Objectives:

• Team 2
  • Try out the ejection timer and crimson ejection charge.
  • Get some more altimeter data.
• Team 3
  • Check out the overall design on two different rockets (fin design, multi-cargo units).
  • Initial launch with E9-4s, altimeter launches with E15-4s.
  • See if double versus single launch lug is important.
  • Try two chutes with no shock cord to see how the altimeter works.
  • Check out egg recovery chute size (14", 16", or 18"X).
  • Check out egg protection packing.

Team 3 arrived first and got off five launches. We launched the Black rocket and the Orange rocket with an E9 Estes black powder engines to see how they fly. We then followed with E15 Aerotech composite engine launches with an altimeter. All five launches were successful, although not very straight. We used the version 2 altimeter from last spring (#C) for all three altimeter launches, but for some reason the data from the first launch was not maintained. All launches were with two real eggs. They all survived. All the landings were within a few hundred feet of the launch site. Here are the two recovered altimeter data sets on an Excel spreadsheet.

Team 2 followed Team 3 with two launches of their V2 rocket with a timer ejection mechanism.  The first V2 launch went off OK, but the timer ejection didn't work.  The ejection charge ignited but it didn't open the rocket.  The timer was set to a little over 2 seconds.  The second launch had a significant failure.  The rocket went unstable in the first 100 feet. It went a spiral and deployed the chute.  The electronics fell out but was recovered.

Lessons

• Team 2
  • We need to make some changes to the timer ejection mechanism.
  • The electronics need to be bound to the rocket (timer, altimeter, and battery).
  • We need a way to level the launch tower (try a plumb-bob in the center).
• Team 3
  • We may have some problems with the overall design, such as fins too small, straight mating of the cargo units, and overall length. The rockets made gradual turns away from the vertical in the first 100 feet.
  • The launch tower seemed too flexible for the heavy rocket, but the video didn't show any problem.
  • The weight is well over 400g and the E15s are not powerful enough.  There was not a big difference between the E15 and the E9.
  • Ejection times need to be 4 seconds.
  • The egg protection seemed sufficient.
  • We lost the first launch altimeter data.  We may want to use multiple altimeters to be sure we get some data and as a test of consistency.
  • The two chutes seemed to work, but didn't arrest the altimeter spikes.  We may need to try smaller air holes for the altimeter, a fixed connection to the rocket body, and some padding.
  • The 16" chutes seemed to give a 20ft/sec descent, which should be about right from 750ft.

 Launches

Pictures