PDA

View Full Version : New Cub landing gear system


Cyclic Hotline
11th Jul 2005, 05:44
Story here (http://www.adn.com/money/story/6694520p-6581423c.html)

Inventor finds a better way to land a Super Cub airplane on difficult terrain

By SARANA SCHELL
Anchorage Daily News

Published: July 10th, 2005
Last Modified: July 10th, 2005 at 04:54 AM


Nearly a decade ago, a complaint at a Christmas party spurred Chugiak airplane part maker Burl Rogers to improve on the suspension system for Super Cubs, the slow, small plane that's endeared itself to Alaska pilots for its ability to land on all kinds of remote and often lumpy terrain, from ridgelines to gravel bars.

Rogers's persistence and wallet were taken to the limit as he revised and abandoned version after version in his shop north of Anchorage, but now he's finally selling a part-titanium contraption, filled with a secret-formula shock absorber, that's getting the thumbs up from pilots.

"This is a better mousetrap," said Mike Butterfield, a Yakima, Wash., pilot and mechanic who said he's been working on Cubs for 25 years. "The original shock wants to fling the plane back into the air."

That system relies on super-heavy-duty rubber bands that can be dangerous as well as bouncy, he said, because an installer can lose a finger stretching bungees that hold 1,000 pounds.

"They're a 'take off across the room, kill the cat' kind of thing," Butterfield said.

Rogers stacks a series of translucent green polyurethane discs inside a metal tube to absorb the jolt of touchdown.

The units are spendy at $2,200 a pair, but cut maintenance costs from some $200 every year or two to $8 for a single seal. Mike Meekin of Meekin's Air Service bought a pair.

"I definitely save money," Meekin said.

Rogers applied for a patent in 2001, got it in 2003, got FAA approval last spring and started manufacturing the units last fall, with financing from Northrim Bank. He estimates he spent $600,000 on research and design.

"It was all out of pocket," Rogers said. "The dollars become a lot more dear at that point."

Coordinating 18 U.S. subcontractors, most in Washington, was a challenge, he said.

"We finally got all the cats herded in the right direction," Rogers said. Now he assembles the parts in his shop near Birchwood Airport.

Butterfield and others report Rogers' discs have a lower bounce-factor on landing.

"He had some really innovative things in his design," including nickel and zinc coatings, said Dave Swartz, senior engineer in the FAA's Anchorage aircraft certification office.

The office's nine engineers mostly solve safety problems statewide. But they still have plenty of time to help Alaska's community of aviation innovators, Swartz said.

Rogers is one of many inventor entrepreneurs who have been cranking out ways to make extreme flying safer for years, Swartz said.

Like extended landing gear for Super Cubs to keep the propeller clear of bushes and rocks, a wider body to hold more, and a special wing that improves control at a wildlife-spotting crawl.

FAA engineers help people design testing for their gizmos to meet FAA requirements, Swartz said, and more if they want.

For the FAA, landing gear has to cope with "a pretty lousy landing on a runway," Swartz said.

"Burl wanted to go beyond that."

Rogers, 62, said he drove his parents crazy spending all his money on model airplane kits. His father, a pilot, moved the family to Alaska in 1953. They drove into town and past Merrill Field in a torrential downpour. Rogers had never seen so many small planes.

"I just went nuts," Rogers said. "I was in heaven."

Rogers has been a pilot, mechanic and manufacturer, making parts from door handles to axles, in Alaska for years, Swartz said, giving him a good group of skills to take suspension up a notch.

"I remember talking to Burl a lot about landing Super Cubs on mountaintops," something Rogers has done often, Swartz said. "The landing gear gets a real good workout."

So Swartz advised Rogers on how to measure his progress toward what he wanted, as well as what the FAA needed. It took more time, but that's OK.

"It's in the interest of safety, so we don't mind," Swartz said. "We know the pilots are going to be out there doing this anyway."

The spark to embark on the project came at a Christmas party about eight years ago, as a friend groused about rebuilding his Super Cub.

Why, in this day in age, hadn't someone invented a better shock and suspension system, Rogers remembered his friend grumbling.

"I thought to myself, 'I could do that,'" Rogers said.

Two years later, he had a prototype that was too stiff.

After two more years, Rogers gave up on making a direct replacement for the standard suspension system.

Committed to a more expensive replacement for the suspension and strut together, he said, he decided to add some "wow" factor and make it adjustable.

If a plane on the old suspension system is overloaded, maybe after a successful hunting trip, the wheels can actually splay, Rogers said.

"Not that that ever happens in Alaska," he added, with a hint of a smile. If it ever did, Rogers said a few torques on his system would pull the wheels back in, giving better control.

Five years into the process, Rogers believed his landing system was ready for an FAA-required "cold" test, onto shocks chilled to minus 20 degrees. He loaded up his FAA-approved testing system that had taken nearly three weeks and a thousand dollars to build, and dropped the weight of a landing Super Cub onto wheels and struts fitted with his suspension system.

"It was an absolute disaster," Rogers recalled.

"It looked like the whole thing was going to go down the tube."

Standing in his tidy shop, neat shelving units lined with cardboard boxes and orange, green and blue plastic containers of parts, an ancient miniature dachshund named Spinner asleep in the corner, Rogers laid out how he'd found his way to a solution.

"You keep following the bread crumbs," he said. Hunting around the world on the Internet, he would ask questions and be referred to someone else.

"Next thing we're dealing with design engineers" for polyurethane, Rogers said, to come up with the secret formula for the shock-dampening discs that still flex at low temperatures.

In May 2004, a year to the day after that disastrous cold-weather test, Rogers was ready to do it again, with FAA inspector Swartz in his driveway, watching and recording into the evening.

"We were swattin' mosquitos at 10 o'clock at night, I think," Swartz said.

Of course there was one more problem to solve.

Rogers needed to chill his shocks and a comparison standard set. He had 100 pounds of dry ice, but couldn't keep both sets equally cold. He tried ice-melting beads to make a cooling solution. That didn't work, but windshield wiper fluid did the trick. With the shocks finally as cold as the FAA required, the tests could proceed.

Three times, Rogers dropped test weights onto shocks chilled to minus 20 degrees.

One last drop remained.

This one, hard as the worst landing the system must withstand, is allowed to make the part bend, but not break.

With his hand on the quick release cord, Rogers realized this was it.

"It all came home to me," Rogers said.

Everything invested -- the years, money, energy -- gathered in the moment and hung there, with the weights, over the shocks.

Rogers pulled.

The weight dropped.

"It landed so soft. My first reaction was 'We could've dropped twice the weight!' " Rogers said.

Now he's actually selling the Alpha Omega Suspension System -- some 40 pairs of them so far, to friends, out of Glacier Aircraft Parts in Palmer, to someone in Kenya -- and getting approvals, known as STCs, to use them on other types of planes.

"Now that the dust is settling," Rogers said he's thinking about other projects. "I have 11 or 12 more STC applications hanging fire."

QDMQDMQDM
11th Jul 2005, 09:25
http://www.supercub.org/phpbb2/viewtopic.php?t=6479&highlight=omega+suspension

Not so much opportunity for a Cub driver to use this system in the UK.

QDM