Tiny tech questions...

Doesn't pulsers use focused gravity to accelerate the darts? That would mean that there is no recoil.

Joat42 wrote:Doesn't pulsers use focused gravity to accelerate the darts? That would mean that there is no recoil.

Unless someone has repealed the basic laws of physics, there has to be some recoil. Conservation of momemtum. If the pulser has a muzzle velocity of 2,000 m/s and the .308 has a muzzle velocity of 800 m/s, if the mass of the pulser dart is 40% of the .308 round, then the recoil is going to be the same, unless she is carrying around a portable acceleration sump to dump it into.

Joat42 wrote:Doesn't pulsers use focused gravity to accelerate the darts? That would mean that there is no recoil.

It seems likely that there is still SOME recoil, but perhaps quite a bit less than a "chemical burner". That said, if the "pulser dart" is about the size of a 3mm, but with presumably more weight, maybe 2/3 of a copper .22 caliber or so, it would be still be equivalent as a kill round, because 2km/sec is about 2/3x faster than a .220 Swift.

Here's the wikipedia spec: "Due to its very high velocity its bullet drop allows dead on sighting on game such as groundhogs to ranges out to 375 yd (343 m), and it is still considered an excellent cartridge for taking varmints by experienced Swift shooters. The original factory load from Winchester provided a 48-grain (3.1 g) bullet launched at 4,100 feet per second (1,250 m/s)".

At which point I go "geez!" that's still a good shot.

fallsfromtrees wrote:

Joat42 wrote:Doesn't pulsers use focused gravity to accelerate the darts? That would mean that there is no recoil.

Unless someone has repealed the basic laws of physics, there has to be some recoil. Conservation of momemtum. If the pulser has a muzzle velocity of 2,000 m/s and the .308 has a muzzle velocity of 800 m/s, if the mass of the pulser dart is 40% of the .308 round, then the recoil is going to be the same, unless she is carrying around a portable acceleration sump to dump it into.

The pulser darts are explosive, so their stopping power isn't predominantly in their sheer kinetic energy. I have very little idea what the mass of the dart is, but if anything can be done to lighten it up consistent with maintaining - really, there's no reason not to use the term - warhead strength, it probably will be.

SharkHunter wrote:

Joat42 wrote:Doesn't pulsers use focused gravity to accelerate the darts? That would mean that there is no recoil.

It seems likely that there is still SOME recoil, but perhaps quite a bit less than a "chemical burner". That said, if the "pulser dart" is about the size of a 3mm, but with presumably more weight, maybe 2/3 of a copper .22 caliber or so, it would be still be equivalent as a kill round, because 2km/sec is about 2/3x faster than a .220 Swift.

Here's the wikipedia spec: "Due to its very high velocity its bullet drop allows dead on sighting on game such as groundhogs to ranges out to 375 yd (343 m), and it is still considered an excellent cartridge for taking varmints by experienced Swift shooters. The original factory load from Winchester provided a 48-grain (3.1 g) bullet launched at 4,100 feet per second (1,250 m/s)".

At which point I go "geez!" that's still a good shot.

The pulser dart leaving forward has a certain momentum. Newton's third Law of Motion is: For every action there is an equal and opposite reaction. The reaction in the case of firing is the recoil, and it is equal to the momentum of the dart (or bullet or whatever). Unless you have a momentum sump to dump the recoil into, you are going to have it.

--snipping

fallsfromtrees wrote:The pulser dart leaving forward has a certain momentum. Newton's third Law of Motion is: For every action there is an equal and opposite reaction. The reaction in the case of firing is the recoil, and it is equal to the momentum of the dart (or bullet or whatever). Unless you have a momentum sump to dump the recoil into, you are going to have it.

That's the handwavium part. If you look at the shell size even on a .223/4 (which I have fired) or a .220 Swift (which I have not), it's a big shell with moderate kick, the combination won't work well in a "single" hand weapon, but the "dart" is supposed to be 2/3 faster. There's also a term for the type of round that is deadlier than a penetrator style bullet, btw but I'd mess up the technical term if I tried to find it.

I think we presume that with a "grav driver", part of the mechanism would be in essence be "a reverse grav driver", aka used as a recoil sump. It has to be enough that when LaFollet etc. are firing in the restaurant to defend Honor, etc., or the King's Own defending Ruth and Berry, they're not having to constantly adjust for recoil. Plus Jeremy-X is described as being a rather smallish man, but one of the deadliest pulser shots in the galaxy. I'd presume that foregoes Popeye size forearms.

fallsfromtrees wrote:The pulser dart leaving forward has a certain momentum. Newton's third Law of Motion is: For every action there is an equal and opposite reaction. The reaction in the case of firing is the recoil, and it is equal to the momentum of the dart (or bullet or whatever). Unless you have a momentum sump to dump the recoil into, you are going to have it.

There is one issue with comparing a pulsar with any current chemically propelled rounds, the pulsar has no chemical propellent. The mass used for calculating recoil is that of the projectile + Propellent. This is in part a simplification, but on average the propellent that leaves the muzzle faster than the projectile is canceled out by that which is going slower than the projectile (and may not even leave the muzzle.

Castenea wrote:

fallsfromtrees wrote:The pulser dart leaving forward has a certain momentum. Newton's third Law of Motion is: For every action there is an equal and opposite reaction. The reaction in the case of firing is the recoil, and it is equal to the momentum of the dart (or bullet or whatever). Unless you have a momentum sump to dump the recoil into, you are going to have it.

There is one issue with comparing a pulsar with any current chemically propelled rounds, the pulsar has no chemical propellent. The mass used for calculating recoil is that of the projectile + Propellent. This is in part a simplification, but on average the propellent that leaves the muzzle faster than the projectile is canceled out by that which is going slower than the projectile (and may not even leave the muzzle.

Any propellent that leaves in a forward direction contributes to the forward momentum component - regardless of the velocity at which it leaves - the slower moving stuff does not cancel out the faster moving.
On average the weight of the propellent is about half the weight of the bullet, and the average velocity of the propellent will be less than that of the bullet (since a lot of the energy of the propellent is used to accelerate the bullet), the component of the momentum supplied by the propellent will be less than 1/3 of the total recoil. There is some, but it doesn't significantly change the calculations - most of which are BOE.

My best somewhat maybe educated guess would be probably under 50 meters, with inside 25 meters being probably better. Lots of basic reasons for this including ... as a summary presentation ...

) The blast and recoil, must be within the ability of Honor to withstand. No matter how the dart is accelerated, there is going to be equal recoil energy to deal with. Human parts present a limit.

2) Size and energy constraints. We are talking about a dart designed to fit into or inside or integrate with something finger sized. This probably means a very small light dart going very fast.

3) Sectional density would not be that great. Any surrounding air pressure would greatly slow down the dart in just a few meters. Thus the limited range. But close in within about 10 meters? Deadly.

My read only. HB of CJ (old coot) Cm.

As a serious handgun shooter I decided to actually run the numbers on this an do some research on dart type projectiles

First the sectional density of a dart would be significantly higher than a traditional bullet . A 55 grain 3 mm dart would have a SD of 3.43 as compared to 1.57 for a 5.56 mm bullet thus the ballistics would be excellent.

As to the questions with recoil. I shoot 44 mag on a regular basis and can hit a standard chest silhouette at 50 yards all day long side arm one handed slow fire.

So I calculated the free recoil energy for my 44 load 1450 fps with a 240 grain bullet over win 296 25 grains: 21.20 ft/lbs

The free recoil energy for a 55 grain bullet at 6000 fps over 1 grain of powder ( I needed something to keep the program happy) is 11.78 ft/ lbs which is about the same as a full power 357 load. Definitely popping but not a structural problem for a normal human at all.