Altitude Control System: Spring Ejection

I designed our spring ejection system in Autodesk Fusion 360, and 3D printed its components from PLA. I designed the system to work as a “pusher” to separate the rocket and deploy the main parachute. This system was controlled by a miniaturized Arduino nano and a barometer. When the arduino red an altitude above the pre-determined threshold, it would spin a small DC motor that would disengage with a lead-screw allowing the spring to be released and the rocket to separate.

This system was incredibly reliable, and had no major impact on the barometric altimeter. This system was flight proven to control the rocket’s altitude to within +/- 15’.

Altitude Control System: CO2

In order to control when the parachute deploys on the rocket, I designed a system to accept a 1.5g 1100psi CO2 cartrage that would be pre-punctured and could be actuated by a small motor and an Arduino. With the oversight of a talented machinist, I milled the major components from 6061 Aluminum. In order to actuate the device, the motor would spin a lopsided drum (not shown) allowing a collar to slide down the barrel providing room for four ball bearings to move radially outwards, giving way for the CO2 cartridge to disengage the forward seal. This was estimated (by the ideal gas law) to pressurize the parachute compartment to 1.5psi above atmospheric pressure.

While unique, and weighing less than 100g, the system proved unreliable, and difficult to prepare, and reset.

Altitude Control System: CO2

I worked with a machinist to design a system to accept an 8g 800psi CO2 cartridge which was pre-punctured. This system used a bar and plunger to press a stack of o-rings to seal against the CO2 cartridge, the bar would slide into two grooves inside two bronze pylons. One of the pylons was attached to a small DC motor (not shown here) such that the motor could rotate the pylon, pushing the sealing bar out of the groove and allowing the CO2 to pressurize the parachute compartment.

This system proved to be incredibly reliable and was able to control the altitude of the rocket to within +/- 8’. This system flew on the 2015 and 2016 competition Rockets.

2015 design and Performance

Before I led the team, I worked as a member that primarily built the composite components of the rocket. The air-frame was made two layers of 3k twill weave carbon fiber, where the fins were made from 6 layers. This was the first year I advocated for the use of the Cesaroni F-79 motor that would later become the backbone of our competition strategy. Later in the year we began using the above mentioned CO2 ejection system.

The rocket and team performed exceptionally well, placing 34/700 and winning the “Best Rocket Craftsmanship“ award, presented by Lockheed Martin.

2014 design and Performance

The records start getting thinner around here. The rocket flew on a Cesaroni F-59 re-loadable motor, and used a phenolic resin infused cardboard booster section and a lighter weight un-infused cardboard payload section.

This was the year I introduced the angled fin concept where the four fins were canted 7.5 degrees towards each-other. Canting the fins, increased drag on the booster section moving the center of pressure further aft-wards increasing the static margin of stability throughout the flight. This decreased wind-cocking and allowed for more consistent flights and better scores over all. This concept of designing a high-drag booster would be carried over for all subsequent years.

Placed 42/700 in the launch and did not compete in presentation.