The P-POD Payload Planner's Guide

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P-POD Payload Planner’s Guide: Revision B – 5/15/00 16 of 19 The Poly Picosatellite Orbital Deployer has been designed to provide a reliable and inexpensive solution to picosatellite deployment in space. It is the intent that universities and industry will be able to use the PPOD as a means of deploying standardized multifunctional satellites in space. The Cal Poly WESTEC team has developed picosatellite specifications for universities and industry wishing to use the PPOD to deploy space bound experiments. These specifications can been seen in DWG 220-112- 001 in Appendix B. An exploded view of the PPOD mechanical assembly is shown in DWG 610-102-001. It uses a pin-puller actuator to release the spring-loaded door. A compression spring provides the initial force to deploy three CubeSats loaded in the PPOD. The picosatellites will be loaded into the device using the configuration shown in DWG 610-103-001. Design Criteria The following criteria was used in the development of the PPOD: • Temperature Extremes: -40°C to 65°C • Maximum Force during Launch: 15g’s • Mass of the deployer must be equal to or less than 1.50 kg [3.3 lb] • The satellites will weigh no more than 1kg • The satellites will be 10cm X 10cm X 10cm • Must ensure that the picosatellites will not tumble upon launch • Must deploy the satellites at an exit velocity of no greater than 0.3 m/s [1 ft/s] (the slower the better but they must get out) • Must provide a faraday cage to shield against any premature transmission from the picosatellites • Must not be a threat to any other mission aboard the rocket • Must be able to accommodate satellites with solar panels mounted on the external walls PPOD Design Results Material: 7075-T7351 AL Mass (empty): 1.67kg [3.7 lb] Fasteners: 6-32 machine screws and lock washers Spring Specs: Constant = .85 lb/in Free Length = 15 in. Solid Ht. = 1.5in
P-POD Payload Planner’s Guide: Revision B – 5/15/00 17 of 19 Part-by-Part Notes DOOR: DWG 210-101-001 The door of the PPOD was designed to be as light as possible without sacrificing strength. The thickness of the door is 0.135 in with portions trussed out to 0.030 for weight reduction purposes. The pin-puller locates its pin through a 0.081in hole in one of the two flanges on the bottom of the door. When the pin on the actuator is triggered, the door will open as a result of the force applied by the torsion spring. It is intended that the force opening the door of the deployer will be strong enough to accelerate the door such that there will be no contact with the top picosatellite as it accelerates out of the deployer. This would prevent the satellite from tumbling upon deployment. The torsion spring and compression spring may need to be adjusted if future testing proves them ineffective in this respect. HINGE ROD: DWG 210-110-201 The hinge rod is a 0.25in diameter steel rod. The door pivots about this rod. SIDE A: DWG 210-103-201 There are two Side A parts to each PPOD deployer. The function of the Side A part is to act as a structural member of the assembly as well as a faraday cage. Side A has three 0.332 in thick bars across the bottom, middle, and top of the part. These bars will eventually serve as mounting surfaces when the attachment configuration has been determined. The thicker material is needed in order to use countersunk fasteners for the final mounting configuration. The remaining material is 0.078 in with portions trussed out to .030 in for weight reduction purposes. The rails are to provide a sliding surface for the picosatellites as they are being deployed. The rails will be treated with a Dicronite coating to reduce the coefficient of friction and to serve as a protective coating. By doing thermal expansion calculations for the given geometries, it was determined a 0.010 in spacing could be left between the picosatellite side and each rail (see calculations in Appendix B). This would ensure that any expansion would not wedge the satellite inside the deployer. A +/- .005 in tolerance is also required for each picosatellite deployed using the PPOD. There are 12 holes in Side A for the 6-32 machine screws to pass through. These holes are not tapped. SIDE B: DWG 210-104-201 There are 2 Side B parts to each PPOD deployer. The Side B parts are identical to the Side A parts except for their width and the location of the holes. The holes in Side B are drilled and tapped blind holes for the 6-32 machine screws. SLIDE: DWG 210-102-001
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