For Safe Landings On Two Planets
The 2013 National Air and Space Museum Trophy Winners.
- By The Editors
- Air & Space magazine, April 2013
NASA / JPL-CalTech
(Page 5 of 5)
I felt strongly that even though the articulated flap array we designed was heavy, it was definitely the way to go for overall safety. The audit gang disagreed, saying we should get rid of the third slot of this triple-slotted flap. When I countered that a double-slotted flap would not meet our performance guarantees for approach, landing, and stall speeds, they replied that those promises should be renegotiated.
Our most important commitments were to launch customer Pan Am. I volunteered to go back to Pan Am and ask whether they would settle for a higher approach speed, but Boeing management turned me down. The audit people felt I was biased and would not do an energetic job of selling this proposed change, which was true, so Maynard Pennell [manager of Boeing’s supersonic transport program] instead attended to it during an SST-related trip to Pan Am in New York. Maynard was well respected. I’m sure he presented this proposed design change as well as anybody could. John Borger heard him out and said, “If you want to take the third segment off, be my guest. But you still have to meet the approach-speed guarantee stipulated in our contract with you.”
Going to a double-slotted flap would have dictated an eight-knot rise in approach speed. Eight knots is 9.2 miles per hour, or 15 kilometers per hour. That’s not a very big difference, so why did it matter to Borger and me both? Because braking distance increases with speed and it’s not a linear increase. Borger knew it would be meaningful in real-world operations and he stuck to his guns, holding us to our promise. I am grateful to him because that triple-slotted flap is a key reason the 747 has consistently been so very safe in service.