Author Topic: Rifle ballistics in LEO  (Read 38622 times)

Offline Spacenick

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Re: Rifle ballistics in LEO
« Reply #100 on: 07/07/2009 07:15 pm »
DPRK would be in huge trouble it's one thing to provoke the Japan with rocket tests and even attacking Japan might not lead to an immediate deadly response, but attaicking the US, Russia, Europe and Japan at the same time gives you quite a good chance to get total nuclear destruction the only question being who will shoot first.

Offline GI-Thruster

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Re: Rifle ballistics in LEO
« Reply #101 on: 07/07/2009 07:31 pm »
The US would never nuke anyone unless it was nuked first.  The worst we might consider is a fuel-air bomb over a military complex and even that is very unlikely.  Instead there'd be a hail of close, precision strikes over many targets lasting several days until there was next to nothing left of Korea's military equipment.  Their military personnel would also certainly suffer and their general public would take a lot of collateral damage.    We need to hope it never happens.

Offline 2.71

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Re: Rifle ballistics in LEO
« Reply #102 on: 07/07/2009 08:16 pm »
Hiroshima.

Nagasaki.
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Offline Spacenick

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Re: Rifle ballistics in LEO
« Reply #103 on: 07/07/2009 10:08 pm »
Well who said it was the US to nuke Russia has at least as much at steak if the ISS is hit. Who knows what they will be doing, it might not be nukes but they'd certainly think about that.
However the chances here are near zero.
Will be much more interesting what happens when Israel starts bombing Iran, I doubt anyone is willing to help the Iranians.

Offline Danny Dot

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Re: Rifle ballistics in LEO
« Reply #104 on: 07/07/2009 10:10 pm »
Keep in mind that Russia just spanked Georgia pretty hard for them shooting at some Russian's.  I wouldn't want to be the country to attack the Russian half of the station.

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Offline kevin-rf

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Re: Rifle ballistics in LEO
« Reply #105 on: 07/08/2009 02:05 am »
The US would never nuke anyone unless it was nuked first.

I actually wonder if we would counter nuke a nuke attack. I think we will end up with a hot air responce from congress, and someone trying to rationalize the nuking of the US. Why kill populance of hostile country when it is the leader and not the population at fault.

For better or worse, the last time we even discussed it as an option was the Korean War. We are not the same country as we where in 1945, and I pray we are never put to the test. 
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Offline JohnFornaro

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Re: Rifle ballistics in LEO
« Reply #106 on: 07/08/2009 01:41 pm »
Well, in August of '07 there were those half dozen nukes flown across the country right around the time that Israel bombed that Syrian "reactor", that the Syrians didn't complain about all that much.  The cascade of necessary "management" errors which led to our nukes traveling to the staging point for Middle Eastern delivery seems more to me like a secretly enacted backup plan, perhaps in support of the Israeli mission, perhaps as a contigency for possible retaliatory action by other parties on the Israelis, or sumpin, rather than an "accident".

Those who could speak with authority and intelligence on our possible first use are a quiet bunch, and not likely to twitter about it.

But if a shotgun launch is attempted by one of the rogue nations, how maneuverable is the ISS?
Sometimes I just flat out don't get it.

Offline kevin-rf

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Re: Rifle ballistics in LEO
« Reply #107 on: 07/08/2009 03:26 pm »

Why would you shotgun ISS? I can think of a dozen better targets that a rogue nation would use to test the water with ;)

You can rationalize shooting down a "spy" sat., claim a victory, ect. Not so much with ISS... Unless you are trying to reduce NASA's budget so we have more money to invest in bombs that we can send on a friendly visit.
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Offline mlorrey

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Re: Rifle ballistics in LEO
« Reply #108 on: 07/10/2009 05:32 pm »
Getting back to the original question, most rifles have a muzzle velocity of 600-1100 m/s.  To get from LEO to GTO requires more like 2400 m/s delta V.  So a lone gunman in LEO can't shoot at GEO targets, even with perfect aim.

Movimg on to shotguns, if the DPRK or Iran decided to put 100 kg of buckshot in a 350 km orbit, would there be any way to defend the ISS?

A rifle cartridge in vacuum would generate greater muzzle velocities than at sea level due to the simple lack of atmosphere means greater pressure differential between the chamber and exterior, no compressive losses ahead of the bullet while travelling through the barrel, and no further aerodynamic losses after exiting the barrel.

Generally speaking the terminal velocity of a rifle bullet falling straight down is about 300-320 fps, so a bullet with muzzle velocity of 2700 fps at sea level should see a muzzle velocity of about 3000 in vacuum.

Secondly, while 3000 fps may not be enough velocity to achieve a Hohmann GTO, it may be enough to reach a apogee of 23,000 miles in a Molniya highly elliptical orbit. Need to crunch some numbers to find out. If its possible, a bullet in a molniya orbit would cause more damage to a satellite in GSO due to higher closing velocity.
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Offline JohnFornaro

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Re: Rifle ballistics in LEO
« Reply #109 on: 07/10/2009 05:37 pm »
For the moment, tho, let's just keep the rifle equipped ASAT in roughly the same orbit as the target birds.
Sometimes I just flat out don't get it.

Offline Jim

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Re: Rifle ballistics in LEO
« Reply #110 on: 07/10/2009 05:48 pm »

Secondly, while 3000 fps may not be enough velocity to achieve a Hohmann GTO, it may be enough to reach a apogee of 23,000 miles in a Molniya highly elliptical orbit. Need to crunch some numbers to find out. If its possible, a bullet in a molniya orbit would cause more damage to a satellite in GSO due to higher closing velocity.

Huh?   That is a bunch of hooey

A Hohmann transfer orbit is the lower energy possible for two orbits in the same plane.

There are only two characteristics for a Molniya orbit 12 hour period and 63.4 degree inclination.    It has nothing to do with minimum energy.  It actually requires more



« Last Edit: 07/10/2009 05:51 pm by Jim »

Offline kevin-rf

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Re: Rifle ballistics in LEO
« Reply #111 on: 07/10/2009 06:19 pm »
Generally speaking the terminal velocity of a rifle bullet falling straight down is about 300-320 fps, so a bullet with muzzle velocity of 2700 fps at sea level should see a muzzle velocity of about 3000 in vacuum.

Can you explain the math behind this ... A bullet exiting a muzzle is going faster than terminal velocity, so why do you add terminal velocity to the muzzle velocity in a vac. The logic is not following. Yes, air slows the bullet down as it exits the barrel, but why is that loss equal to terminal velocity? Why it is not some other value, I just can't see a connection...

Google Book on it, look at page 569 for vac. muzzle velocities : http://books.google.com/books?id=yESNUKSg5aMC&pg=PA543&lpg=PA543&dq=rifle+muzzle+velocity+in+a+vacuum&source=bl&ots=AzzuSCYp9l&sig=egsyeeguufpdzsHmLtViyLlYxHc&hl=en&ei=foZXSq6TEouqNr2f6J0I&sa=X&oi=book_result&ct=result&resnum=1
« Last Edit: 07/10/2009 06:27 pm by kevin-rf »
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Offline GI-Thruster

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Re: Rifle ballistics in LEO
« Reply #112 on: 07/11/2009 07:01 pm »
This linked chart is pretty useless.  The entire notion of "extreme range" is wanting as the bullet is merely falling for most of its tragectory.  The range of a weapon compared to its theoretical range in vacuum is less than 1%.  For instance, none of the listed cartridges would be used for a shot more than 200 yards and that is twice what most of them are useful for, yet the listings are for ~3k yards.

The only published ballistics you want are the kinetic energy and speed at the muzzle and then you add some fraction for lack of vacuum in the barrel depending upon barrel length, time/fraction of propellant burn in the barrel, etc.

Offline JohnFornaro

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Re: Rifle ballistics in LEO
« Reply #113 on: 07/12/2009 01:57 am »
I'm thinking Mike Lorrey's addition of terminal velocity may have been some intuitive response to the addition of the effects of having vacuum in the barrel?

So, could we shoot a 30-06 100 miles?  1000 miles? and still kill the target sat.
Sometimes I just flat out don't get it.

Offline Danny Dot

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Re: Rifle ballistics in LEO
« Reply #114 on: 07/12/2009 11:28 pm »
I'm thinking Mike Lorrey's addition of terminal velocity may have been some intuitive response to the addition of the effects of having vacuum in the barrel?

So, could we shoot a 30-06 100 miles?  1000 miles? and still kill the target sat.

If you could hit it, you could kill it.  The bullet will not slow down.  Targeting is the only problem.

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Offline JohnFornaro

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Re: Rifle ballistics in LEO
« Reply #115 on: 07/13/2009 02:53 pm »
That's what I thought.  So how trivial is it to target?
Sometimes I just flat out don't get it.

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