TARC 2015: There's a Solution to Every Problem

By Nick Becker · February 22, 2015

This past week the Makers Club worked diligently to complete our first prototype rocket. However, with it being the first rocket we’ve ever completed, a few challenges were bound to arise.

Up until a few hours ago, we had planned for today, Saturday, February 21st, to be the first launch test of our design. The rocket was completed, launch systems assembled, and launch location confirmed. However, despite UPS tracking confirming their arrival, we were unable to locate the rocket motors crucial to the launch planned for today.

I had planned for this post to discuss what we’ve accomplished in the past week, the data we planned to record during the launch, and job designations for photography, systems inventory, and launch control. That post will be coming by the end of next week.

While delaying the launch was a disappointment for the whole team, it presents an opportunity to change any doubts we had in the current prototype before testing. Our design isn’t perfect. Here’s how we’re going to fix it.

Current Challenges

We experienced quite the surprise when weighing the rocket for the first time last week. Unfortunately, the Rocksim defaults for 3ply plywood and cardboard density underestimated the weight of what we constructed our rocket with. With that said, our fist priority this week is to decrease the mass of our design and complete the second version of our prototype by Friday.

The New Design

The first step in fixing the existing prototype is to redesign it in Rocksim. In summary, the rocket was made shorter, fins smaller, and mass decreased. We will still need to weigh individual components and override the mass in rocksim to get an accurate center of mass and stability estimate. A complete list of changes is below.

Version 4 Changelog:

  • Fins redesigned (to tarcfinv1)

  • Forward centering ring moved backward

  • Aft centering ring moved forward

  • Motor mount tube length decreased by .5in

  • Booster tube length decreased by 1in

  • Aft bulkhead moved forward .5in

  • Coupler length decreased by .5in

The Plan

Up to date schedule here


Monday will mainly be comprised of cutting materials for construction later in the week and weighing those components for mass overrides in order to improve the accuracy of our simulations. Specifically, the Makers Club will do the following:

  • Cut a body tube for the new booster stage (specifications in Rocksim design)

  • Cut a motor mount for the new booster stage (specifications in Rocksim design)

  • Laser cut centering rings for the motor mount

  • Laser cut the new fin design

  • Laser cut a new bulkhead for the coupler

  • Shorten the coupler by .5 inches

  • Record mass of the fins, coupler bulkhead, eyebolt, centering rings, booster tube, and motor mount tube

  • Override the calculated mass for each of these components in the Rocksim file


Tuesday will be the final day to prepare each component before construction

  • Remove the motor retainer from the existing booster stage

  • Record mass of the motor retainer

  • Install the new (lighter) eyebolt in the new bulkhead coupler

  • Epoxy the bulkhead to the coupler (with significantly less excess)

  • Cut fin slots in the booster body tube (3 fins)

Wednesday & Thursday

These days will be build days for constructing and completing the booster stage.


Friday will be dedicated to last minute construction and launch preparation. By now the launch date will have been selected based on wind/weather conditions.