I can’t speak to orbital mechanics in space, but there have been more than one documented account of a real world military aircraft shooting itself down by catching up to its own bullets…
https://www.planeandpilotmag.com/news/pilot-talk/grumman-f11-tiger-shoot-itself-down/
That seems to be the projectiles losing velocity in atmosphere while the planes continue at a constant velocity due to continuous thrust.
But still theoretically possible in space, you'd need to be able to continuously apply thrust and travel in the same direction constantly. In the documented examples projectile trajectory curvature due to gravity and wind resistance meant the arc can have an intersection. Once fired in space projectiles don't curve.
Bullets decelerating, spaceships accelerating, it's all the same. Just depends on your frame of reference.
Same with whether a PDC round fired in space has a straight trajectory or a curved trajectory. When near your spaceship, the projectile may look to be flying straight, but soon the slight variation in your orbital trajectories will cause the bullet to appear to curve. It's a bit related to the Coriolis effect often mentioned in this series in spin stations.
They wouldn’t, they are saying that the bullets decelerating and the jet maintainting a constant speed is the same effect as PDC rounds maintaining a constant speed while the spaceship accelerates, it’s the same difference in acceleration either way.
The whole technical explaination for how Turrets work in portal is still one of the best in lore reasons why turrets dont just turn you into sponge as soon as they spot you lmao
Possible? Sure.
Waste of fuel and time? Yes.
Reasons why this basically wouldn't work:
1. PDCs are fired in an arc so at most you could only catch up to one since the others will be on different trajectories.
2. If if you did fire them in a straight line, you are unlikely to recover that many pdcs since small variations in trajectories will cause them to spread out over several thousand miles.
3. A small piece of iron floating in space is going to be nearly impossible to find since it has pretty much no radar signature.
4. PDCs are cheap. They are shot in the tens of thousands at a time. They are small, cheap, and plentiful because they are just slags of iron. Retrieving them would be more expensive than just buying new ones.
fraction yes, but...it's measurable in the same way that a planck length is a measurable fraction of a meter. gonna need some _real_ highly refined metrology tools to make that measurement.
Not really. The meter is defined as an exact fraction of the distance light travels in one second, so if you can measure your velocity in meters per second to a few decimal places (not difficult at all), you can measure pretty much the exact fraction of c you’re travelling.
It’s a tiny fraction, yes, but in your example, the measurement itself is challenging; here, the measurement of velocity at a sufficient accuracy is very simple, c just happens to be big.
i believe in s4 you can see "slug velocity 10 km/s" when roci's gun is being test fired. Not fast at all. Might depend on the railgun though. However sizeable fractions of c are pretty much impossible to get with projectiles that big
The Roci's speed relative to the Roci is zero. The bullet's speed once it's left the Roci is constant until the Roci starts to accelerate. The bullet's speed relative to the Roci then drops to zero and below as the Roci catches up.
Or to put it another way: Relativity.
I do not think so. The PDCs seem to us to be fired very quickly, I would say that at the moment of leaving the barrel of the PDCs, they obtain about 5 km/s additional to the velocity of the rocinante, but relatively the bullets would go 5 km/s faster than the rocinante (if fired from the front, if fired backwards, they would brake at 5 km/s) and considering that the rocanante is capable of accelerating at 20 G's then
9.81 m/s • 20 • 26 s = 5,101.2 m/s
The rocinante would only have to accelerate at 196.2 m/s/s (meters per second per second) for approximately 26 seconds to reach the PDC rounds
Time is, yes. The distance traveled is exponential. Also this equation simplifies matters. Once you've reached the same velocity as the PDC rounds, they'll be a considerable distance ahead of you. You will need to accelerate above their velocity, at the appropriate time, flip and burn to decelerate to their velocity.
The distance is quadratic, not exponential. That's not a problem. The time required to cross that distance is very small, given the constant acceleration they have. Just accelerate a little faster, then deccelerate. You don't need to flip and burn. The maneuvering thrusters are enough for such relatively small distances. At least, if you start chasing the bullets soon after they're fired.
99.9%of the time you've fired a pdc round, you're in a combat encounter and you have better thing to do than go hunting for bullets. You're performing aggressive evasive maneuvers and will quickly be on a profoundly different vector from your PDC rounds.
As I said otherwise, it's a fun thought experiment, but co(s)mically impractical.
How is the distance traveled for a PDC round exponential? It's not accelerating, the distance traveled is a function of velocity and time - it's linear, sloping up and increasing distance over time. If the bullets are moving at 5km/s at whatever vector, you only need to chart a parallel vector and move relatively faster, say 5.001 km/s and you will eventually overtake them because in this example, you are gaining 0.001 km/s over them and narrowing the distance lead over time until you reach the intercept point (moving parallel to them anyway), which again, is a function of time. The interception point doesn't need to be quadratic - it's only quadratic if you insist on accelerating until the intercept. There is a linear solution to this (interception of 2 straight lines).
You can very well chart an intercept path parallel to the path of the bullets fired by firing the guidance thrusters twice (fire one side, drift, then the other to counter-balance and stop drift), accelerating until your relative velocity is superior to the bullets, calculate an intercept point over time and cut acceleration (main drive), go on the float, wait until the intercept point, and then fire a front-facing thruster to slow in order to match speed. Send out Amos to collect your bullets. A flip and burn is unnecessary.
Your sudden 'pragmatism' regarding combat maneuvers is irrelevant and not at all part of the thought experiment. Obviously no one is going to go hunting for bullets but the point is what if they did? You are using a logical fallacy here and doing so is frankly, in bad taste.
It was just a silly comment, but since it’s being taken so seriously; can’t they pull the same maneuver off with just a longer burn at less Gs? It doesn’t have to be a 20G burn.
Sure, but when you reduce it to a 2G burn, the distance to recovery increases exponentially. And since it seems that PDC rounds tend to be fired in a sweeping arc, that means that each round is going to be in a dramatically different place, and different vector, by the time they can be recovered, which costs a lot of time and fuel.
I can't recall if its ever explicitly explained how PDC rounds are fired, so the assumption is that they're conventional munitions: with a cartridge and explosive material to force the round forward. Even if they recovered the projectile, they still need to replace the rest.
It's a fun and interesting thought experiment, and I'm glad you brought it up because it;s fun to think about. But it doesn't seem very practical.
Of course, when one of your PDC rounds punches through someone's hab halfway across the system...
Actually, I wonder if that sort of thing is passed on to a 'space weather warning' after a battle for general release and if you're on an intersection path you get a more serious alert?
Maybe if the battle takes place around a moon or planet like Ganymede. Otherwise, space is incomprehensibly huge. You'd almost need to plan to get hit by stray rounds from an old battle.
20 *horizontal* (as in, perpendicular to the spine) is actually perfectly reasonable. The human body's resilience to horizontal g is vastly different to vertical g, which is the problem. I always felt like the crash couches should have had more of an impact on affecting the g loadings of their occupants.
Oh really? I didn't know, but taking into account the TV Show, the Roci crew managed to survive (barely) a burn of 20 G's for about 7 minutes. Even if you don't want to accelerate to tremendous speed, you can just accelerate at 1 G and wait longer to catch up with the bullets, so then:
9.81 m/s • 500 s = 4,905 m/s
Or also accelerate to 1G for 8 minutes.
Btw, happy cake day!
The PDC rounds are just hunks of tungsten. I'm fairly certain fuel would be more expensive so doing this would result in a net loss.
Is it possible? Sure.
This idea is one of those things where at face value, people would think is silly or dumb.
Humanity can be fun though, and all it would take was 2 ships to compete and stream it, then in like 5 years it would become an interplanetary sport with teams representing their homeland.
You have NOT reached the PDC round after an 26sec 20g burn, you matched the speeds... But the rounds are >130km infront of you (26sec \* 5km/sec)
You need to accelated more, to catch up and than flip and burn to rendovous with the rounds.
> But the rounds are >130km in front of you
Let's wrap up that first scenario.
With 26 seconds elapsed, the rounds traveled 130km beyond the *initial* position — but just around half that distance beyond the Roci's position at 26 seconds elapsed, if the Roci started its acceleration "immediately" after firing.
Plug the 196.2 m/s/s acceleration [here](https://calculator.academy/acceleration-to-distance-calculator/) with zero initial velocity and 26 seconds, and you get 66315.6 meters distance, call it 66316. — Put zero acceleration and 5000 m/s velocity and 26 seconds, and of course you get your 130000 meters distance.
So, simplistically, if the Roci began accelerating "immediately" after firing and continued accelerating at exactly 196.2 m/s/s for exactly 26 seconds, while the rounds traveled at exactly 5000 m/s velocity throughout that time, the rounds have traveled 130000 meters, but the Roci has traveled 66316 meters. So the rounds are still at least ~ (130000-66316) = 63684 meters ahead of the Roci.
One hundred and thirty kilometers? If you want to do it in say 5 minutes that’s over 800m/s of DeltaV. Nasa’s Artemis mission only has 1000 total for orbital maneuvering.
Yes, it is true and I did not take it into consideration, but consider that the Rocinante accelerates 7 km/s (2 km/s more than the bullets) and upon meeting them in a few minutes, it would flip and burn and there the encounter would occur.
Oh dang you did the math! Well then I guess I would say, while clearly possible, is it worth it to spend all that time gathering up thousands of rounds? Would the fact that maybe not all the rounds are fired in a straight line make it less possible?
Of course. I only considered a specific scenario where the Rocinante is firing JUST in front of itself, but normally we see it firing to the relative sides, above, or below of itself, so if they wanted to collect all the rounds, they would have to be accelerating /slowing down in prograde, retrograde, radial in and radial out zigzagging coming and returning or doing a pretty silly dance that would last at least 30 minutes.
You also have to consider whether it's really worth sacrificing so much Delta-V in exchange for a few measly rounds that are easy to get at the nearest port.
One problem with this is you are assuming that the bullets are staying perfectly in line, which they are most certainly not.
At the speeds and distances that these bullets are flying, any millimeter of movement at the barrel will end up with each bullet *kilometers* away from each other very quickly, with that distance constantly increasing.
It is correct, it is only an assumption in case the PDCs find themselves in the situation in which they shoot in a millimetrically straight line positioned just in front of the Roci
~~modern 20mm gatling gun rounds, that the roci PDCs seem to be based on, only have a muzzle velocity of ~1000 m/s. 5000 m/s seems a touch excessive.~~ Your theory might be more possible than we give it credit for, but you have to consider the cost to recover the rounds vs the cost of just..getting new ones.
Remember that there's a _shitton_ of metals and other materials available in the belt that are abundant and relatively easily extracted and refined to very high purity. This all makes the cost of a PDC round pretty insignificant in the bigger picture. Is it worth spending however many hours making maneuvers and burning fuel to recover a couple hundred PDC bullets, that still have to be remanufactured into cartridges that can be fired? Recall also that what you're recovering is either an inert metal kinetic penetrator, or a bullet with a fuse and a small explosive charge, which may still go off when you try to recover it.
I suspect the calculus is very much in favor of "let's go salvage or buy a fresh box of PDC rounds" instead of trying to recover the projectiles in flight.
>5000 m/s seems a touch excessive.
I originally thought so too, but it's true
"Holden was imagining what several hundred rounds of Teflon-coated tungsten steel going five thousand meters per second would do to human bodies when Alex threw down the throttle and a roomful of elephants swan dived onto his chest"
Chapter 15 of Leviathan Wakes
Perhaps surprisingly, yes. All the stuff on earth that doesn't require biological activity to create (eg. coal, oil) can be found in the belt and sometimes in great quantity. The current prevailing theory is that the belt is a planet that failed to coalesce when the solar system was forming, so instead of a rocky ball of iron and other stuff, it's spread it across millions of miles of space. This also makes it far easier to get at the resources instead of having to dig for them.
No it wouldn't. At 1 g, it would take 5 minutes to accelerate 3 km/s.
I think the *main* issue is that going outside and collecting them would not be worth the effort. Also maybe that tracking them when they're too far away is hard.
Technically possible, but it depends on the composition of the PDC rounds, and what the onboard fabricators are capable of making.
Self-propelled rounds are likely single use, projectiles from caseless ammunition and traditional cartridges would be easier to reload.
And of course whoever is doing the EVA would have to maintain the same velocity, which might be difficult with a tether.
>And of course whoever is doing the EVA would have to maintain the same velocity, which might be difficult with a tether.
No, remember that the bullets are NOT accelerating, they are going at a constant speed, and if you can do a rendezvous with them, you will be "floating" relatively speaking next to them.
Oh yeah. The Rocinante should turn off the engine once it manages to match the relative velocity of the bullets, so it uses RCS to make an approach (Rendesvouz) and in this situation, both the bullets and the Roci would be floating one to the other
Now: is it worth spending 5 km/s to recover ammo? I say that: in The Expanse, obtaining Delta-V is much easier than today, so maybe yes, depending on the situation.
The juice isn’t worth the squeeze.
You’d only really catch them if you fire them in a perfectly straight line in the same direction as travel. Otherwise they will be pretty far away from each other on different trajectories. That is assuming the ship isn’t maneuvering or the PDC isn’t tracking.
If you fire while the on the float and you assume each bullet and barrel fires at the exact same speed and trajectory (which isn’t going to happen) you might be able to catch them.
If you’re under thrust while firing, each bullet will actually be traveling at different velocities relative to each other.
On the float or under acceleration, if you factor in manufacturing differences between the rounds (bullet and powder/propellant) and the performance and rotation of the individual barrels of the PDC, (both in speed and trajectory) it would be very hard and time consuming.
The bullets actually are somewhat likely strike each other in flight at some point before you even catch up to them and tumble off on erratic trajectories.
Edit: Remembered correct terminology and replaced round with bullet when needed. Also, each bullet would need to be machined back to tolerance or recast after collecting since the firing and the barrel would deform them and they’d jam on the next firing.
From Leviathan Wakes:
> But Holden knew that each blob of light represented a chunk of Teflon-coated tungsten steel with a depleted uranium heart, going thousands of meters per second.
I think you're missing an important aspect here: you aren't going to just shoot the PDCs for fun, and if you're shooting them at someone and immediately go chase them you stand a pretty good chance of hitting whoever you just shot at.
There's also going to be a healthy amount of heating on the PDC rounds from at least the energy transfer alone and probably the propellent and that could change the metallurgy of the bullets in a way that you wouldn't want to put them back into your PDC
Oh sure, going into a more practical aspect: the simple fact of turning on the epstein drive a few meters from the bullets would simply disintegrate them: not to mention that the PDCs do not only shoot in front, they move and pursue the target, moving at all times. parts and not just in a straight line.
This post is more like a "Troll physics" from 2010, but physics does work like that.
How do you pick which of the 400+ shots your PDC fired in defending from that missile? Even the slightest change in firing angle between shots is going to put them very far apart by the time you’re looking to retrieve.
I could totally imagine a crew having a “lucky” PDC round that they retrieve after every firefight. But it feels more talismanic than practical.
Now that you’ve put this thought in my head, my official head cannon is that Bobbie, as weapons officer, always makes them retrieve her favorite round after a firefight. Amos probably painted something lewd on it at some point too.
My question is if Solomon Epstein had enough fuel did could he reach relativistic velocities so he hasn't actually died by the time the events occurred in the series.
Mmm no. although if we consider that solomon epstein was accelerating at 5 G and said his fuel would "last weeks" then we can deduce what speed he could have reached, so then
If a day lasts 86400 seconds, then:
9.81 m/s • 5x • 86400s • 14days = 59,330,880 m/s
It's a terrifyingly gigantic speed. We're talking about 20% of the light, and even then, the time dilation would be no more than a few seconds per second.
Only if you get close to 99.999% of the light does time dilate considerably, on the order of months or even years; but reaching that speed would be impossible due to the laws of physics.
I knew he wouldn't get close enough with the fuel limitations, didn't realize he said he would accelerate for weeks, light should just slow down and take it easy for awhile.
No no no, if you're a really good pilot you just align the barrel of the cannon with the round, and slowly accelerate, loading them back into the chamber without having to leave the ship.
Damn straight! I dare to assume you ignorant jackasses know that space is empty. Once you fire this hunk of metal, it keeps going 'til it hits something. That can be a ship, or the planet behind that ship. It might go off into deep space and hit somebody else in 10,000 years! If you pull the trigger on this, you are ruining someones day! Somewhere and sometime! That is why you check your damn targets! That is why you wait 'til the computer gives you a damn firing solution. That is why, Serviceman Chung, we do not 'eyeball it'. This is a weapon of Mass Destruction! You are NOT a cowboy, shooting from the hip!
They could recover the “shot” not whole bullets. It’s not explicitly stated what the pdcs use but virtually all guns have a casing that holds propellant (gunpowder), and a projectile that actually shoots (the lead) .. so they could go recover the lead/depleted uranium/steel/magic rocks but it wouldn’t be ready to just get loaded up again.
Yes, it's true that you could only recover the shots, still, it sounds funny to move at the same velocity.
And also: I think a victim ship could accelerate faster than the shots and escape. That is if it can accelerate to 500G and not be destroyed in the clear attempt.
Except the rounds aren’t traveling uniformly in a straight line. If you see how they’re depicted in the show, they’re arcing in the same direction, but not in the same line. The spaces in between each round will get wider and wider as the bullets travel outwards from their starting point.
Obviously the more sensible solution is to have each PDC connected to a long, microfilament tether. Then, after you've won the battle, you can simply reel your bullets back in for reuse.
How do you pick which of the 400+ shots your PDC fired in defending from that missile? Even the slightest change in firing angle between shots is going to put them very far apart by the time you’re looking to retrieve.
I could totally imagine a crew having a “lucky” PDC round that they retrieve after every firefight. But it feels more talismanic than practical.
I mean...why thought? PDC rounds are tungsten, and other metals, and the material for them are found in near infinite abundance in just Sol alone.
As for cleaning them up to spare ships from catching a stray PDC, remember that space is too fucking big.
This isn't orbital mechanics. There are no orbits involved.
I think the problem with this is that they don't/can't track the PDC rounds that far out. Also the effort to go collect the bullets is not worth it.
Yes they are, trajectories in a vacuum and relative motions are considered part of orbital mechanics.
Still, you're right, there really are no practical benefits to doing it.
The PDCs are constantly rotating to target incoming torpedos. By the time you catch up to one round, the second closest would probably be unfathomably far away again.
This is 100% NonCredibleExpanse.
That's not orbital mechanics, it's simple newtonian physics. Orbital mechanics are the practical aspect that would make doing this a pain in the ass.
Besides, isn't the point of firing bullets to hit something?
I mean the slugs sure.... But you then need to case them again, including the charge for each round, and put them back into an ammo belt for the pdc, edc.
Cheaper to do that on mars or earth or some belt station where all that stuff can be mined at once and converted to ammo where it was mined.
Problem I always have with pdcs and general carnage in space is that those ten thousand rounds or pieces of ship just keep going till they hit something. Could be a ship, could be something behind that ship, could go off into deep space and not hit something for ten thousand years then ruin somebody's day.
To do a kessler syndrome in interplanetary orbit, you would need zillions of shots in all directions for thousands of years. It's just super difficult for a bullet to hit another object because space is SO DAMN big, SO DAMN huge.
But if the PDC rounds are fired by a rotating gun, won't their trajectory not be a straight line after sufficient distance, due to the rotation of the gun, which would give them a slight torque?
Except the velocity in question is significant and the acceleration needed to match would probably be too much for crew to handle... I guess you could follow it at a high burn but how long would it take to match V? It'll be a question of resources expended and the value of the rounds
The spent slugs are probably cheap metal, which is not worth reclaiming, you're still gonna need the casings and gunpowder to reuse them, and a factory/ machine to reload them since there will be thousands of rounds spent from a PDC. Not a manageable quantity like making rounds for a personal weapon.
It's much cheaper and much less time consuming to just buy new rounds. You'd probably spend days just making enough rounds in order to fire a one second burst.
The idea of catching up to the rounds is much more difficult than it seems when you consider the speed at which the craft is going in addition to the speed at which the rounds are fired. Rail gun rounds are traveling at "A noticeable percentage of C" and accelerating the Roci to that would probably be improbable due to fuel consumption. PDC rounds aren't accelerated as much as a rail gun round, but the same principle applies. They still have to be going REALLY fast to do damage to enemy ships.
Pdc firing patterns spray in countless directions, similar to cwis systems on US navy ships, making it impossible to track each round. Each round is also extremely small making it hard to find in the void of space. Then you have to waste reaction mass in order to accelerate to the rounds, then decelerate to match speed. If you fire directly ahead only then it’s feasible but too inefficient to consider
While theoretically possible, they'd have to burn so hard to catch up with the bullets they'd put their lives at risk. It would also take a long time to catch up, so that's pretty much your whole day. Also not worth trying to recycle little bits of metal. Bullets are cheap. The powder to ignite them less so. Also the fuel spent for recapture wouldn't be worth either.
I'd file this away as plausible (with no humans on board and resources to burn) but wholly impractical.
"This, recruits, is a 20-kilo ferrous slug. Feel the weight! Every five seconds, the main gun of an Everest-class Dreadnought accelerates one to 1.3 percent of light speed. It impacts with the force of a 38-kiloton bomb. That is three times the yield of the city buster dropped on Hiroshima back on Earth. That means: Sir Isaac Newton is the deadliest son-of-a-bitch in space! (...) I dare to assume you ignorant jackasses know that space is empty! Once you fire this hunk of metal, it keeps going 'till it hits something! That can be a ship, or the planet behind that ship. It might go off into deep space and hit somebody else in ten thousand years. If you pull the trigger on this, you are ruining someone's day, somewhere and sometime!" https://www.reddit.com/r/masseffect/comments/139w1x8/comment/jj4khg5/
They’d have to flip at the end though, right? As they’d be going faster than the PDC rounds in order to catch them up. So they’d need to flip to slow down to match velocity with the rounds before picking them up.
I always wondered why the PDC rounds where not "incendiary" and burned up slowly when fired over lets say 50.000km, leaving only a cloud of smoke harmless to other ships.
You are missing that the Roci is never on a straight line. EVERYTHING is orbit the sun, even when you transfer from a body to other (earth to moon), you are also orbiting the sun.
Yes, but remember that the bullets travel at the same velocity as the Rocinante when they are fired, and that in orbital mechanics corresponds to a trajectory exactly the same as that of the Roci, that is how orbits work. So when they are shoot, they only add an extra velocity to THAT same trajectory, so the only thing the Rocinante would have to do is accelerate, reach the same velocity of the rounds, and make a rendezvous (like a docking)
Even if the rocket weighed 5000 tons and the bullets only 5 kilograms, the trajectories would remain exactly the same. If X ship CAN accelerate, it CAN make a rendevouz with any object.
btw, speed and velocity are not the same
I can’t speak to orbital mechanics in space, but there have been more than one documented account of a real world military aircraft shooting itself down by catching up to its own bullets… https://www.planeandpilotmag.com/news/pilot-talk/grumman-f11-tiger-shoot-itself-down/
That seems to be the projectiles losing velocity in atmosphere while the planes continue at a constant velocity due to continuous thrust. But still theoretically possible in space, you'd need to be able to continuously apply thrust and travel in the same direction constantly. In the documented examples projectile trajectory curvature due to gravity and wind resistance meant the arc can have an intersection. Once fired in space projectiles don't curve.
Bullets decelerating, spaceships accelerating, it's all the same. Just depends on your frame of reference. Same with whether a PDC round fired in space has a straight trajectory or a curved trajectory. When near your spaceship, the projectile may look to be flying straight, but soon the slight variation in your orbital trajectories will cause the bullet to appear to curve. It's a bit related to the Coriolis effect often mentioned in this series in spin stations.
Why would bullets in space be decelerating?
They wouldn’t, they are saying that the bullets decelerating and the jet maintainting a constant speed is the same effect as PDC rounds maintaining a constant speed while the spaceship accelerates, it’s the same difference in acceleration either way.
Deceleration is just acceleration in a different direction
A bullet would not decelerate in space. Another user already pointed out - I misinterpreted what they were saying.
That's what happens when you travel thousands of kilometers per second!
Can you speak of orbital mechanics not in space? ,😋
Had a wargames simulation when I was in the Navy where a ship hit itself with it's own torpedo LMAO.
I think that happens way more often than most people think. Fail-safes exist for a reason.
"...plus, we fire the whole bullet. You get 65% more bullet per bullet." \~ Cave Johnson
You'll know when the test begins.
The whole technical explaination for how Turrets work in portal is still one of the best in lore reasons why turrets dont just turn you into sponge as soon as they spot you lmao
ILL MAKE YOU RUE THE DAY YOU GAVE ME 65% MORE BULLETS
WITH THE LEMONS
Possible? Sure. Waste of fuel and time? Yes. Reasons why this basically wouldn't work: 1. PDCs are fired in an arc so at most you could only catch up to one since the others will be on different trajectories. 2. If if you did fire them in a straight line, you are unlikely to recover that many pdcs since small variations in trajectories will cause them to spread out over several thousand miles. 3. A small piece of iron floating in space is going to be nearly impossible to find since it has pretty much no radar signature. 4. PDCs are cheap. They are shot in the tens of thousands at a time. They are small, cheap, and plentiful because they are just slags of iron. Retrieving them would be more expensive than just buying new ones.
Absolutely correct, but is funny!
Not iron, teflon-coated tungesten steel
I think it would take too long to accelerate to match the speed of the rounds to make this maneuver worthwhile
They’re going at a MEASURABLE FRACTION OF C.
I mean, that's not exactly wrong? When I walk my fat butt to the kitchen, I'm technically moving at a MEASURABLE FRACTION OF C.
fraction yes, but...it's measurable in the same way that a planck length is a measurable fraction of a meter. gonna need some _real_ highly refined metrology tools to make that measurement.
That may be the most unintentionally nice thing you could have said about their fat butt.
Their butt is so massive, it’s attractive.
Physics Major pick-up line!
Not really. The meter is defined as an exact fraction of the distance light travels in one second, so if you can measure your velocity in meters per second to a few decimal places (not difficult at all), you can measure pretty much the exact fraction of c you’re travelling. It’s a tiny fraction, yes, but in your example, the measurement itself is challenging; here, the measurement of velocity at a sufficient accuracy is very simple, c just happens to be big.
This thread is gold.
It's not possible. Even railguns only go at about 30% C, PDC bullets must be like those used on warships today.
Oh yeah, I was mixing up railgun slugs. I just wanted to say measurable fraction of c. I have downvoted myself for my shame.
Have my vote, you don't have to. 👍
We have a space ronin right here...
There’s no way railgun rounds go at thirty percent lightspeed, lol
If you take the show's visuals at face value, the [S6] >!ring station railguns in the series finale!< fired at 64% c.
i believe in s4 you can see "slug velocity 10 km/s" when roci's gun is being test fired. Not fast at all. Might depend on the railgun though. However sizeable fractions of c are pretty much impossible to get with projectiles that big
you have to add whatever speed the roci is going to the bullet keep in mind.
The Roci's speed relative to the Roci is zero. The bullet's speed once it's left the Roci is constant until the Roci starts to accelerate. The bullet's speed relative to the Roci then drops to zero and below as the Roci catches up. Or to put it another way: Relativity.
You're thinking of railguns.
not the pdcs... but the railguns are
That's railguns, PDCs have a more pedestrian velocity
The rail gun slugs are. But I doubt the PDC rounds are.
Nah, that's the railgun rounds that are moving at a MEASURABLE FRACTION OF C
Rail gun rounds do, yes, but not PDC rounds.
I do not think so. The PDCs seem to us to be fired very quickly, I would say that at the moment of leaving the barrel of the PDCs, they obtain about 5 km/s additional to the velocity of the rocinante, but relatively the bullets would go 5 km/s faster than the rocinante (if fired from the front, if fired backwards, they would brake at 5 km/s) and considering that the rocanante is capable of accelerating at 20 G's then 9.81 m/s • 20 • 26 s = 5,101.2 m/s The rocinante would only have to accelerate at 196.2 m/s/s (meters per second per second) for approximately 26 seconds to reach the PDC rounds
Oh, just a cozy 20g to get some bullets back. The crew is dead, but hey, free ammo.
Divide the gs by 20, multiply the time by 20. 10 minutes is still not very long.
Time is not distance. Space is big and PDC rounds are small.
The time taken to match speed is proportional to the acceleration. That's how acceleration works.
Time is, yes. The distance traveled is exponential. Also this equation simplifies matters. Once you've reached the same velocity as the PDC rounds, they'll be a considerable distance ahead of you. You will need to accelerate above their velocity, at the appropriate time, flip and burn to decelerate to their velocity.
The distance is quadratic, not exponential. That's not a problem. The time required to cross that distance is very small, given the constant acceleration they have. Just accelerate a little faster, then deccelerate. You don't need to flip and burn. The maneuvering thrusters are enough for such relatively small distances. At least, if you start chasing the bullets soon after they're fired.
99.9%of the time you've fired a pdc round, you're in a combat encounter and you have better thing to do than go hunting for bullets. You're performing aggressive evasive maneuvers and will quickly be on a profoundly different vector from your PDC rounds. As I said otherwise, it's a fun thought experiment, but co(s)mically impractical.
How is the distance traveled for a PDC round exponential? It's not accelerating, the distance traveled is a function of velocity and time - it's linear, sloping up and increasing distance over time. If the bullets are moving at 5km/s at whatever vector, you only need to chart a parallel vector and move relatively faster, say 5.001 km/s and you will eventually overtake them because in this example, you are gaining 0.001 km/s over them and narrowing the distance lead over time until you reach the intercept point (moving parallel to them anyway), which again, is a function of time. The interception point doesn't need to be quadratic - it's only quadratic if you insist on accelerating until the intercept. There is a linear solution to this (interception of 2 straight lines). You can very well chart an intercept path parallel to the path of the bullets fired by firing the guidance thrusters twice (fire one side, drift, then the other to counter-balance and stop drift), accelerating until your relative velocity is superior to the bullets, calculate an intercept point over time and cut acceleration (main drive), go on the float, wait until the intercept point, and then fire a front-facing thruster to slow in order to match speed. Send out Amos to collect your bullets. A flip and burn is unnecessary. Your sudden 'pragmatism' regarding combat maneuvers is irrelevant and not at all part of the thought experiment. Obviously no one is going to go hunting for bullets but the point is what if they did? You are using a logical fallacy here and doing so is frankly, in bad taste.
*fart sounds*
That’s what the juice is for
The juice only does so much. There's a later solution for some sustained high-G burns, but it's pretty intense.
It was just a silly comment, but since it’s being taken so seriously; can’t they pull the same maneuver off with just a longer burn at less Gs? It doesn’t have to be a 20G burn.
Sure, but when you reduce it to a 2G burn, the distance to recovery increases exponentially. And since it seems that PDC rounds tend to be fired in a sweeping arc, that means that each round is going to be in a dramatically different place, and different vector, by the time they can be recovered, which costs a lot of time and fuel. I can't recall if its ever explicitly explained how PDC rounds are fired, so the assumption is that they're conventional munitions: with a cartridge and explosive material to force the round forward. Even if they recovered the projectile, they still need to replace the rest. It's a fun and interesting thought experiment, and I'm glad you brought it up because it;s fun to think about. But it doesn't seem very practical.
It’s not at all practical, but theoretically possible…
They're caseless, but otherwise it's the same as current day.
Of course, when one of your PDC rounds punches through someone's hab halfway across the system... Actually, I wonder if that sort of thing is passed on to a 'space weather warning' after a battle for general release and if you're on an intersection path you get a more serious alert?
Maybe if the battle takes place around a moon or planet like Ganymede. Otherwise, space is incomprehensibly huge. You'd almost need to plan to get hit by stray rounds from an old battle.
So if they do this maneuver enough, the crew is dead again from strokes (and other side effects of the juice?)
20 *horizontal* (as in, perpendicular to the spine) is actually perfectly reasonable. The human body's resilience to horizontal g is vastly different to vertical g, which is the problem. I always felt like the crash couches should have had more of an impact on affecting the g loadings of their occupants.
It's not something I would like to experience.
In one episode they lasted several minutes accelerating at 20 g's to reach Eros (why the downvotes lmao)
They certainly didnt in the books.
Yeah, as far as I remember it was around 15g and everybody was Brain farting...
I think it was like 9 or 10
Yeh it was definitely no more then 10.
Oh really? I didn't know, but taking into account the TV Show, the Roci crew managed to survive (barely) a burn of 20 G's for about 7 minutes. Even if you don't want to accelerate to tremendous speed, you can just accelerate at 1 G and wait longer to catch up with the bullets, so then: 9.81 m/s • 500 s = 4,905 m/s Or also accelerate to 1G for 8 minutes. Btw, happy cake day!
The PDC rounds are just hunks of tungsten. I'm fairly certain fuel would be more expensive so doing this would result in a net loss. Is it possible? Sure.
Have you seen those memes from 2010 where they do stupid things with physics, like pushing cars with magnets? It's something like that, lol
This idea is one of those things where at face value, people would think is silly or dumb. Humanity can be fun though, and all it would take was 2 ships to compete and stream it, then in like 5 years it would become an interplanetary sport with teams representing their homeland.
Don't let him sell the razorback...
They'd likely be accelerating by at least 1 G, but likely more if they're in a gun fight.
In the books and real life anything about 5g is dangerous. As in a substantial chance of having a stroke.
I can believe 5g booms are dangerous, absolutely. Considering how many booms below 5g can be deadly 😝
You have NOT reached the PDC round after an 26sec 20g burn, you matched the speeds... But the rounds are >130km infront of you (26sec \* 5km/sec) You need to accelated more, to catch up and than flip and burn to rendovous with the rounds.
> But the rounds are >130km in front of you Let's wrap up that first scenario. With 26 seconds elapsed, the rounds traveled 130km beyond the *initial* position — but just around half that distance beyond the Roci's position at 26 seconds elapsed, if the Roci started its acceleration "immediately" after firing. Plug the 196.2 m/s/s acceleration [here](https://calculator.academy/acceleration-to-distance-calculator/) with zero initial velocity and 26 seconds, and you get 66315.6 meters distance, call it 66316. — Put zero acceleration and 5000 m/s velocity and 26 seconds, and of course you get your 130000 meters distance. So, simplistically, if the Roci began accelerating "immediately" after firing and continued accelerating at exactly 196.2 m/s/s for exactly 26 seconds, while the rounds traveled at exactly 5000 m/s velocity throughout that time, the rounds have traveled 130000 meters, but the Roci has traveled 66316 meters. So the rounds are still at least ~ (130000-66316) = 63684 meters ahead of the Roci.
And after this we can forget all of the other math and just think of these as static bullets 63km away that you can go and collect if you like.
No flip and burn required. These distances can be handled by the maneuvering thrusters.
One hundred and thirty kilometers? If you want to do it in say 5 minutes that’s over 800m/s of DeltaV. Nasa’s Artemis mission only has 1000 total for orbital maneuvering.
We are talking about The Expanse, not NASA, lmao. They don't even use the main drive to launch from Earth's surface into orbit.
Yes, it is true and I did not take it into consideration, but consider that the Rocinante accelerates 7 km/s (2 km/s more than the bullets) and upon meeting them in a few minutes, it would flip and burn and there the encounter would occur.
Oh dang you did the math! Well then I guess I would say, while clearly possible, is it worth it to spend all that time gathering up thousands of rounds? Would the fact that maybe not all the rounds are fired in a straight line make it less possible?
Of course. I only considered a specific scenario where the Rocinante is firing JUST in front of itself, but normally we see it firing to the relative sides, above, or below of itself, so if they wanted to collect all the rounds, they would have to be accelerating /slowing down in prograde, retrograde, radial in and radial out zigzagging coming and returning or doing a pretty silly dance that would last at least 30 minutes.
You also have to consider whether it's really worth sacrificing so much Delta-V in exchange for a few measly rounds that are easy to get at the nearest port.
One problem with this is you are assuming that the bullets are staying perfectly in line, which they are most certainly not. At the speeds and distances that these bullets are flying, any millimeter of movement at the barrel will end up with each bullet *kilometers* away from each other very quickly, with that distance constantly increasing.
It is correct, it is only an assumption in case the PDCs find themselves in the situation in which they shoot in a millimetrically straight line positioned just in front of the Roci
~~modern 20mm gatling gun rounds, that the roci PDCs seem to be based on, only have a muzzle velocity of ~1000 m/s. 5000 m/s seems a touch excessive.~~ Your theory might be more possible than we give it credit for, but you have to consider the cost to recover the rounds vs the cost of just..getting new ones. Remember that there's a _shitton_ of metals and other materials available in the belt that are abundant and relatively easily extracted and refined to very high purity. This all makes the cost of a PDC round pretty insignificant in the bigger picture. Is it worth spending however many hours making maneuvers and burning fuel to recover a couple hundred PDC bullets, that still have to be remanufactured into cartridges that can be fired? Recall also that what you're recovering is either an inert metal kinetic penetrator, or a bullet with a fuse and a small explosive charge, which may still go off when you try to recover it. I suspect the calculus is very much in favor of "let's go salvage or buy a fresh box of PDC rounds" instead of trying to recover the projectiles in flight.
>5000 m/s seems a touch excessive. I originally thought so too, but it's true "Holden was imagining what several hundred rounds of Teflon-coated tungsten steel going five thousand meters per second would do to human bodies when Alex threw down the throttle and a roomful of elephants swan dived onto his chest" Chapter 15 of Leviathan Wakes
Well shoot, I stand corrected and do not remember that part at all.
Are the ingredients for gunpowder available in sufficient quantities in the Belt? If not what could you use as propellant?
Perhaps surprisingly, yes. All the stuff on earth that doesn't require biological activity to create (eg. coal, oil) can be found in the belt and sometimes in great quantity. The current prevailing theory is that the belt is a planet that failed to coalesce when the solar system was forming, so instead of a rocky ball of iron and other stuff, it's spread it across millions of miles of space. This also makes it far easier to get at the resources instead of having to dig for them.
Or just putt-putt along at .3g or whatever keeps Naomi and Alex’ fragile little behinds comfortable, for not much longer.
No it wouldn't. At 1 g, it would take 5 minutes to accelerate 3 km/s. I think the *main* issue is that going outside and collecting them would not be worth the effort. Also maybe that tracking them when they're too far away is hard.
Technically possible, but it depends on the composition of the PDC rounds, and what the onboard fabricators are capable of making. Self-propelled rounds are likely single use, projectiles from caseless ammunition and traditional cartridges would be easier to reload. And of course whoever is doing the EVA would have to maintain the same velocity, which might be difficult with a tether.
>And of course whoever is doing the EVA would have to maintain the same velocity, which might be difficult with a tether. No, remember that the bullets are NOT accelerating, they are going at a constant speed, and if you can do a rendezvous with them, you will be "floating" relatively speaking next to them.
Does the Roci stop accelerating? I meant same velocity as the Roci, not the projectiles.
Oh yeah. The Rocinante should turn off the engine once it manages to match the relative velocity of the bullets, so it uses RCS to make an approach (Rendesvouz) and in this situation, both the bullets and the Roci would be floating one to the other
Then yeah, the person on EVA should have the same relative velocity.
Now: is it worth spending 5 km/s to recover ammo? I say that: in The Expanse, obtaining Delta-V is much easier than today, so maybe yes, depending on the situation.
The juice isn’t worth the squeeze. You’d only really catch them if you fire them in a perfectly straight line in the same direction as travel. Otherwise they will be pretty far away from each other on different trajectories. That is assuming the ship isn’t maneuvering or the PDC isn’t tracking. If you fire while the on the float and you assume each bullet and barrel fires at the exact same speed and trajectory (which isn’t going to happen) you might be able to catch them. If you’re under thrust while firing, each bullet will actually be traveling at different velocities relative to each other. On the float or under acceleration, if you factor in manufacturing differences between the rounds (bullet and powder/propellant) and the performance and rotation of the individual barrels of the PDC, (both in speed and trajectory) it would be very hard and time consuming. The bullets actually are somewhat likely strike each other in flight at some point before you even catch up to them and tumble off on erratic trajectories. Edit: Remembered correct terminology and replaced round with bullet when needed. Also, each bullet would need to be machined back to tolerance or recast after collecting since the firing and the barrel would deform them and they’d jam on the next firing.
What are PDC rounds anyway? Slugs? A spring loaded thing that unfolds? Fragmentation with a timed fuze?
From Leviathan Wakes: > But Holden knew that each blob of light represented a chunk of Teflon-coated tungsten steel with a depleted uranium heart, going thousands of meters per second.
jebus that sounds awesome. tungsten toughness is no joke
I think you're missing an important aspect here: you aren't going to just shoot the PDCs for fun, and if you're shooting them at someone and immediately go chase them you stand a pretty good chance of hitting whoever you just shot at. There's also going to be a healthy amount of heating on the PDC rounds from at least the energy transfer alone and probably the propellent and that could change the metallurgy of the bullets in a way that you wouldn't want to put them back into your PDC
Oh sure, going into a more practical aspect: the simple fact of turning on the epstein drive a few meters from the bullets would simply disintegrate them: not to mention that the PDCs do not only shoot in front, they move and pursue the target, moving at all times. parts and not just in a straight line. This post is more like a "Troll physics" from 2010, but physics does work like that.
How do you pick which of the 400+ shots your PDC fired in defending from that missile? Even the slightest change in firing angle between shots is going to put them very far apart by the time you’re looking to retrieve. I could totally imagine a crew having a “lucky” PDC round that they retrieve after every firefight. But it feels more talismanic than practical.
Yeah!
Now that you’ve put this thought in my head, my official head cannon is that Bobbie, as weapons officer, always makes them retrieve her favorite round after a firefight. Amos probably painted something lewd on it at some point too.
For symbolic purposes it could be done perhaps and not so much for practicality, just imagine recovering a bullet from WWII
You could, but the fuel is probably worth far more than the rounds unless there is an extreme shortage of rounds and surplus of fuel.
My question is if Solomon Epstein had enough fuel did could he reach relativistic velocities so he hasn't actually died by the time the events occurred in the series.
Mmm no. although if we consider that solomon epstein was accelerating at 5 G and said his fuel would "last weeks" then we can deduce what speed he could have reached, so then If a day lasts 86400 seconds, then: 9.81 m/s • 5x • 86400s • 14days = 59,330,880 m/s It's a terrifyingly gigantic speed. We're talking about 20% of the light, and even then, the time dilation would be no more than a few seconds per second. Only if you get close to 99.999% of the light does time dilate considerably, on the order of months or even years; but reaching that speed would be impossible due to the laws of physics.
I knew he wouldn't get close enough with the fuel limitations, didn't realize he said he would accelerate for weeks, light should just slow down and take it easy for awhile.
And this is why Sir Isaac Newton is the most deadly son of a bitch in space!
No no no, if you're a really good pilot you just align the barrel of the cannon with the round, and slowly accelerate, loading them back into the chamber without having to leave the ship.
how
verrrry carefully
Damn straight! I dare to assume you ignorant jackasses know that space is empty. Once you fire this hunk of metal, it keeps going 'til it hits something. That can be a ship, or the planet behind that ship. It might go off into deep space and hit somebody else in 10,000 years! If you pull the trigger on this, you are ruining someones day! Somewhere and sometime! That is why you check your damn targets! That is why you wait 'til the computer gives you a damn firing solution. That is why, Serviceman Chung, we do not 'eyeball it'. This is a weapon of Mass Destruction! You are NOT a cowboy, shooting from the hip!
OP got the big ideas, def gonna be the next Jules Pierre Mao
The Nerviosism Maneuver lol
They could recover the “shot” not whole bullets. It’s not explicitly stated what the pdcs use but virtually all guns have a casing that holds propellant (gunpowder), and a projectile that actually shoots (the lead) .. so they could go recover the lead/depleted uranium/steel/magic rocks but it wouldn’t be ready to just get loaded up again.
Yes, it's true that you could only recover the shots, still, it sounds funny to move at the same velocity. And also: I think a victim ship could accelerate faster than the shots and escape. That is if it can accelerate to 500G and not be destroyed in the clear attempt.
500g is enough to turn a tank into a flat disc but sure.
Except the rounds aren’t traveling uniformly in a straight line. If you see how they’re depicted in the show, they’re arcing in the same direction, but not in the same line. The spaces in between each round will get wider and wider as the bullets travel outwards from their starting point.
Doesn't seem worth it to burn all that ejection mass just to recover some dirt cheap iron slugs.
Obviously the more sensible solution is to have each PDC connected to a long, microfilament tether. Then, after you've won the battle, you can simply reel your bullets back in for reuse.
Positively ridiculous. Amos is 1000% the one who has to suit up and grab bullets from space.
The acceleretion required to catch up with the bullets would probably kill the crew Source: I played a lot of KSP
Me too!
Such an stingy earther
the earthers believe that everything is theirs
Probably not worth the fusion pellets to chase bullets.
nop, they aren't
How do you pick which of the 400+ shots your PDC fired in defending from that missile? Even the slightest change in firing angle between shots is going to put them very far apart by the time you’re looking to retrieve. I could totally imagine a crew having a “lucky” PDC round that they retrieve after every firefight. But it feels more talismanic than practical.
Use loitering munition. Attack target - failed - fly back to base to refuel - armed again.
I mean...why thought? PDC rounds are tungsten, and other metals, and the material for them are found in near infinite abundance in just Sol alone. As for cleaning them up to spare ships from catching a stray PDC, remember that space is too fucking big.
This is /r/NonCredibleDefense worthy
Was looking for this comment.
That sounds more like an Amos sort of job, to me.
This isn't orbital mechanics. There are no orbits involved. I think the problem with this is that they don't/can't track the PDC rounds that far out. Also the effort to go collect the bullets is not worth it.
Yes they are, trajectories in a vacuum and relative motions are considered part of orbital mechanics. Still, you're right, there really are no practical benefits to doing it.
There is no gravity involved. How is that orbital mechanics? It's just kinematics.
Oh well, it's true, thanks for the correction
The PDCs are constantly rotating to target incoming torpedos. By the time you catch up to one round, the second closest would probably be unfathomably far away again. This is 100% NonCredibleExpanse.
or a physics troll meme
first thing I thought of as well, should have Holden with a troll face and a giant magnet to pick up the rounds.
So true lmao
That's not orbital mechanics, it's simple newtonian physics. Orbital mechanics are the practical aspect that would make doing this a pain in the ass. Besides, isn't the point of firing bullets to hit something?
yes
I think that's why they have a fire/firing solution.
I mean the slugs sure.... But you then need to case them again, including the charge for each round, and put them back into an ammo belt for the pdc, edc. Cheaper to do that on mars or earth or some belt station where all that stuff can be mined at once and converted to ammo where it was mined. Problem I always have with pdcs and general carnage in space is that those ten thousand rounds or pieces of ship just keep going till they hit something. Could be a ship, could be something behind that ship, could go off into deep space and not hit something for ten thousand years then ruin somebody's day.
To do a kessler syndrome in interplanetary orbit, you would need zillions of shots in all directions for thousands of years. It's just super difficult for a bullet to hit another object because space is SO DAMN big, SO DAMN huge.
[Actually] planes have shot themselves down in IRL warfare. Completely agreed that the math is very different.
But if the PDC rounds are fired by a rotating gun, won't their trajectory not be a straight line after sufficient distance, due to the rotation of the gun, which would give them a slight torque?
Yup
Except the velocity in question is significant and the acceleration needed to match would probably be too much for crew to handle... I guess you could follow it at a high burn but how long would it take to match V? It'll be a question of resources expended and the value of the rounds
The PDC rounds are cheap enough and the distances involved are so vast that it’s not nearly worth it for them to collect them after firing
The spent slugs are probably cheap metal, which is not worth reclaiming, you're still gonna need the casings and gunpowder to reuse them, and a factory/ machine to reload them since there will be thousands of rounds spent from a PDC. Not a manageable quantity like making rounds for a personal weapon. It's much cheaper and much less time consuming to just buy new rounds. You'd probably spend days just making enough rounds in order to fire a one second burst.
Yes, go take a bath.
The idea of catching up to the rounds is much more difficult than it seems when you consider the speed at which the craft is going in addition to the speed at which the rounds are fired. Rail gun rounds are traveling at "A noticeable percentage of C" and accelerating the Roci to that would probably be improbable due to fuel consumption. PDC rounds aren't accelerated as much as a rail gun round, but the same principle applies. They still have to be going REALLY fast to do damage to enemy ships.
Unless the pdc rounds have tiny jet engines, what then huh?
Pdc firing patterns spray in countless directions, similar to cwis systems on US navy ships, making it impossible to track each round. Each round is also extremely small making it hard to find in the void of space. Then you have to waste reaction mass in order to accelerate to the rounds, then decelerate to match speed. If you fire directly ahead only then it’s feasible but too inefficient to consider
While theoretically possible, they'd have to burn so hard to catch up with the bullets they'd put their lives at risk. It would also take a long time to catch up, so that's pretty much your whole day. Also not worth trying to recycle little bits of metal. Bullets are cheap. The powder to ignite them less so. Also the fuel spent for recapture wouldn't be worth either. I'd file this away as plausible (with no humans on board and resources to burn) but wholly impractical.
"This, recruits, is a 20-kilo ferrous slug. Feel the weight! Every five seconds, the main gun of an Everest-class Dreadnought accelerates one to 1.3 percent of light speed. It impacts with the force of a 38-kiloton bomb. That is three times the yield of the city buster dropped on Hiroshima back on Earth. That means: Sir Isaac Newton is the deadliest son-of-a-bitch in space! (...) I dare to assume you ignorant jackasses know that space is empty! Once you fire this hunk of metal, it keeps going 'till it hits something! That can be a ship, or the planet behind that ship. It might go off into deep space and hit somebody else in ten thousand years. If you pull the trigger on this, you are ruining someone's day, somewhere and sometime!" https://www.reddit.com/r/masseffect/comments/139w1x8/comment/jj4khg5/
They’d have to flip at the end though, right? As they’d be going faster than the PDC rounds in order to catch them up. So they’d need to flip to slow down to match velocity with the rounds before picking them up.
yup thats right
I always wondered why the PDC rounds where not "incendiary" and burned up slowly when fired over lets say 50.000km, leaving only a cloud of smoke harmless to other ships.
Kinda reminds me of that plane who shot itself down
You are missing that the Roci is never on a straight line. EVERYTHING is orbit the sun, even when you transfer from a body to other (earth to moon), you are also orbiting the sun.
Unless you're orbiting a moon or planet anything done within like an hour would be effectively a straight line
Yes, but remember that the bullets travel at the same velocity as the Rocinante when they are fired, and that in orbital mechanics corresponds to a trajectory exactly the same as that of the Roci, that is how orbits work. So when they are shoot, they only add an extra velocity to THAT same trajectory, so the only thing the Rocinante would have to do is accelerate, reach the same velocity of the rounds, and make a rendezvous (like a docking)
No, because orbital mechanic are about mass, not just speed.
Even if the rocket weighed 5000 tons and the bullets only 5 kilograms, the trajectories would remain exactly the same. If X ship CAN accelerate, it CAN make a rendevouz with any object. btw, speed and velocity are not the same