FAR and missiles

[viktor19]

I've recently started to use FAR. Any tips on missile making/guiding?

[Hodo]

I've recently started to use FAR. Any tips on missile making/guiding?

Weapon type missiles?

Simple, smallest probe core you can get, and make it aerodynamic. Nothing blocky or giant. Look at lawn darts, throwing darts, and real missiles.

[Streetwind]

Try the 0.625m fuel tanks from RLA Stockalike. Failing that, a stack of Oscar-B's. Add an Okto2 probe core, a 0.625m nosecone, a Rockomax 48-7S and voila, guided missile.

You could add fins but they are all very large for a missile of that size, and probably generate too much lift. They're better suited for 1.25m variants.

[viktor19]

I appreciate your help but FAR is obviously making this difficult.

[Streetwind]

"Obviously" to you, not obvious to us because you never actually tell what your issue is...

[viktor19]

I have previously made a lot of missiles in KSP. But since I started using Ferram Aerospace Research everything spirals out of control. How n00b of me.

Edited July 11, 2014 by viktor19
correct a typo

[G'th]

FAR makes the atmosphere realistic. IE, Kerbin's atmosphere is no longer a thick chunky gravy but more of a nice clear glass of water.

The likely reason your rockets are spinning out of control is because you either A, have too heavy a hand at the controls, or B, have way too much TWR.

For the former, turning on caps lock helps. But in general, you'll just have to get used to the fact that you can't just pitch over to horizontal from vertical and have the rocket stay stable. If you go too far past your prograde vector (IE, have a high angle of attack) you'll lose control of the rocket as it stalls.

For the latter, you have to look at what your TWR is. If its above 2.0 you're going to have a bad time, as you'll hit high dynamic pressure (which basically means any major movement in your rocket will likely tear it apart or send it spiraling out of the sky) before you're even past the 10km mark. Sitting on the pad, you want it to be around 1.3-1.4. Idealing speaking, you'd want to keep it around that point for the entire flight, but once your past ~25km up you can go 100% throttle without it affecting your rocket much.

Seeing as you're trying for missiles, you'll have to take both issues into account. It'll take some good piloting to make it work (as well as a well designed missile for that matter) and careful control of your TWR and speed, as losing control of either before reaching your target will spell disaster. Unless you use mostly reaction wheels in your design, you'll definitely need some sort of fins for maneuverability (you can get Procedural Wings for <1.25m designs). Using an engine that can gimbal will also help.

And naturally, you'll also want to cut down on any junk along the missile itself. Anything sticking out that isn't fins will induce more drag which will make your missile less aerodynamic, and thus, harder to use.

[Hodo]

Try the 0.625m fuel tanks from RLA Stockalike. Failing that, a stack of Oscar-B's. Add an Okto2 probe core, a 0.625m nosecone, a Rockomax 48-7S and voila, guided missile.

You could add fins but they are all very large for a missile of that size, and probably generate too much lift. They're better suited for 1.25m variants.

I have come up with a solution to the fin issue. Small control surfaces locked with no control options set to them.

[NathanKell]

In fact if you're making missiles, your best bet will be to slightly tweak the angle of the fins before you place them, so they're constantly applying a bit of roll. That will spin-stabilize your projectile.

[LethalDose]

In fact if you're making missiles, your best bet will be to slightly tweak the angle of the fins before you place them, so they're constantly applying a bit of roll. That will spin-stabilize your projectile.

you could also offset the thrust so the projectile would corkscrew as well.

[Raven.]

you could also offset the thrust so the projectile would corkscrew as well.

Depends on how you want the missile to behave. I believe this was tried with something called the "Hale Rocket" during the Mexican-American war, but it was very in-accurate and it did not have a good range.

Check this out: http://fas.org/man/dod-101/sys/smart/bgm-109.htm

That article is on the Tomahawk cruise missile. If you look at it, it has smaller wings similar to what an actual aircraft has with smaller stabilizers. It also has a longer fuselage compared to its wing span. I think mimicking this would help out quite a bit with FAR.

[NathanKell]

You don't want corkscrewing. That's the opposite of stability. You want spin stabilized *along the steady flight axis.*

[marianoapp]

I made a missile a while ago with 0.625 parts and FAR installed but used kOS to guide it

[dbmorpher]

I made a missile a while ago with 0.625 parts and FAR installed but used kOS to guide it

Woah how'd you do that!

The targeting system I mean

[Hodo]

Woah how'd you do that!

The targeting system I mean

He used KOS to intercept the target. Not that hard all things considered. You can do the samething with MJ and a lot less programming...lol.

[viktor19]

How can you: 1. switch from one vessel to another in atmosphere?

2. make guidance system in MJ?

[peadar1987]

In fact if you're making missiles, your best bet will be to slightly tweak the angle of the fins before you place them, so they're constantly applying a bit of roll. That will spin-stabilize your projectile.

Does spin-stabilisation work in KSP? I didn't know it modelled conservation of angular momentum

[NathanKell]

Yes it does.

[Alias72]

another interesting note: not all missiles use spin to stabilize them. Many missiles use rotating optics to examine the sky and determine range and course and as such need a steady orientation (up must be up). The AIM 9 sidewinder is one of these missiles. stabilization on these weapons is achieved by: 1. articulating control systems 2. Thrust vectoring 3. spinning paddle-wheels running axial tot he missiles flight path. This prevents the missile from spinning like a bullet.

[NathanKell]

Most *guided* missiles are 3-axis-stabilized, yeah.