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http://www.astronautix.com/craft/bonhicle.htm
This is still an interesting opportunity. Seven 500 metric ton flight elements that carry 440 metric tons of liquid hydrogen and liquid oxygen. There is also a 300 metric ton orbital element atop the central stage. Each has an annular aerospike engine at the base, powered by three Pratt&Whitney RS-68 pumpsets - that feed the annular engine. http://www.astronautix.com/engines/rs68.htm http://www.astronautix.com/engines/aeroster.htm The average specific impulse of these engines through their ascent is 435 seconds. The elements are equipped with plumbing (like the Shuttle ET) for cross-feeding propellant. So, all 7 engine sets are firing at lift-off. Four of the six outer tanks are emptied first. This accelerates the spacecraft to 2,657 m/sec (less gravity drag and air drag losses) The after burning 1760 metric tons of propellent, the four empty elements are dropped, and they slow to subsonic speed as they re- enter the atmosphere. They are guided by a GPS system, to close with a targeted recovery plane very similar to a JDAM bomb. There are four recovery planes at the recovery points downrange from the launch center. When the elements are within a specified range of their targeted aircraft, they deploy cruise missile fashion, foldaway winglets, and slow their descent to zero, and their air speed to match that of the recovery aircraft and the direction of the recovery aircraft, just ahead and above the recovery aircraft. The rocket elements then drop a recovery line, very similar to the way KH-1 satellites had their film cannisters recovered and slow their speed further. A tow line from the targeted tow plane is dropped, and the recovery aircraft accelerates and climbs so that its tow line engages the recovery line. The winged rocket elements are then air-towed back to the launch center and released by each of their recovery planes. All elements are recovered and reused in this way. http://abyss.uoregon.edu/~js/space/lectures/lec09.html Meanwhile, at the launch vehicle, three of the seven elements continue to orbit, along with the 300 ton orbital element. The plumbing is such that the two outboard elements are drained while all three engines continue to fire. The 880 metric tons of propellant are emptied and another 2,867 meters per second are added to the velocity of the vehicle. This brings the total to 5,524 m/sec - less air drag and gravity drag losses. The two outboard elements once emptied are dropped, re-enter, and close with their targeted recovery planes, are caught and air-towed back to the launch center. The remaining 500 metric ton booster, with its 300 metric ton orbiter, in line, continue onward. The last element burns 440 metric tons of propellant, and adds another 3,411 m/sec to the vehicle's velocity, bringing it to 8,935 m/sec total speed - less air drag losses and gravity losses of approximately 1,935 m/sec. Thus the final speed of the vehicle is 7 km/sec. nearly orbital speed. The last booster drops away, and continues on a single suborbital flight around the Earth, which brings it back within gliding range of the launch center in 84 minutes after launch - very similar to the Saenger Antipodal Bomber flight path http://www.astronautix.com/lvs/saenger.htm At apogee, the 300 metric ton orbital element burns 30 metric tons of propellant to circularize its orbit. It carries up to 220 metric tons of active payload,45 metric tons of propellant, and has 35 metric ton structure. It operates unpiloted, but can carry a 200 metric ton piloted insert in its cargo bay, which carries up to 65 people, along with supplies. Its volume is large enough that it can carry an additional 200 metric tons of propellant and 20 ton payload for interplanetary operations. It can also carry 100 metric tons of propellant and 120 tons payload for cislunar operations. The orbital element is based on the HL-10 lifting body, and is built with advanced composite materials, and linear aerospike, used for the SSTO program. While not achieving the low structural fraction of that program, it does have quite a respectible performance. With modern avionics and computing technology, combined with advanced GPS hardware (that can position the vehicle accurately in space ANYWHERE within 1million km of Earth) the vehicle provides a capable low-cost access to space. http://www.astronautix.com/project/nasgbody.htm http://www.astronautix.com/engines/l2loster.htm The 300 metric ton lifting body can be replaced with an expendable booster stage, wherein the linear aerospike and pumpset alone is equipped with thermal protection system for recovery of the high value components. Alternatively, a modified Centaur stage, with RL10 engines, is used for high mass missions. 220 metric tons is twice the lifting capacity of the Saturn V moon rocket. 500 metric ton flight elements, containing liquid oxygen and liquid hydrogen propellants, are 2/3 the mass of the Shuttle's external tanks. The P&W RS68 engine set is modified for use as a component in an aerospike engine. The linear aerospike and composite technology, used for the SSTO program, is simply adapted to build these low-cost reusable airframes. Advanced avionics, computing technology, and GPS is used in innovative ways to create a flexible low cost fully reusable space vehicle. The vehicle is large enough to deploy a Mars Direct Vehicle each launch to implement Zubrin's plan to colonize the Red Planet. http://en.wikipedia.org/wiki/Earth_Return_Vehicle http://www.astronautix.com/craft/marirect.htm I have spoken elsewhere about the ability of this vehicle to orbit a 660 satellite network to provide global wireless internet for all of Earth, and through this medium, provide banking, insurance, and other services to improve life on Earth. 28 elements, comprising four vehicles - 3 flight vehicles and 1 spare - are included in that program. Once all 660 satellite are operational, within 18 months after first flight - $50 billion per year - more than NASA's annual budget is available to the operators of the satellite network, to develop payloads and upgrades for the vehicles. The cost of each flight Experimentation with solar power satellites, both Earth orbiting and Sun orbiting, as well as space tourism, to orbit, return to the moon, and space colonization, of the moon and mars, are all possible with this game plan. Solar power satellites massing 250 tons each, put into GEO with a 250 ton expendable kick stage, provides a power sat capable of beaming 1 GW or more of IR laser energy to solar power arrays on Earth. At $6,000 per metric ton for hydrogen and $2,100 per metric ton for liquid oxygen (delivered inside the vehicle) - propellant costs are $9 million per launch. Infrastructure and prep costs are another $3 million. Recovery of each stage and refurbishment, is $18 million. This is a total of $30 million. Payload is 300 metric tons - this is $100 per kg launch costs. Expendable kick stages cost $20 million per flight. The infrastructure that builds the commercial satellite network, allows aerospace costs to drop to double that found in the aircraft industry. A Boeing 777 costs $200 million and masses 140 metric tons. That's $1,500 per kg. Three times this figure is $3,000 per kg. That's $30 million for a 10 ton satellite. 22 of them in a coplanar orbit cost $660 million per launch. The launch cost itself is a small fraction of the total cost. Each element masses 60 metric tons empty, and the orbital element masses 35 metric tons empty. This is $180 million per element, and $105 million for the orbiter. All 8 elements together comprise a $1.365 billion vehicle. With the ability to launch reliably 150 times before a major rebuild, and with 0.5% refurb cost, the hardware cost per launch is $9.1 million and $6.85 million respectively - a total of $15.95 million - another $2 million for downrange recovery operations. A $5.5 billion development program, along with another $2.5 billion infrastructure build out - creates the ability to loft over 200 metric tons to Earth orbit, every two weeks. A global wireless internet earning $50 billion per year in profits after taxes, provides the money to build the $300 million per week in payloads to keep these vehicles busy at a flight rate of once every 2 weeks. In fact, the profits of nearly $1 billion per year from the satellite network (see my post on the satellite system) provides money to deploy significant payloads AND add the cost of deep space operations as well. (not only deploying a mars base, or a lunar city, but funding its operation until profitability is achieved) |
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