Anti-air weapons

Discuss the Traveller RPG and its many settings
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DFW
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Postby DFW » Sun Mar 20, 2011 12:45 am

barnest2 wrote:Though the A-10's gun sin't designed as an air to air weapon :wink:
260mm maybe. Not 26mm...
Right, for air to air I was thinking of the 20 mm vulcan.
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Postby apoc527 » Sun Mar 20, 2011 12:48 am

FWIW, the hypervelocity orbital defense gun is only 26mm because it's "hypervelocity" meaning it's probably launching its projectiles at high hypersonic speeds. Regardless, the entry for the heavy hypervelocity cannon says it can attack ground targets up to 5km away or "targets in low orbit if it can elevate high enough." The same would be true for the orbital defense gun.

I suspect that the "5km" range is really just supposed to represent the horizon (these are direct fire guns), because if you tried any kind of indirect fire, I'm pretty sure you'd be targeting something a few thousand kilometers away given the speed of those projectiles.

As always, GURPS Traveller Ground Vehicles is instructive. The 80mm mass driver, which seems to be slightly lower tech than the "orbital defense gun" can fire an APFSDSDU round about 40 km.
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Postby far-trader » Sun Mar 20, 2011 1:00 am

apoc527 wrote: I suspect that the "5km" range is really just supposed to represent the horizon (these are direct fire guns)...
That makes sense, though the use of that as a range definition without such notation is... misleading at best :)

And even then your horizon will differ depending on world size and terrain features. And as you note if it has the range to do orbital attacks it has the range for over the horizon attacks. Very far over the horizon in fact. And there are guns that will do this through various indirect targeting methods, and I'm sure their listed ranges are the extreme parabolic range maximum, with users left to decide how to use that capacity, either direct los or indirect.

I was going to suggest the decimal "error" for the round size above earlier :)

I'd add a decimal "error" note to the range as well.

So the gun fires a 26cm round with a range of 500km* :twisted:

* that will just reach the lower bounds of LEO at about 200km with a little punch left before falling back (just a guess, but 500km ballistic is not going to get you 500km straight up)
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DFW
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Postby DFW » Sun Mar 20, 2011 1:27 am

apoc527 wrote:FWIW, the hypervelocity orbital defense gun is only 26mm because it's "hypervelocity" meaning it's probably launching its projectiles at high hypersonic speeds.
Even at hypersonic speed, a small 26 mm projectile won't have enough inertia to reach sub orbital altitudes at it will will shed speed too quickly in atmosphere.
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Postby apoc527 » Sun Mar 20, 2011 4:35 am

DFW wrote:
apoc527 wrote:FWIW, the hypervelocity orbital defense gun is only 26mm because it's "hypervelocity" meaning it's probably launching its projectiles at high hypersonic speeds.
Even at hypersonic speed, a small 26 mm projectile won't have enough inertia to reach sub orbital altitudes at it will will shed speed too quickly in atmosphere.
That could also be a reason for its lower-than-expected range. A 260mm projectile would probably be heavy enough.

OTOH, a 26mm projectile made of solid superdense might have enough inertia after all!
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Postby dreamingbadger » Sun Mar 20, 2011 9:12 am

add a "0" to the end job done
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Postby DFW » Sun Mar 20, 2011 9:50 am

apoc527 wrote:OTOH, a 26mm projectile made of solid superdense might have enough inertia after all!
I gave that observation based on the atmospheric drop off rate of a 30 mm DU round... No, you are right in the 1st part. A 260 mm could probably do it.
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Postby Egil Skallagrimsson » Sun Mar 20, 2011 8:45 pm

barnest2 wrote:Ha, that's awesome... I may have to steal that, thankee...

I was flicking through my copy of the CsC (just managed to find it :evil:)
The support weapons and artillery... is it just me or are they at tech levels too high for them really... I mean surely there should be a MG at tl4?
And some artillery? other than the field gun I mean...
CSC, especially the larger weapons, is often daft, even when not suffering from misprints and typos.

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Postby barnest2 » Sun Mar 20, 2011 8:47 pm

Oh, I know... It's a little silly really... oh well...
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Postby Solomani666 » Sun Mar 20, 2011 11:24 pm

Orbital Defence Gun:

TL 14
35 Tones
Cost 40 MCr
Orbital Range of 1000 Kilometers

Does 20d6 /50 = A BIG FAT "ZERO" damage against a starship.



I compare this to a 6 Ton Railgun Barbette and I have to ask:

"Does anyone have any idea of what this gun could possibly be used for?"


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Postby rust » Sun Mar 20, 2011 11:31 pm

Solomani666 wrote: Does 20d6 /50 = A BIG FAT "ZERO" damage against a starship.
Since the ammunition is "Ultimate-AP" it ignores 100 points of armour
(see CSC page 110).
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Postby Jeraa » Sun Mar 20, 2011 11:37 pm

Solomani666 wrote:
Does 20d6 /50 = A BIG FAT "ZERO" damage against a starship.

.
20d6 averages to 70 points of damage. 70/50 = 1.4 damage on average. If you roll a maximum of 120, it would do 2.4 damage. And even a single point of damage is enough to get a Single Hit on an unarmored starship.

Edit: And as rust mentioned it ignores 100 points of armor as well. Though that is an awfully lot in starship combat. I would scale that too. 100/50 = ignoring 2 starship armor.
Last edited by Jeraa on Sun Mar 20, 2011 11:41 pm, edited 1 time in total.
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Postby Solomani666 » Sun Mar 20, 2011 11:41 pm

Jeraa wrote:
Solomani666 wrote:
Does 20d6 /50 = A BIG FAT "ZERO" damage against a starship.

.
20d6 averages to 70 points of damage. 70/50 = 1.4 damage on average. If you roll a maximum of 120, it would do 2.4 damage. And even a single point of damage is enough to get a Single Hit on an unarmored starship.
Mercenary Page 73
Number of "Damage Dice" / 50 rounded down not "Damage Points"

.
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Postby rust » Sun Mar 20, 2011 11:46 pm

Solomani666 wrote: Mercenary Page 73
Number of "Damage Dice" / 50 rounded down not "Damage Points"
My copy says:
must divide its damage by 50
Damage, not damage dice.
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Postby Jeraa » Sun Mar 20, 2011 11:48 pm

Stupid rule, which results in weapons unable to damage a starship that should be able to. IF you divide total damage by 50 instead of dice, at least the heaver weapons can damage a ship.

Edit: If you look at the example combat, it does show the damage dice being divided by 50.
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Postby rust » Sun Mar 20, 2011 11:51 pm

Jeraa wrote: Edit: If you look at the example combat, it does show the damage dice being divided by 50.
Yep, but I very much distrust this rule - either the rule is right and the
example wrong, or it is just plain silly.

Anyhow, the "Ultimate AP" still ignores 100 points of armour, so it would
be hard not to damage a starship with it.
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Postby Solomani666 » Sun Mar 20, 2011 11:52 pm

rust wrote:
Solomani666 wrote: Mercenary Page 73
Number of "Damage Dice" / 50 rounded down not "Damage Points"
My copy says:
must divide its damage by 50
Damage, not damage dice.

Are you reading the English or German version of the rules?
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Postby rust » Sun Mar 20, 2011 11:54 pm

Solomani666 wrote: Are you reading the English or German version of the rules?
English, which does not make the contradiction between "damage" in the
rule and "damage dice" in the example disappear. :lol:
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Postby Jeraa » Sun Mar 20, 2011 11:54 pm

My version is english, and says the same thing.

And if it was dividing the damage dice by 50, not even the meson accelerator on page 105 of Mercenary can damage a starship. And thats the most powerful weapon I could find in the book.

Edit: Also, the Aerospace Defense Laser (CSC, page 125) specifically mentions being used against small craft and starships. At 16d6 damage, if the scaling was by damage dice, this weapon could not scratch either one. If the scaling was by points, it would still do 1.12 damage on average, which is enough to rate as a Single Hit.

Based on what I can find, the rule was meant to scale the damage after rolling by 50, not the damage dice themselves. Its the only thing that makes sense.
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Postby DFW » Mon Mar 21, 2011 12:40 am

Solomani666 wrote:Orbital Defence Gun:

TL 14
35 Tones
Cost 40 MCr
Orbital Range of 1000 Kilometers

Does 20d6 /50 = A BIG FAT "ZERO" damage against a starship.
I compare this to a 6 Ton Railgun Barbette and I have to ask:

"Does anyone have any idea of what this gun could possibly be used for?"
At 35 Dtons it is a medium star shipl ship sized weapon. Common sense would rule IMTU.

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