Monday, June 30, 2008

Day 6

Modifications:
  • Changed launching direction (launch from NE to SW). Wind in favor.
  • Made certain of proper alignment of track.
Test 1
  • Balloon Weight: 166 g
  • Distance: 14.58 m
Test 2
  • Balloon Weight: 134 g
  • CW Prop Angle: 165 +- 5
  • Distance: 24.72 m (drop in height from building not accounted for)
  • Height of Building: 7.27 m
  • Went over railing. Rick owes us a pop!
Test 3
  • Balloon Weight: 264 g
  • CW Prop Angle: 180 +- 5
  • Distance: Traveled straight up and backwards over rail.
  • Sling ring disconnected
Test 4
  • Reset Ring
  • Balloon Weight: 143 g
  • CW Prop Angle: 155 +- 5
  • Distance: -3.5 ft
  • Slipped out of sling
Test 5
  • Balloon Weight: 143 g
  • CW Prop Angle: 155 +- 5
  • Distance: -
  • Sling disconnected (untied)
Test 6
  • Sling reconnected
  • Balloon Weight: 143 g
  • CW Prop Angle: 155 +- 5
  • Distance: 7.46 m
  • Veered left
  • Balloon didn't pop
Test 7
  • Reset track
  • Rick Launched
  • Balloon Weight: 155 g
  • CW Prop Angle: 160
  • Distance: 28.42 m (drop in height from building not accounted for)
  • Height of Building: 7.27 m
  • Balloon didn't pop
Conclusion:
  • Propping the counter weight greatly increases the throwing distance.
What to try for next time:
  • Change throwing arm (more durable) to add more weight
  • Glue strings' knots.

Friday, June 27, 2008

Day 5

Modifications
  • Replaced strings holding counter weight can with 5.25 in. metal bars.
  • Shortened bolts on base that hold the pin (so the trebuchet can sit flat).
  • Trimmed base PVC pipe that holds pin bolts.
Test 1
  • Sling released too soon
  • Balloon went backwards
Test 2
  • Reset.
  • Same results.
Test 3
  • Reset.
  • Same results.
Test 4
  • Used larger balloon.
  • Sling released too soon.
  • Balloon went backwards, popped.
Test 5
  • Added v-shaped metal track.
  • Success! Balloon hit wall on opposite side of balcony (appx. 15 m) before bouncing away.
Test 6
  • Used balloon with thinner rubber.
  • Same results as above. Balloon popped.
  • Traveled 15.27 m.
  • Was launched at slight angle to the right of the trebuchet. Possibly caused by misaligned track.
Conclusion: Adding the v-shaped metal track greatly improved the performance of the trebuchet. What to try next time:
  • Properly align the track.
  • Prop the counterweight.

Photos:




Thursday, June 26, 2008

Day 4

Trebuchet launching canceled due to rain.

Modifications:
  • Shortened sling string length to 4 ft.
Planned Modifications:
  • Replace string holding counterweight with metal bar.
  • Trim base PVC pipe that holds pin bolts.
  • Possible modifications to trebuchet throwing arm.

Wednesday, June 25, 2008

Day 3

The first launching

Test 1
  • Balloon went backwards and over the railing.
Test 2-4
  • Balloon either went backwards or a few meters forwards.

Test 5
  • Balloon was launched a few meters and bounced a few more.
Test 6
  • Balloon was launched backwards landing on balcony barrier.
  • Trebuchet begins to fall apart.
Test 7
  • Pin got stuck on launch causing misfire. Possibly caused from pulling from an angle.
Test 8
  • Pulled pin directly perpendicular to the holding bolts.
  • Balloon went appx. halfway across the balcony and bounced it's way towards the end.
  • Trebuchet falls apart.

Conclusions:
  • The trebuchet needs to be glued together to hold up for multiple launches.
  • Problem with the launch is either caused by the sling, the counterweight, or both.
What to try next time:
  • Modify sling pouch.
  • Shorten sling string.
  • Add more weight.
Modifications:
  • Glued trebuchet together.

Tuesday, June 24, 2008

Day 2

The throwing arm, the base piece for the eye bolts to hold the throwing arm down, and the counterweight holder (coffee can) are given to Bob to be drilled.

The sling is planned to be made from denim.

Monday, June 23, 2008

Day 1

Purchased ~$50 worth of materials for the trebuchet construction:
  • 5 PVC pipes
  • 8 T-joints
  • 8 45 degree joints
  • Purple Primer
  • PVC Glue
The PVC pipe was cut the following way:
  • 2 4" pieces (throwing arm axel holders)
  • 4 4" pieces (to hold together T-joints)
  • 1 7' piece (throwing arm)
  • 2 7' pieces (base)
  • 2 20" (base)
  • 4 51" (supports)

The following are the models being used to as a guide to build our trebuchet:
http://web.archive.org/web/20070722115351/http://www.ripcord.ws/plans/plans.html
http://www.redstoneprojects.com/trebuchetstore/pvc_trebuchet_2.jpg