Yuliy Gerchikov wrote:

That's precisely the problem: exactly what volume of air do I need to exit?

Only that volume of air (the size of your glider) through which the
traffic is about to pass. Quite small, really.


At those distances and rates of closure it is very difficult to estimate the
point of impact in 3D, especially given the extremely limited time for
decision.

Difficult? Limited? Relative to what?


No ball game that I know comes close to the order of magnitude of
parameters that we deal with here.

Then you don't know Baseball.

If you'd ever stood in the batter's box and had a good pitcher throw a
fast ball high and inside, and then compared that experience with a
high speed closure with another aircraft, you'd find that the numbers
don't really tell the story. No number can describe the actual
experience -- you just have to be there, in the game or in the cockpit.

But if you do prefer numbers, here they a at 420 kts closure with
another aircraft (708.8667 fps) from only 1/2 nm out (3038 feet) you
have a leisurely period of 4.2857 seconds which you can use to avoid
impact; compare this with the release of the baseball from the pitcher's
hand at considerably less than the nominal 60' 6" to the plate (but call
it 60 feet) at 90 mph (132 fps, and 13 mph SLOWER than the fastest
recorded pitch) which gives you 0.4545 seconds until impact (hopefully
with your bat and not your head). If this gives you renewed respect for
Ted Williams (life time batting average .344) as a baseball player as
well as a fighter pilot, that's good too. Of course, we need to bat
1.000 when it comes to traffic avoidance, but even with only 0.5 nm
separation at 420 kts we have almost ten times as long as we would when
standing in the batter's box to decide what to do, and make our move.

I assume you have already found out that you can hear a powered
aircraft from the cockpit of your glider. You can hear that baseball
coming too, which adds to the fun. And, you will remember that sound
also, but only if the ball misses your head.


This is closer to dodging bullets than it
is to any ball game.

At a muzzle velocity of 860 fps, the .45 pistol bullet is traveling at
509.5458 kts, or about 21% faster than the aircraft in this example.
However, it has a diameter of 0.45 inch whereas the cross section of the
Hawker 800XP is a 2-3 meter oval, sans wings and tail. Not at all
comparable. I'll take the Hawker 800XP challenge at a half mile every
time over the .45 ACP challenge at 20 paces. YMMV. As for the baseball,
at ~three inches in diameter, it's a better deal than the 230 gr FMJ,
but the Hawker 800XP is still the easiest of all to deal with, by far.

None of these three "sports" is for the indecisive, or the feint of
heart. The advantage is very definitely to the observant, the trained,
and the confidant. One must deal successfully with the numbers, and the
experience -- and it can be done.


Jack