SPP 4m Magnetometer Boom Proposal. Paul Turin 10/17/12. Design Drivers/Choices. Scientists want 4m length for acceptable mag separation Must stow within bus panel length Three segment boom only articulated choice that will fit on deck with imposed constraints Minimize mass
Boom lies on SC centerline
1m between mags, 2m to first FGM
4m fits easily
All joints have kickoff springs to provide high initial deployment forces until components start moving. Provides protection against sticking surfaces etc. while keeping joint drive torsions springs reasonably sized.
544 bronze plungers running in hard anodized bores, compression springs between pairs
Ears support end in cage
Wrist kickoff plunger
Elbow kickoff plunger
Kickoff plungers extended
Roller is caged in slot on shoulder
Shoulder-wrist kickoff plunger
Shoulder kickoff plunger
Rotation of middle tube controlled by cord-payout rate from shoulder
Deployment rate of shoulder controlled by brake
Pulley fixed to end of middle arm
Cord pays out as shoulder rotates
Pulley fixed to shoulder
Assist cords do nothing during normal deployment. If a hinge hangs up, torque of all hinge springs is transferred to stuck joint. Deployment is now governed by stuck joint. This puts triple the torque on that joint.
Cord pulls in as shoulder rotates
Includes same masses as deployed analysis
Cavity for glue
There is room on the bus to easily increase the boom length to at least 4.5m.
Only 82g mass increase
Further analysis is needed to look at effect on modes, but probably not an issue.