What’s required to fire a pellet?
Roughly speaking, how much air is required to fire a pellet?
Say a cylinder at 2000psi, 250mm x 16mm = 19642 cubic mm. Is that enough to fire one at a decent fps?
All Replies
Viewing 14 replies - 1 through 14 (of 14 total)
As I know, 1 inch = 25.4 mm. So 1 cubic (not square) inch equal 25.4*25.4*25.4=16387 cubic millimeters. Or almost 16.4 cubic cm.About Psi – 3000 psi = 207 bar. So You can calculate.PS – metric system – the best 🙂
Thanks South. 🙂
To make that info useful do you happen to know how much air is in one square inch volume at 2000 psi? Or in one square centimeter at 13000nm?
How to calculate how much air you need to fire a pellet:
1 – Check the beginning pressure in your rifle. In Bar (kg per square centimetre). Let it be P1.
2 – Fire pellets through chronograph, counting shots. Your’ll get N shots.
3 – Then calculate middle speed or pellet.
V=(Speed1+Speed2+…+SpeedN)/N.
4 – Calculate middle energy of shot. In Joule.
E=m*V*V*0.5, where m – is mass of pellet in kg. 10.5 grain=0.00068 kg, for example.
5 – Check the ending pressure in your rifle. Let it be P2.
6 – Now we have all digits to calculate expence or air per Joule of each shot:
(P1-P2)*Vol/(N*E)
7 – and You need to know volume of Your rifle reservoir in cubic centimetres. Let it be Vol.
Let’s show it in example of my CZ-200 with 122 cc volume of reservoire.
The beginning pressure is 200 bar, the ending is 121 bar, I get 35 shots with middle speed 288 meters per second by 10.5g bullet.
E = 0.00068*288*288*0.5=28.2 J
(200-121)*122/(35*28.2)=9.64 cc of air per 1 Joule of muzzle energy.
And one more. If You get expence form 8 to 10 cc per J – its a good normal expence. If You get more – You have to improove Your rifle. And if You get less, than 8 – its exellent!
This is right for energy 20-30 J. In case of bigger energy (more than 30) expence of air may be 12-16 cc.
About energies less then 20 J expence of air will be less,but I cant say digits – simply don’t know.
PS – sorry for mistakes 🙁
I’m going to have a go at this so I can get MY rifle sorted, and if it works I’ll happily share it here………….
…………… that was very helpful. 😀
drawings eh? …….. ok 🙄
good luck with your projects.
I don’t know about making a regulator for the rifle, maybe somebody should make one for you, shove it up yo ass and regulate your piss-poor attitude. Problem is I don’t think there’s a material known to man that would be able to withstand the pressure.
I’m going to have a go at this so I can get MY rifle sorted, and if it works I’ll happily share it here………….
…………… that was very helpful. 😀
drawings eh? …….. ok 🙄
good luck with your projects.
What are you on about Voltar? 😕 I posted my drawings previously. How stupid do you think I am? Get rich? The minute I sold anything it would be stripped, back-engineered and produced by anyone with the tools and a liking for Talon air-rifles. 🙄
I’m going to have a go at this so I can get MY rifle sorted, and if it works I’ll happily share it here.
Walkon, I’m aware of the apparent magnitude of the task ahead. But I’m also aware of the fact that when I last handled a lathe I was finishing half an hour before everyone else on the course and found the entire gig something of a piece of piss. Course-work done, within spec, faster than everyone else AND on a sloppy lathe.
My advantage will be that I have no intention of ‘Learning How To Lathe’, I will use the lathe as a tool to do what I want to do. I learned enough, and still remember it, to know how to do what little I will need to do. Will I make mistakes? You betcha. Will I break tools and work? Yes. Will it takle me thousands of hours to get where I want to go? No. There’s knowledge and there’s experience, but there’s also adaptability and improvisation, the value of which I learned working with a POS sloppy lathe and still finishing in-spec long before everyone else.
Nevertheless, my first job will be tidying up my silencer. Then I’m going to polish some .50 cal cartridges I have (empty) 😆 . Then make a muzzle-brake for my brother. I’m also going to play with plastic stock, aluminium and generally fool around so I can get a feel for various functions. Then, when I’m reasonably comfortable and not too scared of wasting tools and stock I’ll have a go at the regulator. There’s a fine line between going too quickly and being intimidated by the machine, and I intend to be on the right side of it.
It’s a fecking machine, and while I may not master it right off the bat I will certainly subdue it. 😉 But if you don’t hear from me for a while it’ll be because I’m down the A&E having my fingers sewn back on.
Thanks Xaloc, that was very helpful. 😀
Lang,
You are jumping into the deep end with lead boots on. You don’t have a lathe yet and once you get it and tool up you will need many hundreds of hours of experience to be able to produce precise parts consistently.
You might want to focus on zeroing your chuck and tailstock and being able to produce a part to an accuracy of .000″ before you jump into making a regulator.
Some good first project would be a knob, an end cap, some baffles or a shop hammer. Making a regulator is a long ways off. Believe me it always looks easier then it is.
build a tank that size then tell us
Being a reasonably intelligent person I thought it might be better to do it the other way around. I’m sure you can work out why.
So do I have this right?
You want answers that you need to build your stuff and have no intention of sharing the findings because you figure to get rich on stuff you haven’t been able to figure out yourself.
Where did the entrepeneurial Can Do (do it myself) optimism disappear to?
Good luck data mining esp if you won’t reciprocate.
Walter….
Depends of how much power. But with 24 J will spend about 0.5 liters or 500 cc of air for every shot.
The calculation is simple:
I have a bottle of 0.5 liters pressurized to 200 bar that is about 100 litres of compressed air inside the tank.
After shooting 100 pellets, it was about 100 Bar in the tank, that multiply by its volume of 0.5 liters are 50 liters remaining.
That means I spent another 50 litres in 100 pellets and if I divide it gives me 0.5 litres per pellet.let say 500cc….And thats is de good volume for building silencers that trap de noise of every shoot.
I hope to be on the correct
A guy in the Bugarian forum wrote that it needs a 8,5 cm3 of air per 1joule energy
build a tank that size then tell us
Being a reasonably intelligent person I thought it might be better to do it the other way around. I’m sure you can work out why.
build a tank that size then tell us
Nobody knows? 😯 😆
Viewing 14 replies - 1 through 14 (of 14 total)
- You must be logged in to reply to this topic.
I don’t know if you would find a volunteer for that. But I think Tron posted something along those lines in the Off Topic 😆