TNE FF&S 2 Munition design

[snrdg082102]

Hello all,

I trying my hand at using TNE FF&S to design warheads and I'm not sure if my work is on the right track.

My first attempt is designing a standard size warhead.

TL 9 10 cm HE warhead:

Weight: 21 kg; Volume: .0042 m^3; Price: Cr210

DV: 20
Burst Size: 31 m

Penetration: Short range = 9/Medium = 8/Long = 7/Extreme = 4

 

[Timerover51]

I guess one question I would have is how much you want this to relate to the real world verses FF&S. In the real world, that would be a pretty heavy projectile for a 10cm weapon, you do not say if it is gun or howitzer or a gun-howitzer. The weight of 21 kilograms is almost the same weight at the projectile for the Russian 122mm howitzer, at 21.7 kilograms. The US 105mm howitzer round weighs 33 pounds, say 15 kilograms, while the older British 4.5 inch (114mm) weighed 35 pounds, just under 16 kilos. The complete round, projectile, cartridge case, and propelling charge for the 105mm is approximately 42 pounds, or 19 kilos.

For a rule of thumb figure on price for a normal HE round in WW2, a value of $1 per pound is in the ball park, and that includes the fuze, the most expensive part of the round, so for a 105mm round I would figure $42 in WW2. It depends on how much you want to allow for inflation, and for Dollar-Credit exchange rate. That looks to be about $4 to the Credit.

As for effective area of burst, for a single HE round, that would be an ellipse of 50 X 15 yards, the 50 yards laterally, the 15 yards range (or line of fire), which is your 50% casualty area for a standing, stationary man in level terrain, which converts to 45 X 13.7 meters. Personally, allowing for vagaries of fuze functioning and large fragments, you could use 50 X 15 meters just as well.

For penetration, with standard fuzes, you can figure that you can probably penetrate brick or stone structures at most any range, small log and earth bunkers at close range but it depends on overhead cover. For shooting at heavy walls, concrete, or reinforced concrete, you would be better off with a specialized steel concrete piercing fuze, otherwise, you stand the chance of the round breaking up with a low-order detonation.

For a shaped-charge, high explosive antitank round, because of the spin imparted by the gun's rifling, you should expect caliber penetration, i.e. penetration of armor equal to the caliber of the projective.

I also have the unit of fire data for various weapons. Would you want that posted here or emailed to you in a PDF file? And should I include effective burst area for mortars and artillery as well?

 

[snrdg082102]

Evening timerover51,

First thank you for the reply and request for clarification on what I'm asking.

I actually trying to confirm that I have grasped the design requirements for FF&S. Over the years I've found that while FF&S and other similar design systems usually don't match the real world, even though I wish they did.

FF&S warhead damage value (DV) is determined using diameter and modifiers.

Burst size is based on the HE warhead's concussion damage value and a modifier. HE has two munition modifiers criteria (1) gun or grenade and (2) mortar, rocket, or aerial bomb

The criteria I'm using is a TL 9 gun with a diameter of 10 cm and a muzzle velocity of 12.1 Mj.

Nice catch with the missing pieces for the warhead.


Thank you very much for the real world comparisons, just as I thought Traveller's materials are heavier than the real world.

Please send me the all the material as PDF, that way I can store to read and probably print out.

Thanks for the time, supporting documentation, and especially the help.

I guess one question I would have is how much you want this to relate to the real world verses FF&S. In the real world, that would be a pretty heavy projectile for a 10cm weapon, you do not say if it is gun or howitzer or a gun-howitzer. The weight of 21 kilograms is almost the same weight at the projectile for the Russian 122mm howitzer, at 21.7 kilograms. The US 105mm howitzer round weighs 33 pounds, say 15 kilograms, while the older British 4.5 inch (114mm) weighed 35 pounds, just under 16 kilos. The complete round, projectile, cartridge case, and propelling charge for the 105mm is approximately 42 pounds, or 19 kilos.

For a rule of thumb figure on price for a normal HE round in WW2, a value of $1 per pound is in the ball park, and that includes the fuze, the most expensive part of the round, so for a 105mm round I would figure $42 in WW2. It depends on how much you want to allow for inflation, and for Dollar-Credit exchange rate. That looks to be about $4 to the Credit.

As for effective area of burst, for a single HE round, that would be an ellipse of 50 X 15 yards, the 50 yards laterally, the 15 yards range (or line of fire), which is your 50% casualty area for a standing, stationary man in level terrain, which converts to 45 X 13.7 meters. Personally, allowing for vagaries of fuze functioning and large fragments, you could use 50 X 15 meters just as well.

For penetration, with standard fuzes, you can figure that you can probably penetrate brick or stone structures at most any range, small log and earth bunkers at close range but it depends on overhead cover. For shooting at heavy walls, concrete, or reinforced concrete, you would be better off with a specialized steel concrete piercing fuze, otherwise, you stand the chance of the round breaking up with a low-order detonation.

For a shaped-charge, high explosive antitank round, because of the spin imparted by the gun's rifling, you should expect caliber penetration, i.e. penetration of armor equal to the caliber of the projective.

I also have the unit of fire data for various weapons. Would you want that posted here or emailed to you in a PDF file? And should I include effective burst area for mortars and artillery as well?

 

[djwildstar]

TL 9 10 cm HE warhead:
Weight: 21 kg;
Volume: .0042 m^3;
Price: Cr210
DV: 20
Burst Size: 31 m
Penetration: Short range = 9/Medium = 8/Long = 7/Extreme = 4

I checked the TNE FF&S second printing, and get the following for a TL-9 10cm HE shell:
Concussion = Tm x D^2 = 0.2 x 10^ = 20
Burst = Sqrt(Concussion) x Mm = Sqrt(20) * 7 = 31.3
Penetration = D x 1.5 - 7 = 10 x 1.5 - 7 = 8C
Mass = 21 (from table on page 141)
Volume = Mass/5000 = 21/5000 = 0.0042
Price = Mass x 10 = 210

The only error I see is that you adjusted the penetration per the rules for KEAP rounds at the bottom of the right-hand column of page 140. This only applies to kinetic penetrators (such as solid shot, hight-velocity armor-piercing, APFSDSDU, etc.) and is incorrect for HE ammunition. HE ammunition depends on the bursting charge in the shell for its penetration, and is constant at all ranges. The correct penetration is 8C per the rules at the top of the right-hand column on page 140.

 

[snrdg082102]

Late evening from the Pacific Northwest djwildstar,

Thanks for checking my work and letting me know I was mixing up rules. At least I now I'm sure my math, at least for the HE round, is working. The problem was not getting that HE has a single penetration value and how to present the data.

Of course part of my confusion is because I've also been working with CT Striker Book 3 which has a contact penetration, burst size, and fragmentation penetration.

The next installment will be for the KEAP and related rounds, hopefully I'll do better. Of course I did get four items right for the HE round, which isn't to bad in my book.

Thanks again djwildstar for checking my work.

I checked the TNE FF&S second printing, and get the following for a TL-9 10cm HE shell:
Concussion = Tm x D^2 = 0.2 x 10^ = 20
Burst = Sqrt(Concussion) x Mm = Sqrt(20) * 7 = 31.3
Penetration = D x 1.5 - 7 = 10 x 1.5 - 7 = 8C
Mass = 21 (from table on page 141)
Volume = Mass/5000 = 21/5000 = 0.0042
Price = Mass x 10 = 210

The only error I see is that you adjusted the penetration per the rules for KEAP rounds at the bottom of the right-hand column of page 140. This only applies to kinetic penetrators (such as solid shot, hight-velocity armor-piercing, APFSDSDU, etc.) and is incorrect for HE ammunition. HE ammunition depends on the bursting charge in the shell for its penetration, and is constant at all ranges. The correct penetration is 8C per the rules at the top of the right-hand column on page 140.

 

[snrdg082102]

I was not awake when I replied back since I forgot to include a revised data card for the HE round reflecting djwildstar's corrections

TL 9 10 cm HE warhead:

Weight: 21 kg; Volume: .0042 m^3; Price: Cr210

Concussion DV: 20

Burst Size: 31. 3 round to 31 m

Penetration: 8C