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Missile Defense

Technology has always found its greatest consumer in a nation's war and defense efforts. Since the last attempts at a "Star Wars" defense system, has technology changed considerably enough to make the latest Missile Defense initiatives more successful? Can such an application of science be successful? Is a militarized space inevitable, necessary or impossible?

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rshow55 - 04:02pm Sep 25, 2002 EST (# 4533 of 17697)
Can we do a better job of finding truth? YES. Click "rshow55" for some things Lchic and I have done and worked for on this thread.

So, for one model airplane, you could track x-y-z position, with respect to the reciever (or any other fixed point) - and plot that position, to ~3 cm uncertainty, every millisecond.

Plotting position against time, for 20 past points, using diffterms, you could have a very good running polynomial approximation of the motion - (and polynomial approximation of its differential equation, with boundary conditions).

A 10th degree polynomial approximation would leave enough points for noise subtraction (of "noise" in the sense of signal that didn't fit a 10th degree polynomial fit).

Integrating the differential equation "predicts that future" according to the de - a de that is continuously updated (say, every millisecond).

You could do the same for 2 airplanes, or 3 - though sorting out which triangles correspond to which points would require some logic. Getting running x,y,z positions, polynomial approximations of equations of motion, and easily integrable polynomial approximations of the de's of the motion of each airplane.

Getting these de's into handy frames of reference (for example, the frame of the individual model airplanes) isn't fancy.

Now, suppose there is a "lead" model airplane that is "flown" -- either by hand, or by machine - without information about how flight path changes going to to logic controlling the "follower" model airplane.

How well can the "follower" follow?

Can the "follower" follow a moving, jagging target?

That depends on how good the information processing is, and how good the maneuverability of the follower is, compared to the target.

Here's a game that competing teams of engineering undergraduates could play, and compete in.

rshow55 - 04:12pm Sep 25, 2002 EST (# 4534 of 17697)
Can we do a better job of finding truth? YES. Click "rshow55" for some things Lchic and I have done and worked for on this thread.

Bats catch moths all the time. Even for trajectories that look very tricky.

That's because a bat can "guess" the future motions of both itself and the moth it is tracking (using a temporal ranging code), and makes "guesses" that get better and better - convergently - so that the bat catches the moth, rather than misses.

Though if a moth hears the bat, and evades, that moth sometimes escapes.

Moths that fly trajectories that the bat can follow become bat-dinner.

They are bat-dinner because the bat can predict flight paths with respect to itself, and "knows" how to adjust its own flight precisely - so that the curve of the target motion and the curve of the bat motion intersect.

To do this, the bat's "guessing" has to be very good - my own guess is so good that it has to be solving very good approximations of differential equations - in every way that matters for quantitative performance.

Something that the model airplanes can also do.

rshow55 - 04:19pm Sep 25, 2002 EST (# 4535 of 17697)
Can we do a better job of finding truth? YES. Click "rshow55" for some things Lchic and I have done and worked for on this thread.

Now, for the first year or two (unless the engineering teams in schools are a little faster than I think they'd be) a "dogfighting" competition might require a "follower" to be MUCH more agile (capable of more accelleration, more speed) than the "target" plane.

The engineering teams would need to get good "transfer functions" on how throttle and flap changes change follower flight paths, and get the following logic straight - but they'd know that if they did that - they could "follow" the lead plane almost perfectly - there would be no "misses."

After a little while, that would get boring, I think. Every team would work out essentially perfect following - for followers much faster than the lead planes. That would be boring.

But the game could go on, and would stay interesting, if in successive years the difference between the "lead" planes and "follower" planes got less.

rshow55 - 05:37pm Sep 25, 2002 EST (# 4536 of 17697)
Can we do a better job of finding truth? YES. Click "rshow55" for some things Lchic and I have done and worked for on this thread.

As of now, we'd be quite close to stability - with military technology and human patterns in place -- if we didn't have bombing.

No one would question US dominance if there was no bombing (or if Americans understood bombing to carry the expenses and exposures that it carried for most of the 20th century.) But the idea that the United States could kill, at a distance, with complete impunity would be gone.

If that idea was gone - we'd be pretty close to the conditions a stable peace requires --- now.

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