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The group velocity of a wave is the velocity with which the overall envelope shape of the wave's amplitudes—known as the modulation or envelope of the wave—propagates through space. For example, if a stone is thrown into the middle of a very still pond, a circular pattern of waves with a quiescent center appears in the water, also known as ...
This is the case on many large aircraft such as the 747, C-17, KC-10, etc. If you are on an aircraft and you hear the engines increasing in power after landing, it is usually because the thrust reversers are deployed. The engines are not actually spinning in reverse, as the term may lead you to believe.
In GvK diagram, the x-axis is the vehicle velocity, and the y-axis is the dimensionless specific resistance.The same kind of vehicle may have multiple different operating velocities, with different corresponding specific resistances, consequently each kind of vehicle generally correspond to a whole region on the GvK diagram, but only the lower-edge of the region is plotted, since specific ...
The outer edges of the diagram, the envelope, show the possible conditions that the aircraft can reach in straight and level flight. For instance, the aircraft described by the black altitude envelope on the right can fly at altitudes up to about 52,000 feet (16,000 m), at which point the thinner air means it can no longer climb.
Superposition of 1D plane waves (blue) that sum to form a Gaussian wave packet (red) that propagates to the right while spreading. Blue dots follow each plane wave's phase velocity while the red line follows the central group velocity. 1D Gaussian wave packet, shown in the complex plane, for a =2 and k =4
A superposition of 1D plane waves (blue) each traveling at a different phase velocity (traced by blue dots) results in a Gaussian wave packet (red) that propagates at the group velocity (traced by the red line). The group velocity of a collection of waves is defined as =.
WASHINGTON (Reuters) -The Federal Aviation Administration plans to convene a review board in the coming weeks to consider safety concerns about engines on Boeing 737 MAX airplanes after two bird ...
A JT9D turbofan jet engine installed on a Boeing 747 aircraft. Jet engines power jet aircraft, cruise missiles and unmanned aerial vehicles. In the form of rocket engines they power model rocketry, spaceflight, and military missiles. Jet engines have propelled high speed cars, particularly drag racers, with the all-time record held by a rocket car.