51A will continue to form the model for the HSSW, which will be compatible with the B-2A internal weapon bay and F-35 Joint Strike Fighter.

[popcorn]

The HSSW is the missile project for the USAF. I am not sure whether that would be an F-35 weapons system solution (size) but that has been hinted in the past. They are spending 600 Million $ on this project split between the AFRL and DARPA. If they really decide to push the range which seems the logical thing to do given the Pacific (Tyranny of distance as the USAF charecterizes the theater) it could become a system for the bomber fleet.

IIRC, from scanty initial reports, HSSW is intended for external carriage on F-35 and internal carriage on LRSB.

[sferrin]

So a solid rocket boost phase and a JP-7 powered steady Mach 4 cruise for 200 miles?

And call it "ASALM". (Except it's more like Mach 5+ and 300 miles.) Yeah, let that sink in. A 35 year old missile, about the size of SRAM, outperformed the X-51 that required a friggin' ATACMs booster and a B-52 to lug it into the air.

[popcorn]

Back to railguns, progress is being reported in efforts to develop smart projectiles
http://www.seapowermagazine.org/stories ... ilgun.html

Railgun Projectiles Achieve Success in Series of Critical Open-Range Testing

SAN DIEGO — General Atomics Electromagnetic Systems (GA-EMS) projectiles with prototype components for a Control and Actuation System (CAS) successfully performed programmed actions and communicated component performance to a ground station via a telemetry link in tests carried out Dec. 7-10 at the U.S. Army’s Dugway Proving Ground in Utah, the company announced in a Jan. 8 release.

[zerion]

^ Invalid address.

Try this
http://www.seapowermagazine.org/stories ... ilgun.html

[popcorn]

Corrected... thanks.

[element1loop]

So a solid rocket boost phase and a JP-7 powered steady Mach 4 cruise for 200 miles?

And call it "ASALM". (Except it's more like Mach 5+ and 300 miles.) Yeah, let that sink in. A 35 year old missile, about the size of SRAM, outperformed the X-51 that required a friggin' ATACMs booster and a B-52 to lug it into the air.

Which strongly suggests there's more to this story than provided specs capture.

Have you considered the Mach=5.1 is the average flight speed, not a peak speed?

Let's say its the average, at a minimum you get (while the engine is still burning):

3.5 mins @ Mach 5.1 average for range under flat 'trajectory' power of 170.6 nm, or 316 km at cutout.

And if you loft an X-51 to 300k ft, minutes before cutout at its 'apex', then going ballistic, or rather, gliding ... in next to no atmosphere?

An ASALM's 300 miles would make it look like a slacker for range compared to an X-51 doing that, I reckon.