at Ma 0.7 compression effect occur. what kind of sensor is able to precisely measure the speed at such a situation?
I live in iran, so i am not sure if GPS based systems work properly in this region.
are you sure they are OK?
First you need to calculate the local speed of sound, which varies with temperature. On a standard day, 59 degrees F, the speed of sound at sea level is 661 knots, or 761 mph. Then measure the ratio of dynamic pressure-to static pressure. Dynamic pressure is measured by the air speed boom directed into the air stream; status pressure is measured at a point flush to the side of the fuselage. When the ratio of dynamic-to-static pressure is 14.45% the aircraft is flying at Mach 0.7, which is 463 knots or 533 mph. To see the math, search "Machmeter" on Wikipedia; then search "Speed of sound" to see how it is computed; or, use the table showing sound speed as a function of temperature.
Hi, at the beginning you have o calculate the corrected temperature with the altitude of the aircraft and the you can use this equation(TAS=M*a*square root of corrected temperature) to calculate the TAS which is aircraft speed. where (a) is the sound speed at the datum properties ISA and (corrected temperature is the ratio of the local temperature and reference temperature according to ISA.
thanks
My last reply, using dynamic pressure, was in error. First you need to calculate the local speed of sound, which varies with temperature. On a standard day, 59 degrees F, the speed of sound at sea level is 661 knots, or 761 mph. Then measure the ratio of total pressure-to static pressure. Total pressure is measured by the air speed boom directed into the air stream; static pressure is measured at a point flush to the side of the fuselage. When the ratio of total-to-static pressure is 1.39 the aircraft is flying at Mach 0.7, which is 463 knots or 533 mph. To see the math, search "Machmeter" on Wikipedia; then search "Speed of sound" to see how it is computed; or, use the table showing sound speed as a function of temperature.
it is easy.
first you must measure static and total pressure of air flow. this is possible with a pitot tube.
then use this equation to compute mach number.
P0/P=(1+M2(gama-1)/2) (gama/(gama-1))
you must compute speed of sound. if you know the height of aircraft, you can approximate it by standard atmosphere
The Mach is the rate of the aircraft speed to the sound speed calculated in the same condition of temperature pressure and altitude. to calculate the speed, you should have an idea at least about altitude to have pressure and temperature and to calculate the sound speed by the known formula including temperature and finally conclude about the aircraft speed.
- Badges
- Science topic