Avril Girl

Sunday, 10 July 2011

Forces on a rocket in flight

Forces on a rocket in flight

Forces on a rocket in flight, rockets that must travel through the air are usually tall and thin as this shape gives a high ballistic coefficient and minimizes drag losses
The general study of the forces on a rocket or other spacecraft is part of ballistics and is called astrodynamics.
Flying rockets are primarily affected by the following:[75]
  • Thrust from the engine(s)
  • Gravity from celestial bodies
  • Drag if moving in atmosphere
  • Lift; usually relatively small effect except for rocket-powered aircraft
In addition, the inertia and centrifugal pseudo-force can be significant due to the path of the rocket around the center of a celestial body; when high enough speeds in the right direction and altitude are achieved a stable orbit or escape velocity is obtained.
These forces, with a stabilizing tail (the empennage) present will, unless deliberate control efforts are made, naturally cause the vehicle to follow a roughly parabolic trajectory termed a gravity turn, and this trajectory is often used at least during the initial part of a launch. (This is true even if the rocket engine is mounted at the nose.) Vehicles can thus maintain low or even zero angle of attack which minimizes transverse stress on the launch vehicle; permitting a weaker, and hence lighter, launch vehicle.

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