Carbon Cub UL climbs above altitude record

The airplane, N14UL, was flown by Alaska pilot Jon Kotwicki and climbed for 62 minutes to where the outside air temperature was minus 51 degrees Fahrenheit.

The turbocharged, 160-horsepower Rotax 916iS engine was operating at 100 percent power and turning 5,826 rpm at 23.2 inches of manifold pressure when the airplane topped out at a pressure altitude of 35,720 feet. Its indicated airspeed was 61 knots (113 knots true airspeed) at the top of the climb.

The Carbon Cub might have gone even higher without the relatively heavy and draggy 29-inch Alaska Bushwheel main tires, or a cooler temperature. The standard temperature at 37,000 feet is minus 56 degrees Fahrenheit, about 5 degrees colder than the Carbon Cub recorded at its apex.

The effort was managed by Paulo Iscold, an aeronautical engineering professor at California Polytechnic State University (Cal Poly) in San Luis Obispo who has been involved in numerous aircraft performance records around the world. It also included assistance from CubCrafters, Rotax Aircraft Engines, Mountain High Aviation Oxygen Systems, and the Los Angeles Air Route Traffic Control Center.

Though not an official record attempt, the team set out to exceed the altitude record for Cub-style airplanes of 30,200 feet. Kotwicki departed San Luis Obispo County Regional Airport just before 10 a.m. Pacific time. The airplane was performing well, and flight conditions were good, so they decided to keep climbing.

“We didn’t know how high we could go,” Kotwicki said, “and we were honestly surprised to reach that altitude . . .”

At one point during the flight, a Southwest Airlines pilot reacted with astonishment when he heard Kotwicki ask ATC for clearance to climb to Flight Level 350, or 35,000 feet.

“What kind of aircraft is that that’s climbing to thirty-five that’s trying to see how high they’re going to go?” the Southwest pilot asked.

When the controller said it was a Super Cub, the Southwest pilot seemed incredulous.

“Absolutely amazing,” the Southwest pilot said. “Good job.”

Kotwicki, whose Alaska flight school and aeronautical bed-and-breakfast were featured in the November issue of AOPA Pilot ('Disneyland for Pilots'), hand-flew throughout the record attempt and said the Carbon Cub handled well at all altitudes.

“The Cub flew really easy,” he said. “It was pretty dang cool to be in a tube-and-fabric bush plane that high, and it was surreal hearing airline pilots over ATC wondering what a Cub was doing up there.”