Golf Ball Cannons

[Lihu]

It also lacks rapid reload capabilities. I think we ought to go for the gatling-style approach in case a mulligan or breakfast ball is needed after the first shot.

I can see this as a fun engineering project. . .

So, you could just scale up a paint ball gun feed mechanism? A simpler design is possible as you probably do not require rapid fire capability?

Here are some materials you might consider obtaining. . .

http://www.harborfreight.com/portable-torch-kit-with-oxygen-and-acetylene-tanks-65818.html

Probably want to make this a permanent part of the gun.

Weld the parts together with a TIG welder http://www.harborfreight.com/240-volt-inverter-arc-tig-welder-66787.html

Firing Tube: http://www.mcmaster.com/#stainless-steel-square-tubing/=zld8fc

Barrel and feed tubing: http://www.mcmaster.com/#8989K358 (There might be some tuning because this is exactly 1.68") Might need a slightly larger ID?

All other parts are shoot metal that can be bent with a brake from HF: http://www.mcmaster.com/#standard-304-stainless-steel-sheets/=zldbnm and http://www.harborfreight.com/36-inch-metal-brake-with-stand-91012.html

The tubing can be cut with a band saw: http://www.harborfreight.com/horizontal-vertical-metal-cutting-bandsaw-93762.html

I have these tools, just not the brake and shear and the rod welder (I have the wire feed). . .The HF tools are pretty usable, you need to make some tweaks to make them more accurate. My son has cut 1/4" thick Damascus steel with the HF band saw I listed, but needed to get quality blades. Mcmaster has carbide tools to cut some of the SS parts. I think the heat guard of Bob's cannon is thinner material and you need to get a punch and die set to make the patterns he made. You can use either cold rolled steel or SS as it's painted anyway.

Basically, Bob's golf ball gun is a work of art, and would be a great starting point for this gun. You need to build up some serious metalworking skills to make what he did. I recommend SS304 for it's toughness, and you need to really work on your TIG rod welding skills to build what he did.

Sounds like $800 to build one with a 30 second repeat rate if you have the tools. <$2000 if you need to purchase all the tools? Guessing 150 hours of work or so? But you should know that we engineers always underestimate time by a factor of 2 or more. . .

[Pretzel]

I can see this as a fun engineering project. . .

So, you could just scale up paint ball gun feed mechanism?

Here are some materials you might consider obtaining. . .

http://www.harborfreight.com/portable-torch-kit-with-oxygen-and-acetylene-tanks-65818.html

Weld the parts together with a TIG welder http://www.harborfreight.com/240-volt-inverter-arc-tig-welder-66787.html

Firing Tube: http://www.mcmaster.com/#stainless-steel-square-tubing/=zld8fc

Barrel and feed tubing: http://www.mcmaster.com/#8989K358 (There might be some tuning because this is exactly 1.68") Might need a slightly larger ID?

All other parts are shoot metal that can be bent with a brake from HF: http://www.mcmaster.com/#standard-304-stainless-steel-sheets/=zldbnm and http://www.harborfreight.com/36-inch-metal-brake-with-stand-91012.html

The tubing can be cut with a band saw: http://www.harborfreight.com/horizontal-vertical-metal-cutting-bandsaw-93762.html

I have these tools, just not the brake and shear and the rod welder (I have the wire feed). . .The HF tools are pretty usable, you need to make some tweaks to make them more accurate. My son has cut 1/4" thick Damascus steel with the HF band saw I listed, but needed to get quality blades. Mcmaster has carbide tools to cut some of the SS parts. I think the heat guard of Bob's cannon is thinner material and you need to get a punch and die set to make the patterns he made. You can use either cold rolled steel or SS as it's painted anyway.

Basically, Bob's golf ball gun is a work of art, and would be a great starting point for this gun. You need to build up some serious metalworking skills to make what he did. I recommend SS304 for it's toughness, and you need to really work on your TIG rod welding skills to build what he did.

Now if only I could convince the engineering honors RAP that a golf ball cannon would be a vital addition to the program. They give out grants to anyone who has a project to improve the program to pay for the entire project and labor. This would be quite a bit of fun to design and build. I have this entire afternoon free, so I might see what I can mock up in Solidworks just for fun.

[Lihu]

Now if only I could convince the engineering honors RAP that a golf ball cannon would be a vital addition to the program. They give out grants to anyone who has a project to improve the program to pay for the entire project and labor. This would be quite a bit of fun to design and build. I have this entire afternoon free, so I might see what I can mock up in Solidworks just for fun.

It's your senior project!

[Pretzel]

It's your senior project!

There we go, nice idea for three years down the line. It'll need to be electronically controlled though, I'm a computer engineering major. Maybe have a screen that calculates trajectory and range based on the current angle of the canon. 

[Lihu]

There we go, nice idea for three years down the line. It'll need to be electronically controlled though, I'm a computer engineering major. Maybe have a screen that calculates trajectory and range based on the current angle of the canon. 

Sounds fun!

That's pretty complicated as the flight is not a simple ballistic trajectory? You can also attempt image controlled firing? Aim for the flag so to speak?

Regardless, you need to take the data and log it and process it with C++ libraries, and this could be a pretty decent CS project. In fact, it could be a really extensive project even if you select very simplistic algorithms. You might even be able to tweak a Masters thesis from this too.

[Pretzel]

Sounds fun!

That's pretty complicated as the flight is not a simple ballistic trajectory? You can also attempt image controlled firing? Aim for the flag so to speak?

Regardless, you need to take the data and log it and process it with C++ libraries, and this could be a pretty decent CS project. In fact, it could be a really extensive project even if you select very simplistic algorithms. You might even be able to tweak a Masters thesis from this too.

True, though there would be not a lot of emphasis on the CS part and more on the actual hardware (sensors and the onboard computer) as a Computer Engineering major. The official designation for it is ECE, which is Electrical and Computer Engineering, so you take all of the courses required of an EE major but add additional programming. Not quite as in-depth as CS majors on the programming, but also much more thorough than an EE major would have. Since I want to place emphasis in controls and embedded systems this would actually be a pretty good project if I included motors to change the angle to produce a desired input range and designed the on-board systems from bare parts. 

As for the complications of the ballistic trajectory, this is made easier by the fact that a golf ball is a sphere, which means you don't have to worry about your projectile rotating out of the proper orientation to increase drag. If you could figure out the drag coefficient of the golf balls you would be able to model the trajectory without needing to account for lift forces, since there would be highly minimal spin on the golf ball exiting the cannon. At that point the modeling itself becomes rather simple once you componetize the x and y velocities and factor in the drag forces and gravitational acceleration to produce an equation for the net force on the golf ball. In the y-direction you just have your constant gravitational force plus whatever the equation for drag is based upon the ball's current x-velocity, and then the reverse (gravitational force minus the drag force) for the way down. The x-direction is even simpler because once you have a total hangtime you can just take the integral of the velocity minus the acceleration provided by the drag force (in terms of the velocity) from t=0 to when it lands and you'd have the total distance traveled. The hardest part of it all would likely be putting all of that into code without making an error. I usually end up with at least one  for every program I write.

[Lihu]

True, though there would be not a lot of emphasis on the CS part and more on the actual hardware (sensors and the onboard computer) as a Computer Engineering major. The official designation for it is ECE, which is Electrical and Computer Engineering, so you take all of the courses required of an EE major but add additional programming. Not quite as in-depth as CS majors on the programming, but also much more thorough than an EE major would have. Since I want to place emphasis in controls and embedded systems this would actually be a pretty good project if I included motors to change the angle to produce a desired input range and designed the on-board systems from bare parts. 

As for the complications of the ballistic trajectory, this is made easier by the fact that a golf ball is a sphere, which means you don't have to worry about your projectile rotating out of the proper orientation to increase drag. If you could figure out the drag coefficient of the golf balls you would be able to model the trajectory without needing to account for lift forces, since there would be highly minimal spin on the golf ball exiting the cannon. At that point the modeling itself becomes rather simple once you componetize the x and y velocities and factor in the drag forces and gravitational acceleration to produce an equation for the net force on the golf ball. In the y-direction you just have your constant gravitational force plus whatever the equation for drag is based upon the ball's current x-velocity, and then the reverse (gravitational force minus the drag force) for the way down. The x-direction is even simpler because once you have a total hangtime you can just take the integral of the velocity minus the acceleration provided by the drag force (in terms of the velocity) from t=0 to when it lands and you'd have the total distance traveled. The hardest part of it all would likely be putting all of that into code without making an error. I usually end up with at least one  for every program I write.

One would be really good. Here's a write up from 1976 on estimating bugs. . .I like this one though. http://programmers.stackexchange.com/questions/41248/how-to-be-a-zero-bug-programmer The solution to be a 0 bug coder? Don't code at all. . .

I think this project would make for a great embedded project. The aiming part would be particularly interesting.

BTW, I think there would be spin coming out of the barrel? Bob in the video noted that the ball flies very high!

 

[No Mulligans]

Thought you all might like this:

[Pretzel]

One would be really good. Here's a write up from 1976 on estimating bugs. . .

Hence the at least one, usually it's quite a bit more. I got lucky once and had one program compile flawlessly the first time I ran it. Only ~300 lines or so, but it certainly made my day.

I think this project would make for a great embedded project. The aiming part would be particularly interesting. I think there would be spin coming out of the barrel?

There would likely be a little bit of spin, but it wouldn't be much if you had a low-friction surface to the barrel. I could look into the effects of rifling the barrel and what pure side-spin does to the ball. I don't think it would affect the trajectory other than to stabilize it since you need a spin axis to cause the curve, but I'm not certain on that.

Edited October 30, 2015 by Pretzel

[Lihu]

Hence the at least one, usually it's quite a bit more. I got lucky once and had one program compile flawlessly the first time I ran it. Only ~300 lines or so, but it certainly made my day.

300 lines with no bugs? The only way our programmers can do that is if there were 299 comment lines! Even then. . .

Hence the at least one, usually it's quite a bit more. I got lucky once and had one program compile flawlessly the first time I ran it. Only ~300 lines or so, but it certainly made my day.

There would likely be a little bit of spin, but it wouldn't be much if you had a low-friction surface to the barrel. I could look into the effects of rifling the barrel and what pure side-spin does to the ball. I don't think it would affect the trajectory other than to stabilize it since you need a spin axis to cause the curve, but I'm not certain on that.

Something to try is to roughen the bottom surface near the muzzle?

That's the ME/EE/CE side of things, though. You need to focus on the aiming at the flag part for the bulk of your project. . .

Thought you all might like this:

Cool!, but this is off topic, that is if we had a topic.

[Lihu]

Scouting wasn't this fun when I was a kid. . .

 

[rkim291968]

Checking out this thread is so refreshing after reading through the political threads.   Now, I want to build one.  God knows my drives are pretty short.   God also knows sometimes I want to shoot other golfers with projectiles that can make a dent on their head.  "What do you mean you were sure you can hit green from 140 yards out instead of our cart ... that was right next to the green ... which we were just putting our clubs away ... and we were about to leave the green area?   <--- happened last week.   The idiot missed my head by a foot.   Given the velocity of the ball, it could have done a serious damage if it landed on my head.    I could have used the cannon then.  

[natureboy]

Here's "Bob's". I could imagine him teeing up on a 650 yard par 5, and overshooting it by a factor of 3. It sounds like a military weapon!

https://www.youtube.com/watch?v=SzL-yGcJG-w

Bob's cannon is awesome. Just the machining alone makes it look like a recoilless rifle. He mentions the 'rise thing' so he's getting ballooning backspin sometimes which will kill potential distance. I would expect to max out the potential distance with that kind of ball speed he'd have to make the top of the barrell slightly rougher to get consistent spin along a horizontal axis and drop the barrel elevation considerably to hit the mother of all Ken Venturi 'riser' shots. With that exit velocity, he'd be more accurate with a smooth (no dimple) ball for a ballistic trajectory.

@Pretzel I think the presence of the dimples on the ball complicates the spin factor. Rifle spin would likely create a very quick turnover dip (duck hook) right or left (depending on rifling direction) into the ground. A low friction barrel could potentially produce a knuckling flight (boy that would be crazy to watch). I think you are likely to get random spin axes without choosing one and because of the magnus effect, pure backspin is probably the best, but like I said above you would need to lower the muzzle elevation significantly - Bob's gun firing down into the valley to hit the hilltop on the other side. Or fill in the dimples and get a more ballistic trajectory like a cannonball. 

This is certainly lamer than combustion launching but of potential interest for geeks on this thread:

 

Edited October 31, 2015 by natureboy

[Lihu]