Differences between revisions 1 and 3 (spanning 2 versions)
Revision 1 as of 2009-07-11 16:59:14
Size: 1124
Comment:
Revision 3 as of 2009-07-11 20:13:11
Size: 2251
Comment:
Deletions are marked like this. Additions are marked like this.
Line 5: Line 5:
For example, when an instantaneous force change is applied to one end of a very long cable, the end does not stretch a little, it moves,
and keeps moving until the force has had time to propagate to the attachment and back. For a 100km stabilization cable, that can be 20 seconds, in which time many meters of cable moves.
For example, when an instantaneous force change is applied to one end of a very long cable, the end does not stretch a little, it moves, and keeps moving until the force has had time to propagate to a stationary attachment and back. For a 100km stabilization cable, and a 10km/s speed of sound, that can be 20 seconds, in which time many meters of cable moves.
Line 10: Line 9:
|| Material || density || modulus || strength || CTE || Vsound || Length || Round Trip || 100Km*100K ||
|| || gm/cm^3^ || GPa || MPa || um/m-K || m/s || m || seconds || m ||
|| Steel SAE980x || 7.9 || 200 || 650 || 12 || 5000 || 8400 || 40 || 120 ||
|| 80% Kevlar ||
|| 80% Spectra ||
|| 80% nanotube ||
|| Material || density || elastic || strength || CTE || Vsound || Support || 100km || Therm exp ||
|| || || modulus || || || || Length || Round Trip || 100Km*100K ||
|| || gm/cm^3^ || GPa || MPa || um/m-K || km/s || km || seconds || m ||
|| || || || || || || || || ||
|| Steel SAE980x || 7.9 || 200 || 650 || 12 || 5.0 || 8.4 || 40 || 120 ||
|| Pure Kevlar || 1.44 || 124 || 3620 || -2.7 || 9.3 || 250 || 22 || -27 ||
|| Pure Spectra || 0.97 || 168 || 2580 || || 13.2 || 270 || 15 || ||
|| Pure Diamond || 3.52 || 1140 || >60000 || 1.2 || 18.0 || 1740 || 11 || 12 ||
|| Pure nanotube || || || || || || || || ||
|| composites: || || || || || || || || ||
|| 80% Kevlar || || || || || || || || ||
|| 80% Spectra || || || || || || || || ||
|| 80% nanotube || || || || || || || || ||

Linear Cables

Stabilization and elevator cables on the launch loop are very long, and propagation delay is a big issue. In most systems people are familiar with, cables are short enough and forces change slowly enough that propagation delay is not a major issue. With a launch loop, forces can change rapidly (milliseconds) while the propagation delays are 10s of seconds.

For example, when an instantaneous force change is applied to one end of a very long cable, the end does not stretch a little, it moves, and keeps moving until the force has had time to propagate to a stationary attachment and back. For a 100km stabilization cable, and a 10km/s speed of sound, that can be 20 seconds, in which time many meters of cable moves.

Material

density

elastic

strength

CTE

Vsound

Support

100km

Therm exp

modulus

Length

Round Trip

100Km*100K

gm/cm3

GPa

MPa

um/m-K

km/s

km

seconds

m

Steel SAE980x

7.9

200

650

12

5.0

8.4

40

120

Pure Kevlar

1.44

124

3620

-2.7

9.3

250

22

-27

Pure Spectra

0.97

168

2580

13.2

270

15

Pure Diamond

3.52

1140

>60000

1.2

18.0

1740

11

12

Pure nanotube

composites:

80% Kevlar

80% Spectra

80% nanotube

LinearCables (last edited 2009-08-14 20:56:24 by KeithLofstrom)