High Speed Video Ball Dropping Into Breach

[AGD]

AO,

As you know we have recently been doing extensive research into ball breakage and what is happening in the breach of a paintgun. One of the questions floating around in Deep Blue right now is how long it takes to get a ball into the breach using gravity and a vertical feed.

Below I have attached a 1.6 meg AVI file showing the ball droping into an Autococker breach with 3 balls stacked on top of it. This is a 4 ball stack and would be equivalent to what you would get in the HALO. This Cocker was a side feed so I tilted the feed tube upright. There was no air blast just the bolt moving back. You can see the bolt finish it's stroke when the body of the gun recoils. This gun was bolted to a large camera tripod. Count for yourself how long it takes for the drop. We also tried single balls and it took even longer. That's why you often chop the last ball.

AGD

www.automags.org/~TomAGD/4drop2.avi

[AGD]

I am having a problem running the file in Real Player one frame at a time. If you guys figure it out please let me know.

thanks

AGD

[Bonx0007]

it worked with WMP

[zads27]

Works for my on Win Media Player..
I didn't do the frame by frame, nice speed though (500 fps).
Keep us posted on your test results Tom, thanks.

[JanStah]

From what I see, the bolt is open at 0.6580s

Also, the ball seems to touch the bottom of the breech at 0.7140s

.7140 - .6580 = 0.056 seconds.

So if we round it up, we can say it takes roughly 0.06s for a ball to drop into an autococker breech.

Jan.

[AGD]

Ok here is more info, the cocker bolt open stroke takes 22ms and the close stroke takes 28ms on the gun I have here. How fast can this gun shoot paintballs?

AGD

[Kaiser Bob]

Well, in Deep Blue I would probably verify the time it takes for the ball to fall in by sticking the weight and distance and other such varibles into your standard physics equations to get the actual time. Alas, its 5am and i havent slept yet so ill use the info provided. 22ms bolt open, 56ms ball drop, 28ms ball close. Not counting the time it takes for air to get the ball moving (Another Deep Blue thing) you get .106s... less than 10bps... sounds a bit slow, I'll try to figure it out using a better method later. Please point out any glaring math errors I made.

[Gecko]

my excal runs at 13 bps with i belive 10ms hammer dwell, 1 ms hammer release time, 55ms second bolt open, ~15 ms bolt forward time after bal fired. The gun feeds reliably without blowback with a halo. I still need to make the bolt forward time a little longer.
Gecko

[squall]

22ms + 28ms = 50ms = .05 sec, so in an ideal case, no paint, no friction, etc, pure cycle speed = 20bps.

I think Kaiser Bob has a little better estimate assuming his numbers are right (they look it). Looking at JanStah's numbers, the autococker should be able to cycle close to 17bps. Very cool video, very cool!

[Additude]

Originally posted by AGD
Ok here is more info, the cocker bolt open stroke takes 22ms and the close stroke takes 28ms on the gun I have here. How fast can this gun shoot paintballs?

AGD

I would say, "As fast as the user can pull the trigger".

[billmi]

Originally posted by AGD
Ok here is more info, the cocker bolt open stroke takes 22ms and the close stroke takes 28ms on the gun I have here. How fast can this gun shoot paintballs?

AGD

From your description above, it sounds much like the test rig I used for the WARPIG Ballistic Labs loader comparison.

You said there was no gas being fired - but is the rest of the cocking system intact, and is the hammer being cycled with each cycle of the bolt (it wasn't on my test bench)?

If not, you're only looking at how fast an Autococker receiver, bolt and ram can be used to feed paintballs - not how fast an Autococker can fire. The extra inertia of the hammer, and resistance of the mainspring on the bolt stroke would cause the bolt to take longer to open.

See you on the field,
-Bill Mills

[Gup44]

Using the times we have...

22ms to open the breach... 56ms for the ball to fall... and 28ms to close the bolt. With that info we can say that it takes

22+56+28=106 ms

to fire one ball. 106ms = 0.106s 1 second devided by 0.106 equals 9.434bps. Assuming there is no extra time that the bolt stays closed to "fire" the ball, I'd say that cocker can shoot about 9 balls per second with a gravity fed hopper (unforced).

[hitech]

Here is what I came up with. To me, it appears that the timing started at .6440 (this is a big assumption).
The ball appeared to me to be "ready" at .7120. The difference being .0680.
The time required to cycle is .050 (if I understand ms correctly).
Add that all together and we get .1180. The max ROF would be 8bps and would take .944 seconds.
This doesn't leave much time for the paintball to exit the barrel. As long as a paintball can accelerate enough in .007 seconds it will shoot 8bps.

[media]

Tom, I tried a search to see if any test simular to this were done to measure ball drop with a warp. I'd be interested in how much time is trimmed off that 60ms when using one.

Anyone have any proof of an autococker shooting faster than 10bps with a warp?

[nutz]

maybe someone with a racegun frame can help us with that

[Paintballer86]

That is so sweet tom

[nerobro]

now, the question is.. usingthe same math ;-) how fast does a mag fire... Again the skeptic in me comes out. I'm quite sure I've seen a cocker do more than 10bps, gravity fed.

A ball can start feeding when the breach is half open. at elast at that point the bolt pulls away from teh ball and it can begin falling. Same for when the breach is closed, as soon as the ball is halfway in, the breach can begin closing.

To be reasonable it takes 14ms before the ball can BEGIN to feed... and I'm not sure how long the ball takes to fall a little more than halfway into the breach.

[Mr. Grumble]

In a prior post by TK we are given 22ms for the bolt to open and 28ms to close. The paintball can begin dropping when the bolt clears 1/2 of the breach. The bolt can begin to close when the paintball has dropped 1/2 way in. If we work with the idea that the breach is .68" high, the paintball has to fall .34". I'm going to assume that the bolt clears 1/2 the breach in 1/2 the time (cuz it's easy).

d=(.5)*(g)*(t)² or .34"=(.5)*(9.8m/s/s)*(t)²
or .008636m=(.5)*(9.8m/s/s)*(t)²
t=.04198s

For the paint to drop .34" it takes .042s (or 42ms).

So, open the bolt 1/2 (11ms) + drop the paint .34" (42ms) + close the bolt (28ms) = 81ms (or .081s).

This gives us a feed and cycle rate (due to gravity) of 12.345 (or 12 balls per second).

Mr. G

[manike]

Nice idea Mr Grumble but in reality you cannot start feeding the ball in that soon or closing the bolt so soon on a half fed ball. It's because of the actual shape of a sphere it's very limiting in terms of how far in it needs to be fed before you can start closing on it...

I calculated it out years ago but to be honest can't remember my figures for how soon you could close the bolt without having a serious risk of chopping the ball... It made only a very small difference.

I'll let some pictures speak for themselves...

Here you can see a ball at when it starts to fall and a ball half way into the breech. I think we can definitely say with a ball half way in this would be the worst point possible for the bolt to start coming forwards.


Here you can see a ball 3/4 of the way in. You can see even now if the bolt starts moving it is very likely to pinch/chop the ball.


You can see when a ball is fully chambered that the closest point to the front of the breech is not actually very far, this is due to the shape of a sphere.


Below you can see that with the ball almost fed all the way in the bolt is still only able to come forwards 3mm without starting to pinch and chop the ball...


Here you can see it from the front and see just how likely that ball is to be chopped.


Here you can how the second ball in a stack can drop slightly into the breech and then git hit by the bolt. This is likely the cause of more broken paint than you would think as the bolt flies forwards and cracks the second ball. This is also appearing as a problem with the Halo as it sometimes forces a second ball slightly into the breech and thus it gets broken by the bolt firing the prior ball. This is an issue due to large bore breeches and bad ball detents.


Another view of that second ball getting smacked as the first is fired.


In all of my testing of vert I've found that the feed rates do actually tie in remarkably well with the theoretical rates that the maths shows us, giving that the ball has to be fully chambered before the bolt comes forwards. The only differences tending to be when blowback and bobble reduces how well it can feed.

I don't have the same testing facilities as AGD but I have done quite a bit of research into this stuff Some things I said about bolt speed back in '97 are just starting to be proven true.

manike

[Mr. Grumble]

First, thanx for the reply.

Now, in reguards to

in reality you cannot start feeding the ball in that soon

You have no choice but to feed the ball that soon. Gravity begins to work on the ball as soon as the bolt breaks contact with it (at the half-way point). The paintball will not hit the bolt as it drops, it can't. The bolt will be clear of the breach in 11ms, the ball will not be back in contact with the bolt until it is half-way in the breach and this takes 42ms (Gravity says so). The bolt moves clear of the breach too fast for the ball to catch up to it in the short time we are talking about. For the paintball to maintain contact with the bolt it would have to already be moving at a constant velosity or it would have to accelerate at a rate that would put it half-way in the breach in 11ms. This would mean it is accelerating faster then gravity.

Next

you cannot start . . . closing the bolt so soon on a half fed ball

I will concede that point. The ball will only clear the edge between the feed tube and breach if it is fully in the breach by the time the bolt is half-way through the return cycle. The return takes 28ms, half-way would be 14ms. For the paintball to fully drop it takes 59ms. I should start to close the breach 14ms short of that (or 45ms) and not the 42ms I had first thought.

This now gives us:
open the bolt 1/2 (11ms) + drop the paint a little past .34" (45ms) + close the bolt (28ms) = 84ms (or .084s).

Which drops the rate of fire to 11.9 (or 11 balls in a given second).

12 balls = chop

Mr. G

[nerobro]

Er... 11.9bps does not equal 11 balls per seccond. :-) it means 11.9 balls are shot per seccond. your following statement.. 12bps = chop is probally correct in this situation. If the timeing period is 1 secconds, then yes, you will only see 11 balls.

Given it's 2 secconds, you'll see 23 balls... By the time you're 5-6 secconds down the line, your assumption of 11 balls is more and more incorrect. Then again as we get into doubble digit rates of fire the decimals become less signifigant.