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The thrust-to-weight ratio is usually calculated from initial gross weight at sea level on earth [6] and is sometimes called thrust-to-Earth-weight ratio. [7] The thrust-to-Earth-weight ratio of a rocket or rocket-propelled vehicle is an indicator of its acceleration expressed in multiples of earth's gravitational acceleration, g 0. [5]
The advance ratio is critical for determining the efficiency of a propeller. At different advance ratios, the propeller may produce more or less thrust. Engineers use this ratio to optimize the design of the propeller and the engine, ensuring that the vehicle operates efficiently at its intended cruising speed, see propeller theory.
A low disk loading is a direct indicator of high lift thrust efficiency. [4] Increasing the weight of a helicopter increases disk loading. For a given weight, a helicopter with shorter rotors will have higher disk loading, and will require more engine power to hover. A low disk loading improves autorotation performance in rotorcraft.
A propeller that turns clockwise to produce forward thrust, when viewed from aft, is called right-handed. One that turns anticlockwise is said to be left-handed. Larger vessels often have twin screws to reduce heeling torque , counter-rotating propellers , the starboard screw is usually right-handed and the port left-handed, this is called ...
When most of the blade surface is covered by cavitation, the pressure difference between the pressure side and suction side of the blade drops considerably, as does the thrust produced by the propeller. This condition is called "thrust breakdown". Operating the propeller under these conditions wastes energy, generates considerable noise, and as ...
A toroidal propeller is a type of propeller that is ring-shaped with each blade forming a closed loop. The propellers are significantly quieter at audible frequency ranges, between 20 Hz and 20 kHz, while generating comparable thrust to traditional propellers. In practice, toroidal propellers reduce noise pollution in both aviation and maritime ...
The Voith Schneider propeller was originally a design for a hydro-electric turbine. [2] Its Austrian inventor, Ernst Schneider, had a chance meeting on a train with a manager at Voith's subsidiary St. Pölten works; this led to the turbine being investigated by Voith's engineers, who discovered that although it was no more efficient than other water turbines, Schneider's design worked well as ...
Its 190-inch propeller diameter (4.7-metre) was smaller than the NK-12's 220–240 in (5.6–6.2 m) diameter, but it produced a power output of 21,007 hp (15,665 kW), delivering a takeoff thrust of 40,000 pounds-force (177 kilonewtons). [12] Even more powerful was the NK-62, which was in development throughout most of the decade.