Search results
Results from the WOW.Com Content Network
A small reaction wheel viewed in profile A momentum/reaction wheel comprising part of a high-accuracy Conical Earth Sensor to maintain a satellite's precise attitude. A reaction wheel (RW) is an electric motor attached to a flywheel, which, when its rotation speed is changed, causes a counter-rotation proportionately through conservation of angular momentum. [1]
Reaction control systems are capable of providing small amounts of thrust in any desired direction or combination of directions. An RCS is also capable of providing torque to allow control of rotation (roll, pitch, and yaw). [2] Reaction control systems often use combinations of large and small thrusters, to allow different levels of response.
Another method for achieving three-axis stabilization is to use electrically powered reaction wheels, also called momentum wheels, which are mounted on three orthogonal axes aboard the spacecraft. They provide a means to trade angular momentum back and forth between spacecraft and wheels. To rotate the vehicle on a given axis, the reaction ...
The slew of 3-axis stabilized spacecraft is typically in closed loop control with thrusters or electrically-powered reaction wheels maintaining or altering the craft's attitude based on sensor measurements. A typical example is a space telescope that should be turned to observe a new celestial object.
A reaction wheel imparts a instantaneous reaction torque into the spacecraft structure when accelerated / decelerated from 'coasting' RPM. The maximum available torque is typically in the order of 0.1 to 0.5 N/m.
CMGs differ from reaction wheels. The latter apply torque simply by changing rotor spin speed, but the former tilt the rotor's spin axis without necessarily changing its spin speed. CMGs are also far more power efficient. For a few hundred watts and about 100 kg of mass, large CMGs have produced thousands of newton meters of torque.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
These avoidance maneuvers are almost always conducted by the firing of onboard Reaction control thrusters, although some other satellite and spacecraft orientation systems like Magnetorquers, Reaction wheels, and Control moment gyroscopes may be involved.