So Janus has been completed. Well, mostly, the details of triggering the FAKA mode have yet to be fully ironed out, but the FEW mode is ready to go. In fact, Chris and Matt went to our old launch field on Saturday (3-20-10) to test the new machine. The purpose wasn't so much to launch great distances, but to verify that our winching and triggering systems would work. We had to reconfigure the winching system, and there are still some bugs to work out there, but after a quick reconfiguration of the triggering system, we were able to attempt 2 shots. On a side note, the complete set-up only took just over 1 hour, as was planned for when we have the full 3-person team present! This is good news.
The first shot was a spike, with the baseball landing maybe 10 feet in front of the trebuchet, leaving a nice divot as well! We were using only 50 pounds of counterweight in these shots. Unfortunately, with a 20 pound arm (weight due to designing for 200 pounds of counterweight), the arm is so heavy that it overswings after release and it smacked into the threaded rod we used for an adjustable prop. This rod was supposed to get cut down before we took the machine out, but we got lazy and left it at the 12" it came in (needs to be 5-6"). It left a nice dent in the arm, but there was no damage.
We shortened up the sling significantly, and fired again, but this time the pouch did not drop out of the projectile holder due to putting too much pretension in the sling lines (you don't want much in a whipper otherwise this happens), and the arm really followed through. Thunk! And the arm and hanger stayed stuck together at the end of the tracks. The prop rod had punched through both walls of the arm!
Luckily, the damage was limited to these 2 new holes, and they are not in a position where they will harm the structural integrity of the arm. The sun was going down, so that was it for the day anyway. After later analysis using Working Model 2D, we found that no matter what the tuning is like, the arm and hanger will always smack into each other as long as we use only 50 pounds of counterweight. So, we will be launching a 1-pound projectile with 100 pounds of counterweight next time!
All in all, it was a successful day. We have to modify the winching process slightly so that we are not putting so much tension into the winch cable (and on the pulleys, bending the eyebolts holding them to the frame), and we need to cut the prop rod down, but neither of these is a deal-breaker. We can easily cock the arm by hand with only 50 pounds of counterweight, and 100 should not be an issue either, so we can play with new ideas and if one doesn't work, we can still fire that day. This is the luxury of having a couple of people on your team for firing operations. The sliding release trigger we bought from Trebuchet.com worked beautifully once put in the right place.
We hope to fire again this weekend, and we are ON for IMAGINE RIT on May 1. Come and see us fire Melon Felon and Janus there! Send us an email at info&$64;teamurbansiege.com for more details if you wish to attend.
