ARLINGTON – For retired Boeing Engineer Neil Knutson, he became enthralled by the wonder of flight as a boy in the late 1950s on the family farm near the Arlington Airport.
Knutson built and launched his first motorized balsa free flight plane, a Ranger 30, from the then ultralight park with too much fuel and too little instruction, and put his name and address on the fuselage. “It went up and up, we heard it for three-and-a-half minutes, then it disappeared, so we went home. In the mailbox a week later, we get a letter from Bremerton, and here was the part of the body with my address label on it. It ‘thermaled” to Bremerton, hit a swing set when it came down in a guy’s backyard and destroyed itself.”
After that flight gone awry, Knutson was hooked on plane building. He moved on to control line and hand-launched gliders, then RC planes.
But he said there’s nothing that brings out the competitive spirit and memories of yesteryear more than rubber band-powered planes. He and a group of like-minded engineers and a science teacher are keeping the fun hobby alive in Arlington – indoors, and sharing it with younger generations.
The so-dubbed “Flyboys of Highland Drive” refers to the road outside the Arlington Free Methodist Church gym, their temporary indoor air park where the members have flown their rubber-band powered planes over the past four years.
“We’re just a bunch of 70-year-olds having fun with six bucks,” said Al Hjort, an age that applies to most of the members.
A grateful Knutson said the gym is an optimal place to flyer because other than the basketball backboards, unobtrusive ceiling lights and a few mounted speakers, there are few other obstructions that can send their planes into a tailspin.
Knutson said between them the group has 245 years of experience.
Not surprisingly, it takes a lot of twists to get a rubber band taut enough to turn a propeller for a long period.
Knutson shared the example of using a micrometer to measure the width of a rubber band loop he plans to use. He ran it through a gear winder hand-built by a machinist.
“I’ll wind the rubber band to destruction, I’ll stretch it out, then figure I should get about 150 turns per inch on this size rubber, so I should get 600 turns,” he said. The process maximizes the amount of tension to near snapping, then the plane is read to soar.
At the same time, group member Dave Higgins, another Boeing engineer, was putting just under 2,200 turns in the 72 inches of rubber band he planned to use for an extended flight in the gym.
“If it goes up and hits the ceiling, I’ll back the number of turns down to avoid that happening,” Higgins said. The flyers keep log books and journals to track progress with their planes.
There’s also the matter of reducing the weight to collectively increase the amount of time the plane will remain airborne. A plane that reduces its weight by 25 percent generally results in a 35 percent increase in flight time.
Knutson said there is plenty of science, math, engineering and design factors that go into making and flying the planes.
“Many of the things that Boeing does for the commercial airliners we incorporate into these planes,” said Knutson, a former Boeing engineer. “We have weight and balance, center of gravity, center of pressure versus center of life and more. There are all kinds of settings that we build into the airplane, and then to make them behave themselves, we tweak them.”
Outside the gym, he flies RC planes with a group called the Arlington Eagles in a field on Highway 530, and on leased farm property east of Marysville-Pilchuck High School.
The group a week ago visited Finn Hill Middle School in Kirkland, a hotbed for youth interested in building and flying rubber band-powered and other planes. The team brought laser cut kit planes for the Mountain Lion Mark III, teaching the kids how to build the seven-gram flyers in just over two hours. A dozen kids entered their planes in a timed competition, and the winners were two 12-year-old girls, one a repeat winner from last year.
Brian Roberts, a member and science teach at M-P, said kids learn a lot when building balsa and bass planes.
“They learn about measurements, how to read blueprints like the ones at Boeing, and use tools” that may seem foreign to them, Roberts said.
“The biggest lesson is when the kids see the visual concept of the plane on paper, then see the actual plane in 3-D,” he said.
Higgins said the technique for take-off is simple. Let the propeller spin a bit at first, then gently release the hand-held plane and give it a little push.
“If the calculations and the number of rubber band turns is right, it should be up in the air for about a minute and a half, but I’m trying to get this plane up to two-and-a-half minutes,” Higgins said.
The plane circled higher and like a hungry Eagle, gaining elevation as it passed the basketball backboard. Then, it went too wide, clipped a wall that deflected it off course to a chorus of “oohs,” then ran out of steam as it landed on the court.
The gym record is 5 minutes, 16 seconds.
“That was a good flight,” recalled Roberts, “But I think we can beat that with the right design.”
Probably, but if they want to challenge the world record of 1 hour and 4 minutes, they have their work cut out for them.
Want to fly?
The group meets the 2nd and 4th Tuesday at 6:30 p.m. in the Arlington Free Methodist Church Gym, 730 E. Highland Drive, (excluding the 4th Tuesday next month on Christmas Eve). They welcome any interested children, parents and adults to stop by and get involved.