The Elevator to Heaven, the Stairway to Space

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The Elevator to Heaven, the Stairway to Space

• Daniel Burton
• Josh Denholtz
• Sergey Galkin

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Topics of Discussion

• Introduction to the Space Elevator
• Original Designs
• Parts of Elevator
• - Ribbon
• - Motor and Rollers
• - Platform
• - Power
• Construction of Elevator / Final Design
• Future Plans

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The Space Elevator

• First in depth study came in 1950s by Dr. John
  McCarthy
• Described a synchronous Earth skyhook going up to
  a space station in geosynch orbit
• Materials not yet available to build elevator

www.beyondsciencepodcast.com
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New Materials Become Available

• Graphite whiskers become available in 1957
• Tensile strength of 210,000 kg/cm2 compared to
  the next best material (fine grade drawn steel
  wire) with a strength of 42,000 kg/cm2
• 20 times better than steel (strength and density
  considerations)

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Carbon Nanotubes

• First invented in 1991
• Has a density of 1.3 g/cm3 (close to half that
  of graphite whiskers)
• Tensile strength is 1,327,000 kg/cm3
• Self support up to 10,204 km (compared to 1,050
  km for the graphite whiskers)
• No other known molecular bonds stronger than this
  arrangement
• 22 tons of nanotubes compared to 700,000 tons of
  graphite whiskers would be used
• Definitely the material to use

www.ewels.info
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Getting Started

• Original startup involves the transportation of a
  rocket containing the parts necessary to build a
  spaceship (counterweight) in orbit
• Spaceship will assemble in orbit and launch a
  smaller ship to anchor the carbon nanotube ribbon
  to the Earth (most likely on a sea based
  platform)
• Climbers will travel up to the orbiting spaceship
  splicing together the ribbon and making it
  stronger

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The Ribbon

• Ribbon will be made of nylon
• Ribbon will be 15 in length (will be dropped
  from the Mezzanine), 6 in width, and .031 in
  thickness
• Strong material and able to withstand forces that
  will be put on it
• Cost efficient means of simulating carbon
  nanotubes

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Platform

• Platform will be made of aluminum
• Will be circular in cross section with a radius
  of 1 and a thickness of 0.25
• Will have a cutout with dimensions 9 by 1
  (necessary for the ribbon to pass through)
• Solar panel will be mounted on the bottom of the
  platform to avoid center of mass and space issues
• Gear box used to house rollers will be made of
  the same material

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Construction of the Elevator

• Motors
• Rollers
• Large Cylinders
• Small Cylinders
• Rods

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First Design

• Mechanism
• Static Performance
• Friction
• Center of Mass

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First Design

• Gear Shaft
• Torque
• Rotational Speed
• Axle

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Second Design

• Mechanism
• Static Performance
• Friction
• Center of Mass

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Second Design

• Moving Parts Together
• Chain
• Miter Gear

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Final Design

• Mechanism
• Gear Shaft
• Torque
• Rotational Speed
• Moving Parts Together
• Chain
• Miter Gear

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Final Design

• Static Analysis
• Purpose
• Quasi-static

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Final Design

• Tension
• Initial Tension
• Tension Formula and Constraints

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Final Design

• Friction
• Results
• Fnet14.8cos4511.88.656.34.63.6cos4541
• 41lt80
• ?

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Final Design (Its not done yet) ?

• Other Friction Factors
• Coefficient of Friction
• Resultant Force
• Small Cylinders
• Rollers

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PowerPhotovoltaic Cells

• Photovoltaic Array on bottom of climber
• Required power output unknown
• Required price unknown

www.isr.us
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Estimated Power and Cost Calculations

• Assume 1000 watts necessary output.
• Assume solar panels have 20 efficiency.
• Assume 6cm diameter cell generates 0.5 volts and
  0.5 amperes of output.
• Required input 1000/(20/100) 5000 watts.
• Total output generated per photovoltaic cell
  0.5 Volts0.5 amperes 0.25 watts.
• Total of cells 1000 watts output/ 0.25 watts
  per cell 4000 cells.

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Calculations (Continued)

• Area of 1 cell 33p 9p sq. cm.
• Total Area 4000 cells 9p sq. cm. per cell
  36,000p sq. cm.
• Radius of Base v(36,000p/p) 189.737 cm 1.90
  m

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• If we were to use flexible solar panels from
  McMaster-Carr (part 4859T11)
• Assume generate 9.2 watts electrical output.
• Total cell area 437 sq. in.
• To obtain 1000 watts of electrical output
• 1000 watts/9.2 watts per cell 109 cells
• Total area 109 cells437 sq. in. per cell
  47,633 sq. in.
• Base radius v(47,633/p) 123.124 in. 3.127 m
• Price per cell 232.00

Solar Panel
www.mcmaster.com
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Ways to Reduce Power Requirements

• Use the solar panels to charge a set of
  capacitors, from which the motors would run.
• Use high revolutions-per-minute motors that
  require less power to operate
• Would use a series of gears to increase the
  torque.

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Power Supply

• For the power-beaming test, there are two
  possibilities
• Manufacture a concentrated light beam emitter
  using a 1000-watt bulb and a parabolic mirror.
• Rent a projector from a supplier
• Approximate cost to rent a projector 150.00

http//library.thinkquest.org
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Future Plans

• Complete Design and Budget Proposal
• Prototype Construction
• Climbing mechanism complete by end of Fall
  semester.
• Power-beaming mechanism complete by end of Spring
  2007 semester.
• Final Assembly and Testing at the end of Spring
  2007.
• Testing will occur at the Rutgers Department of
  Mechanical Engineering Mezzanine.

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Review of Original Goals

• Construct and Test gear-based climbing mechanism.
• Use Type III parachute cord for ribbon
  manufacture.

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Modifications of Original Goals

• Manufacture of ribbon from Type III parachute
  cord proved too time consuming
• Decided to use pre-manufactured nylon ribbon
• Motor costs exceeded total budget.

www.mcmaster.com
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• Project deadline extended to end of Spring 2007
• Design modifications
• Uses a roller system instead of a gear system
• Rollers manufactured to provide maximum friction
• Design additions
• Addition of a power-beaming test concept
• Ribbon modifications
• Increased thickness, shortened length

Changes
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Parts List and Budget (Major Parts)
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References

• Edwards, B., Westling, E. (2003). The Space
  Elevator A Revolutionary Earth-to-Space
  Transportation System. Houston, BC Edwards.

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Special Thanks

• Prof. Haym Benaroya
• John Petrowski
• Yuriy Gulak
• Elan Borenstein