FPS ou JOULES
 

Jai trouver cette articles et je voulait savoir se que vous en penser.

Certains upgrade la puissance de leur réplique pour la faire tirer plus loin et plus précisément. Plus loin, certes, et encore pas de beaucoup… mais plus précisément ça reste Ã* voir ! Passer une réplique de 310 fps Ã* 350 fps fait gagner 7 mètres Ã* une bille de 0.25gr, est-ce vraiment indispensable vu les distances de tir pratiquées en Airsoft ? Quant Ã* la précision, c’est une toute autre histoire !

La forme ronde du projectile n’est absolument pas aérodynamique, la bille traîne derrière elle un remous aléatoire qui perturbera tôt ou tard sa trajectoire. Plus la bille est rapide, plus la traînée est importante et plus la déviation finale sera importante aussi. Quand la force perturbante de la traînée devient supérieure Ã* l’inertie résiduelle due Ã* la masse en mouvement, la bille sort de sa trajectoire.

Une augmentation de l’inertie du projectile améliore la précision, car plus une bille est lourde mieux elle résistera aux effets chaotique de la traînée et plus elle restera précise longtemps. De même, il est surprenant de constater que les billes 8mm ont une rotondité et une qualité de surface supérieure aux 6mm habituelles. Leur meilleur qualité de vol associée Ã* une masse plus importante que la 6mm permet de penser que c'est le calibre idéal du sniper, bien que leur trajectoire soit plus lente.

Pour chaque masse de bille et chaque qualité de canon, une vitesse idéale équilibre les deux forces antagonistes : Plus rapide, la bille sera un peu plus précise sur la première moitié du parcours et beaucoup moins sur la deuxième, plus lente elle ira un peu moins loin et sera plus sensible aux éléments extérieurs (vent, feuille...). Le tout est de trouver le bon compromis poids / vitesse / canon !

Finalement le seul véritable moyen d’améliorer la précision est d’augmenter Ã* la fois la vélocité ET la masse de la bille, mais dans ce cas la courbe des joules monte en flèche… A réserver aux Snipers

Calcul

Finalement le calcul en Fps ne suffit pas pour définir une norme de sécurité sur un terrain, une limite en joule serait préférable car elle tient compte de l’impact réel et non plus d'une estimation variable suivant le projectile ou la réplique. Vous trouverez ci-contre un tableau de référence des différentes valeurs en joule suivant la bille et sa vitesse

http://i213.photobucket.com/albums/c...tsh/joules.gif

qq1 pourait traduire svp pour ceux qui en on besoin?

Where can I find that chart in english?

Les informations de base sont deja ecrites un peu partout sur le site. Le calcul exact demeure impossible puisque chaque airsoft n'est jamais totalement pareil a un autre, sans parler des temperatures ambiantes.

En gros, un airsoft bien ajuste qui tire entre 320 et 360 pieds/seconde avec une bille .20 est plus que suffisant. Au dessus de 400 pieds/seconde, les problemes commencent a se faire voirs.

Presque tout joueur experimente peux meme le demontrer.

A presque tout les jeux, la limite est de 400pieds/seconde avec une bille de .20

Tel que mesure avec un chronometre de precision, en plus. Donc les risques sont minimes. Je ne sais pas si tu est alle a une rencontre encore, mais ti verras que c'est generalement tres bien controlle.

You can ask any game organizer. They normally chrony the guns with .20 ammo.

It's been posted before, in different formats.

jai participer a plusieur events je sais quil y a des chronis

oui le chroni se fait avec des .20 je sais mais une fois le chroni passer les joueurs changent de bbs pour la plupart. Donc le joule augmente. cest pour cela que jai poster ca on devrait pas tester les chroni avec les bbs que le joueurs utilise sinon sa sert a rien non ?

peu etre aussi que je pense comprende et que je ne comprend pas

I'm not trying to be ignorant or trying to sound ignorant but can you repeat that in english please.

Non, a moins d'avoir un canon inhabituellement court les joules n'augmentes pas de façon significative en passant Ã* des BBs plus lourdes. Faudrait revoir ta physique dynamique.

La puissance du ressort, qui comprime l'air qui propulse le BB, demeure la même; un BB plus lourd dans le même fusil aura une vitesse Ã* la bouche du canon inférieur Ã* celle d'un BB plus léger. Donc, de façon générale, la puissance (joules) demeure très similaire.

Une des différences, par contre, est que le BB plus lourd conserve son inertie plus longtemps (la taille et surface du BB, ainsi que la resistance de l'air, demeurent identique pour les BBs de chaque poid différent). Donc, example (i.e., chiffres bidons uniquement pour illustrer), un BB de .2g avec une puissance Ã* la bouche du canon de 1J pourrait avoir .5J après avoir voyagé 50m, mais un BB de .3g aurait encore .7J après avoir voyagé la même distance.

Can someone please help me out, I can;t speak,read,or write french. I would really like to have a chart I can read in english so if theirs anyone that can find me one or point me in the right direction I would be much abliged. Thank-you.

he's just saying that he went to many skirmishes and they chronied the guns with a .20bb ; however, most people change bb's resulting that the joules are higher and chronying is worthless, so he's suggesting that players should get chronied with the bb's that they are using during skirmishes...

that will be 5$ for my service :D

I'll give you 20% discount on your next order Mike.

There are tons of FPS/Joule calculators on Google.

NIA just used a FPS to Joules calculator and made our rules in Joules not FPS.

1-Close Quarters
1 joule or less for full auto
FPS-bb weight
328-.2
293-.25

CQB max FPS
1.14-MAX joules
FPS-bb weight
350-.2
313-.25

Use link to find out your joules http://www.cimmerians.org/FPS_Converter.html?action=fps

2-Open Area
-Max 2.28 Joule Limit
FPS-bb weight
495-.2
443-.25
369-.36
338-.43

-Anyone over 1.49 Joule limit-Semi only
FPS-bb weight
400-.2
358-.25
298-.36
275-.43

I dont know... we learned english to understand you, can you not learn french? There is no forum request that states everything here should be translated.
And translating Quebecois is not immediately obvious.

(I am not going to retract what I said, but I will say I'm sorry. Why did I say it? Because for YEARS myself and anyone else who happens to not be english has been told, even ordered, to learn the 'other' official language of this country to even be accepted into it. And then I see comments like that which just push the wrong buttons. We ALL have the Right to express ourselves in our own language and it is up to us to figure out what is written. We francophones dont ask for every english post, no matter how useful, to be translated for us. Same should be done in return. So I am sorry you did not have the chance, or the time, to learn my language. I hope you do someday.)

Si le test est fait avec .20 et la personne prends du .25 ou plus pesant, la velocite de la bille diminue. Donc la force de frappe ne change pas vraiment.

All you need to know: Most games use .20 to rate the speed of the guns. Most games have a cap at 400fps for several reasons (legal, safety and physics/behavior of the BB itself in flight).

What you use after that is entirely up to you, but the gun tests are normally made with .20

If you want to be 100% sure of your own guns, buy a Chrony. Really, there's no guesswork with those.

merci pour les explications. maintenant je comprend tout ca beaucoup mieux

+1

It's a lot easier to learn English than to learn French. I wouldn't blame him if he wouldn't even want to try :p

P.S: I speak and write broth in French and English fluently.

cinetic energy = 1/2 [Mass X (SpeedxSpeed)]

so bb's weight change the resulting energy, and speed changes it too.
since Speed is elevated to a square, it's the parameter that changes the most the resulting energy.

So do I, obviously. But I will stand by my comments. It's not just about him, really, but everyone else who asks. Every language is hard to learn, in one way or another.

Simply put. A fast light BB will produce the same impact as a slow heavyer BB. But a gun that shoots a .20 gram BB at, say 380fps will probably shoot a .25 at around 360 or maybe even 340. The end result is (for our purpose) the same.

This is ballistics 101.

Ha! Knowing French does help!

FPS is a speed. Joules (If I remember what we talked about in Physics last year and correct me if I am wrong) is an amount of energy*release.

Le probleme, c'est quand quelqu'un veut tricher au chroni et met des balles plus lourdes pour passer Ã* la barre du 400fps.

Les regles de fps max sont basé sur une mesure prise avec du .20g. 400fps avec du .25g ou du .30g c'est pas vraiment la même force de frappe...

Je suis normalement plus diligent pour les snipers BA, puisqu'une seul balle est moin domageable qu'une rafale de 15-20 balles. Pour les AEGS, aux milsims que j'organise, je les mesure avec mes .20g ou au moins, je demande Ã* la personne qu'elle poid de balle est Ã*. Dans le doute, on met mes balles.

Well if he doesn't know X language, someone will translate it for him.

That's correct, FPS is speed and Joules are energy.

In this case you can determine energy with:

(Mv² * W) / 450100


It's the standard equation for kenetic energy of motion: Speed in FPS (in this case Muzzle Velocity) squared, multiplied by the projectile's weight in Grains (1 gram == 15.432 grain). In this case we're also incorporating gravity (for simplicity's sake, we pre-calculate gravity as a constant*). The actual for formula is

(Mv² * W) / 2 G


The result will be in imperial Foot-Pounds (ft-lbs.) since we used imperial units to begin (namely FPS).

You can convert ft-lbs to Joules by multiplying by 1.356 (i.e., 1 ft-lbs. == 1.356 J.)




* gravity is generally accepted to be 980 cm/sec² on Earth. Since we're using FPS we have to convert that, which becomes 32.15 ft/sec². Similarly, we're using Grains rather than Pounds to calculate ft-lbs.: 437.5 grains == 1 ounce, 16 ounces == 1 pound (lbs). So:

( 437.5 * 16 ) * ( 2 * 32.15 ) == 450100

....I feel special :D

Il y aura toujours des tricheurs, c'est pourquoi les tests sont normalement faits par une personne avec les memes billes (ce que tu fait). Les tricheurs se font generalement prendre eventuellement, et se ramassent tout seuls.

I've made a pretty detailed post about this topic before, but to sum it up:

What you've said is true... at the muzzle.

At 100 feet, anyone can attest that a 0.25g BB will hit harder than a 0.20g BB. Why? Because it retains much more energy over the flight path.

The main issue, however, is when gas guns are involved, because their output is not linear. Heavier BBs shot out of a gas gun will output MORE energy than a lighter BB will. In some cases, a gas gun that shoots a 0.20g BB at 330fps can output a 0.25g BB ALSO at 330fps. This is where the danger lies, and why the debate is open on why games should be limited by JOULES, rather than by velocity.

At least when limited by Joules, the gun can be tested with whatever weight BB the gun will be fielded with, as long as the user is honest enough to state that intent and the resources are available to make the appropriate calculations/conversions.

I know, that's why I keep my answers as short as possible. The rest is written down.

We should have a new way to "chroni" gun. Like shooting on a flat surface that mesure the joule output on impact.

No mather what type of BBs used, that test would be very fast and precise. Place the musle on a certain line, fire at the target and the result is shown on a small LCD in joules.

I wish we had that, it would make chroniing a joy.

Shoot into a bowl of Jell-O... like ballistic gel for airsoft. Then we can eat the test material. Everyone wins.

And some asshat will choke on the BB that's stuck in there.

esti de bonne idée ca Fox. cest pour ca jai faite le post voir si dautre etais du meme avis et pour etre sur que jsuis pas dans le champ.

Criss, j'veux du jello maintenant, félicitations drake.

Many good chronos will also give you an energy measurement, once you input the weight of the BB. Then guys with different weights can chrono with what they use, no need for a chart.

That for real? They must be pretty pricey, no?

I think Poh's chrono does energy. He has the Guarder one. Ask him.

I have one for sale that measures velocity (in metres per second), rate of fire (in rounds per minute) and also the energy output (in Joules) as well as a bunch of other functions.

http://www.wgcshop.com/WGC_Shop/imag...3100sc_low.jpg
X3100 Shooting Chronograph
This is one of the most full-featured chronographs available on the airsoft market at this time:
Features:
- Measures muzzle velocity ( M/S )
- Measures rate of fire! ( RPM )
- Muzzle Energy Measurement ( Joule )
- Joule per cm square Measurement
- Bullet Weight & Caliber Adjustment with 10 Settings Memory
- Built-in Light Source
- Large diameter Measuring Tube with detachable hood
- Powered by AA Battery x2 (included)
- Low Power Indicator
- Idle Sleep Mode for power saving
- Tripod Screw to fit camera tripod
- Compact Size ( 130x100x50mm )

Download English User Manual HERE ( Rich Text Format )

Brand new. Comes in packaging.
Price: $165
Qty: 1

I personally have not seen a lot of chrony-ing/fps testing at a number of the games that I went to this year. At most it seems to be voluntary on the part of the shooter who wants to see what he's shooting at. Honestly, I might have missed instances where someone was asked to chrony their gun by a game organizer/field owner, but what are some of your observations? Do you regularly get asked to check your fps (with 0.2 bbs) before games?

I brought my chrony out to a FTF/EOTECH game because my buddies had just upgraded their gear and wanted to get some readings. After a short while, I just left it running on a tripod at the side of the field because there were plenty of other guys wanting to check out their fps. Most were stock/mild-upgrades, but there were a few "surprises" (i.e. "Wow, didn't know it was shooting that fast!!")

As an aside...does anyone know of an chrony, that will read airsoft bbs, that has a shot timer (typical IPSC/IPDA functions) built into it?

ILLusion, how much would you guess shipping to US is??

$500.

Here's a wild idea: ask the people who actually sell it. Quotes are free!