Monday, November 27, 2006

Israeli Missile Defense

The latest Palestinian truce will be no more reliable than its predecessors, and Kassams will soon be falling again. Israel needs to stop this pest without diverting the IDF from its prep for the big war. And that needs an anti-Kassam defense - here's some analysis of its feasibility.

A recent post suggested the land derivative of the Phalanx anti-missile system should knock down most Kassams. Now StrategyPage, that most useful source of weapons information, suggests the system won't work on the Kassam. I don't agree, but could be wrong, so here are the arguments.

StrategyPage (my ellipsis): I
Israel is urgently trying to get their hands on an aid defense system that will knock down the home-made Kassam rockets Palestinians are firing from Gaza into southern Israel. So far, the biggest obstacle has been the poor construction quality of the Kassam rockets, and the resulting erratic flight path that misleads most radar systems designed to spot and predict the path of rockets and artillery shells. Professionally made projectiles are more accurate, and fly a more predictable path, which makes interception more likely.

...a U.S. adaptation of (the) Phalanx naval 20mm autocannon (which works) against conventional artillery, mortar and rocket projectiles (has) trouble with the erratic Kassams.
I'm skeptical of this because the Kassam's unpredictability must be confined to its boost phase. That's in the few seconds when the rocket engine is burning, probably unevenly, causing the weapon to jink and show varying acceleration.

But after this brief burn the weapon follows a ballistic trajectory which be predicted with basic math. The Kassam launchers pictured show an approximately 45 degree elevation, probably for maximum range. That means a flight time of tens of seconds, of which well over half is ballistic - plenty of time to spot the weapon by radar and shoot it down.

The Kassam might tumble during its ballistic phase, which would cause some drag-induced course deviation, but predictive software should be able to correct for that.

The problem of tracking missiles with irregular boost trajectories and some ballistic instability is not new. Modern ICBMs use both to reduce the effectiveness of BMD systems, by "stuttering" the engine during boost and using gas thrusters during the ballistic phase.

Israel has the world's first mid-course BMD, the Arrow system, so should have software to deal with these problems.

If not, it has to develop it ASAP, not only for Kassam defense, but to keep Iranian Shahabs from nuking its cities.