Help with missile design

[tryrar (OP)]

I'm starting to design my own PDCs, and I decided to go with the massive MIRV missile approach. So, I thought I'd get your thoughts on what I came up with:

Minuteman III ISBM:

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Missile Size: 26 MSP  (1.3 HS)     Warhead: 0    Armour: 0     Manoeuvre Rating: 5
Speed: 9200 km/s    Endurance: 1250 minutes   Range: 690.0m km
Cost Per Missile: 18.3482
Second Stage: Apollo B Thermal Seeking ASM x4
Second Stage Separation Range: 30,000,000 km
Overall Endurance: 21 hours   Overall Range: 721.5m km
Chance to Hit: 1k km/s 46%   3k km/s 15%   5k km/s 9.2%   10k km/s 4.6%
Materials Required:    4x Tritanium   0.24x Uridium   15.6832x Gallicite   Fuel x12500

Here's the warheads, which are slightly modded versions of my standard shipkiller, with a little less range to make room for a small thermal sensor.

Apollo B Guided ASM:

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Missile Size: 4 MSP  (0.2 HS)     Warhead: 4    Armour: 0     Manoeuvre Rating: 19
Speed: 35000 km/s    Endurance: 15 minutes   Range: 31.5m km
Thermal Sensor Strength: 0.06    Detect Sig Strength 1000:  60,000 km
Cost Per Missile: 3.6183
Chance to Hit: 1k km/s 665%   3k km/s 209%   5k km/s 133%   10k km/s 66.5%
Materials Required:    1x Tritanium   0.06x Uridium   2.9833x Gallicite   Fuel x875

So, see anything you guys think I can do better?

[wedgebert]

I haven't MIRVed much, but it looks to me like your seperation distance (30,000,000 km) is much larger than than your passive sensor range of 1000 @ 60,000 km. Won't this result in your Apollo's not finding targets?

[tryrar (OP)]

I'm...not sure actually, but for a meaningful range for passive sensors, I'd need to build a size 10 missile or something, so...

[Zook]

Maybe I'm completely confused again, but wouldn't the Minuteman need a sensor as well?

[Konisforce]

Sensor on the 1st stage would only be to re-acquire something if the 1st target was lost I think, no?

[TheDeadlyShoe]

if you are size constrained that bad on your sensor go with an active. they have better performance than passives for the most part. Generally I shoot for 5s of missile travel time in the active.  Going super short is asking to simply fly past a potential target. 

The range of the Minuteman III is probably impractical against anything but stationary targets, owing to the massive fire controls you'd have to use.  You could safely scale it down a bit.  Since you're using a drone, that'll increase its speed too. 

Suggestion:  Reduce the agility on the Apollo B in favor of speed, warhead, and/or sensor.   MR 19 is frankly way overkill.  The max I would shoot for is 100% @ 5km/s.  Bearing in mind ofc that speed affects the accuracy too.

[Havear]

MIRVs work like so: You fire the carrier munition at a target using fire controls. This munition doesn't require onboard sensing equipment as the fire control will work fine. Any stage (such as your second stage submunitions) that want to be able to acquire a target will have to have onboard sensing equipment, and the location they're fired at as an initial target is passed from the stage above. This also means that if you're multistaging a large missile so it can drop empty fuel tanks for longer range, the fuel\engine stages don't require sensors. When the stage currently active reaches separation range of the target, it... well, separates. Note that the original stage and the now separate following stage are both going to continue toward their target.

[Zook]

By the way, can you build three-stage missiles?

[tryrar (OP)]

So, You say I should cut the range down? Ok, by how much? (I was using a max-size active sensor for my C&C PDC, so that's why I had that much range).

[Erik L]

So, You say I should cut the range down? Ok, by how much? (I was using a max-size active sensor for my C&C PDC, so that's why I had that much range).

Optimally, right around the sensor range of your submunitions. It also depends on if you are in a chase battle or a closing battle. For closing you can have a higher separation. For a chase, you'd want lower.

[Shooer]

By the way, can you build three-stage missiles?

Yes.    You can add only one second stage to a design, but that can have it's own second stage, and that one can have it's own second stage, and that one can have it's own second stage. 

To the OP I would reduce the separation range.    If the target is moving away from the missiles your second stage will run out of fuel before hitting.  It's a error I did with my first MIRV as well, they were only good for taking out PDCs and shipping.   (To be fair they were only used on cloaked siege ships)

[tryrar (OP)]

Ok, taking everything into account, here's the new designs:

Minuteman III Mod-II

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Missile Size: 29.527 MSP  (1.47635 HS)     Warhead: 0    Armour: 0     Manoeuvre Rating: 5
Speed: 10800 km/s    Endurance: 849 minutes   Range: 550.0m km
Cost Per Missile: 24.1083
Second Stage: Apollo B Mod-II Guided ASM x4
Second Stage Separation Range: 500,000 km
Overall Endurance: 14 hours   Overall Range: 579.2m km
Chance to Hit: 1k km/s 54%   3k km/s 15%   5k km/s 10.8%   10k km/s 5.4%
Materials Required:    4x Tritanium   3.2x Uridium   17.6833x Gallicite   Fuel x11317.5
I reduced overall range a little, as well as putting in a sane seperation range. I also bit the bullet and upped the size of the apollo Bs to fit in a decent sensor:

Apollo B Mod-II

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Speed: 33600 km/s    Endurance: 14 minutes   Range: 28.8m km
Active Sensor Strength: 0.8   Sensitivity Modifier: 80%
Resolution: 100    Maximum Range vs 5000 ton object (or larger): 640,000 km
Cost Per Missile: 4.725
Chance to Hit: 1k km/s 504%   3k km/s 165%   5k km/s 100.8%   10k km/s 50.4%
Materials Required:    1x Tritanium   0.8x Uridium   3.15x Gallicite   Fuel x1000
So, what you guys think?

[Havear]

I'd reduce the range on the Minuteman to maybe 300 klicks and increase the separation range on the Apollos to 10 million klicks. Actually I'd probably up the separation range to 15, but all things considered I don't think you'll have to worry about AM fire *that* far out unless you're facing Invaders. Your biggest issue with that small of a separation range will be AMM fire from the target. Even a crude AMM can reach 2 million klicks easy.

[sublight]

The Minuteman currently resembles a self-propelled half-day duration mine. If that was the intent, it looks great. Otherwise I'd agree that it's functional, but extremely vulnerable to AMM fire. While one solution would be to increase separation range up to millions of km, that approach would probably require investing in advanced active-sensor scout-craft spotters plus a crazy large ultra-long ranged fire-con on the PDC. If the target control has a long enough range then I think sensors on the missiles become unnecessary.

Alternatively, you could slap two or three levels of armor onto the Minuteman to harden them against AMM fire. To make room for the armor consider dumping fuel off of the Apollo B. The submunitions really only need a range of twice the separation distance at most. Call it 2m km to be extra generous. 28m km is pure overkill for 0.5m km seperation. If reducing Apollo fuel doesn't provide enough room for Minuteman armor, then reduce the payload down to 3x submunitions. You might consider reducing the submunition count anyway to make the minuteman faster.

[tryrar (OP)]

Yeah, you can tell my only experience with second stage missiles is messing around with mines, huh? And that is NOT what I'm trying to do here; I'm trying to make a viable very long range planet-launched missile that will devastate anything that might attack me(especially when launched two at a time from 20 PDCs). I'm currently working on getting better missile and sensor tech right now, so I'll hold off on making any more mods until I get them done. However, can you guys post some examples so I can see what makes a good Anti-ship MIRV missile?