Tuesday, March 27, 2012
Flying The World’s Biggest Single-Engine Biplane
An open letter to all who have asked, “What’s the weirdest airplane you’ve flown?”
When Gothard suggested we try some stalls, I was eager. I knew the huge wings would generate a ridiculously low stall speed, but I had no idea it would be as slow as it was. I reduced power on the big 1,000 hp Shvetsov radial and watched the airspeed wrap backward around the dial. As we decelerated, the Antonov's automatic leading-edge slats banged in and out together or independently when lift was asymmetric. Wrap the Colt into a steep turn, and the slats would adjust to help keep the wing flying.
Speed dropped through 60, 50 and finally all the way down to 40. At that point, the slats were fully extended and the Colt set up a gentle mush downhill, still under total control with no tendency to roll or manifest any other nasty characteristics.
I turned to Gothard and said, "That's impressive for such a big airplane, a 40-knot stall." Gothard smiled. "Those aren't knots," he said.
"Okay," I said, "Forty mph is even more amazing." The owner grinned even wider and said, "Those aren't miles per hour."
My God, I suddenly realized, the ASI was calibrated in kilometers. Stall speed was an indicated 40 kph, equal to 22 knots. Perhaps coincidentally, that's exactly what the book suggests.
Before we returned to land, I had time for a quick cruise check, though Gothard had already suggested speed wasn't the Colt's long suit. At max cruise power, the ASI finally settled on 165 kph, about 90 knots. That was in exchange for 45 gph.
With 770 square feet of wing and such a low stall speed, it's not hard to understand why the AN-2 can land and stop in less than 600 feet. I couldn't check the numbers, but the specs suggest the Colt is one of the few machines that can lift off in less distance than it needs to land. In other words, you can't land someplace you can't get back out of.
The Colt's docile nature at low speeds can be a lifesaver. The flight manual doesn't list a stall speed and even suggests an emergency, zero-zero, IFR procedure of slowing the airplane to minimum flying speed and allowing it to mush through the clouds into the ground.
(According to the manual, "When the airplane slows to a forward speed of about 40 kph [25 mph], the aircraft will sink at about a parachute descent rate until it hits the ground." If the AN-2 is straight and level at touchdown and lands in open terrain, it's liable to be nearly undamaged, and everyone on board is likely to walk away, as well.)
Buzz Gothard's unusual Russian biplane flies like it looks: huge in every respect. Still, the type continues to serve, mostly in Third World countries, all around the globe.
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