Sunday, June 10

Math errors can have bad consequences


Snowflakes and morons believe math is meaningless.  Trivial.  Geek stuff.  If something's really important, the snowflakes will know about it, and won't be shy about telling you.

Ah.  But this photo shows the results of a $20 million math error.

The guy ascending to the sky is--well, was--a member of the Air Force Thunderbirds aerial demonstration team.  They're good pilots, but even good pilots sometimes...

The guy was doing a routine aerobatic maneuver called a "split-S:"  Starting at 50 feet or so, the pilot executes about two-thirds of a loop, but instead of completing the loop, you roll the airplane 180 degrees and pull out at the same height you started--in this case 50 feet or so.

At least that's the idea.

Of course the airplane is only able to pull a certain number of g's --multiples of the force of gravity--so if a pilot starts the pull-out maneuver too low, then even with maximum effort the airplane can't stop descending before it hits the ground.

The height above the ground at which you have to start the recovery is well known (different for each airplane, of course).  The pilot has an altimeter that tells him his altitude, but above sea level, not above the ground.  So before the flight he finds the altimeter reading when he needs to start pulling out by adding the height needed above the ground to the local ground elevation.

This particular demonstration was at Mountain Home AFB, which is about 3000 feet above sea level.  The pilot simply didn't add correctly, with the result that he started the pullout about 700 feet lower than he should have.

Capt. Stricklin and the airplane tried valiantly to pull out, and video shows that the plane did achieve a nose-up attitude before impact.  Unfortunately, although the nose was up, the aircraft was still going down at several thousand feet per minute.  (I flew a jet with similar aerodynamic characteristics, and it's really disconcerting to be nose-up and yet still going down at 6000 feet per minute.)

Stricklin punched out something like two-tenths of a second before impact, and was uninjured.  The poor plane was less fortunate--$20 million bucks of hot aluminum scrap.

So for my students:  When I insist that you do "head math," be very glad that the only penalty for a wrong answer is a few points off, instead of having to punch out of a perfectly wonderful, perfectly working airplane just before it makes a big flaming hole in the ground.

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