Author Topic: Advice on on-board missile sensors  (Read 3050 times)

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Offline smoelf (OP)

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Advice on on-board missile sensors
« on: September 21, 2017, 09:56:46 AM »
In my current game I am experimenting with two-stage missiles, and tried putting thermal sensors of the first stage in case the target blew up too soon. However, it never really worked out too well as the sensor was too weak to be useful. Right now I am upgrading my entire missile system and due to increased fuel efficiency and engine tech I now have room to put some bigger sensors in them that might actually be useful. The question is which type of sensor to use. Fortunately I know something of the ships of the NPR I am primarily fighting. Their stock ship has a tonnage of 9150 tons and a thermal signature of 384. Designing a missile with that in mind and using either thermal or active sensors I get the following options:

Code: [Select]
Missile Size: 18 MSP  (0.9 HS)     Warhead: 0    Armour: 0     Manoeuvre Rating: 10
Speed: 18900 km/s    Engine Endurance: 6.9 hours   Range: 469.4m km
Active Sensor Strength: 2.471   Sensitivity Modifier: 110%
Resolution: 183    Maximum Range vs 9150 ton object (or larger): 3 670 000 km
Cost Per Missile: 17.9046
Second Stage: Size 2 Anti-ship Missile x4
Second Stage Separation Range: 8 000 000 km
Overall Endurance: 7 hours   Overall Range: 484.1m km
Chance to Hit: 1k km/s 189%   3k km/s 60%   5k km/s 37.8%   10k km/s 18.9%
Materials Required:    4x Tritanium   1.482x Boronide   2.471x Uridium   12.1532x Gallicite   Fuel x5700

Development Cost for Project: 1790RP

Code: [Select]
Missile Size: 18 MSP  (0.9 HS)     Warhead: 0    Armour: 0     Manoeuvre Rating: 10
Speed: 18900 km/s    Engine Endurance: 6.9 hours   Range: 469.4m km
Thermal Sensor Strength: 1.2942    Detect Sig Strength 1000:  1 294 200 km
Cost Per Missile: 16.0222
Second Stage: Size 2 Anti-ship Missile x4
Second Stage Separation Range: 8 000 000 km
Overall Endurance: 7 hours   Overall Range: 484.1m km
Chance to Hit: 1k km/s 189%   3k km/s 60%   5k km/s 37.8%   10k km/s 18.9%
Materials Required:    4x Tritanium   0.7764x Boronide   1.2942x Uridium   12.1532x Gallicite   Fuel x5700

Development Cost for Project: 1602RP

It seems to me that the active sensor is the better option here, giving me a detection range of 3.67m km while the thermal has a detection range of about a third of the listed 1,29m km. However, most of what I have read suggest that thermal sensors are preferred on missiles.
  • Is there a reason for this that I am not seeing?
  • Or could it be that the NPR in my case simply has so weak engines, that active sensors becomes the better option?
  • Relative to your own experience with on-board sensors on your own missiles, are these detection ranges realistic and even worth it, or should I rather cram an extra second-stage missile on to them instead of a sensor?
 

Offline Garfunkel

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Re: Advice on on-board missile sensors
« Reply #1 on: September 21, 2017, 04:20:08 PM »
Detection range needs to be slightly higher than what enemy ships can move in 5 seconds. Because the best use for them is to avoid overkill. Missiles with sensors on them will automatically retarget if their current target is destroyed and there is a new hostile target inside their sensor range.

Thermal sensors are good because engines put out a lot of heat and are always on (EM sensors go for active sensors and shields only) but if you can get a decent range with active sensor without compromising the missile otherwise, then go for it.

Note that the resolution in your first missile is pretty damn high. Note how the range given is for 9150 ton object. Many NPR/spoiler ships will be smaller.
 

Offline El Pip

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Re: Advice on on-board missile sensors
« Reply #2 on: September 21, 2017, 05:16:42 PM »
I'm a bit rusty on two-stage missiles, but surely those are never going to work as intended?

If the separation distance is 8million km, but the sensor has only (at best) 3.9m km, then the second stages will have separated long before the sensor could ever see anything.

On the wider point, thermal is preferred over passive EM as passive EM doesn't work. An active missile will be active from the moment you launch, so if the enemy has a large EM sensor they will may get a lot more warning of incoming missiles.

The other point is that your missiles are now super optimised against enemy cruisers and at that resolution functionally blind against FACs. A thermal seeker who still struggle, but would probably have a much better chance.
 

Offline Steve Walmsley

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Re: Advice on on-board missile sensors
« Reply #3 on: September 22, 2017, 03:48:28 AM »
Passive sensors on missiles will be much more effective in C# Aurora due to the changes in the passive sensor model
 

Offline Tuna-Fish

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Re: Advice on on-board missile sensors
« Reply #4 on: September 22, 2017, 02:10:05 PM »
Quote from: El Pip link=topic=9684. msg104307#msg104307 date=1506032202

If the separation distance is 8million km, but the sensor has only (at best) 3. 9m km, then the second stages will have separated long before the sensor could ever see anything.

The missile fire control will happily guide the second stage in (and will do so even if it has no sensors).  The sensors only come into play if the firing ship fire control for any reason loses contact with the target ship, for example because it goes beyond the fire control range, beyond the range of your active sensors, or, the most common reason, the ship they were originally fired at dies.
 

Offline Detros

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Re: Advice on on-board missile sensors
« Reply #5 on: September 22, 2017, 04:55:53 PM »
The missile fire control will happily guide the second stage in (and will do so even if it has no sensors).  The sensors only come into play if the firing ship fire control for any reason loses contact with the target ship, for example because it goes beyond the fire control range, beyond the range of your active sensors, or, the most common reason, the ship they were originally fired at dies.
...or this original-target-ship lands inside another ship.
 

Offline El Pip

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Re: Advice on on-board missile sensors
« Reply #6 on: September 23, 2017, 04:07:17 PM »
The missile fire control will happily guide the second stage in (and will do so even if it has no sensors).  The sensors only come into play if the firing ship fire control for any reason loses contact with the target ship, for example because it goes beyond the fire control range, beyond the range of your active sensors, or, the most common reason, the ship they were originally fired at dies.
I had thought that you only needed a constant active sensor lock for a missile. I know (having tested it) that you do not need to keep the target in fire control range, just sensor range. I had also thought that a sensor on a missile only works for that missile, not any 'payload' missiles after they have launched.

It just seems an amazingly niche scenario when that sensor would work for a two stage missile. You need to make sure there is >8m km between each wave of missiles, anything less and the separation will have occurred and the smaller Size 2 missiles (that have no sensors) are off flying blind and self-destruct. You then need to make sure that the next target will be within 3.7m km of the original target location (when it was destroyed) or is flying straight towards the launch platform, or the missile sensor won't see it.

Could be I'm wrong on the mechanics, I've not actually tested two-stage missiles with sensors in the 'bus' missile. If I'm wrong then maybe they are more useful, but if they work as I think they do then it seems to require the enemy to really co-operate with your plans for the sensors to be of benefit.
 

Offline smoelf (OP)

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Re: Advice on on-board missile sensors
« Reply #7 on: September 24, 2017, 02:05:16 AM »
Thanks for the answers so far. I think I might end up designing them just to see if they work, as that seems to be a bit unclear right now.

The reason behind my question is that in the first generation of this missile, I did not know how effective they were, so I wasted a lot of missiles. Then I put the sensor on in the second generation, but it didn't work because it was way too small. In an effort to not waste missiles, I would only send a new load when the first one had already hit. This results in a bit tedious and long combats where I would only launch missiles every six hours or so.

So here comes my idea for the presented generation. I know that it takes less than five minutes for the smaller missiles to hit their target. This means that if I launch the missiles five minutes apart the first salvo will have hit their target before the second has been released. So a sensor on the carrier should then start looking for a new target, if the original target was destroyed.

I'm still worried that 3,7m km is far too short a distance to be functional, but you never know until you test it.
 

Offline Garfunkel

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Re: Advice on on-board missile sensors
« Reply #8 on: September 25, 2017, 04:04:45 PM »
I had thought that you only needed a constant active sensor lock for a missile. I know (having tested it) that you do not need to keep the target in fire control range, just sensor range.
Are you 100% absolutely sure? I could've sworn that if the the firecontrol loses the target, the missiles under its guidance will self-destruct, if they do not have onboard sensors to lock to a new target.
 

Offline El Pip

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Re: Advice on on-board missile sensors
« Reply #9 on: September 25, 2017, 04:13:05 PM »
Are you 100% absolutely sure? I could've sworn that if the the firecontrol loses the target, the missiles under its guidance will self-destruct, if they do not have onboard sensors to lock to a new target.
Last time I tested it the key factor was being in sensor range, not within fire control range. It's entirely possible this is a bug and not what is intended, but at present you only need to be in fire control range to launch. Post-launch something, not necessarily the launch platform, needs to keep the target in active sensor range, the launch platform can go back out of range.

I tested it with fighters, so I know they can launch, head out of fire control range, land on their carrier (which is out of range) and start re-arming, all while their missiles are still heading to the target.

Not sure if the launch ship can leave the system, I didn't check that. And I think the missiles are destroyed if the launch platform is destroyed, which is odd and is why I think this behaviour might not be as intended.
 

Offline serger

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Re: Advice on on-board missile sensors
« Reply #10 on: October 03, 2017, 11:35:00 PM »
Missile fighters can leave the system and land their carrier at the far side of the JP, while their missiles are still heading to the target. (My favorite tactics.)