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#1
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Small, cheap, reusable rocket launcher
The rocket launchers are not economical because they
are not reusable. When they reenter the atmosphere, their slender bodies soak up so much heat from the ambient atmosphere that they burn up. The Space Shuttle is somewhat reusable, but its slender body has to be protected with a thermal protection system that is expensive (because it covers large surface) and unreliable (because it has to be lightweight despite its large size). A rocket launcher shaped like a big conical reentry capsule would be more reusable than the Space Shuttle because its thermal protection system would be smaller (because it would cover only the bottom surface of the cone) and cheaper. The conventional rocket launchers are shaped like a pencil to minimize aerodynamic drag during the first minute of the flight. A cone-shaped rocket launcher would generate too much drag unless it was slowly lifted above the dense part of the atmosphere (to the altitude of about 30 kilometers) with a balloon or a helicopter. Hydrogen balloons are cheap, but not reusable. Helicopters are reusable, but they need special engines that can operate at the altitude of 30 kilometers. There are three such engines: 1. Hydrogen peroxide monopropellant turbine has simple design, but the monopropellant is rather expensive and its catalyst bed can be contaminated with commercial grade monopropellant. 2. Steamjet engine is described in U.S. patent 6,202,404. Its most practicable implementation, called mass injection precompressor cooling (MIPCC) is a turbojet cooled with copious amounts of water and liquid oxygen. The cooling enables the turbojet to generate thrust up to the altitude of about 30 km. More info: http://tinyurl.com/msqra 3. Electric motors are cheap and can operate at the altitude of 30 km. Their energy source can be either a battery or a generator standing on the ground. The motors and the batteries need a cooling system when they operate at high altitude. 3a.Magnesium hydride battery with Ni catalyst has the highest energy density (http://www.energyadvocate.com/batts.htm) but it is not yet mature technology. Li-ion batteries have energy density of only 534 kJ/kg, but they are very reliable and reusable. (They provide auxiliary power for my laptop computer.) The Li-ion batteries can be used as the power source if used up batteries are discarded during the flight. It takes about 300 watts of helicopter power to lift 1 kg of weight. At the beginning of the flight the total weight of the batteries is about one half of the launcher weight. During 15 minutes of vertical flight the helicopter reaches its maximum altitude of 30 km, drops off nearly all its batteries on parachutes, and finally drops off the launcher. When the helicopter descends, most of its propellers (rotors) are used as wind turbines which provide power for the remaining propellers. The last batteries are used up during landing. My laptop batteries cost $418/kg. Assuming payload fraction of 6 percent and total battery weight of one half the launcher weight, the batteries cost 418/0.06/2 = $3483 per kilogram of payload. The capital cost of the batteries may seem rather high, but the batteries are reusable and very easy to use. 3b.Aluminum wires linking the motors with a high voltage generator standing on the ground are expensive and difficult to use. High voltage generators are available from many sources, for example: http://www.kato-eng.com/hacgen.html They cost about $0.1/W. At the payload fraction of 6 percent, the generator cost is about 0.1*300/0.06 = $5556 per kilogram of payload. In the absence of the generator, the power is provided by the grid. The cost of connecting to the grid depends on the distance; electrical utilities charge between $10,000 and $50,000 per kilometer of transmission line. The wires must be reinforced with strong (Zylon) rope and suspended on balloons so that they do not touch the ground. The design of such helicopter is similar to the design of airborne wind turbine generator: http://www.skywindpower.com The helicopter is vulnerable to lightenings and strong winds, so it must fly near the equator (away from the jet streams): http://www.skywindpower.com/ww/page010.htm. Electric motors powered by batteries are the best choice because they are cheap, reliable, safe, and easy to use. If the helicopter lifts the rocket launcher above the dense part of the atmosphere, the launcher can transport payloads that have low density and large size, for example large space telescope or large greenhouse. THE LAUNCHER SCALES DOWN VERY WELL BECAUSE IT IS REUSABLE AND BECAUSE ITS ATMOSPHERIC DRAG IS NEGLIGABLE. ITS TRUNCATED CONICAL SHAPE LEAVES PLENTY OF ROOM FOR A VERY LARGE EXHAUST NOZZLE WHICH IMPROVES THE EXPANSION RATIO AND SPECIFIC IMPULSE. LAST, BUT NOT LEAST, THE SHAPE OF THE EXHAUST NOZZLE IS OPTIMIZED FOR FLIGHT IN THE VACUUM, BECAUSE IT IS NOT USED IN THE DENSE ATMOSPHERE. This means that a little guy can cobble together a little rocket launcher that has high specific impulse despite its primitive, low-pressure design, and that he can compete on launch cost with the giants of the industry (if he can afford the legal expenses). If the launcher has three stages, only the last stage has to be protected with the expensive composite called reinforced carbon-carbon. The second stage can be protected with a thick coating of silicone rubber. The first stage does not need any thermal protection. |
#2
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Small, cheap, reusable rocket launcher
In article ,
Andrew Nowicki wrote: The rocket launchers are not economical because they are not reusable. When they reenter the atmosphere, their slender bodies soak up so much heat from the ambient atmosphere that they burn up. The Space Shuttle is somewhat reusable, but its slender body has to be protected with a thermal protection system that is expensive (because it covers large surface) and unreliable (because it has to be lightweight despite its large size). A rocket launcher shaped like a big conical reentry capsule would be more reusable than the Space Shuttle because its thermal protection system would be smaller (because it would cover only the bottom surface of the cone) and cheaper. The conventional rocket launchers are shaped like a pencil to minimize aerodynamic drag during the first minute of the flight. A cone-shaped rocket launcher would generate too much drag unless it was slowly lifted above the dense part of the atmosphere (to the altitude of about 30 kilometers) with a balloon or a helicopter. Hydrogen balloons are cheap, but not reusable. Helicopters are reusable, but they need special engines that can operate at the altitude of 30 kilometers. There are three such engines: 1. Hydrogen peroxide monopropellant turbine has simple design, but the monopropellant is rather expensive and its catalyst bed can be contaminated with commercial grade monopropellant. 2. Steamjet engine is described in U.S. patent 6,202,404. Its most practicable implementation, called mass injection precompressor cooling (MIPCC) is a turbojet cooled with copious amounts of water and liquid oxygen. The cooling enables the turbojet to generate thrust up to the altitude of about 30 km. More info: http://tinyurl.com/msqra 3. Electric motors are cheap and can operate at the altitude of 30 km. Their energy source can be either a battery or a generator standing on the ground. The motors and the batteries need a cooling system when they operate at high altitude. 3a.Magnesium hydride battery with Ni catalyst has the highest energy density (http://www.energyadvocate.com/batts.htm) but it is not yet mature technology. Li-ion batteries have energy density of only 534 kJ/kg, but they are very reliable and reusable. (They provide auxiliary power for my laptop computer.) The Li-ion batteries can be used as the power source if used up batteries are discarded during the flight. It takes about 300 watts of helicopter power to lift 1 kg of weight. At the beginning of the flight the total weight of the batteries is about one half of the launcher weight. During 15 minutes of vertical flight the helicopter reaches its maximum altitude of 30 km, drops off nearly all its batteries on parachutes, and finally drops off the launcher. When the helicopter descends, most of its propellers (rotors) are used as wind turbines which provide power for the remaining propellers. The last batteries are used up during landing. My laptop batteries cost $418/kg. Assuming payload fraction of 6 percent and total battery weight of one half the launcher weight, the batteries cost 418/0.06/2 = $3483 per kilogram of payload. The capital cost of the batteries may seem rather high, but the batteries are reusable and very easy to use. 3b.Aluminum wires linking the motors with a high voltage generator standing on the ground are expensive and difficult to use. High voltage generators are available from many sources, for example: http://www.kato-eng.com/hacgen.html They cost about $0.1/W. At the payload fraction of 6 percent, the generator cost is about 0.1*300/0.06 = $5556 per kilogram of payload. In the absence of the generator, the power is provided by the grid. The cost of connecting to the grid depends on the distance; electrical utilities charge between $10,000 and $50,000 per kilometer of transmission line. The wires must be reinforced with strong (Zylon) rope and suspended on balloons so that they do not touch the ground. The design of such helicopter is similar to the design of airborne wind turbine generator: http://www.skywindpower.com The helicopter is vulnerable to lightenings and strong winds, so it must fly near the equator (away from the jet streams): http://www.skywindpower.com/ww/page010.htm. Electric motors powered by batteries are the best choice because they are cheap, reliable, safe, and easy to use. If the helicopter lifts the rocket launcher above the dense part of the atmosphere, the launcher can transport payloads that have low density and large size, for example large space telescope or large greenhouse. THE LAUNCHER SCALES DOWN VERY WELL BECAUSE IT IS REUSABLE AND BECAUSE ITS ATMOSPHERIC DRAG IS NEGLIGABLE. ITS TRUNCATED CONICAL SHAPE LEAVES PLENTY OF ROOM FOR A VERY LARGE EXHAUST NOZZLE WHICH IMPROVES THE EXPANSION RATIO AND SPECIFIC IMPULSE. LAST, BUT NOT LEAST, THE SHAPE OF THE EXHAUST NOZZLE IS OPTIMIZED FOR FLIGHT IN THE VACUUM, BECAUSE IT IS NOT USED IN THE DENSE ATMOSPHERE. This means that a little guy can cobble together a little rocket launcher that has high specific impulse despite its primitive, low-pressure design, and that he can compete on launch cost with the giants of the industry (if he can afford the legal expenses). If the launcher has three stages, only the last stage has to be protected with the expensive composite called reinforced carbon-carbon. The second stage can be protected with a thick coating of silicone rubber. The first stage does not need any thermal protection. Ideas similar to this have been proposed in the past. The reason you do not see anyone with money pushing them is that there is at least one element in the plan that has no physical or economic solution. Until a solution to that element is found there is no need to even consider any of the other elements. In your idea the helicopter seems to me to be one of those difficult elements. You should lookup information on how lift is generated in helicopters, and wing theory. Note that you are especially interested in flight in the very low density air at 30 km. Start with your rocket weight say 40,000 kg and you assume the helicopter, motors, and wires etc are made from that miracle material engineers like to specify, unobtainium. :-) You may find that the blades of the helicopter must be several hundred meters in length before you add the weight of the weight of the other items. Now go hit the books and report back what you find about the rotor diameter and RPM needed to support the assumed weight of the rocket at the altitude you pick to start the rocket launch at. -- Mike Swift Two things only the people anxiously desire, bread and circuses. Decimus Junius Juvenalls |
#3
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Small, cheap, reusable rocket launcher
In article ,
Andrew Nowicki wrote: The conventional rocket launchers are shaped like a pencil to minimize aerodynamic drag during the first minute of the flight. A cone-shaped rocket launcher would generate too much drag unless it was slowly lifted above the dense part of the atmosphere (to the altitude of about 30 kilometers) with a balloon or a helicopter. Hydrogen balloons are cheap, but not reusable. But airships (whether filled with hydrogen or helium) are. Big ones can have a quite impressive lift capacity, too. Re. helicopters: 3. Electric motors are cheap and can operate at the altitude of 30 km. Their energy source can be either a battery or a generator standing on the ground [connected by wires]. Did you consider a power source on the ground beaming power to the helicopters in the form of lasers or microwaves? Electric motors powered by batteries are the best choice because they are cheap, reliable, safe, and easy to use. It's an interesting idea, though recovering all those batteries parachuted from 30 km strikes me as a logistical problem, which will therefore drive up the costs. An airship might work better. Best, - Joe |
#4
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Small, cheap, reusable rocket launcher
Mike Swift wrote: In your idea the helicopter seems to me to be one of those difficult elements. You should lookup information on how lift is generated in helicopters, and wing theory. Note that you are especially interested in flight in the very low density air at 30 km. Start with your rocket weight say 40,000 kg and you assume the helicopter, motors, and wires etc are made from that miracle material engineers like to specify, unobtainium. :-) You may find that the blades of the helicopter must be several hundred meters in length before you add the weight of the weight of the other items. As I understand it, helicopters are unable to rescue people off Mount Everest, K2 or other mountains. It seems that the Pakistani army has special helicopters that can go up over 6,000 metres. |
#5
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Small, cheap, reusable rocket launcher
Joe Strout wrote:
But airships (whether filled with hydrogen or helium) are. Big ones can have a quite impressive lift capacity, too. The problem is how to bring the balloon or the airship back to the earth -- you would have to release lots of expensive hydrogen. The cost of making hydrogen is about 0.7 $/kg, but the cost of liquefying and transporting hydrogen from the oil refinery to the user raises the cost to about 3 $/kg. Hydrogen, like chlorine, is a destroyer of the ozone layer. If the rocket weighs 10 tons, you would spend about $50,000 on the hydrogen alone. Helium is even more expensive. Did you consider a power source on the ground beaming power to the helicopters in the form of lasers or microwaves? Leik N. Myrabo experimented with this idea some 20 years ago. It works, and it is not very expensive. The microwave electronics would cost about $100 per 1kg of the rocket weight. (Batteries cost about $200 per 1kg of the rocket weight.) I did not mention microwaves because the safety concerns would drive up the cost. The cost of electric motors is only about $30 per 1kg of the rocket weight. |
#6
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Small, cheap, reusable rocket launcher
Mike Swift wrote:
Now go hit the books... The physics, in terms of order of magnitude estimate, is trivial. If you had been able to handle high school level physics, you would not have made this comment. sci.space.policy is a much better place to ask high school level questions than sci.space.tech. |
#8
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Small, cheap, reusable rocket launcher
In article ,
Andrew Nowicki wrote: Joe Strout wrote: But airships (whether filled with hydrogen or helium) are. Big ones can have a quite impressive lift capacity, too. The problem is how to bring the balloon or the airship back to the earth -- you would have to release lots of expensive hydrogen. Why? Normal airships don't release lifting gas; they compress it, by inflating internal bladders with air. I don't see why it should be any different for this application. Did you consider a power source on the ground beaming power to the helicopters in the form of lasers or microwaves? Leik N. Myrabo experimented with this idea some 20 years ago. It works, and it is not very expensive. The microwave electronics would cost about $100 per 1kg of the rocket weight. (Batteries cost about $200 per 1kg of the rocket weight.) I did not mention microwaves because the safety concerns would drive up the cost. But they reduce the logistical issues. I wonder whether the safety issues can be mitigated by careful selection of the wavelength used. Best, - Joe |
#9
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Small, cheap, reusable rocket launcher
Back in the 50's when no one knew if spaceflight was even possible,
several tests were made with sounding rockets launched by balloon at high altitude. However the payload capability of even very large balloons declines at extreme altitude, and launching a large balloon is tricky. Because of the long period climbing to launch altitude cryogenic propellants were not practical. Ultimately it was not possible to carry rockets capable of getting into orbit. A similar problem will occur with rotorcraft. On the other hand, a fixed-wing aircraft.i.e. the B-70, can indeed be designed to carry a large payload at high altitude. While a large blunt cone would have to much drag for external carriage on an aircraft, a saucer-shaped vehicle could be carried and launched edge first and re-enter flat side first; this is pretty much what Rutan's SpaceShip One does with its pivoting tail. This can spread the heating over a large area as with the Apollo Capsule, reducing thermal loads. |
#10
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Small, cheap, reusable rocket launcher
"Andrew Nowicki" wrote in message ... Joe Strout wrote: But airships (whether filled with hydrogen or helium) are. Big ones can have a quite impressive lift capacity, too. The problem is how to bring the balloon or the airship back to the earth -- you would have to release lots of expensive hydrogen. The cost of making hydrogen is about 0.7 $/kg, but the cost of liquefying and transporting hydrogen from the oil refinery to the user raises the cost to about 3 $/kg. Hydrogen, like chlorine, is a destroyer of the ozone layer. If the rocket weighs 10 tons, you would spend about $50,000 on the hydrogen alone. Helium is even more expensive. I'd think it would be cheaper to buy kerosene and build a conventional LOX/kerosene first stage than it would be to build and operate an airship big enough to replace said first stage. The airship, after all, is going to be so huge, it would need some big engines of its own just to maneuver back to base once it's launch vehicle has been released. Jeff -- "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety" - B. Franklin, Bartlett's Familiar Quotations (1919) |
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