Tinkerer Displays Modifications At AirVenture 2007

by ANN Correspondent Jeremy King

It started out innocently enough. Art Mattson bought a Cherokee 140 in 1991, and he quickly realized there were many airports he couldn't operate out of. 

"There are a lot of grass airstrips around here," Mattson said, "But they're too short for a stock '140. I could land there; taking off was another story, though."

Mattson's desire to make his Cherokee into a STOL performer, however, doesn't justify why his Cherokee 140 -- which looks stock from a couple rows away -- was parked amongst the racing speed demons at AirVenture 2007. That story takes some telling.

"So I came here [in 1992] with the intent of learning how to make my plane a short-field performer," Mattson said. "I listened to three designers: Steve Wittman, John Roncz and Chris Heintz. All three told me that the wing-to-fuselage juncture was critical; two of them told me that vortex generators were a must."

He went home and started cutting metal, but first he had to re-license his airplane as Experimental-Research and Development.

"I did the first flight test with the VGs and was totally astounded," Mattson said. "What they did was so dramatic, on both ends of the flight envelope. Yes, they dramatically improved the airplane's ability to get off the ground, but they gave me speed on the top end. Almost everyone said, 'It can't be,' and that led to racing."

"I'd heard about the race at Sun N' Fun," Mattson continues. "At that point, I had the vortex generators and new wingtips installed, and I had an early start on gap seals."

He won his division with what he called "a ratty plane. I was one tenth of a mile an hour slower than the Cherokee 180s. The speed bug bit me."

The vortex generators' effect was so dramatic, he wanted to share the magic with other pilots, but that takes a Supplemental Type Certificate. After working with the FAA, Mattson worked up a STC -- the first of four so far, and they're for what he says are must-haves for Cherokee 140 owners: the vortex generators, a propeller-tip modification, wingtips and gap seals. Mattson has STC's for each.

Mattson says his customer list is 2,000 strong, but cautions that many don't go for all modifications. Those four modifications yield the most improvement, though.

So what's next? The wheel pants sport winglike appendages on the main wheels, and the nosewheel pant is a bulbous affair that might defy logic, but Mattson says it's solidly based on computations. They've only flown a couple of times so far, and the numbers aren't etched in stone.

Take a look at his plane next April in Florida, and you'll know whether the pants work. Right now, with an extra 10 horsepower, Mattson says his plane is good for 160 mph; he says he'll be happy with 170. We'll see how long that idea sticks.

FMI: www.pipermods.com