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Rodger Farley p1 Super Nova/Acceleration Probe 16 November 2001 Mechanical Mechanical Overview Rodger Farley Mick Correia Judy Brannen 16 November 2001.

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Presentation on theme: "Rodger Farley p1 Super Nova/Acceleration Probe 16 November 2001 Mechanical Mechanical Overview Rodger Farley Mick Correia Judy Brannen 16 November 2001."— Presentation transcript:

1 Rodger Farley p1 Super Nova/Acceleration Probe 16 November 2001 Mechanical Mechanical Overview Rodger Farley Mick Correia Judy Brannen 16 November 2001

2 Rodger Farley p2 Super Nova/Acceleration Probe 16 November 2001 Mechanical Mirrors:ULE Primary:90% light weighted Secondary,Tertiary and Fold: 50% light weighted Structure: M55J composite Total Instrument Mass: 1011kg (includes spacecraft interface structure 50kg)

3 Rodger Farley p3 Super Nova/Acceleration Probe 16 November 2001 Mechanical Metering Structure similar to HST design Spider 3 point tangent design to give torsional stiffness Mirrors and Aft optics are kinematically mounted using both bi-pods or flexures

4 Rodger Farley p4 Super Nova/Acceleration Probe 16 November 2001 Mechanical Secondary Mirror Focus Mechanisms Requirements:  Tip: 1 arc sec  Tilt: 1 arc sec  Focus: + / mm total travel, 1 micron incremental motion  Transverse X: + / mm total travel, 10 micron incremental motion  Transverse Y: + / mm total travel, 10 micron incremental motion

5 Rodger Farley p5 Super Nova/Acceleration Probe 16 November 2001 Mechanical Design suggestion:  Three point ball-screw mechanism developed by Swales Aerospace.  Heritage: FUSE spacecraft, tip-tilt-focus for 15 kg UV mirror. Used once per orbit approximately. It has exceeded the design life by many factors.  Demonstrated Performance: 0.35 micron resolution, +/- 1 mm total travel  Mass Estimate: approx 18 kg

6 Rodger Farley p6 Super Nova/Acceleration Probe 16 November 2001 Mechanical Aperture Door Requirements :  Non air-tight, nor particularly light-tight  Re-closable, designed for 100 actuations guaranteed  Re-close in 100 seconds  Deploy to out of the FOV  Deployed frequency above 10 Hz  Unpowered holding torque: ???

7 Rodger Farley p7 Super Nova/Acceleration Probe 16 November 2001 Mechanical Design suggestion :  HST-like, with Moog Schaeffer type 5 actuator.  Heritage: HST-ish  Demonstrated Performance: 2.25 deg/s fast, 0.23 deg/s slow for first and last 5 degrees of rotary motion  Mass Estimate: 61 kg door and associated mechanisms, 6.5 kg electronics  Note: the mass can be reduced by using composite materials  Mass moment of inertia about the hinge line: 63.7 kg-m^2 (HST)  Power Estimate: 14 watts at fast speed plus 12 watts peak for drive electronics

8 Rodger Farley p8 Super Nova/Acceleration Probe 16 November 2001 Mechanical Type 5 rotary actuator One time launch latch Folding hinge line at mid door position if required Concerns regarding rotary actuator: Torsional Stiffness for frequency Detent holding torque for maneuvers

9 Rodger Farley p9 Super Nova/Acceleration Probe 16 November 2001 Mechanical Shutter Mechanism Requirements :  Light-tight to:?  Shutter speed: If a fast shutter is possible, then operate in 1/40 of a second. If a slow shutter is reasonable, then operate in 1 second to open or close, with a position vs. time curve having 1/40 second accuracy. It is desirable but not necessary that the shutter should operate such that the exposure times for all detector CCDs are the same to within 1/20 of a second.  Fail-safe requirements? (fail open, fail close, don’t bother?)  Frequency of operation: 800 actuations (open or close) per day for 3 years (2 per 220 seconds). This works out to about 1x10 6 actuations for the mission.

10 Rodger Farley p10 Super Nova/Acceleration Probe 16 November 2001 Mechanical Shutter Mechanism Design :  Considerations are the location relative to a pupil or a focus  Fast shutters have problem of impact transient vibrations and require large forces. Fast shutters would require snap- action mechanism  Slow shutters require a PID controller with sensors  Locations considered —Behind the primary —Behind the folding flat —Inside the folding flat —Just in front of the folding flat

11 Rodger Farley p11 Super Nova/Acceleration Probe 16 November 2001 Mechanical Lampton Scissors Shutter with snap action

12 Rodger Farley p12 Super Nova/Acceleration Probe 16 November 2001 Mechanical Clam shell four-bar linkage shutter

13 Rodger Farley p13 Super Nova/Acceleration Probe 16 November 2001 Mechanical Bow tie and half bow tie shutters

14 Rodger Farley p14 Super Nova/Acceleration Probe 16 November 2001 Mechanical Boomerang Shutter

15 Rodger Farley p15 Super Nova/Acceleration Probe 16 November 2001 Mechanical Cross section of folding mirror Port lid type shutter

16 Rodger Farley p16 Super Nova/Acceleration Probe 16 November 2001 Mechanical Suggested Qualification Program:  Build brass-boards, as many as needed. Determine how much of the design is sensitive to workmanship  Build engineering test unit that will go thru the qualification program of vibration and thermal cycling  Build a life test unit and test in thermal vacuum chamber  Cycle 1 million times, then inspect for wear  Continue life test till 10 times required life


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