That's because it's using the rubber energy directly with an extremely heavy projectile, you could not propel the same projectile at 50 fpe using the piston I'd say, but a lighter one would easily reach much higher velocity.Joerg's slingshots are directly producing 50 fpe.
PimpAssasinG wrote:no im strong but you are a fat gay mother sucker that gets raped by black man for fun
The slingshot pouch speed becomes the speed of the projectile.inonickname wrote:That's because it's using the rubber energy directly with an extremely heavy projectile, you could not propel the same projectile at 50 fpe using the piston I'd say, but a lighter one would easily reach much higher velocity.Joerg's slingshots are directly producing 50 fpe.
Looking forward to it anyway.
PimpAssasinG wrote:no im strong but you are a fat gay mother sucker that gets raped by black man for fun
Absolutely true.. for the much heavier projectile of the arrow. When working with pellets that have a mass close to the mass of the bowstring, the efficiency changes and the energy transfer through an air spring is more efficient at the higher velocities.Ragnarok wrote:Unfortunately, the numbers disagree with you.Technician1002 wrote:This why I like the air as a spring.. Less kinetic energy lost to the spring, bow, string, arm, etc, and more transferred to the projectile.
Springers are about 30% efficient in converting spring energy to kinetic energy. Crossbows - over 90% efficient.
This energy is all wasted in the compression of the air.
So, with a straight mechanical energy transfer like a crossbow or similar, you can stand to lose quite a lot of that efficiency into the mechanism (provided of course you don't damage it in the process) and you'll still be winning out.
...Actually, I've just been helpfully reminded of a design I did last year for a high velocity crossbow that used mechanical advantages to propel projectiles to much higher speeds than normal (at surprisingly little efficiency loss) but the problem is although I can remember the basic principles of the design, I can't immediately remember the finer points of its operation.
First part is very true.. The speed is of the slingshot pouch.The projectile, light, or heavy, is the speed of the slingshot pouch.
The weight of a 14gr .pellet or a 200 gr ball does not appreciably affect the retraction speed of a 35 pull rubber.
It's also worth pointing out that the detonation of lubricant in many springers is actually providing some of the power, adding chemical energy to the mix. Springers are considered a "black art", even by today's engineering standards, it's always a question of trial and error and getting it right is tricky.inonickname wrote:You realize that a big thing with springers is that the rapid motion of the piston adiabatically heats the air, causing a higher particle speed in the gas, and therefore a higher velocity?
Only reason some springers will happily go mach. It's also the cause of them being destroyed after using the wrong lubricant (i.e. diesel).
Bear in mind, 30-40% is the limit of springer efficiency. (30% being typical). Regardless of projectile weight, you won't see more than that.Technician1002 wrote:Absolutely true.. for the much heavier projectile of the arrow.
Very approximately, there's about 0.05-0.1 grams of air in the compression chamber of my air rifle (I'm not about to fart around measuring the chamber volume). Pellets are 0.5 grams, so that's about an order of magnitude more than the air.When working with pellets that have a mass close to the mass of the bowstring, the efficiency changes and the energy transfer through an air spring is more efficient at the higher velocities.
Fair.jackssmirkingrevenge wrote:It's also worth pointing out that the detonation of lubricant in many springers is actually providing some of the power, adding chemical energy to the mix. Springers are considered a "black art", even by today's engineering standards, it's always a question of trial and error and getting it right is tricky.inonickname wrote:You realize that a big thing with springers is that the rapid motion of the piston adiabatically heats the air, causing a higher particle speed in the gas, and therefore a higher velocity?
Only reason some springers will happily go mach. It's also the cause of them being destroyed after using the wrong lubricant (i.e. diesel).
On a small footnote, I had forgotten about it, cheers
Very true, but can you provide the same gas temperature? The light gas from compression heating is part of the gain and helps near SOS in the sling gun.boyntonstu wrote:
I can conceive of a burst valve that should give the slingairgun the same performance as any other pneumatic gun with the same chamber volume and pressure that it sees at the end of the stroke.
BoyntonStu
Latent Heat of Confusion
"Ragnarok wrote:Bear in mind, 30-40% is the limit of springer efficiency. (30% being typical). Regardless of projectile weight, you won't see more than that.Technician1002 wrote:Absolutely true.. for the much heavier projectile of the arrow.
The truth is, springers tend to get higher muzzle energy with lighter pellets (around 8 grains in .177", as opposed to heavy 10-11 grain pellets).
So, ~30% for springers with projectiles "of the ideal mass".
However, bows can hit 90%+ with projectiles "of the ideal mass".
Very approximately, there's about 0.05-0.1 grams of air in the compression chamber of my air rifle (I'm not about to fart around measuring the chamber volume). Pellets are 0.5 grams, so that's about an order of magnitude more than the air.When working with pellets that have a mass close to the mass of the bowstring, the efficiency changes and the energy transfer through an air spring is more efficient at the higher velocities.
We'll say 10% of the mass is in the air.
Typically, an arrow is about 25 grams (~400 grains), for either bows or crossbows. A reasonably modern bowstring (for a bow, rather than a crossbow) is ~7 grams.
That means that that about 20% of the mass is in the string.
That means that MORE of mass proportionally is in the bowstring than in the air. The air rifle has a more favourable mass split, but it still has less than half of the efficiency.
So, it's nothing to do with the fact that the arrow is heavier. As a proportion of the accelerated mass, the arrow is lighter!
You can get faster with springers, but it's done much less efficiently.
PimpAssasinG wrote:no im strong but you are a fat gay mother sucker that gets raped by black man for fun
This is true, but except at relatively point blank range I don't think you can ever include "accuracy" among those attributes, unless you create some sort of trigger mechanism. Still, if you have no other legal options when it comes to firing projectiles, it's certainly not a bad route to takeJoergS wrote:Having said that, there is a lot of potential in modern rubber. You can build fine weapons with it, inexpensive, silent, efficient and compact.
I guess you can say you are as accurate as your average smoothbore shotgunJoergS wrote:I am very accurate with my slingshots. I can hit a shoebox size target at 20 Meters easily and reliably.
Noone ever attacked me, but that kind of accuracy is probably all you ever need.
The fastest slingshot in the West
as I pointed out earlier in this thread, you are lucky to have the sort of upper body strength which can take full advantage of the slingshot's potential and give a lot more energy to the projectile than the average person.Luck? It was hard work, countless hours in the Gym.jackssmirkingrevenge wrote:you are lucky to have the sort of upper body strength which can take full advantage of the slingshot's potential
