This project is a continuation of our efforts from the Summer 2017 semester.
Typically, upper tier hobbyist rockets utilize chemical reactions, such as a controlled black powder detonation, to achieve separation and parachute release after the apogee altitude is reached. These methods are relatively straightforward and reliable, but they are also dangerous due to an inherent risk of fire, and accidental detonation. Additionally, substances such as black powder leave behind a messy residue, and must be reloaded before each flight. Consumable resources add to the cost of launching a rocket.
The goal of the mechanical separation project is to develop an alternative method of rocket separation that does not rely on the use of chemical reactions or consumable resources (excluding batteries). A mechanically separating rocket will be able to launch and recover several times, requiring only a new propulsion motor (and perhaps batteries) between flights.
Progress to Date
Since the end of the 2017 Summer semester, great progress has been made in the design and development of our two distinct prototype systems: A purely mechanical system, and an electromagnetic system. Much of the Summer 1 semester was utilized to brainstorm together and develop our designs in sketches and CAD. We didn’t want to begin ordering materials until we had at least one promising design. Summer 2 saw the beginning of fabrication and testing of our designs.
The purely mechanical system utilizes a servo driven power screw (made of a threaded stud and a threaded hexagonal standoff) to control a latching mechanism which holds the two halves of the rocket together under spring compression. By activating the servo, the latch will be released, and the compressed springs will force the two rocket halves apart. The system is already partially assembled, with the exception of a few components. The software for this system must also be written and tested.
The electromagnetic system involves fewer moving parts. Rather than a mechanical latch holding the springs compressed, a permanent electromagnet will be utilized. This magnet attaches itself to a strike plate on the upper rocket half, and “turns off” when it is given power. The switch which allows power to the magnet will be controlled by the same stratologger signal which is typically used to fire off e-matches. The circuitry was difficult to troubleshoot. What should have been a simple circuit to set up actually had the issue of floating current coming from the apogee signal pin on the stratologger. This system has been successfully ground tested, and has been proven to be repeatable (video here).
Plan for the Spring
This project has been ongoing since Summer 2017 and has plans to launch a rocket with a mechanically separating system on-board at the end of the Spring 2018 semester!