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What would be the minimum distance required for an F-16 to turn either sideways or upwards in order to avoid a collision (assume an infinitely long wall both length and breadth wise).

Also would it be better for such planes to turn sideways or upwards? Which is faster and requires less distance.

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  • $\begingroup$ Someone please help me with the tags, I don’t think that they are sufficient. $\endgroup$ – Valay_17 Jan 24 '20 at 2:00
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    $\begingroup$ To clarify, are you asking about the diameter of a 180 degree course reversal? (Because you only need to turn a few degrees to avoid a collision...) $\endgroup$ – Michael Hall Jan 24 '20 at 3:24
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    $\begingroup$ @MichaelHall : I am assuming an infinitely long wall so turning a few degrees won’t help. Also, I want to know about the radius of a 90 degree course reversal, a 180 diameter would help too. $\endgroup$ – Valay_17 Jan 24 '20 at 3:27
  • $\begingroup$ Ok, I read the wall part, but didn't really get it. I can't calculate the answer, but rolling inverted and pulling will give the best radius because you aren't fighting gravity. You get an extra one G from mother earth... $\endgroup$ – Michael Hall Jan 24 '20 at 3:33
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    $\begingroup$ On the other hand, an upward turn (half-loop) will have gravity helping you slow down, which will decrease the turn radius assuming you're limited throughout by max permissible structural G load. You'd want to pull the power to idle too. $\endgroup$ – pericynthion Jan 24 '20 at 4:05
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According to this F-16 turn performance chart, at the rated maximum airspeed of 800 knots, an F-16 can turn at about 10.5 degrees per second, so a 90° turn would take about 8.5 seconds. The turn radius would be 9,000 feet. Since you specified a 90° turn to avoid an infinite wall, the pilot would have to start their turn at or before 9,000 feet from the wall in order to avoid a collision.

However, this doesn't tell the whole story. The F-16 can't maintain speed in such a turn, and the reduced speed would in turn reduce the turning radius. If the plane, for whatever reason, absolutely had to maintain its maximum speed, then it would be limited to a turn rate of 3.5 degrees per second and a turning radius of 25,000 feet.

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    $\begingroup$ If the point of the exercise is to avoid the infinite wall, then bleeding airspeed would be immensely helpful since it reduces your turn radius... go idle, 90 degrees bank, and pull 9 G's; the speed will bleed off rapidly and the turn will be complete much sooner than 9,000'. Or idle & pull 9 G's straight up, bleeding speed in the vertical, adding power as necessary to complete the Immelman. $\endgroup$ – Ralph J Jan 24 '20 at 5:38
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    $\begingroup$ @RalphJ True, but since the OP was very specific about the "flying as fast as possible" part, I assumed they wanted top speed maintained throughout the turn. Unfortunately, I don't know of any published performance information for any plane that includes variable-speed turns, so you'd either have to simulate the turn mathematically (something that's beyond me), or else get a real F-16 and test it (also beyond me). $\endgroup$ – HiddenWindshield Jan 24 '20 at 6:06
  • $\begingroup$ @HiddenWindshield : Your assumption was right(should have mentioned it, my fault sorry). Also, could you include the turning downward part so that that I can mark it as the answer. $\endgroup$ – Valay_17 Jan 24 '20 at 11:54
  • $\begingroup$ @RalphJ : Would the pilot experience 9 G’s!! of force ?!?! $\endgroup$ – Valay_17 Jan 24 '20 at 12:01
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    $\begingroup$ @HiddenWindshield If the scenario is to avoid crashing into an obstacle, the idea of maneuvering but only in such a way that the speed can't decay (even if that requirement impedes the ability to avoid death by crashing), has left the realm of reality & entered into an academic, and not particularly interesting, exercise. If you're not allowed to pull max G because doing so would bleed airspeed & reduce the turn radius, then "maintain parameters" has become more important than survival, and it's hard to keep caring about such a hypothetical at that point. $\endgroup$ – Ralph J Jan 24 '20 at 16:30

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