Striker CBM Burst Size

[snrdg082102]

Afternoon all,

The HE round has per Book 1 Rule 24 Indirect fire a ground and air burst size dependent on the fuse. The ground burst size is listed in the CPR Gun table on DST pages 6 and 7. The air burst size per Book 1 is 2 x the ground burst size

Can a CBM round have both an air burst and a ground burst size similar to an HE round?

 

[Carlobrand]

Striker Book 1, Rule 24, Indirect Fire Hit Determination:

"Air Burst HE: This type of round (actually the same round as ground burst with a different fuse) inflicts fragmentation hits only, but its burst size is twice that specified for the weapon. ... CBM: This type of round inflicts both contact hits and fragmentation hits. It s burst size is four times that specified for the weapon."

Air burst size is 2x ground burst size. CBM burst size is 4x ground burst size. The CBM round's submunitions are little 4cm rounds, by the Striker rules. The 4cm round doesn't earn a fragment penetration rating until TL 12, so air-bursting a 4cm - and by extension a CBM - is pretty much pointless until that point.

Note that the TL 7 CBM has a contact and frag penetration of 6; again, the TL 7 4cm HE has no frag penetration. In other words, the game's assuming the person got directly hit by the 4 cm submunition (or was close enough as made no difference), not by fragments. The TL 8+ CBMs have a contact penetration equal to a 4 cm HEAP and a frag penetration equal to a 4cm HE direct hit; again, there's no HE fragment penetration to the 4cm until TL12, and then it's a 1, so in that instance you're either getting directly hit (and taking HEAP damage) or are so close that the blast gets you (and take HE damage), and fragments are not an issue.

The CBM main round ejects its submunitions some ways above the ground in order to ensure an effective dispersal pattern, and then they fall the rest of the way and do their bit. If you wanted an air burst CBM (assuming TL 12+), you'd have to make sure the submunitions dispersed evenly over that larger area in order to get that larger burst size - or they'd just overlap each other to no effect. Having the main round disperse them higher doesn't ensure you'd get that optimal wider dispersal pattern; you'd have to design a round specifically to achieve it. At the end of that effort, you'd have a non-canon but perfectly reasonable specialized air-burst CBM round.

Except ... that it only has a penetration of 1, and by TL 12 everyone and their third cousin twice removed is in some sort of defensive armor - cloth at the very least. So, the new TL 12 air burst CBM wouldn't actually do much of anything unless you were firing it at a crowd of rioting civilians (which is considered to be very poor taste) or wanted it specifically for the TL6-and-below armies (who are a pushover for TL12 folk, so a specialized weapon isn't really needed).

 

[snrdg082102]

Morning Carlobrand,

Thank you for the review of Book 1 Rule 24, which is what started this particular topic while I was messing around with an 8.8 cm round.

Striker Book 1, Rule 24, Indirect Fire Hit Determination:

"Air Burst HE: This type of round (actually the same round as ground burst with a different fuse) inflicts fragmentation hits only, but its burst size is twice that specified for the weapon. ... CBM: This type of round inflicts both contact hits and fragmentation hits. It s burst size is four times that specified for the weapon."

The burst size of the CBM round is, as I thought, equivalent to the HE round air burst. My original impression was that the CBM had a single burst size. Unfortunately, I read through Book 1 Rule 24 which resulted in trying to figure out if the CBM burst size was similar to the HE ground and air burst sizes.

Obviously, my thought processes were badly scattered otherwise I would not have needed to ask the obvious.

Air burst size is 2x ground burst size. CBM burst size is 4x ground burst size. The CBM round's submunitions are little 4cm rounds, by the Striker rules. The 4cm round doesn't earn a fragment penetration rating until TL 12, so air-bursting a 4cm - and by extension a CBM - is pretty much pointless until that point.

Note that the TL 7 CBM has a contact and frag penetration of 6; again, the TL 7 4cm HE has no frag penetration. In other words, the game's assuming the person got directly hit by the 4 cm submunition (or was close enough as made no difference), not by fragments. The TL 8+ CBMs have a contact penetration equal to a 4 cm HEAP and a frag penetration equal to a 4cm HE direct hit; again, there's no HE fragment penetration to the 4cm until TL12, and then it's a 1, so in that instance you're either getting directly hit (and taking HEAP damage) or are so close that the blast gets you (and take HE damage), and fragments are not an issue.

The CBM round fragmentation penetration round, per DS 2 Step L 5 Striker Book 3 page 15, is equal to the contact penetration of a 4 cm HE round not the HE round fragmentation penetration value.

The CBM main round ejects its submunitions some ways above the ground in order to ensure an effective dispersal pattern, and then they fall the rest of the way and do their bit. If you wanted an air burst CBM (assuming TL 12+), you'd have to make sure the submunitions dispersed evenly over that larger area in order to get that larger burst size - or they'd just overlap each other to no effect. Having the main round disperse them higher doesn't ensure you'd get that optimal wider dispersal pattern; you'd have to design a round specifically to achieve it. At the end of that effort, you'd have a non-canon but perfectly reasonable specialized air-burst CBM round.

Except ... that it only has a penetration of 1, and by TL 12 everyone and their third cousin twice removed is in some sort of defensive armor - cloth at the very least. So, the new TL 12 air burst CBM wouldn't actually do much of anything unless you were firing it at a crowd of rioting civilians (which is considered to be very poor taste) or wanted it specifically for the TL6-and-below armies (who are a pushover for TL12 folk, so a specialized weapon isn't really needed).

The dispersal of the bomblets or sub-munitions you described is how I thought, not as clearly detailed though, the CBM worked.

Using the HE contact penetration column instead of the HE fragmentation column a TL 12 CBM round, unless I can't count, has a fragmentation penetration value of 8.

Thanks again for the support.

 

[shield]

I always thought that CBMs were a special case and were airburst already - in order to disperse those bomblets and hence the burst area 4 x HE ground burst stands.

 

[snrdg082102]

Howdy shield,

I always thought that CBMs were a special case and were airburst already - in order to disperse those bomblets and hence the burst area 4 x HE ground burst stands.

My first go through of the ammunition rules I did only one burst size for any round that has that characteristics.

Also I vaguely recalled that a CBM round broke apart at a predetermined height to disperse the sub-munitions. The type of sub-munitions can be a single type or a combination types which include anti-personnel, anti-tank, or munitions designed to punch holes in say a runway.

Then with pointers from members here I began checking the rules in Book 1 and 2. Reviewing Book 1 Rule 24 is what put the bee in my bonnet that the CBM burst size was similar to an HE round and had two sizes.

Between you and Carlobrand the bee in my bonnet has been dislodged and the CBM round burst size has a single value.

 

[Carlobrand]

The CBM round fragmentation penetration round, per DS 2 Step L 5 Striker Book 3 page 15, is equal to the contact penetration of a 4 cm HE round not the HE round fragmentation penetration value.

I'm sorry, I'm explaining poorly again.

A CBM - cluster bomblet munition - is a bomb that consist of a lot of little bombs inside a big casing. It achieves its wide burst area by throwing those bomblets out away from the casing as it falls; there are a number of fascinating strategies to do that. That part you almost certainly know. I wasn't referring to the CBM's fragmentation penetration. I was referring to a hypothetical case in which you set the bomblets themselves to blow up high above the target after ejection so you could shower the target with fragments from the little bomblets, rather than having the bomblets fall and hit the target directly.

In other words, I was exploring your idea of having an air-burst CBM. In that case, the fragments would be fragments of the little submunitions.

The dispersal of the bomblets or sub-munitions you described is how I thought, not as clearly detailed though, the CBM worked.

Using the HE contact penetration column instead of the HE fragmentation column a TL 12 CBM round, unless I can't count, has a fragmentation penetration value of 8...

You are correct: a TL 12 CBM round has a fragmentation penetration of 8, equal to the contact penetration of a 4 cm HE round, which is what the CBM's submunitions are. However, as I said, I wasn't trying to describe the canon CBM round. I was speculating on the features of a hypothetical airburst CBM in which the little bomblets blew up in the air instead of on contact.

 

[snrdg082102]

Morning Carlobrand,

Nope, your explanation was great my interpretation was off the mark, not to mention my hazy attempt at asking if the CBM has two brust size values like HE.

Had my brain not been locked in a loop I would have realized the CBM burst size was in the air above the target zone.

My apologies for the impression I was thinking about the sub-munitions
also having an air burst value.

I agree then that the smaller muntions air burst size frag pen would not be effective.

Remember Carlobrand I am but a poor old simple retired submarine sailor that more often than not needs to have stuff explained in simple words.

I'm sorry, I'm explaining poorly again.

A CBM - cluster bomblet munition - is a bomb that consist of a lot of little bombs inside a big casing. It achieves its wide burst area by throwing those bomblets out away from the casing as it falls; there are a number of fascinating strategies to do that. That part you almost certainly know. I wasn't referring to the CBM's fragmentation penetration. I was referring to a hypothetical case in which you set the bomblets themselves to blow up high above the target after ejection so you could shower the target with fragments from the little bomblets, rather than having the bomblets fall and hit the target directly.

In other words, I was exploring your idea of having an air-burst CBM. In that case, the fragments would be fragments of the little submunitions.



You are correct: a TL 12 CBM round has a fragmentation penetration of 8, equal to the contact penetration of a 4 cm HE round, which is what the CBM's submunitions are. However, as I said, I wasn't trying to describe the canon CBM round. I was speculating on the features of a hypothetical airburst CBM in which the little bomblets blew up in the air instead of on contact.

 

[Timerover51]

Hmmm, I will need to look at Striker to see why the 4CM bomblet has no fragmentation effect. 4CM is the caliber of the current US Army grenade launcher, and has been that size since the Vietnam War. The effective casualty radius of the 4CM grenade is 5 meters. That does assume unarmored targets, although I have my doubts about the use of full-body cloth suits, so even with some ballistic protection for the torso, you still have exposed arms and legs.

The HEAP round, High Explosive Armor Piercing, for the 4CM launcher is designed to produce the same fragment radius and also penetrate 2 inches/5CM of armor. Again, that is what the actual current round does.

I probably should go back and check all of the Striker data against my copy of Ballistic Performance of Ammunition, and also radius of effective burst for artillery and mortar rounds from some other sources. Probably need to check AP performance too. I was planning on getting out my NDRC Weapons Effects info anyway, so will kill two birds with one stone.

 

[snrdg082102]

Morning timeover51,

Thanks for the reply and providing some up to dates on real world munitions.

Hmmm, I will need to look at Striker to see why the 4CM bomblet has no fragmentation effect. 4CM is the caliber of the current US Army grenade launcher, and has been that size since the Vietnam War. The effective casualty radius of the 4CM grenade is 5 meters. That does assume unarmored targets, although I have my doubts about the use of full-body cloth suits, so even with some ballistic protection for the torso, you still have exposed arms and legs.

The HEAP round, High Explosive Armor Piercing, for the 4CM launcher is designed to produce the same fragment radius and also penetrate 2 inches/5CM of armor. Again, that is what the actual current round does.

I probably should go back and check all of the Striker data against my copy of Ballistic Performance of Ammunition, and also radius of effective burst for artillery and mortar rounds from some other sources. Probably need to check AP performance too. I was planning on getting out my NDRC Weapons Effects info anyway, so will kill two birds with one stone.

One of the things I've found when translating a real world object with a design sequence, in this cast Traveller, is that they usually don't match. One example is my attempt to recreate the World War II German 8.8 cm canon used in the roles of anti-aircraft, tank main, and anti-tank guns.


In MT I've tried, using the COACC design sequence and maritime ship design sequence found in three or four issues of the Challenge magazine to recreate some real world aircraft and ships. In COACC some of the aircraft I tried came in close in some specification and in others they weren't even close. In the Challenge article on maritime ship design I tried recreating the HMS Hood and Titanic. Unfortunately, I haven't gotten past the step for the propellers since they method for calculating the speed doesn't come close to the real world speeds of the two ships.


Again thank you for the new data on munitions.

 

[Timerover51]

Morning timeover51,

Thanks for the reply and providing some up to dates on real world munitions.



One of the things I've found when translating a real world object with a design sequence, in this cast Traveller, is that they usually don't match. One example is my attempt to recreate the World War II German 8.8 cm canon used in the roles of anti-aircraft, tank main, and anti-tank guns.


In MT I've tried, using the COACC design sequence and maritime ship design sequence found in three or four issues of the Challenge magazine to recreate some real world aircraft and ships. In COACC some of the aircraft I tried came in close in some specification and in others they weren't even close. In the Challenge article on maritime ship design I tried recreating the HMS Hood and Titanic. Unfortunately, I haven't gotten past the step for the propellers since they method for calculating the speed doesn't come close to the real world speeds of the two ships.


Again thank you for the new data on munitions.

Are those design sequences available online? I have some background in naval architecture, and several books on warship design, so I would be interested in at least the naval design set up. They are worried about designing propellers? Methinks some people had WAY too much time on their hands when they put that sequence together.

Would you be interested in what I come up with on real world weapon effects?

 

[snrdg082102]

Hello again timerover51,

Are those design sequences available online? I have some background in naval architecture, and several books on warship design, so I would be interested in at least the naval design set up. They are worried about designing propellers? Methinks some people had WAY too much time on their hands when they put that sequence together.

Would you be interested in what I come up with on real world weapon effects?

COACC can be ordered through Drivethrurpg.com in electronic format.

The naval design sequence is titled Wet Navy and was written by Terrence R. McInnes in three parts in Challenge 53, 54, and 60. Charles G. Gannon wrote a follow-up piece titled Wood & Wind Steel & Steam in Challenge 61.

Harry Bryan is attempting to pull the Wet Navy article by Mr. McInnes into a single book. Unfortunately, I got distracted and lost touch with his efforts.

The MegaTraveller CD-ROM by Far Future Enterprises may have the article as part the collection.

Yes, I would be interested on anything relating to the research on real world weapons relating to Traveller.

 

[Timerover51]

I will see what I can do about getting some accurate data posted here, and probably some fragment pattern diagrams too. The actual fragment pattern of a HE shell resembles a butterfly when viewed from above. The greatest range is to the sides of the burst, the shortest effective fragment range is in the direction of fire, while you have a bit longer range for fragments further down range, but considerably shorter than the effective range to the sides as well. A mortar comes closest to achieving a circular pattern because of the steepness of the trajectory. Bomb fragment patterns work the same way.

Also, generally all fragment casualty radii are based on a probably that 50% of the vulnerable individuals in the burst radius will become casualties. That assumes standing, non-moving, person in flat terrain. Walking reduces the vulnerability, while rough terrain or prone troops reduce it greatly. Shell expenditure on dug-in troops with overhead cover starts at 100 times more than required for casualty production of standing, non-moving, troops in flat terrain.

I am going to try and figure out posting of images to the site, and then post some of the data that I have.

 

[snrdg082102]

Hello timerover51,

I was going to reply on the same day as this came in, unfortunately I was working on rebuilding my spreadsheet for Striker Book 3 DS 2 and forgot until now.

I will see what I can do about getting some accurate data posted here, and probably some fragment pattern diagrams too. The actual fragment pattern of a HE shell resembles a butterfly when viewed from above. The greatest range is to the sides of the burst, the shortest effective fragment range is in the direction of fire, while you have a bit longer range for fragments further down range, but considerably shorter than the effective range to the sides as well. A mortar comes closest to achieving a circular pattern because of the steepness of the trajectory. Bomb fragment patterns work the same way.

Also, generally all fragment casualty radii are based on a probably that 50% of the vulnerable individuals in the burst radius will become casualties. That assumes standing, non-moving, person in flat terrain. Walking reduces the vulnerability, while rough terrain or prone troops reduce it greatly. Shell expenditure on dug-in troops with overhead cover starts at 100 times more than required for casualty production of standing, non-moving, troops in flat terrain.

I am going to try and figure out posting of images to the site, and then post some of the data that I have.

Thanks for the information on the real world frag pattern and the mayhem that follows.

Most games I know of simplify the pattern, which for me is probably the best since I can't draw a butterfly or a straight line. Give me a round can and I might get close to a circle.