September 29, 2007: Burlington!
Burlington was great! I will get some videos up eventually, but I don't have room to edit them now. A ton of great pictures were uploaded. See them on the main page for now.
September 22, 2007: Pumpkin On A Stick testing!
First we bent the arm on deceleration. After fixing that we eventually cut the sling loop for the firing pin, then we tried 3 pullers and broke a pulley and bent an upright. I guess I will be buying 4 stronger pulleys and a new upright. I don't think I will try more than two people again unless I can find a stronger replacement for the uprights which I don't think I would have time to install anyway.
Also, the arm got a bit screwed up when the pulley broke because the load became unbalanced because it rubbed on the screws.
The disadvantage of the double redirect system is that it triples the load on the frame which seemed to be too much with 3 people.
On the bright side, it actually worked and threw around 20 yards with a completely horizontal release. We might get 100 feet with just 2 people which would be cool.
August 28, 2007: Traction!
No traction treb yet, but the frame is nearly done (it needs 4 safety pegs installed). Plans for the arm are developing. I have some great plans, but nothing is sure yet. It will be cool; I can say that.
August 21, 2007: Onagenator 2 broken
Today Matt and I set out to test the minor changes to Onagenator 2 including a reinforced draw down loop on the arm, pins to prevent the bundle from unwinding and a longer sling. Because of space limits we used a heavier 5 ounce lacrosse ball rather than a golf ball as a projectile. The sling was too long for the heavier projectile, but the the changes worked well, too well. We increased the bundle twists in large increments to quickly get up to last times failure point where the modulus slipped. Our new pins worked (but bent) however with our greatly increased torque there were problems. First our spanner has some minor problems, but that would be easy to fix. More importantly one of the pegs in the modulus that the spanner hooks up to got pulled out of alignment as the oak deformed. This did not stop us, and nether did the breaking off of one of the onager's feet which don't do much now. What did stop us was much more impressive, the sliding release trigger rated at 150 pounds failed. I don't know how, but the trigger clearly released while we were cocking the onager. As always during the cocking and loading process all people were clear of the plane of rotation and no one was hurt, but the most amazing thing happened: we broke the arm into three pieces! The bottom break was just past the end of the bundle in the steel reinforced section. The steel clearly need more wrapping to add sheer strength as it was intended to resist compression which it did. Video will be added soon! (Sorry, no video of the break) See onagenator2 page for pictures
August 17, 2007: Burlington Info Received
Today I finally got the information I needed about the Burlington Pumpkin Pitch. If all goes well there will be a youth division 11-17 throwing 4 pound pumpkins which I will compete in. Should there be less than three entrants in the division it will not exist and I will be throwing 8 pound pumpkins in the adult division. I may take action to make the youth division exist by finding some other people to enter it and/or entering more than one device. Should this status change it will be updated here.
August 2, 2007: Mini KA day Two
Matt and I did some more testing with Mini KA today. We tried the racket ball with some more room and threw 63'4" and tested a smaller bouncy ball some where around a half ounce which got lost on top of a 31 foot high building 124 feet away. The throw would have gone about 200 feet. This shows that my Mini KA can be very efficient through a wide range of mass ratios through the adjustment of the arm ratio, secondary trigger, sling length, and pin angle.
Here is today's video. As you can see I'm getting better at video editing.
July 31, 2007: Blog Creation and Mini KA
Today I created this blog about my hurling. For earlier information see my blog on the hurl.
My Mini KA:
The day before yesterday I started making a small King Arthur inspired by the great CW I had laying around: A 3 1/4" long 2" diameter can filled with 3 1/2 pounds of solder. I grabbed a few pieces of 1/4" by 3/4" wood and started cutting with no real plan. A bit different from my normal computer modeling then building process. I finished the trebuchet yesterday and tested it today.
CW: 3 1/2 pounds
Projectile: 1 1/4 ounces (roughly)
Axle Height: 13 1/2"
Long Arm: 12 3/4"
Short Arm: Adjustable (4 1/4")
Sling: Adjustable (13 3/4")
Frame: 1 1/4 pounds (roughly)
Test went well. Tuning was very good, but room was lacking. My joke desktop trebuchet with almost an equal sized counterweight and projectile, but 45:1 mass ratio, threw through part of a tree and uphill for a range of roughly 50 feet. I hope to do some testing with more room soon.
Frame seems quite strong (Took a few misfires and getting flipped) but the original axle bent, probably when the frame bounced; it gets about an 1 1/2" of air under the back wheels on a regular throw. New skinnier and stiffer axle works great.
A single shot at real speed.
Contains some pictures and slow motion.