Login    Register
User Information
We are a free and open
community, all are welcome.
Click here to Register
Who is online

In total there are 61 users online :: 4 registered, 0 hidden and 57 guests

Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Global Moderators
global_moderators.png CS

1'' Bouncy ball pistol with clip system. With video

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
  • Author

Unread postAuthor: Ragnarok » Sun Sep 13, 2009 9:34 pm

velocity3x wrote:The ridge line in the pic is a measured 1,200 yards down range. GB's are still climbing out when they cross the ridge line and disappear on the other side.

I find a claim that a golf ball is "still climbing" at over a kilometre away highly dubious (not that I'm claiming you're intentionally misleading us).
Partly because of the unbelievably insane velocities simply needed to do that, but mostly because human eyesight simply isn't good enough to allow you to even see a golf-ball at those distances.

For a human with a typical eyeball, even with decent eyesight and no visual problem, the mathematical limit on the minimum something can be and still be made out is about ten thousandths of a radian.
Because of the way radians works, this means things have to be closer than roughly ten thousand times their "diameter" in order to be made out, which means that a golf ball can't be made out at a huge amount further than a quarter mile away.
I might believe that someone with notably good eyes might make out one at a bit over half a kilometre, but beyond that, no.

So, if you think you see anything much further away than ten thousand times its "diameter", you're almost certainly mistaken on the distance.

Of course, this throws even more doubt on claims of making out 1/2" projectiles at half a mile. I had to struggle to find 20mm projectiles at 650 metres, and those were painted with glo-paint, not to mention I'd already modelled where I was expecting them to be. (Even then, I lost most of the ones I fired)

This does assume you're using the human eye without magnification. But I find the suggestion that you could track a projectile using binoculars even more laughable - and that's before you even start to suggest you can work out the distance through them.

EDIT: Minor grammatical error.
  • 0

Last edited by Ragnarok on Mon Sep 14, 2009 6:47 am, edited 1 time in total.
Does that thing kinda look like a big cat to you?
User avatar
Chief of Staff
Chief of Staff
Posts: 5366
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 10

Unread postAuthor: Technician1002 » Sun Sep 13, 2009 10:11 pm

I am working on an illuminated projectile for a night shot to help track and retrieve it. At the church camp, launching water bottles at dusk and after dark into the target tree made it very easy to track the projectile and find it. At the camp we used a water bottle with a glow stick. I am looking to finding a day to drill holes into a golfball and insert several mini glow sticks just to measure range. I would use a tripod mounted laser pointer to point the last location sighted and follow the beam to the landing zone. The other spotters would do the same to the impact zone.

I can recruit several down range spotters to find the landing if it lands in brush. It will need to be a time when I have the space. My suburban location is not the place.
  • 0

User avatar
Chief of Staff
Chief of Staff
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14


Return to Pneumatic Cannon Database

Who is online

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], Yahoo [Bot]

Reputation System ©'