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Pogo oscillation is a self-excited vibration in liquid-propellant rocket engines caused by combustion instability. [1] The unstable combustion results in variations of engine thrust, causing variations of acceleration on the vehicle's flexible structure, which in turn cause variations in propellant pressure and flow rate, closing the self-excitation cycle.
Most rockets need to be supported and held down for a few seconds after ignition while the engines build up to full thrust. The vehicle is commonly held on the pad by hold-down arms or explosive bolts, which are triggered when the vehicle is stable and ready to fly, at which point all umbilical connections with the pad are released. [2]
A gravity turn is commonly used with rocket powered vehicles that launch vertically, like the Space Shuttle. The rocket begins by flying straight up, gaining both vertical speed and altitude. During this portion of the launch, gravity acts directly against the thrust of the rocket, lowering its vertical acceleration.
A space vehicle's flight is determined by application of Newton's second law of motion: =, where F is the vector sum of all forces exerted on the vehicle, m is its current mass, and a is the acceleration vector, the instantaneous rate of change of velocity (v), which in turn is the instantaneous rate of change of displacement.
Space launch involves liftoff, when a rocket or other space launch vehicle leaves the ground, floating ship or midair aircraft at the start of a flight. Liftoff is of two main types: rocket launch (the current conventional method), and non-rocket spacelaunch (where other forms of propulsion are employed, including airbreathing jet engines).
A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage rocket, but the term is more general and also encompasses vehicles like the Space Shuttle.
The Mercury-Redstone Launch Vehicle, designed for NASA's Project Mercury, was the first American crewed space booster.It was used for six sub-orbital Mercury flights from 1960–1961; culminating with the launch of the first, and 11 weeks later, the second American (and the second and third humans) in space.
The Atlas LV-3B was a human-rated expendable launch system used as part of the United States Project Mercury to send astronauts into low Earth orbit.Manufactured by American aircraft manufacturing company Convair, it was derived from the SM-65D Atlas missile, and was a member of the Atlas family of rockets. [2]