Simviation Forums

ok i have a question about the speed in fsx ?
i always when in  normal flight i dont get the normal cruising speed ?
for example i made a 747 flight on an altitude of 36,000ft and i wanted a speed of 350 knots i had the speed holder engaged on 350 knots and after this i disengaged it and dove the plane so it gains speed when it just passed the 307 knots an overspeed sign showed
why dont i get the speed that i want  ??? and remember i dont have speed brakers or flaps activated ?

Well, I don't think commercial jets fly as fast as 350 kias, the FSX 747 isn't supposed to go that speed either.

I believe 340 knots is usually the point of overspeed for the 747.

But 307 sounds weird.

how come and its written in the aircraft description cruising speed 400 knots

You must be talking groundspeed, which is unrelated to overspeed.

thats because your working with IAS - indicated airspeed.

"Indicated Airspeed

Indicated Airspeed is more of a measure of the amount of air particles going over the wing at one time. It is measured in knots. It is related to the performance of the aircraft because at an indicated airspeed of 90kts there is always the same amount of air going over the wings. Regardless of the air pressure."

So at higher altitudes, you have less air molecules hitting the sensor, which means that an IAS of 300 at 30,000 ft is very different ground speed, or True speed even, TAS, then IAS 300 at 1000 ft.

at 36000 ft at IAS of 307, your actually going 487 TAS.

Right you are flavio, but when we're talking V speeds, we're still working in KIAS, where never-exceed speed is 340 knots or something.