starship sez,
....33.8 tons payload size with the single 1000 ton Mars engine is more practical and fitting your specifications and converting 1 ton of propellant fuel to the required energy.
Guordhead sez
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Since the total mass of the ship including propellant mass is constantly decreasing, are you varying Ve or q or both to maintain acceleration at one g? How many kg/sec of propellant is actually being discharged (if variable, on average)? What material is actually being discharged? What is the ratio of mass loss to energy conversion to that of the actually expelled propellant?
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Using the Mars engine for star travel I vary both Ve and q as the average propellant flow rate (q) for the Mars engine is 6.8 pounds/sec ejected at .44 C. The Mars rocket configuration arrives with the approximate same mass (99,000 tons) as it left earth with 101,000 tons so both Ve and q vary only slightly over the trip time of 1.73 days and so the mass converted to energy in that time is approx. equal amounts.
For the star journey as the payload is reduced to 38 tons the mass taking off is a very small fraction of the mass arriving with the mass fraction estimated at 48 tons / 1038 tons. That requires I vary both Ve and q with the adjustable liquid reduction nozzle used to vary Ve but as q remains the same at the input and output of the reduction nozzle, to very q I decrease the number of radioactive fuel disks inserted as the ship becomes lighter. A balancing act twixt Ve and q so to speak by varying the one ton of converted mass to energy in plasma generator steps and smoothing the "step" shaped acceleration curve of incrementally smaller plasma generators inserted over the travel time with changing the exhaust velocity over time maintaining a constant one g acceleration the total rocket time of 34.9 years to wolf star with a varying ship mass.
As average velocity of a exhaust particle at the liquid ablative walls of the elliptical plasma chamber is Mach 30 of a molar mass of hydrogen and the force 16 times that inserted on the supercritical metal plasma of surface area 1/16 that of the plasma chamber so compresses it to it's liquid state with the viscosity of asphalt on a cold day remaining for all practical purposes a solid though liquid undergoing fusion converting some mass to energy. As the water propellant is heated to it's plasma state the oxygen fissions to hydrogen atoms converting some mass to energy. So the ejected propellant is mostly hydrogen mixed with a small percentage of water and a smaller percentage of oxygen fission products coined "plasmelt" with an average molar mass of hydrogen. In both the Wolf trip and the Mars trip approximately 1 ton of the 1000 tons of supercritical mass and water propellant is converted to energy.
Interstellar space is mostly empty as particle mass collects in stars gravity wells and I am traveling at a very small fraction of light speed in those wells so steer away from the asteroids and ort cloud of comets. Well outside those wells I am traveling at light speed and beyond and the probability of collision decreases when velocity increases so the probability of me colliding with any mass at light speed and beyond is insignificant if not zero
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Indeed it is mostly empty, but only mostly. The center of the Oort cloud, radially speaking, is about one light year away; how fast do you plan to go through it. We can not be sure that the intragalactic density of Oort-cloud-like-stuff is insignificant. Caution is advised. It is not unreasonable to expect a cloud similar to the Oort around most stellar systems.
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As I said I do not plan to go through the Ort cloud. Like our galaxy our solar system is basically flat with the planets, asteroid belt and ort cloud forming a relative thin orbital plane. I take to the stars in a trajectory perpendicular to that plane. I could go through it as dispacement(distance) = Acceleration times (time squared)/2 so by the time I get to light speed in 356 days at a constant 1 g I am far beyond the Ort cloud.
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Why do you think going fast reduces the chances of collision?
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I observed the Monte Carlo simulations for particle collisions in 1968 programmed with the laws of probability. In probability theory's rain drop effect one gets less wet running from his house to the door way across the street than he does by walking as he gets hit by fewer water drops from the field of drops as his velocity increases. I also use the same effect in reverse to keep all radiation from the crew and melting the engine casing. Place a radioactive source near a detector and place a 1/2 inch thick wall of water in a class tube between the source and detector. Increasing the velocity of the water and soon the radioactivity detected drops and any heat emitted drops to zero.
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My guess is that stellar systems are slingshotting projectiles into individual galactic orbits from time to time thereby keeping intergalactic space well stocked with things to run into. Have you considered what limits to put on the radius of curvature of course changes required to avoid obstacles as a function of ship velocity? Even relatively small changes in direction at velocities near light speed can generate very strong g-forces perhaps sending you and other loosely anchored objects through the side of the ship if not ripping off the engines. Also, as you approach 0.5c radar-type detection of objects won't return data in time to initiate a successful maneuver.
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That is a dramatic scenario and so good grist for science fiction novel; however the math does not support the conclusion.
Besides my rocket shape is streamlined as the probability decreases with the cross section as it does with velocity so the probability of collision is considered insignificant if not zero besides the electric armor of my own invention adds additional protection as does precise steering controls and a window facing forward
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