Missile Guidance

[SkyFall2489]

So, I've been building warships in KSP recently.

I found that fireworks, although very effective at close range, tend to always miss at longer ranges. So, I'm looking at missiles.

However, all my missile designs so far just miss their targets too. Even if they hit, they don't do much damage. Ore tank equipped missiles can do a lot, but the are big and hard to transport on small ships. And they still miss. How can I get missiles to hit targets, in orbit, from several kilometers away? I'm willing to use autopilot mods, or maybe try and code something in KOS.

[Superluminal Gremlin]

you need speed.

lots of speed

you'll need some form of autopilot, but i recommend having a rocket with as much DV as possible with as high TWR as possible.

A single thumper SRB could do some relatively significant damage i reckon.

You could then for the warhead have it as a like a cluster bomb. Loads of radial separators could in theory work...

 

[SkyFall2489]

18 hours ago, Superluminal Gremlin said:

you need speed.

lots of speed

These missiles are launched from spacecraft and aimed at other spacecraft. With vessels, going too fast (450+ m/s) leads to phasing through and not colliding, not doing any damage. 

18 hours ago, Superluminal Gremlin said:

you'll need some form of autopilot, but i recommend having a rocket with as much DV as possible with as high TWR as possible.

TWR won't be too important, from several KM away, 450 m/s can easily be reached. Only 450 m/s DV will be needed, these are all not the issue. What do you mean by some form of autopilot? any reccomendations? This is mainly what I'm asking about.

18 hours ago, Superluminal Gremlin said:

A single thumper SRB could do some relatively significant damage i reckon.

Well, it would, but I feel like that will be hard to haul around on a small, maybe 20 ton battleship.

18 hours ago, Superluminal Gremlin said:

You could then for the warhead have it as a like a cluster bomb. Loads of radial separators could in theory work...

Well, I need low part count. From what research I've done, a big heavy part on the missile is most effective, say a full ore tank.

[SkyFall2489]

19 hours ago, Superluminal Gremlin said:

You could then for the warhead have it as a like a cluster bomb. Loads of radial separators could in theory work...

Although, witha cluster warhead, it's a higher chance of at least some of em hitting the target.

[Superluminal Gremlin]

I've given this topic some thought and here's what I've came up with.

- A small missile won't be able to take out a massive battleship, so these missiles are more like ASAT's than Harpoons, Kitchens, or Sandboxes.

So how do we do it?

1. Install a mod which gives you extremely accurate "docking" info (How close your intercepts are), like MechJeb

2. Boot up KSP.

3. Build a rocket to your specifications of size and DV.

4. Launch into an orbit matching the target.

5. Then burn to raise you Pe of your orbit by 450m/s, or however much fuel is on your missile

6. Circularize your orbit.

7. Create a maneuver node which intersects the target as closely as possible (<0.5*target radius) m.

8. Execute that stray satellite

you could also have a few clusters to take out a larger craft with a small missile

 

1 hour ago, SkyFall2489 said:

TWR won't be too important

Ahhh yeah i thought these more like space RIM's than like Harpoons

[SkyFall2489]

1 hour ago, Superluminal Gremlin said:

4. Launch into an orbit matching the target.

2 hours ago, SkyFall2489 said:

These missiles are launched from spacecraft and aimed at other spacecraft.

I do have MechJeb, by the way. The usual distance between attacking ship and target is maybe 2-5 KM.

[Superluminal Gremlin]

You could also consider using an inflatable heatshield or the DLC robotics to make a sort of net or blade (kind of like the ninja hellfire the Americans used a few months back to do a few little antics)

Scatter weapons which are linear in nature, like the booster boosts it to speed, then linear decouplers activate to have as many smaller warheads as you want. Could possibly do more damage.

[SkyFall2489]

10 hours ago, Superluminal Gremlin said:

You could also consider using an inflatable heatshield or the DLC robotics to make a sort of net or blade (kind of like the ninja hellfire the Americans used a few months back to do a few little antics)

Scatter weapons which are linear in nature, like the booster boosts it to speed, then linear decouplers activate to have as many smaller warheads as you want. Could possibly do more damage.

Well, that would all be great, if I could get them to hit the targets at all. I’m hoping for accuracy down to 2 or 3 m. This is the question I am asking: how do I get them to reliably hit?

I don’t need to worry about warheads yet, I just need them to hit at all.

[Superluminal Gremlin]

Some mod which provides docking guidance. Also, should show how far your intercept is away from the target. Get that down to 2 or 3 meters. Just like docking, but at speed.

Just get the intercept distance as close as you can.

 

[SkyFall2489]

14 minutes ago, Superluminal Gremlin said:

Some mod which provides docking guidance. Also, should show how far your intercept is away from the target. Get that down to 2 or 3 meters. Just like docking, but at speed.

Just get the intercept distance as close as you can.

 

And how do I best do that?  Is there any mod that does that for me? I tried doing that manually but it was not precise enough. 
 

Alternatively, how might I write a KOS script to do it?

MechJeb does have the intercept distance data I need though.

[Superluminal Gremlin]

Yeah, so i don't know the mod. I know that there IS one.

If Mech Jeb has the data, then should be good enough. Using a maneuver node to get the intercept distance down to zero (<100m error) then adjusting with RCS when your coasting and it should work.

Also, do you know the mod which extends the physics range, or at least enable you to jump between crafts moving in the atmosphere?

 

EDIT: I FOUND IT IT. (i think)

[1.12.3] Precise Maneuver (KPM) 2.4.99-adoption <Kerbal Floating Point Precision> edition [25 Mar 2022] - Add-on Releases - Kerbal Space Program Forums 

 

Edited November 1, 2022 by Superluminal Gremlin

[SkyFall2489]

13 minutes ago, Superluminal Gremlin said:

Yeah, so i don't know the mod. I know that there IS one.

If Mech Jeb has the data, then should be good enough. Using a maneuver node to get the intercept distance down to zero (<100m error) then adjusting with RCS when your coasting and it should work.

Also, do you know the mod which extends the physics range, or at least enable you to jump between crafts moving in the atmosphere?

 

EDIT: I FOUND IT IT. (i think)

[1.12.3] Precise Maneuver (KPM) 2.4.99-adoption <Kerbal Floating Point Precision> edition [25 Mar 2022] - Add-on Releases - Kerbal Space Program Forums 

 

Uh, physics range extender?

 I still don’t trust myself to manually guide a missile to its target. How would you get a robot to do it? Just a very detailed sequence of instructions.

I was thinking aim at target, accelerate until required speed, then do some math thing to subtract the direction to the target from the prograde vector, then use RCS to move that error value toward zero?

[Superluminal Gremlin]

Just now, SkyFall2489 said:

physics range extender

Thats the name

Thank you.

 

Im not saying to manually guide the missile. Imagine it like docking. You get a intercept of <100m, then you perform the burn. Then you use MechJeb to bring that value down to <x meters. Its docking without the hard part 

 

[SkyFall2489]

38 minutes ago, Superluminal Gremlin said:

Thats the name

Thank you.

 

Im not saying to manually guide the missile. Imagine it like docking. You get a intercept of <100m, then you perform the burn. Then you use MechJeb to bring that value down to <x meters. Its docking without the hard part 

 

Thing is, MechJeb's docking autopilot won't do that. You know, because docking generally involves NOT smashing int the target at 400 m/s...

Is there a way I can make it do that?

Wait, you mean accelrate, then use MechJeb's manuver setter to do it? that's an interesting idea.

[Superluminal Gremlin]

Yeah, so don't use docking guido then. 

Yep, mechjebs maneuver first then accelerate.

Then adjust.

[SkyFall2489]

Just now, Superluminal Gremlin said:

Yeah, so don't use docking guido then. 

Yep, mechjebs maneuver first then accelerate.

Then adjust.

Wait, so A or B:

A: Laucnh the missile, use MJ to set a node to "intercept target in N seconds", where N is <dist to target in m> / 400.

B: Launch the missile, aim at target, accelerate manually until TGT vel is 400, then set MJ to fine tune closest approach to target, 0 m.

[Superluminal Gremlin]

Whatever works i guess...

B would be my guess

If you test please tell me

Im considering starting a series about weapons development

[SkyFall2489]

6 minutes ago, Superluminal Gremlin said:

Whatever works i guess...

B would be my guess

If you test please tell me

Im considering starting a series about weapons development

Thanks, then! I don't have much time at the moment, I'll test your ideas out on saturday.

[Superluminal Gremlin]

I probably will as well

You've inspired me