Janus Fires, Outshoots 850-Foot Range
Posted Apr 03, 2010 by Matt | Tags: launches
It's a week old now, but here's what has happened recently. Last Saturday (3-27) we took Janus out to a new field. Since analysis with Working Model and our videos from the previous week, we knew that using only 50 pounds of counterweight was a recipe for disaster with a 20-pound arm, the arm is just way too heavy and will over swing and hit the hanger at anything less than 100 pounds. So we upped to 100 pounds. We also made a pair of 1 pound projectiles, they were tennis balls slit open some with a few small (3/8 ounce) chunks of lead and lots of steel BB's thrown in. With the outside wrapped up with a few layers of duct tape, they weighed in at 1 pound, 3/8 ounce each, and were full (no room for more BB's!).
The first shot, with only a guess at pin angle and sling length, was actually very impressive. The projectile took off like a shot on a pretty good trajectory (later found to be about 35-40 degrees). Frame-by-frame video analysis revealed that the sling was way too long, however, as the arm had traveled way past the "stall" point, such as it was with such a heavy arm, before the sling got into position. The arm was probably around the 10 o'clock position at release! Still, we got a launch velocity of 110 miles per hour, and the projectile was gone! It had such a long hang time that we felt like we were back in Delaware shooting pumpkins 1000 feet. In fact, we lost sight of the landing point of the projectile, but it was well past a soccer goal at roughly 550 feet away. In fact, we are pretty sure it landed in a swampy area that began around 850 feet away, we never found it since the ground was so wet out there. Still, we are sure it went at least to the swamp, and probably a ways beyond that. It would not be surprising to hear that we hit the 1000 foot mark! We hadn't positioned anyone downrange because we all wanted to see this shot, otherwise we might have at least gotten a rough idea of the landing point.
Since we were already out-shooting the new range (this was at RIT in fact), we decided not to shoot the other weighed tennis ball, as it would only get lost as well. But we did have a pair of 1.25 pound cabbages that we tried throwing. We had to rig up a sling for them, and we had 2 misfires before we got the cabbage to launch forward. When it did, it took the sling with it, and an explosion of green leaves erupted about 50 feet away. We figured that the cabbage had just died right there, but in fact the core of it still traveled 450-500 feet downrange before hitting the ground and exploding itself!
It is clear that this machine has tons of power even at only 1/2 the designed counterweight. Now we need to find a new range and begin working up to the 200 pounds of counterweight. We are preparing for Imagine RIT, and will be ready to go with both the Melon Felon and Janus on May 1 when Imagine is held! Come and see us if you are in the Rochester, NY area. We are exhibit 337.
