PS7 Flashcards
Lenses need to be retained by screw fixings with pre-loads typically 50 x the lens’s weight. Why is such a large pre-load needed?
For small stiff objects (lenses are typically < 1 kg mass), the launch accelerations are amplified by relatively high-Q’s, and thus it is necessary to apply a large pre-load to hold the lens rigidly in place
Give two glue types that are suitable for space us
Certain epoxies, acrylic glue
An optical support assembly could be made from aluminium or carbon-fibre/PEEK. Which would be the best choice and why
It is important that the dimensions of an optical assembly change minimally over temperature, therefore we need a rigid, light structure with a low CTE. Carbon/PEEK would therefore be best as it have very high specific strength and has a very low CTE
Explain the advantages and disadvantages of brushless DC motors over conventional brushed motors
Brushless DC motors have excellent lifetimes as there are no brushes to wear out. They also have excellent controllability. However, their drive electronics is more complex than for brushed motors
