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The rocket equation says that an SSTO vehicle needs a high mass ratio. One way to increase the mass ratio is to reduce the mass of the empty vehicle by using very lightweight structures and high-efficiency engines.
This tends to push up maintenance costs as component reliability can be impaired, and makes reuse more expensive to achieve. Another is to reduce the weight of oxidant carried, by burning the fuel in air during the atmospheric stage of flight.
The margins are so small with the SSTO approach that there is uncertainty whether such a vehicle could carry any payload into orbit. Another way that SSTO can be made to work is to reduce the amount of velocity the launch vehicle needs to achieve to reach orbit.
This can be done by using a ground accelerator to accelerate the launch vehicle to Mach 1 or higher, air launching from a carrier aircraft such as Stratolaunchor using a combination launch system.
Multiple stages[ edit ] Two stage to orbit uses two vehicles, joined together at launch.
Usually the second-stage orbiter is times smaller than the first-stage launcher, although in biamese and triamese  configurations both vehicles are the same size. Besides the cost of developing two independent vehicles, the complexity of the interactions between them both as a unit and when separating must also be evaluated.
In addition, the first stage needs to be returned to the launch site for it to be reused. This is usually proposed to be done by flying a compromise trajectory that keeps the first stage above or close to the launch site at all times, or by using small air-breathing engines to fly the vehicle back, or by recovering the first stage down range and returning it some other way often landing in the sea, and returning it by ship.
Most techniques involve some performance penalty; these can require the first stage to be several times larger for the same payload, although for recovery from downrange these penalties may be small. The second stage is normally returned after flying one or more orbits and reentering.
This is also called a combination launch system. As the orbiter burns fuel, crossfeeds from the tanks of the booster stages may be used to keep it topped up.
Once a booster runs dry it separates and typically glides back to a safe landing for re-use. The fully reusable BAC Mustard project included an engine in each of its near-identical modules, allowing its shut-down engines to be discarded along with the empty tankage, where the Shuttle had the penalty of carrying its shut-down engines into orbit.
A criticism of this approach is that designing separate orbiter and boosters, or a single vehicle that could do both, would compromise performance, safety, and possible cost savings.
Compromising maximum performance to reduce cargo cost, however, is the point of the clustering approach. Stacking two or three winged vehicles can also be challenging. Launch[ edit ] All orbital vehicles to date have been launched vertically. Non-rocket spacelaunch systems provide a theoretical increase in efficiency.
Since rocket delta-v has a non linear relationship to mass fraction due to the rocket equationany small reduction in delta-v gives a relatively large reduction in the required mass fraction; and starting a mission at higher altitude also helps.
A vehicle which takes off, or separates from the previous stage horizontally, needs wings.STENNIS SPACE CENTER, Miss., June 4, – Aerojet Rocketdyne has completed assembly of its first AR rocket engine built for Boeing (NYSE:BA) as part of the U.S.
Defense Advanced Research Projects Agency (DARPA) Experimental Spaceplane program. This new Boeing spaceplane, called Phantom Express, is intended to demonstrate a new paradigm for more routine, responsive and affordable space. This project is developing the next generation ion engine technology and is managed by the NASA Glenn Research Center.
NEXT is a propulsion system that could revolutionize the way we send science missions deeper into the solar system. Space Transportation Initiative NPSS Review IIIIIII III r i III Background •Growing importance of advanced space transportation propulsion systems and simulations to support development &.
Aerojet Rocketdyne is the world’s leading supplier of space propulsion system products and services. Aerojet Rocketdyne provides services for architecture and mission design, systems engineering, design and development, manufacturing, and test. At Penn State, we are conducting research in a number of areas relevant to space propulsion.
In the area of chemical propulsion, our experimental research includes characterizing the unsteady combustion behavior of solid and liquid propellant rockets by means of advanced diagnostics. NASA's Project Orion, which was initiated in , proposed propelling a spacecraft by detonating a series of atomic bombs behind the vehicle, a concept known as nuclear pulse propulsion.