Beyond Flaps

Boeings 727 has always been one of my all-time favorite airplanes. Ive never flown in one as anything other than self-loading freight, but Im old enough to remember when the 727 (and the DC-9) brought jet comfort and performance to smaller, outlying airports where the eras long-haul mainstays-707s and DC-8s-couldnt operate. These days, of course, economics-fuel burn, plus the need to pay three pilots-and noise regulations have relegated the venerable three-holer to tramp-freighter status or the scrapyard.

Joseph E. (Jeb) Burnside

Monday, August 20, 2018 at 12:00 AM ET

Verified

Key Takeaways:

Aircraft like the Boeing 727 achieved superior low-speed performance and control through specialized wing designs featuring high-lift devices.
Key among these are slotted Fowler flaps, which increase wing area and delay airflow separation, and leading-edge slats/Krueger flaps, which enhance camber and create slots to boost lift.
Further aerodynamic aids, such as wing fences and vortex generators, are employed to control spanwise airflow and energize the boundary layer, respectively, maintaining lift and control effectiveness closer to a stall.
These innovations are crucial for enabling operations from shorter runways and improving overall safety and handling during slow flight conditions.

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Boeing’s 727 has always been one of my all-time favorite airplanes. I’ve never flown in one as anything other than self-loading freight, but I’m old enough to remember when the 727 (and the DC-9) brought jet comfort and performance to smaller, outlying airports where the era’s long-haul mainstays—707s and DC-8s—couldn’t operate. These days, of course, economics—fuel burn, plus the need to pay three pilots—and noise regulations have relegated the venerable three-holer to tramp-freighter status or the scrapyard.

I didn’t know it at the time, but one of the things that enabled the 727 to reliably operate to and from smaller, regional airports was its wing. Not having pylon-mounted engines helped simplify things a lot, but the real tricks were in the slotted Fowler flaps and leading-edge slats all 727s came with, and which are now commonplace aboard jet transports of almost any size and configuration, as well as general aviation airplanes. What’s so special about these devices, and what else might help with the low-speed handling of the personal airplanes we fly?