Difference between revisions of "SpaceElevatorClimber"

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See [[Climber Hull Workpage]] for more information
See [[Climber Hull Workpage]] for more information


==Was Here==
==Current Climbers at the Space Elevator Games www.spaceward.org==
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Include images and videos from the SE Games
Include images and videos from the SE Games
Include design write-ups
Include design write-ups


== Major Development Issues Related to this Component ==
== Major Development Issues Related to this Component ==

Revision as of 03:06, 25 July 2008

Title: Space Elevator Climber

[Cover Img]

About:

  • Author: Brad Edwards
  • Created: July 6, 2008
  • Modified: July 6, 2008

Tags:

  • This article is in progress
  • Discipline(s): Engineering
  • This article is about Climber
 

The Climber

Ascending the ribbon efficiently and reliably is crucial. The climber utilizes current technology throughout and is under development through the Spaceward Foundation Space Elevator Games.

Value details
Mass 30 tons Baseline mass has been 20 tons (13 payload and 7 climber) but larger systems are being considered. Initial climber mass breakdown File:Climber mass.ods
Height 20 meters Only roughly determined at this time. Height will be determined by stability and tracking studies.
Width 20 meters Determined by photovoltaic array size
Payload 60 tons Baseline mass has been 20 tons (13 payload and 7 climber) but larger systems are being considered
Maximum Velocity 200 kph This limit was set by the state of current technology with no maturation. This rate is likely too slow for many human transport applications.
Power usage 10 MW Determined by maximum velocity expected and capabilities of lasers adn receivers. This power delivery is larger than listed as baseline in the past to account for the larger climbers being considered.
Motor DC electric Various designs are possible. Brushed, rare-Earth motors regularly run at 90% efficiency. Issues come in the variable speed and power required, operation from atmospheric pressure through vacuum and thermal issues.


Climber model image.jpg


The working climber design is File:Climber model.dxf. Notes on the design are located [climberdesignnotes.odt here]

Overview

In the grand Space Elevator scheme of things, climbers can be easily identified - they are the things that move. The climber moves up (and possibly down) the stationary Space Elevator ribbon, carrying payload with it.

A picture of the climber is shown below:

File:Not here yet

Climbers have 3 main parts:

  • A beam convertion system, which captures incoming light and converts it into electricity
  • A traction and drive system, which uses the ribbon to propel the climber
  • A hull, which encoumpases all of the non-climber related functionality, such as attitude control, communications, and life support. **NEAD A TERM FOR THIS**

Since only the first two systems are unique to the Space Elevator, they usually get most of the attention, since we think we know how to make a space-worthy hull. This is a common misconception, since so very much of the way spacecraft are built, down to even the basic choice of construction material, is goverened by the fact that they are designed to sit on top of rockets.

Climber design SEG07 2.JPG

Status

Most recent work on climbers has been done in the framework of the Space Elevator games.

These climbers demonstrate the basic principles of a Space Elevator Climber, since they contain all the basic functionality, but they do not really have a direct lineage to real spaceworthy climbers.

Traction Mechanism

Full article: Climber Traction Mechanism

The traction mechanism has to be developed along with the Ribbon Macro Structure and it is likely that the considerations that go into the development of the latter will override those that define the former. In short, the traction mechanism will be built around the ribbon, and not the other way around.

It is possible at this point, however, to start considering how to handle very fine ribbon at high speeds in a way that is safe. The traction system is the #1 candidate to break a Space Elevator.

See Climber Traction Mechanism Workpage for more details.

Power Conversion

Full article: Climber Power Conversion System

The power receiving unit has to be deloped along with the Power Beaming Source. The receiving unit has to be both lightweight and efficient. A 20 ton climber will be expading 10 MWatt when traveling at even 50 m/s, and any inefficiencies create heat that has to be ratiated away, which introduces mass penalties. Current space power systems are in the 100 kWatt range, two orders of magnitude below what we plan to have.

At this point, we should be looking at the range of PV alternaives out there, since it is a rapidly evovling field.

In propulsion terms, the overall climber must a thrust-to-weight ratio of 1! This a tough requirement.

Hull

See Climber Hull Workpage for more information

Current Climbers at the Space Elevator Games www.spaceward.org

Value Units
Mass 25 kg
Height 2 meter
Width 2 meter
Payload 10 kg
Maximum Velocity 18 kph
Power usage 9 kW

Include images and videos from the SE Games Include design write-ups

Major Development Issues Related to this Component

  1. Climber Tracking on the Ribbon
  2. Full Design of the Climber System


Additional Work Needed

The climber has the most engineering work that needs to be done and the most opportunity for individuals and groups to get directly involved.

Item Notes Completed and Ongoing Efforts
Categorize the available PV cells for use with the power beaming system Need manufacturer, size, thickness, cost, efficiency curves, radiation degradation curve, ...
Categorize the available motors Need manufacturer, power, efficiency curve vs RPM, mass, operational in vaccuum, cost,...
PV array design Optimize for collection, efficiency, mass, use in unidirectional -0.1 to +1 gravity,...
Roller design Minimize mass, operational with low-friction ribbon, minimal variation in force applied across the ribbon, tons per roller drive, ...
Overall structure design Minimize mass, design to handle oscillations, operation in wind, operation in unidirectional and two directional gravity field (-0.1 to +1.0)
Operations Work out a detailed operational scenario including fault handling, start-up through ascent, power loss and restart,

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