Modified Floating Arm Trebuchet

WE WON!!!!!!!!!!



I'll get the pictures and videos up as soon as I can. Our machine threw an official 283ft. The closest competition threw 128ft.

We dominated!


UPDATE: The new launch date is December 6th!


My office does a good job of having fun activities for us during the year. This is the first year that we've had a catapult contest though, and for the first time I had nothing to do with coming up with the idea. Here are the rules.

1. No ready-made kits
2. Catapult devices cannot exceed 4 feet in height up to the pivot point
3. All catapults will be launched on a grass field. They must sit on the ground. No tables.
4. The catapult cannot be staked into the ground.
5. All catapults will launch a 4lb medicine ball.
6. No combustion, explosions, compressied gases or air pressure may be used to enhance the performance of your catapult.
7. Surgical tubing, or elastic/bungee cords are not allowed.
8. No electric motors allowed.
9. Counterweights cannot exceed 100lbs.
10. Each team will enter the best of 3 launches to determine the winner.

After initally reading these rules I decided that an Onager was the best bet as the pivot point was near the ground and that the counterweight restriction wouldn't apply. We found a few simulators online and found out that we would need in the neighborhood of 1000ft-lbs of torque on the rope bundle to throw the 4lb ball and distance so we scrapped that idea.

The next idea was to build a trebuchet. This is the machine that the rules were written for. We had to find a way to bend the rules in our favor, and the trebuchet was close, but not quite there.

Enter the modified floating arm trebuchet. This machine lets you get your counterweight higher than a traditional trebuchet but keeps the pivot point low enough to keep with the rules of our competition. I purchased a set of plans from here, for a whopping $7. The plans came with brief instructions on scaling the machine up as the designs built a table top machine. We spent a good deal of time building our own plans and instructions based on the plans we had purchased.

I'm happy to report that after two days of construction we have a fully functional machine.

Picking up the lumber



Building the inital frame. Yes, those are lapped together 4x4's connected with 1/2" Grade 5 hardware.



Adding the columns to the base.



Adding the runners to the top of the columns. The pivot wheels will run on these boards.



Here we have test fit the throwing arm into the base. You can see the 1" all-thread that will hold the weights at the bottom. The wheels are caster wheels with needle bearings and servicable grease zerks.



Here we have added a few weights to the arm and added the bracing that's needed to keep the columns straight.



More bracing, and the guide wheel for the arm has been added. We later discovered that the wheel was too high. The wheel needed to be flush to the top of the runners in order to make a smoot transition for the arm.



Here is the release pin for the sling. You can see that the pin is adjustable to allow us to change the trajectory of the projectile. A shallower angle means higher flight, and the opposite for a steeper pin angle.




Here's the slow motion video of the first shot.

http://player.vimeo.com/video/53449494?badge=0



More pictures and video to come.

 

looks like a fun little project. you'll have to post up a video of it in action.

 

Wicked.

 

SICK! I want one...

 

Man a trebuchet would be fun in my back yard, easier that hitting golf-balls with a bat

 

Looks sick! Make sure that thing is beefy for a 4lb medicine ball. Looks really beefy so far. In my high school physics class we made trebuchets. The floating arms went the farthest, but some of them started tearing themselves apart, and we only had to throw a lacrosse ball.
Subbed!

 

Damn... that's an awesome thing to do for work!

 

That's awesome! Def need a video of it in action

 

Why are you hitting golf balls with a bat? You know they make something for that...

 

This reminded me of something i did as a teen, me and my buddy snuck onto a golf course and swiped some balls from the middle of a fairway and batted them out of his back yard, think the sound of large pieces of glass breaking, I was a bad kid growing up, having a trebuchet would have been much, much worse, especially Halloween and thanksgiving, we probably would have sent flaming gourds all over the place.

 

This is awesome.

Not surprising at all coming from someone who votes on the Transylvanian Impaler plank. If I had been more industrious in high school and had the google back then, I would probably be in federal ass-pounding prison now.

 

You guys don't know the half of it! It probably would have considered domestic terrorism nowadays

Well Scott, do you disagree that Vlad would have dealt with the BS in Congress in short order????

 

I think heads on stakes would be a fine addition to the circumference of National Mall.

 

Tell McConnel and Reid "Hey, uh look, you had great careers and all, but it's time to go now, BTW, here's your 'severance package'"

 

subbed this looks pretty sick

 

sub'd.

 

Here is the completed machine under wraps awaiting tomorrows competition. I have the first throw video uploading now. It doesn't show the distance, but does show the machine working.