view the rest of the comments
NonCredibleDefense
A community for your defence shitposting needs
Rules
1. Be nice
Do not make personal attacks against each other, call for violence against anyone, or intentionally antagonize people in the comment sections.
2. Explain incorrect defense articles and takes
If you want to post a non-credible take, it must be from a "credible" source (news article, politician, or military leader) and must have a comment laying out exactly why it's non-credible. Low-hanging fruit such as random Twitter and YouTube comments belong in the Matrix chat.
3. Content must be relevant
Posts must be about military hardware or international security/defense. This is not the page to fawn over Youtube personalities, simp over political leaders, or discuss other areas of international policy.
4. No racism / hatespeech
No slurs. No advocating for the killing of people or insulting them based on physical, religious, or ideological traits.
5. No politics
We don't care if you're Republican, Democrat, Socialist, Stalinist, Baathist, or some other hot mess. Leave it at the door. This applies to comments as well.
6. No seriousposting
We don't want your uncut war footage, fundraisers, credible news articles, or other such things. The world is already serious enough as it is.
7. No classified material
Classified ‘western’ information is off limits regardless of how "open source" and "easy to find" it is.
8. Source artwork
If you use somebody's art in your post or as your post, the OP must provide a direct link to the art's source in the comment section, or a good reason why this was not possible (such as the artist deleting their account). The source should be a place that the artist themselves uploaded the art. A booru is not a source. A watermark is not a source.
9. No low-effort posts
No egregiously low effort posts. E.g. screenshots, recent reposts, simple reaction & template memes, and images with the punchline in the title. Put these in weekly Matrix chat instead.
10. Don't get us banned
No brigading or harassing other communities. Do not post memes with a "haha people that I hate died… haha" punchline or violating the sh.itjust.works rules (below). This includes content illegal in Canada.
11. No misinformation
NCD exists to make fun of misinformation, not to spread it. Make outlandish claims, but if your take doesn’t show signs of satire or exaggeration it will be removed. Misleading content may result in a ban. Regardless of source, don’t post obvious propaganda or fake news. Double-check facts and don't be an idiot.
Other communities you may be interested in
- !militaryporn@lemmy.world
- !forgottenweapons@lemmy.world
- !combatvideos@sh.itjust.works
- !militarymoe@ani.social
Banner made by u/Fertility18
Once fired, the bullets would just retain their muzzle velocity.
I don't know what kind of muzzle velocity increase would happen -- no air means that they'd be moving somewhat-faster. I'd think that that'd depend on a number of things, probably fluid dynamics and stuff. But maybe you can back-of-the-napkin it by figuring that any acceleration is roughly bounded by the energy required to accelerate the mass of air involved to muzzle velocity. I don't know exactly how much air that is. Certainly the air inside the barrel, but also some of the air outside the muzzle.
https://en.wikipedia.org/wiki/Density_of_air
https://oow-govmil.com/firearms/50-m2hb-qcb-2/
https://en.wikipedia.org/wiki/.50_BMG
So that's about
(.511/2)^2*3.1415*45
=9.22850 in^3, or 0.00015122811 m^3, so .00018525 kg, so 0.1g of mass of air in the barrel.https://barrett.net/products/accessories/ammunition/50bmg/
~15.4g per grain, so ~43 grams. So I figure that the mass of the air in the barrel probably isn't a huge factor, and I don't know how to compute the effective amount of air that needs to be accelerated outside the barrel and how much...that's probably a fluid dynamics question .
Let's just say that it's three times that amount of air. Even if so, that's a pretty miniscule factor compared to the mass of the bullet, like under half a gram. So I figure that the muzzle velocity probably isn't all that much higher in space.
Are we moving fast enough to do much in terms of orbit change?
https://en.wikipedia.org/wiki/Low_Earth_orbit
https://www.gd-ots.com/wp-content/uploads/2017/11/M2HB-50-Caliber-Heavy-Machine-Gun.pdf
Hmm.
https://space.stackexchange.com/questions/15349/how-can-the-delta-v-to-a-specific-altitude-in-earth-orbit-be-calculated
So, the International Space Station is at 340 km. So figure that our astronaut is acting as gunner on a vehicle in LEO at 300 km, can use the above table.
The upper end of LEO is 2000 km.
So you've got about 1 km/s in terms of delta V to work with there. So if our astronaut is acting as roof gunner on a Humvee in LEO, that's actually quite a lot of ability to reach. Given sufficiently-accurate aim, and maybe willingness for a bullet to do a sufficient number of orbits before it collides with a target, he's got the range to hit anything in low earth orbit.
He can't hit GPS/Galileo/GLONASS satellites (19k km to 23k km). And he can't hit escape velocity, so that Model S that Elon Musk launched into an eccentric path wandering the solar system is probably safe. But he can hit a lot of stuff.
Okay, the image is of the Moon. How about acting as a gunner there?
https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html
No. From the surface of the Moon, his bullets are going to come back to the Moon. So he can fight lunar battles, but he can't be engaging targets on other celestial bodies or in their orbit, like the Earth.
Major concern here for LEO engagements is that any shots that miss are a liability coming back to hit the gunner.
Basically once a bullet's fired, a new orbit is defined for that bullet, a new elipse can be drawn. That now elipse is constrained by the position and direction of that bullet the moment it's fired. Unfortunately that means that one bullet orbit later the bullet is going to be in the exact same position with the exact same velocity. The gunner had better hope that orbit phases are misaligned.
Shooting at targets in the retrograde direction might be safest, they're more likely to dip into the edge of the atmosphere and start to lose a bit of velocity ensuring they never come back.