EXTRAPLANETARY, Prep for the Stars
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Cable-in-conduit conductors (CICC) magnets can turn off / on relatively easily. For example, they can ramp up from 0 to 15 Tesla in minutes. When magnetic fields change intensity, they create electrical currents in adjacent conductors; with current comes heat. CICC magnets can handle this heat because the superconducting wires are bathed in liquid helium.
While CICC magnets are much more efficient then resistive magnets, they still use a small amount of power. For the short duration of interplanetary flights, this amount is almost inconsequential. G-force accelerated trips to near planets will take days and at most weeks. Thus, CICC type magnets prove more than adequate. Their slight energy consumption will be relatively inconsequential compared to high momentum exchange from near light speed exhaust particles. |
Wire-wound (WW) magnets can operate without power during most of long voyage's powered flight. After initial power ramp up (a few weeks), wire-wound magnets disconnect from their power supply, because the superconducting current continues on its own.
For longer flights, the wire wound type will be even more important because the greatly reduced energy consumption will prove significant for an acceleration period of many months and possibly years.
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CICC quickly ramps up
but consumes some power throughout the trip.
Good for interplanetary trips inside KB.
Longer voyages need something more.
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WW slowly ramps up
but needs no additional power once there. This enormous gain in power efficiency would greatly benefit much longer voyages which will last months and perhaps years.A ship with WW superconductors would need to accommodate this ramp up period prior to takeoff. Thus, preflight procedures might require a few weeks to ramp up; small price to pay for a trip which might take years. |
Hybrid????
A ship with both types of superconductor magnet systems could start the voyage with CICC, then switch to WW after rampup process completes. PERHAPS, designers could implement a tradeoff between deleting preflight rampup period and adding considerable weight to facilitate a parallel magnet system.
Perhaps hydrids might help
more advanced vessels. |
To determine range capabilities of shorter duration flights, intuition leads us to approximate range by dividing original fuel load by daily decrement, Δ (% GW0). |
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Use division: R = %TOGW/Δ to quickly approximate, useful range durations. Use Efficiency Factor: ε = 4, a static estimate to conveniently assume some practicality. Use Newtonian Motion Equation: d = g × t2/2 to quickly approximate acceleration distances. RELATIVISTIC GROWTH (mr) At rest mass (ffSec) expands to exhaust particle mass (ffExh). |
1) Greater velocity increases contribution to momentum exchange.
EXAMPLE: Conserve momentum and ignore relativity.Assume perfect efficiency. Let particle exhaust velocity be .866c, VExh = .866 × 299,792,500 m/s = 224,831,184 m/s MShip = ffSec × VExh /g = 22,790,794 ffSec [i.e., about 23 million times one second fuel flow. If ffSec is one gram of exhaust particles, then Ship Mass is about 22.8 metric Tonnes (mT)].
2) Relativistic growth increases exhaust masses to contribute even further.
EXAMPLE-2: Conserve momentum and consider relativity. Assume perfect efficiency. Let particle exhaust velocity by .866c. Lorentz transform indicates exhaust particle mass doubles. (mr= 2.0). Previous work leads to following formula: MShip = ffSec√(mShip²-1) × c / g = √(4-1) × 30.57×106 × ffSec = 52,942,581 ffSec (i.e., about 53 million times one second fuel flow. If ffSec is one gram of exhaust particles, then Ship Mass is about 52.9 metric Tonnes (mT). Of course, inevitable inefficiencies would decrease this amount. |
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DAILY DIFFERENCE (Δ) Fuel needed for one day of g-force.
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EXAMPLE:
mr= 1/√(1-dc2) Let VExh be 86.6% light speed and arbitrarily assume perfect efficiency. At that speed, mass growth factor is 2.0 (i.e., mass doubles). mr = 1/√(1-.8662) = 2.00 Daily decrement of ship's mass is a small percentage of vessel's GW. Δ = .2826%GW/√(mr2-1) Δ = 0.163%GW/Day |
DIFFERENT RANGES (R) for nearby destinations. | |
Theoretical Range: Assume fuel to be 100% of ship's GW (entirely all fuel).
For convenience, assume:
Feasible Range: assume ship's fuel between 10%-90% of GW. For this example, let initial fuel be 40% of ship's initial GW.
We could intuitively assume following: |
Practical Range: Assume much less than perfect efficiency (E=100%). For inner planetary ranges, let E=25% and efficiency factor be 4 (ε = 1/E = 4). Approximate:
1) Phase 1 is acceleration from departure to midpoint.
2) Phase 2 is deceleration from midpoint to destination. 3) Phase 3 is acceleration while returning back to midpoint. 4) Phase 4 final phase is deceleration from midpt back to departure. Since all 4 phases are equal, TE assumes one fourth of practical range i for Phase 1, acceleration time, tAcc. |
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DISTANCE (d) and TIME (t) to nearby destinations. | |
Phase I Acceleration Time (tAcc): Previous tables show value derived from Particle Exhaust velocity. In turn, this value is basis for following terms.
Phase I Acceleration Distance (dAcc): ... can be closely approximated via Newtonian method: |
Total Time Destination (tTtl):
Add acceleration time and deceleration time. Since those times are equal, it doubles acceleration time: tTtl = tAcc + tDec = 2 × tAcc Total Distance Destination (dTtl): Since Phase I Accel takes vessel to midway point, half the distance to destination; then, Phase II Decel distance must be remaining half. Thus, total distance to destination is double the distance to midway. |
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Closer Destinations (VExh from .1c to .866c enable g-force ranges up to 30+ days.)
| SIDEBAR: Daily Decremental | |||||||||||||||||||||||||||||||||||||
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As with trains, planes and automobiles, g-force vessel's GW decreases with fuel consumption. How do we compute ever decreasing Gross Weight (GW)?
Following intuitive model could approximate first few days of fuel consumption.
EXAMPLE-1: If fuel for one day of g-force propulsion (Δ) is 0.652% of vessel's initial Gross Weight (GW0); then, common sense suggests an arithmetic method of approximating fuel consumptions.
EXAMPLE-2: If original fuel is 40% of ship's original GW, what is ship's range?
Let daily differential of ship's GW (Δ) continue to be 0.652% GW0. Intuition leads us to approximate range by dividing original fuel by Δ. Thus, Approximate Range (RApp) is 40%/Δ = 40%/0.652% per day =61.35 days. |
To determine range capabilities of longer duration flights, use exponential methods; they are more accurate and more generous than division. |
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EXAMPLE-1 (Assume a very impractical 100% Efficiency): Previous work indicates exhaust particle speed of .866c; theoretically, g-force vessel uses daily fuel consumption of Δ = 0.163%GW Thus, fuel consumption for 10 days of g-force could theoretically reduce vessel's GW as shown: GW10 = (1 - Δ)10 GW0 = (1 - .163%)10 GW0 GW10 = (0.99837)10 GW0 = 0.98382 GW0 | EXAMPLE-2 (Assume more practical efficiency of E=25%) For every unit contributing to propulsion, vessel must consume 4 units; thus: ε =1/E=1/.25= 4 Practical fuel consumption for 10 days of g-force could reduce vessel's GW as shown: GW10 = (1 - εΔ)10 GW0 = (1 - 4×.163%)10 GW0 GW10 = (0.99348)10 GW0 = 0.93668 GW0 NOTE: Practical Fuel (F) consumed after 10 days g-force: F10 =GW0 -GW10 = .06332 GW0 |
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EXTRA-PLANETARY RANGES (need greater precision)
When a propulsion system accelerates exhaust particles to near light speeds, resultant momentum can propel an even larger spaceship at g-force for a much longer duration. For greater precision, Extra-Planetary Tables use more accurate methods than the Inner Planetary Tables.
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Mass consumed at rest (ffSec) expands to exhaust particle mass (ffExh). ffExh = mr× ffsec |
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EXAMPLE: Let relativity growth factor, mr, be 5 and arbitrarily assume perfect efficiency.
Daily decrement of ship's mass
is a small percentage of vessel's GW. Δ = .2826%GW/√(mr2-1) Δ = .2826%GW/√(52-1) Δ = .058%GW/Day |
Computed Feasible Range: Let initial fuel (%TOGW) be 40% of ship's initial GW. Use logarithms to model range durations. EXAMPLE: Let relativity mass growth (mr) = 6. Compute: RFeas=log(1-%TOGW)/log(1-Δ)=log(1-40%)/log(1-048%)=1069 days Efficiency Factor, ε, of ship's propulsion system. TE uses an arbitrary function to generate dynamic values which map to mr values. Actual efficiency factors will eventually come from observations of actual propulsion systems. For now, arbitrarily compute: ε = 41/(mr-1) Computed Practical Range: TE assumes Efficiency (E) will ever approach but never reach perfection (E = 100%)..Thus, TE assumes efficiency improves as propulsion performance improves (increasing value of mr). Compute: RPrac = log(1-%TOGW)/log(1-εΔ) = log(1-40%)/log(1-1.32×.048%)=810 days Phase 1 Acceleration Time (tAcc ): Compute this value as one fourth of Practical Range: tAcc = RPrac /4 |
Phase I Acceleration Time (tAcc): Previously computed (see above.) Einsteinian Velocity: Δ is daily progress of g-force vessel toward light speed, c. Δ = day×g/c = 86,400sec×9.8065m/sec² /299,792,500m/sec = .2826%c (1-Δ) is daily remainder of ship's velocity till reaching light speed. (1-Δ)=.997173c Earth observer measures subsequent daily reminders per exponential: (1-Δ)t c Earth observed vessel velocities: c - (1-Δ)t c Phase I Acceleration Distance (dAcc): ... Calculus gives us distance solution. Phase II Deceleration Time (tDec): To maintain g-force, deceleration duration must be same as for acceleration (Phase I).
Total Time Destination (tTtl): Double acceleration duration from Phase I. This includes acceleration time from departure to midpoint and deceleration from midway to destination.
Total Distance Destination (dTtl): Double acceleration distance from Phase I which sums acceleration distance plus deceleration distance.. Note this distance is much less than distance achieved by g-force acceleration for same time |
SIDEBAR: Daily Exponential | Oort Cloud Destinations G-force performance can be measured by relativistic mass growth (mr). For Oort Cloud, mr values 2 to 10 generate propulsion ranges exceeding 52,000 AUs. |
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Fuel consumption reduces ship's Gross Weight (GW). Let daily decrement (Δ) be fuel consumed for one day of g-force propulsion.
EXAMPLE: if Δ = .163% GW; then, vessel's will decrease by .163% in one day. For subsequent days of powered flight, vessel's GW will continue to shrink.
Exponential Model
For longer duration voyages, use exponentials to readily determine vessel's gross weight for t days of g-force flight
GWt = (1-Δ)t × GW0
For corresponding fuel requirements.
Ft = GW0 - GWt
For the lengthier voyages, the precise exponential model yields much more encouraging results than the daily decremental model.
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CONCLUSION
After travel to/from Oort Cloud
becomes routine,
interstellar travel is next.
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