Hi Hawkmoon; Re threat posed to aircraft. Actually, I wouldn't design a heat seeker for use against commercial jets. They're huge targets in visible. I'd look for a dark pattern against a bright sky and aim for the center of mass. The objective would be to get the rocket to penetrate the central fuel cell. If there was much residual propellant a warhead would be completely unnecessary, since a 50 pound rocket at 700 feet per second would punch through thin aluminum quite easily. The damage would be similar to what happened to TWA flight 800. The alternative, flying into an engine, is more difficult, and less catastrophic for the aircraft. Fuel cells are probably the most lucrative large targets on aircraft for direct rocket hits. If they're full you can get shock loading that splits them wide open, causing massive fuel spills. The fuel may get sucked into engines, destroying them, or it may cause other secondary effects. If they're mostly empty you get the TWA flight 800 secondary explosion effect, which is just as bad, or worse.
Re: "But my main point was that the larger the rocket is, the more complex and robust must be the guidance and directional system, with the result of added weight."
The control electronics doesn't change. In fact, larger rockets simplify the design of the control electronics (other than that larger rockets typically have more fail safe stuff built into them). Larger rockets can carry heavier directional equipment, miniaturization is what's difficult. Larger rockets are more stable, and require lower frequency course control feedback loops, which also simplifies electronics.
The first guided anti-aircraft missile was the Nike, with a weight of 2,500 pounds, first fired in 1946:
wsmr-history.org
The Stinger weighs 35 pounds.
So. If antiaircraft missile design was more difficult for larger missiles, then why did the US start at the very high end of the scale?
And besides, how much evasive maneuver can you expect from a civilian airliner? The difficulty with larger rockets is in the mechanical realm (i.e. moving the control surfaces), not in the guidance electronics.
What's happened with electronics is that the speeds have increased millions of times since the US first developed seeking missiles. Solving these problems is much easier now than it was in 1955.
Re: "... will leave this missile redirecting itself towards someone with a cigarette lighter before it ever gets to a jet-liner." You can eliminate this sort of behavior by the following simple techniques: (1) Make your sensors only point at the front of the rocket (far less than 180 degrees in width), towards the air, rather than towards the ground. (2) Lock the sensors on to the target before launch. A little TV display would do. (3) Convince your launch personnel to take up Nicoderm. Smoking is bad for your health, and besides, it's dangerous to do around rockets.
-- Carl |
