Golf ball challenge! Help appreciated.

[Reactor4]

Hey . a trebuchet ! thats a great idea!

[rcman50166]

Oh god, a trebuchet is not the most accurate thing in the world. Also they seem more appropriate for larger projectiles than golf balls. Of the three medieval weapons I'd choose the ballista. Think ancient crossbow. You can make it spring powered and get rid of all the temperature differential problems of a sling shot. (you are correct moonbog) They also have guide rails by design so it would be accurate and relatively easy.

[Reactor4]

Yea ballista's are pretty kick @ss. I've seen countless numbers of those in medieval type movies. And you could put a catch on the rails too, for an accurate tension. (I'm not all that good with medieval weaponry, obviously
). I have seen the show Doing DaVinci on Discovery though!

[jackssmirkingrevenge]

I have seen the show Doing DaVinci on Discovery though!

Sounds like renaissance pr0n "Da Vinci does Venice"

[Reactor4]

Haha well hey it is a really good show! They use period materials to build DaVincis inventions, and the good part, they actually work (and don't fall apart upon testing.) !

[jackssmirkingrevenge]

They use period materials to build DaVincis inventions

If I had more free time at work I'd photoshop Leonardo's helicopter made out of a tampon framework held togther with tampon string, with sanitary towel rotor blades

[Reactor4]

hahaha thats awsome. a combination of creativity and boredom im assuming?

[mysticjbyrd]

The team has decided to go with a ballista style setup with a crossbow. I dont know all the details atm, but when I get some more info I will let you know.

Thx for the help thus far.

[Moonbogg]

Ballista FTW! Rain, sleet, heat or snow, 50 yards the ball shall go!

[Fugaloo]

Your grade is not going to depend on the accuracy of a machine that somebody else has gone and prototyped and developed for you. Build the best launcher and stand that you can for the budget and tear that thing apart. They only take a day or two for the beginner to build. But they take a while to learn how to operate properly. the answer is in disecting whatever launcher you have and showing the science to back it up. I think building a mediocre launcher and a great stand will produce more consistent results. Good luck

[Moonbogg]

Nor wind or fire nor hail or rain, its 50 yards the ball shall gain!

[Technician1002]

I gave this a shot modeling the Marshmallow cannon in GGDT. Using a short 24 inch long barrel, most of the targets can be hit with less than 13 PSI. This should be able to get past the safety inspectors to have the launcher set with a 20 PSI pop-off.

The small tank with the 1 inch valve hits 50 yards at under 12 PSI. A low pressure gauge and regulator will be needed to accurately dial in the pressures. At close range there is a narrow pressure range between did not launch and launches too far, so as recommended by others, it may be best to adjust distance by adjusting elevation, not pressure.

[mysticjbyrd]

I gave this a shot modeling the Marshmallow cannon in GGDT.

In your marshmallow cannon what are you using to seal the pin you pull back to release the quick dump valve?

The current plan is to use a crossbow from wal-mart that costs $25. Sounds cheap to me, but I havent seen it yet. Anyways we will attach the arrow onto the string, which always goes back a set distance, and then change the angle to get different distances. The ball will rest on a sort of cup on the end of the arrow and will push the ball up a tube that will launch the ball.

Sort of like a sling slot mixed with a cannon.



There are 2 backup plans I have come up with.
1. The first backup plan is really simple and easy. It is basically a pinball machine, or at least the part that launches the ball. A spring attached to a metal pin that will either hit the golf ball through a tube or push it. The only part I havent worked out is how to accurately compress the spring the exact same amount for each shot.

2 is basically an air cannon that uses steam instead of compressed air. I believe it would compensate for some of the error involved with compressed air, however I am thinking of scrapping this idea because it would be difficult and complicated to build.

[Technician1002]

I gave this a shot modeling the Marshmallow cannon in GGDT.

In your marshmallow cannon what are you using to seal the pin you pull back to release the quick dump valve?

The current plan is to use a crossbow from wal-mart that costs $25. Sounds cheap to me, but I havent seen it yet. Anyways we will attach the arrow onto the string, which always goes back a set distance, and then change the angle to get different distances. The ball will rest on a sort of cup on the end of the arrow and will push the ball up a tube that will launch the ball.

Sort of like a sling slot mixed with a cannon.



There are 2 backup plans I have come up with.
1. The first backup plan is really simple and easy. It is basically a pinball machine, or at least the part that launches the ball. A spring attached to a metal pin that will either hit the golf ball through a tube or push it. The only part I havent worked out is how to accurately compress the spring the exact same amount for each shot.

2 is basically an air cannon that uses steam instead of compressed air. I believe it would compensate for some of the error involved with compressed air, however I am thinking of scrapping this idea because it would be difficult and complicated to build.

There is no seal of any kind along the length of the rod. This is intentional to permit trapped air to vent slowly through the center of the piston out the back of the cannon. The shot duration is so short there is little of the charge lost to this path. The twin o rings seal the chamber so there is no leakage before the shot from the chamber.

A spring launcher should be able to do the job. Picking a tension to reach 50 yards accurately at 44 degrees and then simply adjusting elevation to adjust range should work well. Having multiple tensions could be difficult to repeat. I like the design. I hope the repeatability is good.

What is the contest day?

Edit

I made a short golf ball barrel for the Marshmallow cannon. It is one size that cannon did not have. If weather improves next week, I may connect a welding regulator to my compressor and do some field testing for repeatability. I'll see if I can drop golf balls into a 5 gallon bucket at 20 yards. If I can, it should be proof the repeatability is good enough to hit a 2.5 foot radius circle.

[mysticjbyrd]

The competition is not until early December, so I have a lot of time to work on it.

Cool thanks for the help.