Jump to content

How fast could a steel pushed bullet go...


Colors

Recommended Posts

We've seen Wax amplify the speed and power of his shots in the past.

How fast do you think a Fullborn sniper with a spike for abrasion could push a bullet?

Imagine, they can increase their weight in the same manner as Wax, they could use a duralumin assisted steel push, and they could negate the friction imposed on the bullet completely.

Any way to calculate roughly how fast they might be able to push a standard rifle bullet?

Link to comment
Share on other sites

Well, physics of Pushes is wildly inconsistent (if you Push with constant force coins should be handily supersonic, which they are not), so sadly no proper calculation can be done.

Theoretical maximum with Abrasion applied (and assuming Abrasion won't interfere with pushing), is of course speed of light, however they won't reach that.

I'd wager something along the lines of several dozens of Machs.

Link to comment
Share on other sites

2 hours ago, therunner said:

Well, physics of Pushes is wildly inconsistent (if you Push with constant force coins should be handily supersonic, which they are not), so sadly no proper calculation can be done.

Theoretical maximum with Abrasion applied (and assuming Abrasion won't interfere with pushing), is of course speed of light, however they won't reach that.

I'd wager something along the lines of several dozens of Machs.

That's actually not true, friction is not the only source of drag.  Even with zero surface friction there is inertial drag from the mass of air that is getting compressed and/or shoved out of the way, and these forces become far more significant when you reach the speed of sounds of whatever atmosphere you are in. 

For the math, it will be fundamentally different and more complicated on Roshar where gravity and the atmosphere are both non-standard for earth, so assume Scadrial for ease.  It's not an easy calculation without a lot of assumptions because the math all starts at the chemical energy released by the gunpowder mix, and then it will depend on the bullet size and shape.  Also, a frictionless bullet is not going to react to barrel rifling, so you'll have to find some other way to impart spin on the bullet, or it might prove no more effective than a musket-ball.  

Link to comment
Share on other sites

1 hour ago, Quantus said:

That's actually not true, friction is not the only source of drag.  Even with zero surface friction there is inertial drag from the mass of air that is getting compressed and/or shoved out of the way, and these forces become far more significant when you reach the speed of sounds of whatever atmosphere you are in.

Good call, forgot all about that.

Quote

For the math, it will be fundamentally different and more complicated on Roshar where gravity and the atmosphere are both non-standard for earth, so assume Scadrial for ease. 

Not fundamentally different or more complicated. Gravity won't play a role at all (at most in range, but that is not part of question), and atmosphere mix will change how reactive atmosphere is. However, acceleration would be dominated by the Duralumin Push, not by the gunpowder explosion, so atmosphere will play only a minor role.

 

Link to comment
Share on other sites

1 hour ago, Quantus said:

That's actually not true, friction is not the only source of drag.  Even with zero surface friction there is inertial drag from the mass of air that is getting compressed and/or shoved out of the way, and these forces become far more significant when you reach the speed of sounds of whatever atmosphere you are in. 

For the math, it will be fundamentally different and more complicated on Roshar where gravity and the atmosphere are both non-standard for earth, so assume Scadrial for ease.  It's not an easy calculation without a lot of assumptions because the math all starts at the chemical energy released by the gunpowder mix, and then it will depend on the bullet size and shape.  Also, a frictionless bullet is not going to react to barrel rifling, so you'll have to find some other way to impart spin on the bullet, or it might prove no more effective than a musket-ball.  

Great point, I had not considered about the rifling. 

As far as abrasion, that's fascinating. So even with abrasion applied the bullet would not travel as if in a vaccuum, in theory the the compression of the air in it's path would add some degree of drag even without friction? 

Link to comment
Share on other sites

Well... let's do a bit of loose math with some internet calculators to get a rough idea of how much force we're talking here. In TLM Wax was able to launch himself while carrying Wayne on his back in a single impulse to a boat traveling from Bilming to Elendel. The distance between Bilming and Elendel is about 100 miles based on the in book map. To aim low, let's assume to boat was only 30 miles away from Bilming and as they were at an elevated position on a tower probably near the coast, I'll say they were about 500 feet in the air. Reeeaaally loose numbers. For context, the fastest bullet according to Wikipedia has a muzzle velocity of 1422 m/s.

Using this calculator, assuming a 45 degree angle launch, starting 500 feet above the target, taking into account gravity, and to hit a target 30 miles away, Wax and Wayne would need to be moving about 1550 mph. Let's assume that Wax shed all of his weight prior to launch and is only carrying himself, Wayne, and their weapons, so... let's say Wax launched 250 pounds of mass. That's what, 27,000,000 joules of kinetic energy? Toss that into this calculator for bullet kinetic energy, assume a 140 grain round, and if you apply 27,000,000 joules of force you'll need... a velocity of 254,000 feet per second, or 173,000 mph which... makes me question my math. That's almost 7 times faster than what you would need for escape velocity. That's probably fast enough that if you fired it horizontally it still wouldn't land on the planet, and that's just Wax with a Duralumin spike. If we add in air resistance, Wax retaining some weight, or assuming the ship is farther out then that force just gets higher.

I'll need ballistics people to tell me if I got that right or not, as well as how much force would actually be transferred to the target or if it would just leave a nice neat bullet hole going straight through with relatively little energy transferred to the rest of the target's body. So... I'll say that a Fullborn could fire a bullet faster than they would ever have a practical need to do so.

If I was a sniper Fullborn with a single surge, I might take Gravitation actually. I couldn't fire them out of a conventional gun, but Lashing the bullet towards my target before Pushing on them would let me ignore drop from Gravity entirely and that takes a significant variable out of the aiming equation.

Link to comment
Share on other sites

2 hours ago, Duxredux said:

Well... let's do a bit of loose math with some internet calculators to get a rough idea of how much force we're talking here. In TLM Wax was able to launch himself while carrying Wayne on his back in a single impulse to a boat traveling from Bilming to Elendel. The distance between Bilming and Elendel is about 100 miles based on the in book map. To aim low, let's assume to boat was only 30 miles away from Bilming and as they were at an elevated position on a tower probably near the coast, I'll say they were about 500 feet in the air. Reeeaaally loose numbers. For context, the fastest bullet according to Wikipedia has a muzzle velocity of 1422 m/s.

Using this calculator, assuming a 45 degree angle launch, starting 500 feet above the target, taking into account gravity, and to hit a target 30 miles away, Wax and Wayne would need to be moving about 1550 mph. Let's assume that Wax shed all of his weight prior to launch and is only carrying himself, Wayne, and their weapons, so... let's say Wax launched 250 pounds of mass. That's what, 27,000,000 joules of kinetic energy? Toss that into this calculator for bullet kinetic energy, assume a 140 grain round, and if you apply 27,000,000 joules of force you'll need... a velocity of 254,000 feet per second, or 173,000 mph which... makes me question my math. That's almost 7 times faster than what you would need for escape velocity. That's probably fast enough that if you fired it horizontally it still wouldn't land on the planet, and that's just Wax with a Duralumin spike. If we add in air resistance, Wax retaining some weight, or assuming the ship is farther out then that force just gets higher.

I'll need ballistics people to tell me if I got that right or not, as well as how much force would actually be transferred to the target or if it would just leave a nice neat bullet hole going straight through with relatively little energy transferred to the rest of the target's body. So... I'll say that a Fullborn could fire a bullet faster than they would ever have a practical need to do so.

If I was a sniper Fullborn with a single surge, I might take Gravitation actually. I couldn't fire them out of a conventional gun, but Lashing the bullet towards my target before Pushing on them would let me ignore drop from Gravity entirely and that takes a significant variable out of the aiming equation.

Your case for Wax and Wayne jump is interesting but I think Iron screws with it a lot more. Momentum is conserved thus tapping a massive weight and duralumin pushing would build a TON of momentum... then shedding that weight would actually cause you to accelerate as well while flying. 

If I remember correctly the support beams bent in as well. Any crumple in the structure being pushed off means there was even more initial energy that was lost in that push as well.

The only reason I want to blame Iron for the feat instead of duralumin steel is because it seems more consistent with what we have seen outside of Vin running on the mists and ascending. 

The conservation of momentum seems more viable as in theory every time you half the weight you double the speed. We know Wax can store millions of pounds worth of his own weight to use.  In fact if Wax is 180lbs and stores 33% of that all the time then he is storing 59lbs all the time. Lets round it out to 60lbs.

If Wax stores 60lbs per second for 18 hours a day he stores 3,888,000 lbs for use later. Tapping that much... if you have the anchors to make a push and get airborne (which duralumin with steel could do) you would take off with so much momentum and it would carry you further than a high velocity alone.  

That thought is just to say that I don't think Wax's jump accurately shows what could happen to a bullet. Wax can hack and gain speed after the push is over with thanks to his iron feruchemy. The bullet can't. And there is only so much of a push that you can do on a bullet before it is beyond your ability to push it more. Where Wax could still be manipulating his jump well outside of steel pushing range. 

Link to comment
Share on other sites

  • 3 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...