LH463 From United States of America, joined Apr 2006, 68 posts, RR: 0 Posted (10 years 1 month 1 week 3 days 4 hours ago) and read 2683 times:
I was just wondering if an airplane had to break the sound barrier by passing it on it's KIAS. I know the actuall speed depends on many factors such as temperature, air density etc., but is there any way the sound barrier could be broken by an aircraft (normally incapable) with a tail wind? (Assuming it can withstand the forces)
Pilotpip From United States of America, joined Sep 2003, 3176 posts, RR: 9
Reply 1, posted (10 years 1 month 1 week 3 days 3 hours ago) and read 2673 times:
Winds only affect your groundspeed. Airspeed is only relative to the speed of the relative wind around the aircraft. If the aircraft is in level flight at say, mach .99 and there is a tail wind, it is at mach .99. It will not break the speed of sound because it is traveling at an airspeed that is below the speed of sound.
Bri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 3
Reply 3, posted (10 years 1 month 1 week 2 days 5 hours ago) and read 2524 times:
Quoting Viv (Reply 2): No, because airspeed does not increase in a tailwind (or decrease in a headwind).
That's right, and actually, the opposite happens. God forbid I bring out the conveyor belt loonies again, but I hope we can agree on this. If, at some place on the surface of the Earth, the wind blew as fast as the speed of sound in those particular conditions, an observer standing there would experience winds at the speed of sound (not a good idea).
Extending the concept a little, if an airplane was crusing in still air at, say, mach .75, or 75% of the speed of sound in those conditions, and a sudden current of wind came by, aimed directly at the nose of the plane, aligned with the fuselage, at least as fast as 25% of the speed of sound, it would suddenly be flying through the air faster than the speed of sound. Not being designed for it, and not having the power to sustain flight at those speeds, it would experience a violent deceleration. Most planes would probaly sustain significant structural damage. Fortunately, even in turbulent air, it's highly unlikely that winds on Earth will ever change quickly enough in a short enough time to make this happen.