Free chronograph

A place for general potato gun questions and discussions.
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Juggernaut12121
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Mon Apr 07, 2014 8:02 am

Sorry about the quality of the video, I'm horrible at making them! Anyway all you have to do is fire your cannon straight into the air, count the time it takes to hit the ground again, divide that in half, and multiply it by the acceleration due to gravity (either 9.8m/s/s or 32ft/s/s) and you get the velocity of the object you fired :)

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jackssmirkingrevenge
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Mon Apr 07, 2014 9:43 am

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hectmarr wrote:You have to make many weapons, because this field is long and short life
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POLAND_SPUD
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Mon Apr 07, 2014 1:23 pm

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Ragnarok
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Mon Apr 07, 2014 1:26 pm

And as a corollary to what Jack said, if you have got a projectile that's coming back down at a similar speed to that at which it went up, firing it straight up into the air is rather dangerous...
Does that thing kinda look like a big cat to you?
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Anatine Duo
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Mon Apr 07, 2014 3:05 pm

ummm I have 2 questions as it's been decades since I took physics...

1: how does this figure air resistance?

2: how do I get the projectile to come straight-ish down? I rarely get that to happen with a paintball gun (lying on my back with goggles on, grinning) despite many attempts
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jackssmirkingrevenge
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Tue Apr 08, 2014 6:29 am

POLAND_SPUD wrote:chrono connect mobile
How does that work, time between shot sound and impact sound?
I rarely get that to happen with a paintball gun (lying on my back with goggles on, grinning) despite many attempts
I am proud and honored to live on the same land mass as you sir :D
hectmarr wrote:You have to make many weapons, because this field is long and short life
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POLAND_SPUD
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Tue Apr 08, 2014 6:57 am

How does that work, time between shot sound and impact sound?
Exactly. Add to that some ballistic calculator and you've got a nice tool for airgunning
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jimmy101
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Tue Apr 08, 2014 2:22 pm

Welcome to the board ~NooooooB~ (hey, you picked the name :) )

1. Air drag is pretty significant.
2. The projectile doesn't hit the ground with the same velocity as the muzzle velocity, it hits moving at some fraction of the object's terminal velocity. (For a tennis ball the terminal velocity is about 100 FPS which is a lot lower than the muzzle velocity of even a basic spud gun.)

See here.

If you don't have a true shooting chrony either build one or just use a laptop (or smart phone) to record the sound of firing against a hard target at fairly short range. A sound analysis program (like Audacity) can extract the flight time between the two bangs. A tape measure and a paper and pencil is all that is needed to calculate the average velocity over the firing distance. If you tilt the target you can keep the round from bouncing back and hitting you in the head. :D
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Juggernaut12121
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Tue Apr 08, 2014 5:40 pm

I can see that I've made a bit of a failure now :oops:
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jimmy101
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Thu Apr 10, 2014 12:28 pm

We always kick noobies in the butt once, just so they don't get too big a head. :D
We also randomly kick experienced spudders just to be a-holes. :bounce:
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jackssmirkingrevenge
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Mon Apr 14, 2014 5:16 am

jimmy101 wrote:We also randomly kick experienced spudders just to be a-holes. :bounce:
:D :D :D
hectmarr wrote:You have to make many weapons, because this field is long and short life
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