Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

US Navy's Railgun Now Undergoing Tests in New Mexico

thedrive.com

Post reply on HN
Print view View original

231–240 of 277 posts

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#231

Post by PopeDotNinja »

CapricornNoble wrote: post #225
PopeDotNinja wrote: post #222

Earlier quoted context omitted.

> ...huge battleship guns ... were slow to fire ... I was curious about how fast battleships could actually fire, so I googled around and found a couple stats. On an Iowa class battleship: - Armed with nine 16"/50 caliber Mark 7 guns [1] - Each 16" gun is quoted as having a firing rate of 2 rounds per minute [2] - Each shell weighed between 1900lbs / 865kg and 2700lbs / 1225kg pounds [3] So math says 2 rounds/minute…

A few minor corrections. The 16-23 rounds/minute is for the secondary battery of 5" guns, not the primary battery of 16" guns. If you watch a video of the loading/firing process of a 16" inch gun you'll quickly see why a firing rate of 1 round per 3-5 seconds is physically impossible. So 2/min * 9 guns * [900kg;1225kg]/gun = 16,200kg/min high explosive broadside or 22,050kg/min armor piercing broadside Your concludin…

Aw, thanks for the correction. My eyes missed the section break as I was scanning. Will fix.

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#232

Post by CapricornNoble »

minikites wrote: post #68
SEJeff wrote: post #65

Earlier quoted context omitted.

Do you not see that materials science from high performance cruise missiles might work its way through other uses of materials science such as structural engineering and bridges? Bridges can be used to hold tanks, does that mean all bridge engineers are bad?

There's no way other than weapons engineering to make those discoveries?

The survival instinct is the greatest motivator of human activity. Nothing provides an impetus for the mind to innovate quite like "figure this shit out or we're dead."

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#233

Post by percutaneous »

sandworm101 wrote: post #230

Some forgotten limitations of railguns: There is a maximum speed for projectiles in naval warfare. Earth is round. So anything moving too fast (~8000m/s) simply cannot hit distant targets. If fired horizontally, the shell will climb up as the earth curves away. This causes all sorts of difficulties if trying to attack another ship. At best, your shells will hit horizontally, far above the waterline. You would need a…

Theoretically you could have a projectile with downforce. This would allow you to break that limit. I imagine it's highly impractical though. I hadn't thought of that limit though, good comment!

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#234

Post by CapricornNoble »

Waterluvian wrote: post #39
Someone1234 wrote: post #26

Earlier quoted context omitted.

Plus doesn't infrastructure spending normally result in higher returns than it costs? > A recent Business Roundtable study found that $737 billion in public investment over 10 years would set us on the path toward reviving our national infrastructure. While those numbers seem daunting, the report also showed that every additional dollar invested in infrastructure delivers roughly $3.70 in additional economic growth o…

Yeah. So I forget macroeconomics class from a long time ago. But there's some effect where a dollar changing hands in a local economy 3 or 4 times has a huge multiplicative effect on economic growth. And being labour and trade intensive means you can campaign on creating jobs for your blue collared workers.

That's the aptly named Multiplier Effect: https://en.wikipedia.org/wiki/Multiplier_(economics)

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#235

Post by cascom »

sandworm101 wrote: post #230

Some forgotten limitations of railguns: There is a maximum speed for projectiles in naval warfare. Earth is round. So anything moving too fast (~8000m/s) simply cannot hit distant targets. If fired horizontally, the shell will climb up as the earth curves away. This causes all sorts of difficulties if trying to attack another ship. At best, your shells will hit horizontally, far above the waterline. You would need a…

Article references a goal of achieving a 100 mile range? How do they plan on doing that then?

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#236

Post by PopeDotNinja »

steve19 wrote: post #224
PopeDotNinja wrote: post #222

Earlier quoted context omitted.

> ...huge battleship guns ... were slow to fire ... I was curious about how fast battleships could actually fire, so I googled around and found a couple stats. On an Iowa class battleship: - Armed with nine 16"/50 caliber Mark 7 guns [1] - Each 16" gun is quoted as having a firing rate of 2 rounds per minute [2] - Each shell weighed between 1900lbs / 865kg and 2700lbs / 1225kg pounds [3] So math says 2 rounds/minute…

Interesting but I don't think that's sustained fire. You see crazy him rpm for firearms. The rate of fire is restricted by the magazine size (ship guns do have magazines) and how fast the gun can cool. The US Army changed the barrel of the M4 Carbine (automatic rifle) after some troops during a sustained defense of some hill had barrels failing after glowing white hot. Machine guns often have barrels that can be repl…

Good point. I removed the reference to sustained fire. Still a lot of ordinance for the receiving end to dodge! The dent those guns put in the water when firing is mind boggling to me => http://i.imgur.com/5aKQulg.jpg

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#237

Post by sandworm101 »

cascom wrote: post #235
sandworm101 wrote: post #230

Some forgotten limitations of railguns: There is a maximum speed for projectiles in naval warfare. Earth is round. So anything moving too fast (~8000m/s) simply cannot hit distant targets. If fired horizontally, the shell will climb up as the earth curves away. This causes all sorts of difficulties if trying to attack another ship. At best, your shells will hit horizontally, far above the waterline. You would need a…

Article references a goal of achieving a 100 mile range? How do they plan on doing that then?

100 miles to what? An aircraft? A very tall ship? A bunker on a mountainside? Until they have a reliable system that can be run over and over for days, I don't think anyone knows exactly how these things will be employed.

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#238

Post by nradov »

SEJeff wrote: post #150
nradov wrote: post #113

Earlier quoted context omitted.

Existing conventional munitions are absolutely used against surface and air targets.

Yes, but not both. You have ground to air, ground to ground, ship to ground, ship to ship. For the most part (with some standouts that do multi-role such as the Tomahawk) each munition is specialized for a single role. The railgun is being heralded as being capable of doing all 3 for limited use cases, which is fairly unique.

The SM-6 is effective against both air and surface targets.

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#239

Post by sandworm101 »

percutaneous wrote: post #233
sandworm101 wrote: post #230

Some forgotten limitations of railguns: There is a maximum speed for projectiles in naval warfare. Earth is round. So anything moving too fast (~8000m/s) simply cannot hit distant targets. If fired horizontally, the shell will climb up as the earth curves away. This causes all sorts of difficulties if trying to attack another ship. At best, your shells will hit horizontally, far above the waterline. You would need a…

Theoretically you could have a projectile with downforce. This would allow you to break that limit. I imagine it's highly impractical though. I hadn't thought of that limit though, good comment!

Then it needs to fly, which means it cannot be spinning. And it probably needs some internal mechanisms to control that flying. Now it is more a hypervelocity drone than a inert kinetic impactor.

Re: US Navy's Railgun Now Undergoing Tests in New Mexico

#240

Post by semi-extrinsic »

RantyDave wrote: post #179
semi-extrinsic wrote: post #128

Earlier quoted context omitted.

Nitpick on 2 a): you can't turn water vapor into steam, water vapor is steam .

No, it's water vapour. Steam is a gas.

Water vapour is steam, i.e. it is the gaseous phase of water mixed with other gases (N2, O2, etc). Just like liquid water is still water if you mix it with alcohol. There is no possibility for a phase transition.
Post reply on HN