Cheapest rocket possible

chriscdc · Jul 13, 2005

What would be the cheapest rocket (to escape velocity) possible, allowing realistic future developments. Think maximum reliability and cost to refuel. I think that you could make the outer structure out of diamonds with elastic films between them. This would allow sight deformity to reduce any chance of shattering (unless anyone here nows that such a large single diamond could survive lift off). The fuel tanks could be made of graphite sheets. Simlpy a large multi-walled carbon nanotube. Use heaters to increase tank pressure feeds-like in spaceXs' falcon. The engine nozzle and reaction vessel would be diamond or carbon ad could be repairable. Recovery of the first stage by parachute. You could use solar cells on the ground to continuosly split water for fuel. Simply, once you get over the staggering initial costs you would have a practically indestructable rocket. With very little cost per launch. Pick it up from whever it landed, refuel it and put it back on the pad. Any damage and you could patch it by taking the damaged plant and coating it in carbon again. It is actually rather easy to make large diamond now. Larger diamonds only need larger versions of the types they use in prossesor manufacture. How De-beers is reacting to this is rather interesting, in a watch the evil cartel panic as its company begins to collapse kind of way. Any things you lot can add would be helpfull. Other similarly outlandish ideas will be appreciated. Any info about the physics involved are desperatly needed.

vogon13 · Jul 13, 2005

Orion, hands down. Pennies a pound, 4000 tons to LEO. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

glutomoto · Jul 14, 2005

<img src="/images/icons/smile.gif" /> I'm sorry "cheapest rocket possible" and "make the outer structure out of diamonds", just don't seem to go together. You might be interested in reading how A Rocket a Day Keeps the High Costs Away. by John Walker - September 27, 1993. Conventional wisdom as to why industry and government choose not to invest in this or that promising launch technology is that there aren't enough payloads to generate the volume to recoup the development cost and, in all likelihood, there never will be. How much would it cost to find out if this is true? very interesting. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

chriscdc · Jul 14, 2005

The price of (large) diamonds has been kept artificially high for the last 200 years. Granted they were still rare and so had a large value. However we can grow diamonds now. Get a source of carbon ie graphite. Heat it until the chemical bonds break. Direct the carbon atoms to a seed diamond( to keep the crystal structure without any flaws) and the diamond grows. Of course you would have to massively scale up the process but overall it would be cheaper than say the shuttle. On second thought, you wouldn't need seperate tanks just voids in the diamond structure. And the reaction chamber would just be another void. Because the structure could be a single crystal there would be no problems with fatigue. If the launcher wasn't damaged then it would be fine to launch again. On the other hand if it failed then it would be one interesting explosion. But without damage you could use the same launcher for hundreds of years. What are the temperatures and pressures at work in a rocket reaction chamber?

spacefire · Jul 14, 2005

4000tons huh? http://www.astronautix.com/lvs/orion.htm <div class="Discussion_UserSignature"> http://asteroid-invasion.blogspot.comhttp://www.solvengineer.com/asteroid-invasion.html </div>

vogon13 · Jul 14, 2005

1950s atomic bomb propelled Orion concept. Not puny bottle rocket NASA uses to launch tadpoles to study weightlessness for 2 minutes. I am outraged name Orion has been recycled on the likes of this petahk! This little Orion smells of elderberries! <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

chriscdc · Jul 14, 2005

Orion can get alot of mass into orbit but the nukes would cost alot to build. It would also need a massive infrastructure to be set up. It would also not be that useful for moving small numbers of people. I would also prefer the exhaust to be water. Just imagine what would happen if one of the bombs went off inside the ship. I understand that the nuke would only fall for a second or so before detonating. If the timing is off then you get the worlds largest dirty bomb. I would however want to use orion for diverting asteroids or evacuation of earth etc.

vogon13 · Jul 14, 2005

I have been enthralled with the interstellar version of Orion. Craft departs (presumably) high earth or lunar orbit with a mass of 25 million tons and heads for alpha centauri on a 150 year flight. Payload includes enough people for a viable genetically diverse human colony and a realistic amount of supplies and material to set up the colony. First craft could have been launched 20 years ago, I don't want to wait another 50. Solar system goals for an Orion craft would be to set up sustainable colonies on the moon, and Mars, bases could be established on Phobos, Deimos, as many asteroids as you want, and several of the moons of Saturn and Uranus. Asteroid/comet deflection and retrieval (!) would be feasible. Large independent space colonies (like the L5 ideas of the seventies) could be established. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

scottb50 · Jul 14, 2005

Alpha Centauri is actually three stars. Non of which would be a very good destination, they are rather hot. Also I haven't seen anything to indicate any planets have been found around any of them. <div class="Discussion_UserSignature"> </div>

vogon13 · Jul 14, 2005

That was destination for calculated flight time from Dyson book on subject. Suspect a far more capable Orion interstellar craft would be feasible now. Applying advanced materials and another 40 years of nuclear weapon research to original Orion concepts would have to upgrade capabilities a great deal. I am speculating here, but it seems if staging was applied to this scenario it would also help. Not having to decel entire pusher plate at destination would increase payload and/ or speed of craft. These improvements and a tolerence for 200 year flight times could get an Orion craft out quite a ways. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

scottb50 · Jul 14, 2005

200 years would get you nowhere. The nearest discovered planet is more than 100 light years away, the size of Jupiter and orbits it's star every few days. Just a guess, not a good place to plan a vacation to. The only use I can see for Nuclear propulsion is powering plasma engines, a rather sedate way to travel. Out to the asteroid belt Solar Power would provide adequate power for a lot less mass and complication. Beyond that, at least for manned missions, I don't see our doing that for a long time and hopefully something better will become available by then. A major problem with plasma engines is getting rid of the velocity they impart, gradually accellerating and decellerating seems counter productive, so the faster you get there the more velocity you have to lose once you get there. The only way I know we could do that is chemical engines. <div class="Discussion_UserSignature"> </div>

vogon13 · Jul 15, 2005

Advanced Orion concepts look like upper limit of speed may be 3 to 4% C. Does anyone have anything faster that could take a craft the size (and mass) of 5 to 10 US Navy aircraft carriers to Tau Ceti, or Epsilon Indi? And do it as cheaply as Orion? Current stellar planet search techniques skewed to finding 'hot Jupiters', better planet candidates will be discovered as astronomers refine search equipment. I would not advocate sending a load of colonists to a star without reasonable assurance of a habitable planet being there. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

MBA_UIU · Jul 15, 2005

To get anything beyond 3% or 4% of C you need to go beyond rockets. Even the most advance rocket engine cannot go faster then the fuel it burns. This is where ion propulsion comes into play. Though it takes a great deal of time to build up speed its thrust, or the speed at which the ions leave the engine, are at or near the speed of light. In theory, given enough time, an ion drive should power its craft to somewhere near .5 of C. Another possible source of power is the nuclear expansion drive. <div class="Discussion_UserSignature"> <img id="268587ce-7170-4b41-a87b-8cd443f9351a" src="http://sitelife.space.com/ver1.0/Content/images/store/6/8/268587ce-7170-4b41-a87b-8cd443f9351a.Large.jpg" alt="blog post photo" /> </div>

vogon13 · Jul 15, 2005

________________________________________________________________ Even the most advance(d) rocket engine cannot go faster than the fuel it burns. ________________________________________________________________ If your meaning is the rocket can not go faster than the nozzle velocity of the burning fuel, the space shuttle disproves your assertion every flight. If you have an alternative idea there please clarify. thanx! <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

scottb50 · Jul 16, 2005

That's the idea with an ion/electric engine, it puts out minimal thrust but it does it continuously over a long period. If you could take enough propellant you could do the same thing with a chemical engine. The problem here is to have a viable Nuclear engine it would have to be an ion/electric engine, to carry enough mass to accelerate by heating it alone would be as prohibitive as carrying enough propellant for a chemical engine. The current thinking is to use chemical engines to provide the initial boost and either coast to a point where you have to slow down to enter an orbit, or use ion/electrics to add additional velocity while enroute. The problem here is it takes more chemical propellant to slow down once you get somewhere the more you increase your velocity. When you figure the mass of an ion engine, plus the solar panels, or Nuclear reactor to power it, and the added chemical propellant needed to slow down it doesn't make a lot of sense for Earth Moon, Earth Mars or even Earth Asteroids. Where an ion engine makes sense is where you don't have to slow down. <div class="Discussion_UserSignature"> </div>

MBA_UIU · Jul 16, 2005

To assert that a rocket can go faster then the escape velocity of its exhaust, which is where the engine¡¦s thrust is released, violates Newton¡¦s third law of motion. Newton¡¦s third law basically states that for every action there is an equal and opposite reaction. ¡§Specific impulse is a measure of propellant efficiency, and numerically is the thrust produced divided by the weight of propellant consumed per second (ending up with units of seconds). So, Isp is really another measure of a rocket¡¦s exhaust velocity¡¨ As a matter of fact VE (or velocity of escape) is part of the required formula for determining the size of engine needed to put a rock into space. ¡§The purpose of a rocket is to place a payload at specified position with a specific velocity. This position and velocity depends on the mission. We can equate the energy needed to do this to the change in velocity (or delta-v, ƒ´v) the rocket imparts to the satellite. For a rocket, the ideal ƒ´v gain depends on the Isp (exhaust velocity, ve ) and the mass ratio.¡¨ For a real good read on the theory of rocket engines, including ion and nuclear drives, go here: http://space.au.af.mil/primer/rocket_theory.pdf <div class="Discussion_UserSignature"> <img id="268587ce-7170-4b41-a87b-8cd443f9351a" src="http://sitelife.space.com/ver1.0/Content/images/store/6/8/268587ce-7170-4b41-a87b-8cd443f9351a.Large.jpg" alt="blog post photo" /> </div>

tap_sa · Jul 16, 2005

"To assert that a rocket can go faster then the escape velocity of its exhaust, which is where the engine¡¦s thrust is released, violates Newton¡¦s third law of motion." Every orbital launch vehicle has been breaking Newton's third law or your interpretation of it is wanting. LOX/kerosene exhaust gas speed is 'only' about 3000m/s, best LOX/LH2 engines somewhere around 4500m/s. Yet they achieve the orbital speed nearly 8000m/s.

vogon13 · Jul 16, 2005

That post belongs in Phenomena. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

kmarinas86 · Jul 16, 2005

To assert that a rocket can go faster then the escape velocity of its exhaust, which is where the engine¡¦s thrust is released, violates Newton¡¦s third law of motion. WRONG. For example, you have a firework on the equator, and it is launched there, will it go faster than the equator - yes! Does the firework mass have to move faster than the equator? NO WAY. You are simply WRONG. So, Isp is really another measure of a rocket¡¦s exhaust velocity¡ Yes, but THRUST depends on the mass of that propellant. It is the THRUST that determines the acceleration. As long as there's thrust, there will be acceleration as long as there's not enough friction to stop it. It is the ISP that determines how efficently the propellent is used. But no matter the ISP, thrust makes the rocket accelerate (given nothing to stop it). It doesn't matter what its inital velocity is.

MBA_UIU · Jul 17, 2005

"WRONG. For example, you have a firework on the equator, and it is launched there, will it go faster than the equator - yes! Does the firework mass have to move faster than the equator? NO WAY." How can the "firework" go faster then the equator but not its mass? Explain that one for me as the last time I looked the firework and its mass are one and the same!! You really need to stop posting and start reading simple books on natural laws. <div class="Discussion_UserSignature"> <img id="268587ce-7170-4b41-a87b-8cd443f9351a" src="http://sitelife.space.com/ver1.0/Content/images/store/6/8/268587ce-7170-4b41-a87b-8cd443f9351a.Large.jpg" alt="blog post photo" /> </div>

MBA_UIU · Jul 17, 2005

From: http://www.hq.nasa.gov/office/pao/History/SP-4404/app-b8.htm Vehicle velocity. Expressed in meters per second (m/s). Vehicle velocity is a function of the rocket exhaust gas velocity, mass ratio of the vehicle, aerodynamic drag during flight through the atmosphere, gravitational pull expressed in terms of burning time of the rocket, and the trajectory. In 1903 Tsiolkovskiy derived the velocity for a rocket in vertical flight, disregarding drag and gravitational pull. This yielded the fundamental rocket flight equation named after him and so identified in the text. The equation is: V = Ve ln(Mo/ Me ) where V is vehicle velocity, Ve is exhaust gas velocity, Mo is gross mass, Me is empty mass, and ln is the natural logarithm. The, direct relationship between vehicle velocity and exhaust gas velocity accounts for the interest in high energy propellants that yield high exhaust velocities. Multistage rocket. A vehicle composed of two or more complete rocket systems, each including propellant and associated controls and structure. The last (upper) stage carries the spacecraft as the payload. The payload of the first stage is the upper stages and the spacecraft. Investigators learned a very long time ago that rocket vehicle velocity could be increased by having one rocket unit riding piggy-back on another until the first expends all of its propellant. The dead weight of the first stage is normally jettisoned. The second rocket unit or stage begins operating at the velocity given it by the first stage and adds its own velocity increase, for a much higher final velocity. If the first two stages have identical exhaust velocities and mass ratios, for example, the final velocity will be twice that of either operating singly. To understand this further read this http://dep</safety_wrapper <div class="Discussion_UserSignature"> <img id="268587ce-7170-4b41-a87b-8cd443f9351a" src="http://sitelife.space.com/ver1.0/Content/images/store/6/8/268587ce-7170-4b41-a87b-8cd443f9351a.Large.jpg" alt="blog post photo" /> </div>

tap_sa · Jul 17, 2005

"V = Ve ln(Mo/ Me )" Well now that you brought up the venerable rocket equation you must see that if the ratio Mo/Me is bigger than e (~2.718) then V > Ve.

MBA_UIU · Jul 17, 2005

You're close but you have to do the whole equation. F = l ve + ( pe - pa ) Ae This equation consists of two terms. The first term, called the momentum thrust, is equal to the product of the propellant mass flow rate and the exhaust velocity ve with a correction factor l for nonaxial flow due to nozzle divergence angle. The second term is called the pressure thrust. It is equal to the difference in pressures pe and pa of the exhaust velocity and the ambient atmosphere, respectively, acting over the area Ae of the exit plane of the rocket nozzle. The combined effect of both terms is incorporated into the effective exhaust velocity c. Thus the thrust is also written F = c where an average value of c is used, since it is not strictly constant. The exhaust exit pressure is determined by the expansion ratio given by e= Ae / At which is the ratio of the area of the nozzle exit plane Ae and the area of the throat At . As the expansion ratio e increases, the exhaust exit pressure pe decreases. The thrust is maximum when the exit pressure of the exhaust is equal to the ambient pressure of the surrounding environment, that is, when pe = pa. This condition is known as optimum expansion and is achieved by proper selection of the expansion ratio. Although optimum expansion makes the contribution of the pressure thrust zero, it results in a higher value of exhaust velocity ve such that the increase in momentum thrust exceeds the reduction in pressure thrust. A conical nozzle is easy to manufacture and simple to analyze. If the apex angle is 2a , the correction factor for nonaxial flow is = ½ (1 + cos a ) The apex angle must be small to keep the loss within acceptable limits. A typical design would be a = 15° , for which l = 0.9830. This represents a loss of 1.7 percent. However, conical nozzles are excessively long for large expansion ratios and suffer additio <div class="Discussion_UserSignature"> <img id="268587ce-7170-4b41-a87b-8cd443f9351a" src="http://sitelife.space.com/ver1.0/Content/images/store/6/8/268587ce-7170-4b41-a87b-8cd443f9351a.Large.jpg" alt="blog post photo" /> </div>

tap_sa · Jul 17, 2005

You quoted fine summary of rocketry 101 but made zero effort to use it to prove your claim. I'm not a rocket scientist but do have Sutton's bible in my bookshelf so your equations were familiar.

vogon13 · Jul 17, 2005

That is about the most concise and lucid way of putting that I have ever seen. If still not clear to MBA_UIU, then we have another BB situation. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

Cheapest rocket possible

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