Hairbear541
07/04/14 12:11 PM
173.189.222.215
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two questions
1- are NAC smooth or rifled bore
2- are any of the shells RAPed (rocket assisted propulaion)-[initially developed by the USN in mid-Vietnam era to give between 10 to 20% more range]
thanks for the help
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Cray
07/04/14 05:57 PM
97.101.96.171
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Quote:
Hairbear541 writes:
two questions
1- are NAC smooth or rifled bore
2- are any of the shells RAPed (rocket assisted propulaion)-[initially developed by the USN in mid-Vietnam era to give between 10 to 20% more range]
thanks for the help
Naval autocannons are not related to real world battleship guns. Your average USS Iowa Mark 7 16"/50 gun or Mark 12 5"/38 doesn't fling a 1-ton projectile to a distance of 720 kilometers at 50 kilometers per second or 164,000 feet per second (The Mark 7 fires a heavier shell than even NAC/40s, but only at 2680fps). Propulsion is by a contained nuclear explosion (see Tactical Operations), not bags of gun powder, since no chemical explosive expands that rapidly. To answer your questions:
1) Velocities like that aren't kind to rifling, so they're smoothbore.
2) They're not rocket assisted; it's kind of moot when you're detonating a nuke under their tail to get their current range.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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Hairbear541
07/04/14 07:16 PM
69.40.63.69
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well you never know how close to real life the game developers try to stick if you don't ask what might seem a stupid question . as far as tacops goes I don't have it yet , so as for initial propulsive charge I knew it couldn't be bagged cordite(no air in vacuum for it to ignite) , but a solid propellant charge much like the caseless ammo now in use I could imagine , but a contained nuclear detonation that's wicked . thanks for the feedback
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Hairbear541
07/04/14 08:34 PM
69.40.59.153
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since the propulsive charge is a contained nuclear detonation , what is the yield rate measured in , microtons or kilotons .
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Cray
07/04/14 10:23 PM
97.101.96.171
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Quote:
Hairbear541 writes:
well you never know how close to real life the game developers try to stick if you don't ask what might seem a stupid question
Ask away. I love to pontificate about BT from my ivory tower. 
Quote:
so as for initial propulsive charge I knew it couldn't be bagged cordite(no air in vacuum for it to ignite)
Cordite has plenty of oxygen, as do all gunpowders, so any guns will fire in a vacuum at least once. The breach (breech?) or brass cartridge of a gun only has about 1/2000th the oxygen needed to combust the gunpowder shoved into it, so the gunpowders need their own oxygen.
Even ye olde blackpowder is about 40-50% oxygen by weight. It is 1 part sulfur, 3 parts carbon, and 9 or 10 parts saltpeter. The saltpeter is potassium nitrate: potassium, nitrogen, and 3 parts oxygen. It'll fire fine in a vacuum.
Follow-up shots depend on the design of the gun. Your average firearm doesn't have the cooling or lubricants meant to work in a vacuum. Failure will be from overheating or jamming, not because the powder doesn't work.
Quote:
but a solid propellant charge much like the caseless ammo now in use I could imagine , but a contained nuclear detonation that's wicked . thanks for the feedback
Yep. The idea came from some 1940s-1950s concepts of nuclear propulsion that predated the cooler Project Orion, and also Project Pacer (a completely viable way to generate fusion power). I figured that if those guys thought it'd be viable to detonate small nukes in steel containers, then BT should have no problem pulling it off with its laser-triggered mini-nukes and magical materials.
Quote:
since the propulsive charge is a contained nuclear detonation , what is the yield rate measured in , microtons or kilotons
"Whatever it takes to fling projectiles hundreds of kilometers in one combat turn."
It's cool to specify things like "Naval autocannons use contained laser-triggered fusion explosions to propel their projectiles," but a lesson from writing for BT is that when you start giving hard numbers you'll run into the player who can prove it doesn't work for those numbers. So, TacOps stayed vague on that count.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
Edited by Cray (07/04/14 10:27 PM)
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Hairbear541
07/04/14 11:18 PM
69.40.62.206
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yes I've heard of that proposed propulsion system , but if I remember correctly the detonation were supposed to go off in roughly a bell shaped containment vessel to focus the blast rearwards . so I guess it makes sense to dust off ideas of the 40's and 50's and give them new life . talk about retrotech .
I know when I got out of the service there was a lot of talk about suitcase sized nucs , and now it's a fact , and the scuttle but was they were trying to get them even smaller with a blast radius of no more than the area of one big pro sports stadiums . so I guess just about anything is possible given enough research , time developing and money .
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Cray
07/06/14 07:39 PM
67.8.171.23
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Quote:
Hairbear541 writes:
yes I've heard of that proposed propulsion system , but if I remember correctly the detonation were supposed to go off in roughly a bell shaped containment vessel to focus the blast rearwards . so I guess it makes sense to dust off ideas of the 40's and 50's and give them new life . talk about retrotech .
Freeman Dyson oversaw the "Orion Project" by General Atomics in the late 1950s/early 1960s, which used external nuclear pulse propulsion. That's what you're describing, and is hands down the most famous of the nuclear pulse propulsion systems thanks to books like Niven and Pournelle's "Footfall." If you've never read Footfall, I highly recommend it. Humans versus aliens that ends with an American-built nuke-propelled (Orion-style) space battleship going toe to toe with the invaders' generation ship. I need to read that again.
http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
However, there were a number of earlier, different visions of nuclear pulse propulsion. Launching rockets with nuclear power started getting serious attention in (surprise) 1945, once there were tangible examples of nuclear power. For example, in 1946 Dandridge Cole at the Martin company (now part of Lockheed Martin) proposed "Helios." This would detonate mini-nuclear bombs (10 tons of TNT) in a 130-foot steel sphere weighing 500 tons. Between detonations, huge amounts of water would be sprayed into the chamber. The bombs would generate steam, directed out a rocket nozzle.
http://up-ship.com/blog/?p=5353
http://rocketdungeon.blogspot.com/2010/02/colehelios-internal-nuclear-pulse.html
Anyway, if the 1940s-1950s figured that they could contain mini-nukes with 500-ton steel structures, then I'm sure the 24th Century could figure out how to use a 3000-ton naval autocannons to fling cannon shells with some form of nuclear propulsion.
Quote:
I know when I got out of the service there was a lot of talk about suitcase sized nucs , and now it's a fact , and the scuttle but was they were trying to get them even smaller with a blast radius of no more than the area of one big pro sports stadiums . so I guess just about anything is possible given enough research , time developing and money .
The smallest nukes tested ran around 51lbs. They generated 10-ton yields, give or take, but wouldn't fit into a suitcase because of their odd shape. M388 The "Davy Crockett" recoilless rifle munition used the W54 warhead:
Picture of the M388 round: http://en.wikipedia.org/wiki/Davy_Crockett_(nuclear_device)#mediaviewer/File:Davy_Crockett_bomb.jpg
Article on the warhead: http://en.wikipedia.org/wiki/W54
Backpack weapon (for extra big backs): http://en.wikipedia.org/wiki/W54#mediaviewer/File:SADM_container_H-912.jpg
10 tons of TNT is comparable to the Oklahoma City bombing, which would mess up a stadium but, if it detonated in the middle of the field, wouldn't destroy it. (Very small increases in weight would bring the weapon up to 100 to 1000 tons of yield, which level the stadium.)
The ultra-tiny nukes like the Davy Crockett and its 10-ton explosion had weird effects. Usually, a nuke would broil and smash you with its blast and heat far beyond its lethal radiation dose radius. However, those little nukes were the opposite. They generated lethal radiation pulses far outside their lethal explosion radius. The M388 Davy Crockett would give a (probably) lethal dose of 600 rem at a quarter mile (400 meters), but would kill with its explosion at less than 100 meters on open ground. The extra special fun of the M388 Davy Crockett is that it only had a range of 1200 meters when fired by an M28 120mm recoilless rifle, so it was quite likely when NATO troops started firing it in the Fulda Gap to stop the Goddless Commie Hordes some Crockett users would be giving themselves fatal radiation doses.
That sounded like a good idea in the 1950s.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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Hairbear541
07/06/14 08:52 PM
173.189.217.118
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evening cray , you keep reminding me of things that had slipped my mind . there was another project I think was called project hyperion of a single stage to orbit vehicle from back when dr. von braun was still chief brain in charge at nasa . the design bears a striking resemblance to 2 of the military droppers used in bt (overlord & fortress) , so I guess one of the early bt designers must have at the very least seen the the consept pictures that were released to the public . size wise somewhere between the 2 droppers. supposed to be built in 2 variants , passenger and cargo . the only major difference I see is the propulsion suites . they would have been a great boon to the real conquest of space to really get it kick started . thanks for all the other info , since most of my info came to me from scuttle but from the navy nuc community , and then in very , very generalized terms . nothing really definite or with hard facts to back up their ramblings .
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Hairbear541
07/19/14 03:04 PM
173.189.223.224
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now strictly for anology sake were would the different NAC sizes fall in comparision to wet navy gun caliber sizes . questions- comments
the original old salty sea dog
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Cray
07/20/14 12:06 PM
67.8.171.23
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Quote:
Hairbear541 writes:
now strictly for anology sake were would the different NAC sizes fall in comparision to wet navy gun caliber sizes . questions- comments
Relatively small considering the size of the gun. The NAC 40 only fires a 2600-pound shell, on par with a 16-inch "super heavy" shell like the US Navy fired. The rest are smaller. The NAC/35 and NAC/30 fall within the range of lighter US 16-inch munitions, while the NAC/10 is closer to 10 or 11-inch. The NAC 20 and 25 fall in between.
That's all assuming the naval autocannon fires a single shell per shot. If smaller BT autocannons are any example, they might fire several to even dozens of shells per attack. In that case, caliber drops off rapidly.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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