Solar Panel Deployment Mechanism
There are five distinct phases to the deployment of the Solar panels on Delfi-C3: hold down, release, deployment, confirmation and stopping/locking. Each phase or action is performed by a different component of the Solar panel deployment mechanism (SP-MechS). The Solar panels are deployed to an angle of 35 degrees to obtain the most consistent power from the incoming Sun light.
The SP MechS is built around a custom hinge that is the mechanical interface between the Solar panel and the structure. The hinge structure leaf is connected to the structure and the hinge panel leaf is connected to the Solar panel. The leaves are made from Bronze. The hinge axle is made from stainless steel and is fixed in place with a nut at either end.The Solar panels are stowed against the satellite structure until deployment after ejection from the P-POD. The stowing is performed by a single Dyneema wire per Solar panel. Dyneema is a synthetic polymer material from DSM with a higher strength and lower melting temperature (150 ºC) compared to Nylon (fishing wire). The wires are connected to the structure under pretension to prevent the Solar panel from vibrating freely during the launch.
The Dyneema wire is run over two metal film resistors (MULTICOMP MF1275R) that perform the release by melting the Dyneema wire. The resistors are connected in parallel, making the release mechanism redundant: only one resistor is required to melt the wire. The limitations in available power result in a maximum power consumption of 2 Watts for the release of the deployables. Vacuum tests have been performed with satisfactory results, release occurs within 5 seconds.The actual deployment is done by two spring steel helical torsion springs that are mounted on the hinge axle. Two torsion springs are used as a redundant solution in case one of the torsion springs cold welds to the axle. The torsion springs have a safety factor of two, so they are strong enough to deploy the Solar panel if one should fail. The deployment time of the Solar panels is about 0.35 seconds. This was supported by preliminary testing that was done with an Aluminum mock up of the Solar panel.
The deployment is confirmed to turn of the release mechanism of a Solar panel. This is done with a single tact switch (ITT Cannon KSR223GNC) per Solar panel. Only one switch is used because the confirmation can also be deduced from the TFSC temperature measurement and the Solar flux reference cell measurement. This makes the confirmation redundant without doubling the mechanism itself.
The final phase is the stopping/locking of the Solar panel at the correct angle of 35 degrees. The SP MechS makes use of two plunger springs from Vlier Inc.. that are mounted on the hinge. These plunger springs are also used to separate 1-unit CubeSats after ejection from the P-POD. The plungers lock into holes in the hinge panel leaf to fix the Solar panels at an angle of 35 degrees. A hard stop is not used because it limits the accessibility of the satellite during integration as the deployment angle is much smaller than 90 degrees. Preliminary testing showed that a single plunger spring locks the Solar panel and that no overshoot occurred.
| 
