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Dynamics & Control

Dynamics & Control . Anne DeLion 6 February 2001 Preliminary Design. Two types of deployment: Spinning Linear All calculations done for Hab, but code can easily be converted to work for ERV. Tether Mass ~ 500kg Tether Mass < 1% of Hab mass, therefore it is considered negligible

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Dynamics & Control

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  1. Dynamics & Control Anne DeLion 6 February 2001 Preliminary Design

  2. Two types of deployment: Spinning Linear All calculations done for Hab, but code can easily be converted to work for ERV Tether Mass ~ 500kg Tether Mass < 1% of Hab mass, therefore it is considered negligible Tether Reel System ~ tether mass [Powell] Deployment

  3. Assumptions: Tether will deploy smoothly and uniformly All DV manoeuvres will be instantaneous Connected Hab/NTR modelled as a cylinder Spinning Deployment: Spin up connected Hab/NTR Release Hab & NTR to deploy the tether As the tether deploys, the rotation rate of the system will decrease After deployment, a second DV gives vehicles 2rpm spinrate Spinning Deployment

  4. Spinning Deployment • Advantages • Constant tension on tether during deployment • Easy to implement • Disadvantages • Requires greater DV • Possible attitude problems

  5. Spinning Deployment

  6. Linear Deployment • Deployment by initial linear velocity, spin up after tether deployment • Assumptions: • Tether will deploy smoothly off a reel • Initial velocity will be given by pyrotechnics, and will remain constant unless friction or braking is considered in the reel system • System c.m. will remain constant with respect to the orbit reference frame

  7. Linear Deployment Method: • After initial velocity, the tether will have to be decelerated. • Reel/Braking system • Friction included in reel

  8. Linear Deployment • Advantages • Lower DV needed for gravity spin-up • Disadvantages • How to keep constant tension? • What system to slow velocity of deployment?

  9. No Spin .5 rpm Spin-Up Initial Rotation Rate (rad/s) 0 0.0524 Initial Tension (N) 0 2365 Initial Velocity (m/s) Hab 0 .6021 NTR 0 1.5708 Rotation after Deploy (rad/s) 0 7.198e-4 Tension after Deploy (N) 0 3.75 Velocity after Deployment (m/s) Hab 0 .0695 NTR 0 .2051 Gravity Spin-up Rate (rad/s) .2094 .2094 Tension after Spin-up (N) 317470 31740 Velocity After Spin-up (m/s) Hab 20.2109 20.2109 NTR 59.6903 59.6903 Total Delta V for Spin-Up (m/s) Hab 20.2109 20.7436 NTR 59.6903 61.0559 Deployment - Comparison

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