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
"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
"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.