Killing Momentum?

Ok, here's the setup:

Using the examples from the wiki, I managed to work out a little homing missile-type item that goes after the closest non-me person within a 40m radius (uses a single SetForce to act as propulsion, and obviously it's also buoyant). In testing, though, when it passes through a target and turns around, each time it does so, it gets further from the person, as opposed to closer, and starts almost orbiting them, depending on how they and it moves.

How can I reliably keep this thing from getting too fast and still retain some of the characteristics it has now (such as changing targets midflight and being 'avoidable')?

I haven't tried this, but will vector llGetForce() return the remaining force in the object or will it merely return the amount of the setforce that had been applied?

Are you calculating the force required based on the distance to the target each time, including when it turns? Or are you using a set amount of force?

Well when you use llSetForce you are giving it a constant thrust. Sounds like that is too fast. Consider reducing it as the proximity closes to prevent the whizzing-through?

You could try to call llSetPrimitiveParams([PRIM_PHYSICS, False]); and then back to a physical object with a new force..

You could use llApplyImpulse instead of llSetForce, because, as others pointed out, the latter will keep applying the same level of thrust, accelerating your object to higher and higher velocities. You could also balance the llSetForce() with friction using the Vehicle system... although combining the Vehicle system with llSetForce() may be unsupported.

There are a lot of ideas available for this on the Internet. Try googling "boids" and "flocking" and "reynolds" (I think).

In your case, it sounds like leaving llSetForce() on will cause it to go faster and faster. If you check the velocity once in awhile, you can reduce the force as you get closer to some max velocity threshold. The crudest version would be

if (GetVel() > MAX)
then
SetForce(0)

I'm trying to work with friction on the side-to-side movement, but the wiki help for vehicles is nearly non-existant, and so I've tried everything I can think of, but nothing seems to be working...

if wiki.secondlife.com doesn't have what you need try lslwiki.net they have more info on the lsl commands though I think even they don't have much on physics calls since those are fairly undocumented wherever you go so your probably stuck doing trial and error.