Welcome, Guest. Please Login
SLINGING.ORG
 
Home Help Search Login


Pages: 1 2 
Send Topic Print
Projectile Speed (Read 17886 times)
Aussie
Past Moderator
*
Offline


Joined Nov. 1, 2006  Luke
14:14

Posts: 3265
Melbourne, Australia
Gender: male
Re: Projectile Speed
Reply #15 - May 18th, 2008 at 6:27pm
 
Thomas wrote on May 18th, 2008 at 9:59am:
Aussie

I used that sound program you recommended to time an air pistol. The published muzzle velocity is 400 fps. I fired through two paper targets spaced 19feet apart, the farthest one at 10 m or about 33 feet. I used a tiny Sansa recording mp3 player located at the midpoint of the two targets. My measurement was 320fps, which seems reasonable.

tom


Thanks for letting me know. I'm glad that my suggestion was of use. Your result seems very consistent with expectation. The 400 fps is undoubtedly a slightly optimistic muzzle velocity and .177 cal air rifle pellets lose velocity extremely quickly. Additionally penetrating the first sheet of paper would have also wiped off a few fps. Would it be possible to get a truer reading by bringing the target closer and using the report of the pistol as the timing start?

Aussie
Back to top
 

Cranks are little things that make revolutions.&&
 
IP Logged
 
Aussie
Past Moderator
*
Offline


Joined Nov. 1, 2006  Luke
14:14

Posts: 3265
Melbourne, Australia
Gender: male
Re: Projectile Speed
Reply #16 - May 18th, 2008 at 6:38pm
 
JTK wrote on May 18th, 2008 at 10:51am:
u can use a digital camera to record your throw, time the stone from realese to hit, and find the distance of the throw.  the formula would be distance/time=feet/yards/meters per second


Hi Justin,

Your method works perfectly and I also used it before I hit on the sound recording idea which for me is easier. If you get a good side view you can also see how far your ball travels between frames. I used this technique to cross check the results I got from the sound recording method.

Aussie
Back to top
 

Cranks are little things that make revolutions.&&
 
IP Logged
 
Thomas
Senior Member
****
Offline


Rocks?

Posts: 292
NORTHEAST OHIO
Gender: male
Re: Projectile Speed
Reply #17 - May 18th, 2008 at 7:58pm
 
Aussie

I used the two page method because that will be my slinging setup outdoors in the park after the target frames are ready. The sound record also includes the discharge sound. The sounds from a slinging setup should be virtually identical and the tiny sound from the sling itself will be useless unless I find some of those pull string firecrackers. 

tom 
 

Back to top
 
 
IP Logged
 
Burner
Interfector Viris Spurii
*****
Offline


Take me out to the ball
game........

Posts: 1238
Northeast Florida
Gender: male
Re: Projectile Speed
Reply #18 - May 18th, 2008 at 9:36pm
 
Thomas,

  Sorry that I used all the old ones you had back in 1980.They were in the bathroom inside that tan camera bag.I'm sure we can find them in FLA.
Back to top
 

Cleveland Rocks!
 
IP Logged
 
Aussie
Past Moderator
*
Offline


Joined Nov. 1, 2006  Luke
14:14

Posts: 3265
Melbourne, Australia
Gender: male
Re: Projectile Speed
Reply #19 - May 18th, 2008 at 11:57pm
 
Thomas wrote on May 18th, 2008 at 7:58pm:
Aussie

I used the two page method because that will be my slinging setup outdoors in the park after the target frames are ready. The sound record also includes the discharge sound. The sounds from a slinging setup should be virtually identical and the tiny sound from the sling itself will be useless unless I find some of those pull string firecrackers.  

tom  
 



Maybe your sling is quieter than mine but I had no trouble hearing or recording the swish, even outdoors. Try it as you may save yourself a good deal of work. The beauty of this method is that it eliminates the need for accuracy in your slinging. I was just banging away at my "couldn't possibly miss it at that range" garage wall at a distance of 8.1 metres.

Even if it really doesn't work you may try adding a small whip cracking tail to your sling which should make a louder swish and have no effect on velocity. Should be easier than the double screen method.

Aussie.

PS. I used the comparatively small distance of 8 metres because the projectile's speed loss should be minimal and the time interval is large enough to be measured with a high degree of accuracy. This gave me a very close approximation of release velocity. The two screen method would be very useful for determining how much velocity drops off at any given distance from the slinger. Provided you can record the sound of the release you would be able to calculate both the average velocity for the entire cast and the final velocity between the screens, all from the one sound recording. INTERESTING! Please write up your results if you go down this path. If you want to be super pedantic you could assume the speed of sound at 300 m/s and make corrections to the time intervals according to their individual distances from the recording device.
Back to top
 

Cranks are little things that make revolutions.&&
 
IP Logged
 
Pages: 1 2 
Send Topic Print
(Moderators: joe_meadmaker, vetryan15, Kick, Morphy, Chris, Curious Aardvark, Rat Man)