Monday, July 12, 2010

Prompt Global Strike

The Navy is looking into adapting surface-ship vertical launching tubes into a long-range strike weapon. The missile will be an SM-3 with a "hypersonic glider" and it will be capable of delivering a warhead of 100-200lbs.

A general rule-of-thumb is that for a bomb delivered by aerial means, roughly one-half (or less) of the bomb is high explosive. So for a 100-200lb warhead, the stuff that will go "boom" will be 50-100lbs or less, which makes it smaller than the average car bomb. I have no idea what the all-up cost is for one of these rounds, but I suspect that anybody who thinks that it will cost less than a million dollars a shot is smoking crack.

Seems to me that is a lot of money to drop a tiny bomb on something, unless that payload is a nuke or a chemical shot.

Then there is the point that VLS cells are not reloadable at sea. VLS loadout is a zero-sum game; in an SM-3 capable ship there would then be SM-3 ABM missiles, SM-2 air defense missiles, VLS ASROC and, now, long-range strike rounds. Whoever plans the loadout will need a damned good crystal ball. PGS rounds would likely be a national-command-level weapon, not a tactical one. And it will probably have to be used against fixed targets, unless there will be some method of real-time control over the hypersonic glider.

Color me "skeptical". This smacks of a weapon designed to keep the DDs and CGs relevant in a war against a land-locked low-tech insurgency. Against the Iranians, who presumably are mindful of the risk of being hit by far larger bombs, this weapon may be a popcorn fart.

(H/T1H/T2)

3 comments:

  1. This has all the tell tale signs of a defense contractors wet dream.

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  2. Perhaps battleships can be built that can fire actual cars with bombs in them so that we might, at a nominal trillion dollars per ship, compete with dirty peasants who also have some mysterious means of moving explosive cars around.

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  3. 100-200lbs payload is more than enough for a lot of time critical missions. As a point of reference the small diameter bomb (SDB) has a 50lb payload and it can take out bunkers, buildings, parked planes, runways, power plants, when the CEP of your weapon goes sub 10 meters you don’t need 1000’s of pounds of boom. With M-code GPS 5 meter CEP would be the norm and sub 3m could be achieved with terminal radar augmentation. You can bet this will carry a two way EHF sat uplink so mobile and time critical target are toast. Hitting a target at mach 5+ even with just steel as the payload would convert not a small portion of that target and steel to vapor the kinetic energy at hypersonic velocities turns solids into fluids and vapors. Its called hyperkinetic behavior.

    For “soft targets” the Navy is already testing a barrage round that deploys tungsten darts at close to mach 5. At hypersonic velocities these darts would carry more kinetic energy than a 50 caliber round but only weight 1/8th as much 700gr 50 cal = 87.5gr dart
    There are 7000 grains to an lb so 200lbs is theoretically 16000 darts a density of 1.6 per square meter would cover a 100X100 meter area in reality the dispersment would be conical in shape as the deployment system would probably be aft released in groups so a 100 meter diameter circle. Dropping the equivalent of 16000 50 caliber bullets on a foot ball field sized target would be devastating to anything living not under 6+ inches of armor plating. Fuel tanks, vehicles, radar, sam systems, would look like a meat grinder had passed over. Alternatively 2 LOCAS hunter killer drones could be carried they are under 100lbs each, these little jewels have a 45 min jet powered loiter time and a multi mode warhead with lidar and heat sensors to seek out moving high value targets.

    This should be looked at as a 2000 mile sniper rifle used to eliminate fleeting uber high value targets targets. Think enemies of the state. Example ole huey chaves is in his motorcade and we decide to take him out but have no SOF guys on the ground, we have real time satellite data that shows his motorcade moving in the countryside away from collateral damage. A single SM-7 PGS lifts off in the Atlantic 600 miles north boosts to the edge of space at Mach 7 and coasts for 10 minutes skipping in and out of the upper atmo like a stone on water, now at 500000 feet above ole huey the dart shaped glider noses over vertically having just updated its GPS and INS system it begins its terminal dive. At 10000 feet and mach 6 the millimeter wave radar kicks on and scans below for the unique signature of moving vehicles against vegetation, final adjustments are made and at 2000 feet and mach 5 the payload is deployed, first the carrier vehicle slams into the largest moving target at more than mach 4 instantly turning it to a shower of melted metal, a fraction of a second later every remaining vehicle in the motorcade explodes as thousands of mach 5 depleted uranium darts penetrate and pyrophoricly burns there way though any known armor available for wheeled vehicles. Light armored SUVs would be smoldering wreaks anyone inside incinerated in the 3000+ F plumes as the darts passing though.

    I should point out that this weapon would have good tactical nuke capability too. In the 1980’s we designed and fielded artillery shell sized nukes that didn’t weigh more than 60lbs and this was the whole shell the physics package could be as light as 20kg for a multikiloton yield and less than 5 inches in diameter. Small maneuverable mach 5 gliders would be a nightmare to shoot down this in not even putting a terminal ramjet system to keep the speed and MARV capabilities up. 44lb warhead 100lbs fuel and ramjet if I was a limited nuclear power this would make me very very uneasy accurate tactical nukes are most certainly usable in the modern era.

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