Paintball mortars? Can it, has it been done?

[MoeMag]

Paintball mortars? Can it, has it been done?

I have a local scenario event coming up and I have been approached to make an artillery piece, due to my experience with potato guns. Is a high trajectory device ever been made and implemented successfully in paintball?

/\ /\ /\ for general discussion. \/ \/ \/ should be in deep blue but there is no one in there.

Mostly my concern is with the terminal velocity of a paintball. Once it reaches the highest point of its trajectory it will still maintain the same rate of de acceleration in the x-axis which is not a problem, but as it begins to fall again it will only accelerate to the paintballs terminal velocity along the Y-axis.
Does anyone know what this speed it, and how long of a free fall is required to reach that speed. More importantly will a ball break at that velocity?

[geekwarrior]

i think claymores would be more effect than a mortar....my friends tried the mortar idea with little success, turned out to be a better paintball shotgun than anything. The only way I can see it working is a larger size trajectory, like a water ballon filled with paint. You can get those slinshot things for them....but with mortars you really risk injuring somebody.

[MoeMag]

is a larger size trajectory, like a water ballon filled with paint..

you mean projectile? Trajectory is the parabolic path of an object in ballistic flight.

A claymore mine? Interesting idea but we are planing on long range here.

We have permission to use this artillery piece at 300+ muzzle velocities as long as the barrel cannot be dropped lower than 50° from horizontal. So that is why I am concerned about terminal velocity so much. Sure we can launch it 250 yds down range, but will they break when they fall?

[VFX_Fenix]

I'd look into using, as was mentioned, large caliber projectiles, like Water Baloons filled with paint or paint grenades (Squadbusters, Meteor Showers, etc) in sabots of something like paper cups.

A short barreled variant of common scenario bazooka/LAW/etc. launchers should probably do the trick if arranged in an "L" or "U" type configuration. I think the biggest problem you'll run into is just getting propper charge to get your projectile to travel a desired distance safely because of the small nature of such a device.

[geekwarrior]

you mean projectile? Trajectory is the parabolic path of an object in ballistic flight.

A claymore mine? Interesting idea but we are planing on long range here.

We have permission to use this artillery piece at 300+ muzzle velocities as long as the barrel cannot be dropped lower than 50° from horizontal. So that is why I am concerned about terminal velocity so much. Sure we can launch it 250 yds down range, but will they break when they fall?


yes, sorry, im tired

[PnueMagger]

I'm too lazy and it's too late to bust out the fluid dynamics text, but there is an equation that calculates the drag force based on shape, approximate surface finish, and density(or weight). Just google it. It's a simple force balance with the velocity on the drag coefficient side as the unknown.

[MoeMag]

I'm too lazy and it's too late to bust out the fluid dynamics text, but there is an equation that calculates the drag force based on shape, approximate surface finish, and density(or weight). Just google it. It's a simple force balance with the velocity on the drag coefficient side as the unknown.

Okay this is some reading for some other time than 1 am
http://lennon.csufresno.edu/~nas31/nsa/physics.html

Okay, so what is the minimum velocity needed for a paintball to break?

*Also apparently large caliber mortars are not allowed at many fields...

"1. Mortars are not allowed on NPA insured fields as the danger of knocking off a mask is too high and the price of an eye is too high." some pb tank website

It was and always has been our intention to use paintballs in a grapeshot style load... apparently due to this restriction, sorry guys.

[ThePixelGuru]

There's no way a ball falling can somehow pop from the speed. Only way to do that would be much greater acceleration, and paintballs can take upwards of 1500Gs.* It's seeing close to 0Gs when in free fall. Keep in mind that the horizontal speed will change, though - on a trajectory that long, air resistance will play a role in where the shot lands. Also, what are you going to use for a launcher? You're going to need something fairly consistant to have any hope of landing shots where you want them. As for terminal velocity, as long as it's not less than the muzzle velocity, the balls will accelerate to almost the original muzzle velocity by the time they hit the ground. If it goes up at 300FPS, it comes down at almost 300FPS.

* http://www.automags.org/resource/tech/tomstech/01_barrel_eff.shtml

[MoeMag]

Found it!

Mathematically, terminal velocity is described by the equation

http://upload.wikimedia.org/math/a/a/6/aa655c43b739a78987896fb94277e6a6.png

where

-Vt is the terminal velocity ~11.22 m/s... 36.8016ft/s
-m is the mass of the falling object... 3.5*10^-3kg
-g is gravitational acceleration... 9.8 m/s^2
-Cd is the drag coefficient... .07 to .5 for a smooth ball
-ρ is the density of the fluid the object is falling through...approximately 1.2 kg/m3. varying with pressure and temperature
-A is the object's cross-sectional area. (3.14159265359...)(.017272m)^2


For others information...
The terminal velocity of an object falling towards the ground, in non-vacuum, is the speed at which the gravitational force pulling it downwards is equal and opposite to the atmospheric drag (also called air resistance) pushing it upwards. At this speed, the object ceases to accelerate downwards and falls at constant speed. An object moving downwards without power at greater than the terminal velocity (for example because it previously used power to descend, it fell from a thinner part of the atmosphere or it changed shape) will slow down until it reaches terminal velocity. Thus a paintball that goes up at 300fps, will not hit going 300 fps... it could be faster but most likely slower.

****************
Okay this is assuming that the drag coefficient of a paintball is .5 (the slowest possible result), the terminal velocity is 36.8016ft/s (25.1 Miles per hour). Is that fast enough?

Its so late I could have screwed up the math... I will check it again later.

Thanks pnuemagger.
:cheers:

[buzzboy]

Go ask on forums.spudtech.com Those guys can answer any and all questions about stuff like that.

Have you come up with a design yet. I have seen many LAW/pbshotgun devices that use a 2" chamber connected to a 1.5 barrel by a pneumaticly actuated sprinkler valve. With that style gun you can lob paint onto a large group of troops or some people load them with twinkies to be shot at tanks(mmmm cream filling).

Will you be running it off of 12g co2's or through a remote line from a larger tank. The later option is usually easier becuase using 12gs requires a larger chamber so there is no overpressuration/rupturing.

[craltal]

you could always fire the little nerf-like rockets, but cut off the tip and slit it so a paintball will fit in the tip so a direct hit wil mark the target...

Helps discourage the "your rocket didn't hit me" especially when it's a different color paint than normal...

[Lohman446]

To simplify the question. As long as the projectile is fired on a balistic arch (not directly at the target) there is little concern of the initial velocity. The question is, falling from 300 feet (or 1000 feet high, or whatever) what is the highest speed the paitnball will reach from gravity. Is that speed safe and is it enough to break the ball? I understand the question, but do not have the knowledge to answer from a physics stand point Having fired balls straight up and watched them come down I would say yeh, they have adequate speed to break - I do not know if it is low enough to be deemed "safe" or under 300FPS. What is the terminal velocity of a paintball. Simple question I guess

[Major Ho]

From Tippmann Ordiance, been around for some time now, expensive:
"Mortar Launcher" (http://www.tippmannordnance.com/mortars.html)
http://www.tippmannordnance.com/images/military_mortar_profile.jpg
http://www.tippmannordnance.com/images/test35-1-2.jpg
http://www.tippmannordnance.com/images/test35-3.jpg
The M1A-M compressed air delivery device is a paint marker system resembling a military crew served mortar, similar in visual impact to a standard military 81mm mortar. The marker system is a smooth bore, muzzle loading, gas/Co2 operated, manually fired, high angle-of-fire training device. The device propels a marker round (water soluble marker paint), that produces a 70+ feet in diameter fragmented area. The device is made of all steel, with a cannon of aluminum. The device is shipped in a wooden crate with flexible handles on either end, which supports field transport and storage. The device consists of three components; cannon assembly, mount and base-plate assembly, and traversing and elevation (T & E) assembly . The cannon assembly consists of a barrel assembly and Co2 expansion chamber assembly with the upper base-plate and barrel-attaching bracket, charging valves, gauges and quick release firing valve (cannon is constructed of .250 thick wall aluminum). The mount assembly consists of a functional elevation control screw, traversing control screw and the bipod leg assembly. The traversing mechanism consists of the yoke and the traversing spindle assembly and mount which provides a functional traversing and elevation sighting system to provide functional indirect fire control. The base-plate assembly consists of a 12 inch by 12 inch by .250 inch thick steel plate with ground lugs and lower base-plate and barrel attaching bracket.
Ammunition for the M1A-M crew served mortar system consists of liquid fill contained in a latex tubing bladder encased in a cardboard and urethane cast shell casing.
Rounds are impact detonated causing casualties through simulated fragmentation effects.

They took away the pics of the actual rounds. They used a breakaway cardboard shell with a water balloon style innard.

[doc_Zox]

ball valve
yuk

diaphragm valve
yum

high pressure and PVC is a darwin call

run it at sub 80 psi and use a greater volume to push the sabot

my current test bed:
http://premium1.uploadit.org/docZox/boomstick/canon01.jpg

it does a 230 fps launch at 30 psi

[craltal]

http://www.rustyspaintballgear.com/rs/catalog/bytype.asp?type=Mortars

[buzzboy]

Doc, what size valve is that, 1.5" or 2"? How big of a barrel do you use?

[Ken Majors]

I remember some time ago....maybe around 2001?, at Tippmann World Challenge 1 (might have been TWC2), they were launching squadbusters into the village area of the Hell Survivors. They were using the mortar/artillery type launcher. Not sure who made that thing, might have been Tippmann Ordnance. They launched about 10 or so of those things and had warned everyone out there that they were doing it. Apparently one of these grenades hit a referee in the back of the head, knocking him senseless, and knocking his mask off.
That was the last time they allowed the use of the launcher at TWC. I was at the game but
I didn't personally witness the hit, so it is hearsay. I do know that they only use that launcher now to launch T-shirts into the crowd at the closing ceremony.

Just a note to say that if you are going to use one of these. Be careful.

[p8ntball72]

First, Be sure that your Cannon can Pass the requirements of the Scenario producer and Meet the insurance guidelines of the field.

*Most Rules say the expansion/air chamber must be made of metal and can not exceed 80 psi when charged.

*Most rules say cannons must chrono under 230 fps.

*Most rules say when launching cannon rounds {ie. lose paintballs} you must launch at at 45* angle.

In my on field experience, when you meet all the guidelines the cannon/mortar becomes an ineffective weapon.

[doc_Zox]

thats a $15, 1 inch rain bird 100-DV
http://www.sprinklerwarehouse.com/detail.aspx?ID=152
40 gallon per minute

a 2 incher is a 75 dollar valve
http://www.sprinklerwarehouse.com/detail.aspx?ID=143
200 gallon per minute flow!

[MoeMag]

thats a $15, 1 inch rain bird 100-DV
http://www.sprinklerwarehouse.com/detail.aspx?ID=152
40 gallon per minute

a 2 incher is a 75 dollar valve
http://www.sprinklerwarehouse.com/detail.aspx?ID=143
200 gallon per minute flow!

Wow, thanks for the link glad to know there are 2 inchers.
Now this is what I'm talking about...http://www.sprinklerwarehouse.com/detail.aspx?ID=148

The people I am doing this for are the ones that are running the event sponsor/field owner. They made it very clear to me what they want, and when I got finished with the basic dimensions I was in shock. This thing should be called a howitzer. In fact it is so large, it would be impractical to carry a 10 ft ram rod :eek:, so it is a giant locking bolt action modeled after none other than the Automag. It is going to be a low-pressure high volume device. I have been given the okay to use 2 80cu ft scubas running into a inline LP regulator that then is mounted to a joystick air fill station that will fill the chamber. I am looking at using a solenoid valve or a spring-loaded ball valve. I like the spring load ball valve because there would be less to go wrong and cheaper. It will have to be mounted on a turret on their tank or a trailer. I am leaning towards the trailer idea because their tank isn’t visually large enough, but it sure could pull it.

I was up late last night because if I get the "ok" here in a few hours when I show them what I have, it will be a few weeks before it will be done. A prototype has to fire in 1 week if they pick up my design, and it will have to be event ready for the last weekend of the month.

I will post pictures and firing data as soon as I am told it’s "declassified". The guys doing this don't want anyone in the event to know about it until it fires. They have $10,000 in prizes on the line for this event, and if they could win some of it back they would be very happy :D

[p8ntball72]

10,000 in prizes and Holding the Event at the end of the month?

Is this an Event in AZ.?

If it is, 2 weeks isn't much notice for some of the Larger Scenario teams in the state.

*Edit

**Found it....... APD SHELL SHOCK**

Good luck with your project.

[doc_Zox]

you might also want to look at a supah valve
http://www.spudtech.com/detail.asp?id=39
a piston opens a huge port ASAP

theses are a solid set of plans:
http://www.antennalaunchers.com/csv19/index.html

venting the backside of a diaphragm with a blowgun works quite well

check out this system:
http://www.pettypb.com/cannon/aircannon1.jpg
http://www.network54.com/Forum/9013/message/1144065230/Air+Cannon+pics...

[MoeMag]

you might also want to look at a supah valve
http://www.spudtech.com/detail.asp?id=39
a piston opens a huge port ASAP

theses are a solid set of plans:
http://www.antennalaunchers.com/csv19/index.html

venting the backside of a diaphragm with a blowgun works quite well

check out this system:
http://www.pettypb.com/cannon/aircannon1.jpg
http://www.network54.com/Forum/9013/message/1144065230/Air+Cannon+pics...

:eek: that supah valve is awsome. How the hell does that work!?
I really think we are going with a spring loaded 2in ball valve. We have seen 4 inchers but they are really hard to pull.


http://www.pettypb.com/cannon/aircannon1.jpg
YUP. that is about what it looks like... only they are about 300 rounds short of what we are planning. :D and my bolt is better :p

I'm off to se if it will be a reality... back in a few hours.

[doc_Zox]

1st Merc has a nice piece of field arty:
http://premium1.uploadit.org/docZox/firstMerc/IMG_9587.jpg

http://premium1.uploadit.org/docZox/firstMerc/IMG_9589.jpg

it's a sort of bergles cannon design with the pressure vessel sleeving the barrel
http://www.armoredfistpaintball.com/bergles_cannon.htm

more sur***e:
http://www.bavetta.com/aircannon.html

http://bradschmid.tripod.com/id9.html

[doc_Zox]

piston valve theory:
http://www.spudfiles.com/forums/viewtopic.php?t=299

[MoeMag]

piston valve theory:
http://www.spudfiles.com/forums/viewtopic.php?t=299

Wow thats really smart. kind of reminds me of a ion...

***
I looked into the sleeve design... I wasn't to keen on that. I don’t like the idea of the barrel taking a load from the outside then instantaneously taking a load inside. Just seemed like too much stress and possibility for failure. My motto is KISS... Keep It Simple Stupid, that way it keeps the chances of something from happening to a minimum.

***
That calculator said that my barrel needed to be 25 ft long... ha ha thats funny. I had calculated it out to be about 9 ft. I want to see their reasoning behind that.

***
southwest voodoo... are you all going? If so SHHHH.

***

Just got back from the shop (APD)... they were a little blown away with the dimentions, but I didn't get to talk to the head guy who really wanted to do it so my fingers are still crossed.

[buzzboy]

Why are you going for such a large valve? Unless you are going to have a giant toted behind a vehicle beast then a 3/4" or 1" valve would be plenty sufficient.

[doc_Zox]

the bigger the valve, the larger the port
a larger port flows more volume in a shorter time

big butterfly or ball valves will work, but they need to be opened in a consistent, fast manner

on Mythbusters they constructed an air cannon that used a 12 inch butterfly.
to open it in a repeatable fashion, they but a 4 foot cheater on the handle and hung a few bench weights on the end.

it dropped open

i have run several ball valve LAWs and they are prone to leak down
and will bloop a nerf out if they are not snapped open

snapping open the ball valve can pull you off of target

i have seen spring or bungie assisted ball valve designs

Diaphragms and pistons snap open when the trigger side is vented
and you can also run the trigger valve in a remote location in a grip frame

i did a leak down test on my new rig
it held 70 PSI for 4 days

[MoeMag]

Well I guess the cat is out of the bag so...

We want to be able to fire 500 rounds. 500 rounds can be compacted to 12" X 4.77" cylinders and they weigh in at 1.75kg. That’s heavy. To fire that safely, successfully, and efficiently, a high volume of relatively low-pressure air is required. Yeah, a 1-inch would probably be fine, but the larger the diameter of the valve, the faster the chamber is dumped, and the more efficient the gun is. This thing is going to be a monster. I have been working on some more math today and it looks like the longer 24’ barrel that I was skeptical of earlier mathematically makes full use of the acceleration that the chamber is capable of producing. However, I think that the additional length of pipe will cause an increase of friction, actually causing the load to begin slowing as it travels down the barrel. At this point using math and my previous experience with this stuff it seems like the design can launch them with a muzzle velocity around 200ft/s (actually legal) about a quarter mile up and about a third of a mile in distance with the balls traveling at terminal velocity on the receiving end of about 25 MPH. In this case the large mass of the paintballs is our friend. F=ma, so the high mass of that many paintballs should make up for the low acceleration. The equations that I have and my understanding of them really do not take into some very necessary variables, thus I think experimentation with an actual model is required before I can make any concrete claims, but at least I am in the ballpark.

Also I have been thinking about the supah valve. That thing is really cool. being able to dump that high of a volume of air that quickly with a small ball valve. I think I can make one, but it probably wont be ready for the event... that is unless I get some real nice motivation ($$$).

[ttink]

I say make a double barrel cannon that you can load one barrel and fire the other at the same time so you can crank out rounds much faster :D Im sure my idea is somehow totally flawed, but it sounds cool.

[MoeMag]

As much thought as I have put into this I will definitely do it eventually. But for this event I just found out we have something BETTER and a whole lot more expensive so this just got put on the back burner. Because I don’t know if it is really going to happen or not, I will keep my mouth shut. Will defiantly post pics and vid, it will for sure be a first time and it will make at least the local news! They have already interviewed them about the tank and let them pump the event.
I suppose if someone guesses I will respond with a smiley face or something.
April 30!

[craltal]

http://www.g503.com/forums/viewtopic.php?t=62752

That'd be a surprise at a scenario..

[sol tank]

if you want to check out scepter combat sytems.
They currently have a working paintball mortar that should be for sale soon.
Talk to them over at the milsimog forums
sweet little contraption