strange behaviors

Cool doings from the natural and human worlds

  • Richard Conniff writes about behavior, in humans and other animals, on two, four, six, and eight legs, plus the occasional slither.

  • Categories

  • Wall of the Dead

Ready for Takeoff Part 3: Time for a Stunt

Posted by Richard Conniff on May 18, 2011

Preparing for the first Atlantic crossing

By 1998, McGeer was regularly flying Aerosondes, often operating out of an old school bus von Flotow owned. But atmospheric research was a niche market at best, with few customers in sight. “Maybe it’s time for a stunt,” von Flotow suggested. He had in mind the first Atlantic crossing by an unmanned aircraft. “I didn’t want to do a stunt,” says McGeer. “I wanted to fix our problems. We needed to test-test-test, break, fix, test-test, but we didn’t have the money to do it.”

He lost four aircraft in 200 hours of flight that spring—an average of 50 hours between failures. But even at $25,000 apiece, his cost at the time, drones are meant to be expendable. McGeer figured that an Atlantic crossing would take about 25 hours, “and I said, ‘OK, so if we send four aircraft across the ocean, our chances that one will make it are better than 90 percent.’ ” A major defense contractor in San Diego was also planning the first Atlantic crossing, with a drone (and a budget) the size of a 737. The Los Angeles Times billed it as a David-and-Goliath contest.

That August, on Bell Island in Newfoundland, McGeer sent a rental car racing down the runway with an Aerosonde on top, the first of two launches that day. On South Uist Island in Scotland, a BBC crew set up movie cameras and waited. Back then, says McGeer, ground control could communicate with a drone for only about 50 miles at either end. The team programmed in GPS waypoints and prayed that the planes would find them on their own. The plan, developed with a meteorologist from the University of Washington, was to make the 2,000-mile crossing on 1.5 gallons of fuel. After both drones failed to arrive the next day, the BBC packed up and went home.

Three days later, McGeer launched two more drones. On South Uist the next day, a blip flashed on a laptop screen, then disappeared, leaving the landing crew tensely waiting. Soon after, a drone dropped down from the sky and landed softly in the grass. McGeer got the word by phone, in classic mission control monotone: “We have something you lost.” When he returned his rental, McGeer was thinking, “‘This is a historic car!’ But we had scratched the roof a bit and decided not to mention it.”

The achievement attracted potential customers in the tuna industry, which had suffered a series of deadly crashes of fish-spotting helicopters. The Pentagon also “began to make cooing noises,” says McGeer; drones had been doing military work almost as long as there had been aircraft, with uneven results.

McGeer and von Flotow decided to focus on tuna. “Tad has a basic conflict with the Eisenhower military-industrial complex thing,” says Juris Vagners, a colleague who teaches at the University of Washington. “He wants to do civilian stuff.” For the tuna industry, McGeer and von Flotow developed the SeaScan, a drone with a camera turret. They also had to figure out how to make takeoff and landing user-friendly for fishermen working on the deck of a small ship. For the launch, they devised a catapult powered by a Sears, Roebuck air compressor, with a release mechanism triggered by a man yanking a rope. Recovery was more complicated.

McGeer eventually hit on the idea of flying one wing of the drone into a vertical rope, with the rope quickly slipping out along the leading edge of the wing to snag on a hook at the tip. Cutting the rope with the propeller wasn’t an issue because the prop is mounted at the tail, safely out of the way. The problem was developing a hook that would cause the plane to hang in midair, rather than slide down the rope and smash into the ground.

They tested mechanisms on von Flotow’s farm, using a plywood model of a SeaScan at the end of a five-foot rope. “I stood on a trailer and spun it around like a hammer thrower,” recalls Cory Roeseler, who does what he calls “grunt engineering” for McGeer and von Flotow. But instead of releasing it like an Olympic athlete, he sidled the model over to a vertical line stretched down the corner of a barn. “When you hit the line, you can figure out which hooks snag and which hooks fail. You can do that in an afternoon. Good ideas rise to the top quickly if you have some plywood, a cordless drill and some good thinkers.”

Skyhook

The “skyhook” technology they developed in this fashion now gets used a thousand times a month, on land and sea, almost always without incident. But it is still a spectacle. The drone circles for its approach, then comes whining in at about 50 miles an hour. GPS devices on the skyhook and the plane communicate, like air traffic control talking to a pilot, and the plane adjusts to an accuracy of a half-inch or less. Then it slams into the rope and snags 25 feet in the air, causing the skyhook to buck and sway as in an earthquake. “Holy Christ! That’s violent,” says a visitor seeing it for the first time. An engineer’s view, says McGeer, with a proud, parental smile, is, “Just violent enough.”  (Continued)

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s