Re: calculs de ballistique resultats aberrants

[secret de l'acier]

http://www.airsoftcore.com/forum/index.php?showtopic=46331

How it works:
The method of "clocking" your gun is based on the time it takes for a bb to travel from the moment you fire a shot, to the moment that the bb impacts an object at a known distance. Hence the term Feet Per Second. FPS.

1. Find an area with 5-15 feet of space near your computer to shoot.(guaging the speed closer than 10 feet is difficult - but yields an FPS close to the actual muzzle velocity)

2. Setup a solid target, or an object that will make a loud sound when the bb hits it. (Not your friend. We are looking for something like a popcan.)

3. With the measuring tape measure how far away you intend to shoot

4. Position the microphone to pick up both the sound of a shot being fired, and the bb hitting the target.

5. Load up Audacity

6. Cock your gun

7. Wait for silence(tell your friend to stop talking) and Hit the record button

8. From the measured distance - fire your gun.

9. Stop recording.




Calculating the FPS:

All we are going to do at this point is to find the time between these 2 peaks, of these 2 sounds.

To do this all you need to do is select the space between the two waves with the mouse, and on the bottom it will show the time between the two waves.


FPS = Distance/Time

In this example, I used a distance of 22.5 feet and got a time of .085682 seconds

FPS = 22.5 feet /.085682 seconds = 262 FPS

Summary, Extra Notes
With this calculation we are merely calculating the average FPS over the distance we measured. Not the true muzzle velocity.

If you do this test, post your results!

-----------------------------------------------------------------
Tips:
*To get precise results, select only the sound of the shot and the initial hit (first 2 waves) and trim everything around it. You should also note that some microphones will pick up the sound of you pulling your trigger, don't mistake that for the sound of the shot. Zoom in and select the distance from the highest point from the shot, and ricochet to get consistent results.

*Place the microphone in the middle between the popcan and the firing position, this negates the speed of sound from the result.

*Also be aware of the position of your gun in relation to the distance you measured on the floor. If you are holding your gun 3 feet over the line, you will be skewing your results.

*If you want to get an approximate muzzle velocity(what they guage for competition) try the test from a closer distance(like 5 feet). If you want consistant easy results for comparing one gun/configuration to another, use a larger test range.

[chapap]

Oui, mais en françois ?
Parce qu'on n'accepte pas les colporteurs, les vrp, les délégués syndicaux, les chiens, les messages en SMS !!!!!!!!!!!!!

[erwann56]

moi j'ai déja fait sa avec un micro

une fois que tu a effectué tes mesure calculer l'interval entre les deux feuilles tu auras la vitesse a 15m.
après tu va dans chairgun tu mes en unité métrique tu choisis ton plomb si il n'est pas référencé et que c'est un diabolo(plomb plat) ils ont en général un coef balistique de 0.01
ensuite regarde dans la colonne vitesse (dans la table) et tu te concentre sur la ligne 15m
modifie la vitesse au canon pour que les deux vitesse soit identique.
avec cette méthode tu obtiens la vitesse en sortie de canon et l'énergie développé par ton arme.
je vais réessayer dans les prochains jour vu que j'ai un chony je vais pouvoir savoir si cette méthode est précise ou non.

[pascal]

ET ??????

je ne suis pas sûr de comprendre...

Tu veux calculer la puissance par rapport à un niveau sonore ???

la puissance par rapport à la vitesse oui, mais la vitesse par rapport à un niveau sonore.............. ?!?!

https://www.forum-airguns.com/t16652-calcul-de-la-vitesse-du-plomb-a-40m-avec-un-micro

On en avait déjà parlé ici il y a un bon moment...

[Contenu sponsorisé]