Errata Discussion: Missile Guidance

[DonM]

Looks good.

I'm going to0 add a query:

Special Supplement 3: missiles

Errata states the standard missile is a 5G6, but then it gives a fuel price for what appears to be a 6G5. Was the standard intended to be a 6G5, or is the fuel price wrong?

I think I corrected that, but I'd left it off the list... let's see how this pastes.

Page 3, Missile Identification, second paragraph (correction): The second paragraph should read: For example, the standard missile in Traveller is a 5G6 continuous burn (35 kg, Cr3,500, TL 8), mass sensing (1 kg, Cr1,000, TL 10), proximity detonator (1 kg, Cr500, TL 6), high explosive (10 kg, Cr500, TL 6) warhead missile (all produced at their standard tech level), costing Cr5,500 and massing 47 kg. This price does not take into account tech level effects. At TL 9, this missile costs Cr5,800; at TL 12, it costs Cr4,400.

Apparently I cannot make the text blue where it should be... Edit... apparently I can :rofl:

 

[Carlobrand]

Morning Carlobrand,



I pretty much went through SS3 and SS3-R, issued on the CD-ROM, one of the areas dealt with the cost of the missiles. Looking through my errata document, JTAS 21 SS3, and SS3-R the continuous burn missile does not need a controller since the course cannot be corrected per JTAS 21 SS-3 page 4 Second Paragraph last sentence: "Continuous burn systems cannot alter course; they continue on the course given when fired."

Tom R

I think I corrected that, but I'd left it off the list... let's see how this pastes.

Page 3, Missile Identification, second paragraph (correction): The second paragraph should read: For example, the standard missile in Traveller is a 5G6 continuous burn (35 kg, Cr3,500, TL 8), mass sensing (1 kg, Cr1,000, TL 10), proximity detonator (1 kg, Cr500, TL 6), high explosive (10 kg, Cr500, TL 6) warhead missile (all produced at their standard tech level), costing Cr5,500 and massing 47 kg. This price does not take into account tech level effects. At TL 9, this missile costs Cr5,800; at TL 12, it costs Cr4,400.

Apparently I cannot make the text blue where it should be... Edit... apparently I can :rofl:

I apologize if this is not the right setting, not meaning to start a debate on the specifics of missile tech, but inasmuch as it does bear on a potential point of errata regarding what is considered the standard missile:

If a continuous burn missile "cannot alter course; they continue on the course given when fired," ...

(which frankly is absurd: all you need is a good gyroscopic system to turn the missile while the motor burns continuously and, voila, a continuous burn missile that maneuvers - it just does so at the same G-rating until it runs out of fuel or hits something)

...and therefore do not need and cannot use a controller that makes it possible for them to adjust course after launch, ...

(the aforementioned gyroscopic system)

...then why is it receiving a guidance system of any sort? It has a proximity detector to tell it when it is close enough to detonate the warhead. What does it need with a system that tells it where the target went when it can't do anything but fly straight on in whatever direction it was launched?

For that matter, why bother giving it more than a turn's fuel when a target more than a turn away can evade 100% of the time by "sidestepping"? If the standard missile is to make use of a mass detector or any other guidance system, then it needs to have a limited burn or discretionary burn propulsion system - and a controller, of course.

 

[DonM]

I apologize if this is not the right setting, not meaning to start a debate on the specifics of missile tech, but inasmuch as it does bear on a potential point of errata regarding what is considered the standard missile:

If a continuous burn missile "cannot alter course; they continue on the course given when fired," ...

(which frankly is absurd: all you need is a good gyroscopic system to turn the missile while the motor burns continuously and, voila, a continuous burn missile that maneuvers - it just does so at the same G-rating until it runs out of fuel or hits something)

...and therefore do not need and cannot use a controller that makes it possible for them to adjust course after launch, ...

(the aforementioned gyroscopic system)

...then why is it receiving a guidance system of any sort? It has a proximity detector to tell it when it is close enough to detonate the warhead. What does it need with a system that tells it where the target went when it can't do anything but fly straight on in whatever direction it was launched?

For that matter, why bother giving it more than a turn's fuel when a target more than a turn away can evade 100% of the time by "sidestepping"? If the standard missile is to make use of a mass detector or any other guidance system, then it needs to have a limited burn or discretionary burn propulsion system - and a controller, of course.

Good point. Let's pull this out of the compendium thread and build a proper replacement?

 

[snrdg082102]

Howdy Carlobrand,

I brought the issue about the continuous burn propulsion and no guidance here and over on ctstarships, unfortunately I didn't think about using a gyroscope, which of course resulted in a very short topic.

Great point.

Tom R

I apologize if this is not the right setting, not meaning to start a debate on the specifics of missile tech, but inasmuch as it does bear on a potential point of errata regarding what is considered the standard missile:

If a continuous burn missile "cannot alter course; they continue on the course given when fired," ...

(which frankly is absurd: all you need is a good gyroscopic system to turn the missile while the motor burns continuously and, voila, a continuous burn missile that maneuvers - it just does so at the same G-rating until it runs out of fuel or hits something)

...and therefore do not need and cannot use a controller that makes it possible for them to adjust course after launch, ...

(the aforementioned gyroscopic system)

...then why is it receiving a guidance system of any sort? It has a proximity detector to tell it when it is close enough to detonate the warhead. What does it need with a system that tells it where the target went when it can't do anything but fly straight on in whatever direction it was launched?

For that matter, why bother giving it more than a turn's fuel when a target more than a turn away can evade 100% of the time by "sidestepping"? If the standard missile is to make use of a mass detector or any other guidance system, then it needs to have a limited burn or discretionary burn propulsion system - and a controller, of course.

 

[aramis]

Many modern continuous burn solid fuel missiles at present have thrust deflection capability, as well. They can use guidance packages.

 

[Carlobrand]

I think it's pretty clear that engineering a method to execute course changes is not a problem. It's a missile in vacuum - we contrive a way to change its orientation, and we've got thrust shoving it in a new direction.

Issues?

The main one is the intercept. The Book 2 combat rules are basically snapshots in time: the ship is here with this vector, then a thousand seconds later the ship is here with this vector. Missiles, if I understand it, hit by finding themselves within 25 mm (2500 km) of a target at the end of any turn, which is about as good as it gets when you're eyeballing vectors instead of using advanced sensors and microcomputers to track and close with a target. However, in the context of a continuous burn propulsion system adding X millimeters to its vector every turn, it's very easy for it to be too far away in one "snapshot" and then completely overshoot on the next, even if it's flying straight up the ol' tailpipe and should have impacted somewhere between the two "snapshots".

One option is to draw a line between the missile's former position and its desired new position: if the player can place the missile so that a line between the former position and desired new position intersects (or comes within 25mm of, I guess) the target, the target is hit - or will hit unless struck by antimissile fire or destroyed by ECM.

A second issue is the treatment of limited burn missiles. Put bluntly, what's good for the goose is good for the gander. It's fine to have a pricier, higher quality fuel, but if there are ways to steer a continuous burn missile, those same ways work for a limited burn missile without resorting to this "half the remaining G's" calculation to make a course change. (I never have understood the logic there.) The only value to the limited burn missile becomes that higher-price, higher-performance fuel. Besides, if the continuous burn missile is good enough to hit home, then there is no benefit to the limited burn missile's odd "half the remaining G's" calculation.

(Given that there's great angst over the extreme levels of power delivered by the basic continuous burn system, it might be worth considering to eliminate the limited burn and its superior fuel altogether. That still leaves us with a constantly thrusting solid-fueled propulsion system and a liquid-fueled system that maneuvers like a ship.)

One issue to think about is why the SS3 design rules designed what appeared to be impaired missile propulsion systems? Why have a missile that can't change course, or a missile that can change course only by sacrificing a large part of its thrust? Were missiles overpowered otherwise? Missiles overall weren't weakened because there remained the discretionary burn propulsion to deliver a warhead to target, but that system is pricier; the impaired systems were cheaper than the more versatile discretionary burn system. What did the designer feel was added to the game by offering a class of cheaper but impaired missiles, and what alternative do we need to consider to bring similar benefit without indulging in unrealistic restrictions?

 

[DonM]

No suggested fixes?

 

[Piper]

Continuous burn missiles were originally intended to impact their target on their first turn of movement:

... continuous burn missiles are most effective if fired against targets which can be intercepted during the first phase of movement. For example, a 6G6 missile can intercept a target within 600 millimeters of its launch point during its first turn of movement. Chances of interceptions in subsequent turns are much less.

Initial guidance is provided by the launcher:

Any powered missile will impact the target on the first turn of movement; initial guidance by the launch racks is sufficient in this case.

Beyond that first movement impulse, they lose the ability to impact (as opposed to intercept) and are virtually worthless against a maneuvering target.

If you're going to stick with fuel measured in G-turns rather than G-burns it doesn't make much sense to have more than a single turn of fuel in a continuous burn missile.