Transcript The Elevator to Heaven, the Stairway to Space

The Elevator to Heaven, the
Stairway to Space
Daniel Burton
Josh Denholtz
Sergey Galkin
Topics of Discussion
Introduction to the Space Elevator
 Original Designs
 Parts of Elevator
- Ribbon
- Motor and Rollers
- Platform
- Power
o Construction of Elevator / Final Design
o Future Plans

The Space Elevator

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
www.beyondsciencepodcast.com
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
New Materials Become Available



Graphite whiskers become available
in 1957
Tensile strength of 210,000
kg/cm^2 compared to the next best
material (fine grade drawn steel
wire) with a strength of 42,000
kg/cm^2
20 times better than steel (strength
and density considerations)
Carbon Nanotubes

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
First invented in 1991
Has a density of 1.3 g/cm^3
(close to half that of graphite
whiskers)
Tensile strength is 1,327,000
kg/cm^3
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
Getting Started


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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
The Ribbon

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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
Platform

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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
Construction of the Elevator


Motors
Rollers



Large Cylinders
Small Cylinders
Rods
First Design


Mechanism
Static Performance


Friction
Center of Mass
First Design
Gear Shaft


Torque
Rotational Speed
Axle
Second Design

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Mechanism
Static Performance


Friction
Center of Mass
Second Design

Moving Parts
Together


Chain
Miter Gear
Final Design

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Mechanism
Gear Shaft

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
Torque
Rotational Speed
Moving Parts
Together


Chain
Miter Gear
Final Design

Static Analysis

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Purpose
Quasi-static
Final Design

Tension

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Initial Tension
Tension Formula
and Constraints
Final Design
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Friction
Results
Fnet=14.8cos45+11.
8+8.65+6.3+4.6+
3.6cos45=41
41<80

Final Design (It’s not done yet) 

Other Friction
Factors

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Coefficient of
Friction
Resultant Force
Small Cylinders
Rollers
Power
Photovoltaic Cells
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Photovoltaic Array
on bottom of
climber
Required power
output unknown
Required price
unknown
www.isr.us
Estimated Power and Cost Calculations
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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 Volts*0.5 amperes = 0.25
watts.
Total # of cells = 1000 watts output/ 0.25
watts per cell = 4000 cells.
Calculations (Continued)
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Area of 1 cell = 3*3*π = 9π sq. cm.
Total Area = 4000 cells * 9π sq. cm. per
cell = 36,000π sq. cm.
Radius of Base = √(36,000π/π) =
189.737 cm = 1.90 m
Solar Panel
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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 cells*437
sq. in. per cell = 47,633 sq.
in.
 Base radius = √(47,633/π) =
123.124 in. = 3.127 m
Price per cell = $232.00
www.mcmaster.com
Ways to Reduce Power Requirements

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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.
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
Future Plans
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Complete Design and Budget Proposal
Prototype Construction
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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.
Review of Original Goals

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Construct and Test gear-based
climbing mechanism.
Use Type III parachute cord for
ribbon manufacture.
Modifications of Original Goals

Manufacture of
ribbon from Type
III parachute cord
proved too time
consuming


Decided to use premanufactured
nylon ribbon
Motor costs
exceeded total
budget.
www.mcmaster.com
Changes
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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
Parts List and Budget (Major Parts)
Part
Part #
Quantity
Price
Total Price
Aluminum
8973K45
1
166.14
166.14
Rollers
85035K21
2
27.04
54.08
Smaller
Rollers
84975211
10
1.07
10.70
Smaller Parts
N/A
N/A
50
(estimated)
50
Ribbon
8730K26
15 ft
1.53 per foot
22.95
Metal Wire
8904K75
1
8.91
8.91
Total Estimated Budget (Not Including Motor and Power) = $336.03
References

Edwards, B., & Westling, E. (2003). The Space Elevator:
A Revolutionary Earth-to-Space Transportation System.
Houston, BC Edwards.
Special Thanks
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Prof. Haym Benaroya
John Petrowski
Yuriy Gulak
Elan Borenstein