How speed of aircraft or satellite is measured?

Question

How speed of aircraft or satellite is measured?

Answer 1

Traditionally, the forward speed of an airplane is measured by the airspeed indicator, which reads the flow of air against the leading edge of the wing.

The faster the airplane goes, the harder the air presses on the mechanism of the indicator, so that the pointer is moved further.

You can learn much more about airspeed indicators by doing an internet search on "airspeed indicator."

Some airplanes also have radio and satellite navigation devices that display ground speed readings calculated from radio signals received from ground stations and satellites.

You can learn much more about these things by doing an internet search on "radio air navigation," or "global positioning system."

The speeds at which satellites move are much higher, and are calculated by means of astronomical calculations based on gravity, altitude, and orbital geometry.  The speed of a satellite can also be measured by watching it through a telescope and recording the time required to cross a measured area of the sky.

You can learn much more about this by doing an internet search on "satellite speeds," or "orbital mechanics."

Have fun, and good luck!

Answer 2

The basic airspeed indicator on a Cessna 152 or an F-15E both read Indicated Airspeed (IAS). This device measures the difference between STATIC pressure (usually from a sensor not in the airstream) and IMPACT pressure (called the stagnation pressure received from an aircraft's PITOT TUBE -- which is in the airstream). When the aircraft is not moving, the pressures are equal (and the airspeed is zero). On takeoff, the on-rushing air will result in a greater pressure in the PITOT TUBE and this difference in pressure from the static sensor can be used to calculate the airspeed (in miles per hour (MPH) or nautical miles per hours (KNOTS)) at which the aircraft is moving through the air.

Answer 3

Aircraft have speedometers. Satellite speed has to be calculated mathmatically. Aircraft use air pressure on a pidot tube and a correction factor for altitude. There is practically no air for satellites to use this method. If you know the orbit circumference and calculate the time of a round trip, you can figure the speed pretty well, unless it is a geosynchronous oribit and the speed relative to earth is 0 mph or knots.

Answer 4

nm (aka nautical miles)

Answer 5

nauticalmiles

Answer 6

Chito is right on!!!!  Aircraft also use "groundspeed" to calculate estimated time enroute and therefore estimated time of arrival as well.  Good to know for fuel planning.  Most planes have GPS that will figure your groundspeed nowadays, but back in the day...