What Engineers Do…

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Engineers

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Energy Absorption

Energy Absorption • Impetus for project

– Rocket and Crew Capsule separation events (reduce mass, deploy parachutes, …)• Video - CST-100 https://www.youtube.com/watch?v=etOABxGbCMY• Video – SpaceX Pad Abort https://www.youtube.com/watch?v=OpH684lNUB8 (16:00 pad abort)• Video – Pyrotechnics & Delta4 (1:16 ground test, 5:32 delta4 sep) https://www.youtube.com/watch?

feature=player_detailpage&v=PM2qoTCVgEA

– Some separation events require bolt capture and impact reduction to protect vehicle, reduce ‘shock’ to electronic components. One approach to impact reduction is to remove energy (crushable material, damping) of projectile prior to impact• Space Shuttle bolt catcher (next slide)

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This is an instrumented test bolt catcher; the flight catchers

burned up during reentry with the External Tank

Energy Absorption – Shuttle Bolt Catcher

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SRBET

Bolt Catcher

Holes Were Added Prior to

STS-1 to Reduce the Impact Area (and therefore

the Load)

• The ET and SRB were held together by the forward separation bolt until the separation command was given by the Orbiter

• Pyrotechnic charges were fired at each end of the bolt

• The bolt was internally loaded by the pyrotechnic charges until the bolt broke

• The head and nut ends were accelerated to around 75 to 80 fps (80 fps = 55 mph)

• Each bolt half weighed about 35 pounds

• The head end was stopped by the bolt catcher

• The nut end was stopped by the energy absorber in the SRB thrust post

Final Honeycomb Design