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(spoilers) what is the termnal V of a Long 12 cannon barrel?

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Re: (spoilers) what is the termnal V of a Long 12 cannon bar
Post by Louis R   » Thu Nov 17, 2016 2:09 pm

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IIRC those are essentially Parrot Rifles. Which means a 12" would be well short of 20' long and well over 12,000lbs: a real 10" model is 156" for 26,000lbs and change.

FYI a "modern" [nobody built them after c.1912] 12" rifle is ~50' long & ~50T. So you can see that Safehold still has a way to go.

WeberFan wrote:Thought he was talking about one of the new 12" Fultyn Rifles...
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Re: (spoilers) what is the termnal V of a Long 12 cannon bar
Post by evilauthor   » Sun Nov 20, 2016 7:36 pm

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Also, a cannon carried on a Zeppelin is far less effective than a single spotter balloon directing entire battalions of ground based artillery to fire on targets.

The only advantage the Zeppelin would have would be the ability to range beyond the reach of ground based artillery. But it would be so inaccurate and do so little damage to what it did hit that it just wouldn't be cost effective, not with the kind of tech lead Charis has had over the Church armies.
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Re: (spoilers) what is the termnal V of a Long 12 cannon bar
Post by chrisd   » Mon Nov 21, 2016 8:40 am

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Louis R wrote:Stabilisation is a solvable problem. In fact, Barnes-Wallis solved it by hand when he designed the Tallboy & Grand Slam bombs in 1940. Which are _not_ weapons you're going to be emulating with captured smooth-bore gun barrels even if they're Fultyn Guns. A major reason that the Brits never made many of them is the machining required to smooth the body enough to be aerodynamic. The half-dozen machine shops that could handle 10,000lb castings had to-do lists from hell. Nonetheless, keeping them stable in the trans-sonic regime is a matter of getting the right spin on them. And that in turn is a matter of getting the tail assembly design just right. A non-trivial problem for anybody except OWL.

However, as it turns out, that's not a problem from 10,000'. Terminal velocity will be well under 245m/s - how much under depends on just how good your aerodynamicist is - or Mach0.8. Stability isn't going to be a huge problem at that speed, but it would still surprise me if the 'bomb' didn't break up on impact. Cast iron is brittle, and most Safehold steels are still not that much better, which is what forces them to use wire-wound barrels for their best guns. Tallboys dropped from 18,000' did go supersonic, and are known to have penetrated 60' of earth and rock or 16' of reinforced concrete, so I'm guessing that cawest's design, assuming it didn't just break up, would make it through 10-12' of packed dirt.

Of course, that also assumes you could build suitable fuses for them, too.

Dilandu wrote:


Do not forget the RN/USAAF joint effort at a "bunker buster" initially using a naval 8" AP shell with seven 2" AA rockets bolted "up its ar5e", subsequently developed into the "Disney Bomb".

Too long to fit in the bomb bay of a Lancaster but two could be carried "underwing" by a B17.

Dropped from altitude the rockets were fired at 5,000 ft by a barometric igniter and, as such, timed to be still burning/accelerating at ground impact at considerably over "Mach 1".

They shattered part of the Atlantic Wall and the U-boat pens and IIRC got through over 20ft of Reinforced Concrete before exploding.

Very bad for U-boat crew morale.

See both Neville Shute's autobiography "Slide Rule" and Edward Terrell's "Admiralty Brief"
Last edited by chrisd on Mon Nov 21, 2016 11:02 pm, edited 1 time in total.
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Re: (spoilers) what is the termnal V of a Long 12 cannon bar
Post by saber964   » Mon Nov 21, 2016 10:24 am

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Suggest you guy's look at the Naval Weapons page at navweaps.com. This site has information on naval guns going all the way back to the 1880's. My guess is RFC was using information off this page for the guns used on the KHVII class ships
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