Canadian Airgun Forum

Bonjour,
me semble que j'avais deja vu dans un article qu'il etait possible de trouver la velocité d'une arme a plomb avec un micro et un ordinateur. Si oui comment on fais???
Merci d'avance:)

Velocty testing using PC and mic

Ou de l'ancien Airgun Canada Forum.
From: HotSky23 Sent: 19/05/2005 12:09 PM
OK here it goes : )

You need 3 things

1. PC (or a Mac)

2. A Microphone (not to be build in) - I got mine from a dollar store

3. A sound rec/reading software

I use Audacity program (free from http://audacity.sourceforge.net/)

You need to set up a backstop (pellet trap) something that is not too soft, ‘cause you need the pellet to make some noise when it his it.

Measure a distance between the gun and a backstop, make sure you measured it accurately or your results will be off ( I used 3m). Place a Mic half way between the gun and the backstop (this is important too).

When everything is set up, Open the software (Audacity has a REC button so you can do everything with in that program) set up your Input Volume (on the top right corner beside a mic icon) somewhere from 0.2 -0.5 (worked best for me). Start recording, fire the gun and press the stop button.

You will see a wave of sound, delete the parts where the wave is flat (no noise) - you don’t have to do it but it’s easier that way. Zoom in on the part where the gun shot happens. You will see two major waves; first from the gun shot, second from the pellet hitting the trap/backstop.

Write down the time (shown at the bottom of the screen) at the beginning of the first wave rise and of the second one (you might need to play with the zoom tool to get the best view).

Now you need to do some simple math;

Subtract the lower number from the higher one. Now divide your distance (in my case 3m) by the number you just got. This number is your velocity is m/s. (If you wantit to be in fps bust divide it by 0.3048)

Is might sound really complicated, but trust me it’s not. You might mess up a couple of shots to figure it out, but it’s pretty easy stuff.

Let me now if you try it

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From: perry_pan Sent: 19/05/2005 2:56 PM
Brilliant idea. You were using 3m? I am just thinking if a longer distance in garage (like 8m) would make analyze data easlier and minimize the error.
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From: HotSky23 Sent: 19/05/2005 3:21 PM
Yeah, can shoot at 8m, it would be easier to to calculate, but you need to remember that it calculates Average Velocity from 0 to whatever (3m in my case). You can try any distance and see how it works.

I tested my handguns (around 400fps) so, it wasn't too bad, but if you’re trying to measure a 1200fps gun it will probably be fairly hard to it at accurately at 3m.

if you do it at 8m the velocity will show lower than what it actually is, since the pellet slows down in flight. I figured at 3m the pellets will still have all the original velocity, so it should be pretty accurate.
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From: NovaScotiaAirgunner Sent: 19/05/2005 7:45 PM
Well HotSky23, i just got the program installed in my LapTop and i got me a computer microphone CHATEAU PS-800 for $1.15 at the Dollard Store. Now i just have to figure everything out. I got this

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René

Merci , c'est plein ce que je cherchais. Au plaisir:)

Ou tu peut toujour te pogner un Chrony ! Tiens le liens de la cie! http://www.shootingchrony.com/

under500fps, tu viens de faire mon bonheur !

Est-ce que c'est précis ?

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Facebook is like ancient Egypt, people write on walls and worship cats

You can’t buy a single airgun for everything. Golfers use many different clubs, airgunners need more than one gun

Le son se propage à environ 340 mètres/seconde dans des conditions normales, alors je croirais bien que OUI!!! Ce doit être assez précis !
Pour encore plus de précision il suffit d'enlever le temps que le son prendra d'un coté comme de l.autre à se rendre au micro mais rendu là ça deviens de l'acharnement.

C'est précis mais il faut savoir quelles ondulations de sond prendre .
La plus part du temp elles sont les deux plus grosses .

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René