the obsessives

60 popular science May 2008

WING MENOn the eve of the world championship of remote-control flight, an American financier, a three-star general, a jet engineer and the Air Force’s most powerful civilian have come together in Thailand to build the perfect fighting plane—at 1:5 scale By ToM Clynes phoTographs By john B. CarneTT

three key facts

The annual Top Gun competition, the Olympics of remote-controlled aircraft, draws the world’s elite hobbyists.

Mike Selby, an American expatriate living in Thailand, has assembled a team of military and civilian aeronautics experts to create a super-sophisticated scale jet.

The result, an A-10 “Warthog” fighter 10 feet across, should dominate—if it doesn’t crash first.

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If A sOdden rIce paddy feels soft and forgiving underfoot, it is not a merciful place to set down an airplane at 200 mph. And that’s only one of Mike Selby’s reasons to look nervous as he watches his A-10 Warthog—a 10-foot-wide, 65-pound, hand-built model—begin its maiden takeoff roll down a rough asphalt runway near Bangkok, Thailand. Selby, who spent over $12,000 and the better part of a year fabricating and building this radio-controlled jet, stands runwayside with his thumbs hooked into the belt loops of his jeans, trying to look relaxed as he draws on a Cuban cigar. But he can’t stop tapping his foot. Next

to him, pilot Ray Johns, a U.S. Air Force general and test pilot who has flown everything from Air Force One to the U2 surveillance plane, chews a wad of gum with anxious rapid-fire chomps and leans back against the weight of the control console hanging from his neck.

It’s been nearly a year since Johns last flew one of Selby’s finished mod-els, at the Top Gun competition in Lakeland, Florida, and the memory haunts them both. Top Gun, held each April, is the de facto world champion-ship of radio-controlled scale-model aeronautics, an invitation-only event that hosts some 130 entries, jets and prop-planes alike, from around

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fLIGHT cOnTrOL From left: Bill Davidson, Pornchai Saechour [hidden], Ray Johns and Mike Selby with their remote-control A-10 jet

the world. Selby had spent the two years before the event building and tweaking his Embraer Tucano 312 (a Brazilian turboprop fighter trainer), and the plane had a grip on first place going into its final competi-tion flight. But suddenly, as it went into a tight turn, the plane stopped responding to Johns’s control inputs. “We saw it jink to one side, and then it just keeled over and dove into the forest,” Selby says. “We had to rent a helicopter to recover the pieces.”

Now, half a world away, Selby’s chance at redemption is taxiing into place on the runway: a sophisticated new plane that’s already creating a buzz among the top echelon of the model-aeronautics community. “I wouldn’t be surprised if he blows the event away with the A-10 this year,” Top Gun organizer Frank Tiano told me earlier by phone. He’s seen pic-tures and specs. “It’s big, it’s a jet, it’s twin-engined, it has an extremely high level of detail and function. As far as I can tell, there’s rarely been an airplane this ambitious, with as much character and as much charisma.”

But it’s not an airplane—model or full-size—until it flies. Johns, from his position halfway down the run-way at Bang Nam Prio, commands bystanders to silence and seems to grow taller as he pushes the remote-control throttle forward. The A-10’s twin engines scream to life, turning

the head of a straw-hatted woman herding a group of water buffalo on the other side of the runway.

As the turbines spool past 100,000 rpm, Johns releases the brakes, and the A-10 begins to roll. With its twin rudders buffeted by a gusty crosswind, the fighter jet zigzags awkwardly at first, before Johns gets it straight-ened out. It shrieks past us at full throttle, tracking down the runway’s centerline. Then, with a subtle tug of his index finger, Johns lifts the plane’s nose, and it bounds into the air with an almost startling decisive-ness. Selby squints and watches his creation climb and bank to the left, its silhouette tapering into the sun.

BesT Of THe BesTScale-model jets are the apogee of radio-controlled model aeronautics: The technical challenge of building jet power in miniature is far beyond the abilities of the average hobby-ist. Handcrafted by an elite cadre of backyard aviators, these models can fly at speeds of up to 300 mph, and at Selby’s level of competition, they’re built to look and perform exactly like their real-life counterparts.

“We’re at the obsessive end of the spectrum,” Selby says. At the age of 53, he’s thin and fit, with a calm, quick smile. He flew model airplanes as a kid in Rochester, New York, and brought his hobby with him when he began

as these guys. There are about 200 who have the skills to execute what they dream up. And of these 200, there are maybe two dozen guys like Mike who can create something truly remark-able.” Those people would be Selby’s competition at Top Gun in April.

Among them is Walt Fletcher, who retired from the U.S. Army Spe-cial Forces to run the Hobby Hut in St. George, Utah. He is readying a one-third-scale Fokker DR-1 triplane, flown by World War I flying ace Baron Manfred von Richthofen, a.k.a. the Red Baron. The pilot’s head will turn left or right, and he’ll be able to wave to the judges as the plane goes by, Fletcher tells me. “And it’s got speakers that blast out sound bites of the Le Rhone rotary engine and the machine guns.”

David Wigley of Smithtown, New York, pilots Boeing 767s for American Airlines in what he calls his “full-size life.” His entry in the Top Gun Mas-ters class this year will be a Westland

Wyvern, a British Royal Navy strike fighter from the early 1950s. Wigley designed and built the obscure plane from scratch over four years. Among its details are counter-rotating pro-pellers, a droppable torpedo, and a functioning pneumatic tail hook for landing on model aircraft carriers.

But Selby and Johns, also 53, have built a Top Gun dream team over the years, and the roster inspires confi-dence. Their crew includes Bangkok scale-jet-engine builder Pornchai “Hard Porn” Saechour and pit crew/logistician Bill Davidson. By virtue of his position as administrative assistant to the Sec-retary of the Air Force, Davidson is the top career civilian in the U.S. Air Force, and he may know more about military aircraft than anyone alive. (According to his wife, Peg, he can sit inside their house and identify just about any over-flying plane by sound alone.) Practice time for the flight crew is limited to a week each January, when Selby, Johns

at the top gun competition “they’re judging realism in flight,” selby says. “whether it turns quickly like a fighter or sluggishly like a bomber,” it has to fly the same in miniature.

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working in Asian finance in his 20s. Selby made prescient investments in everything from airfreight to fish pack-ing, and after a stint as chief of staff for the sultan of Brunei, he now man-ages the assets of the Thai monarchy. He collects fast cars, big boats and Khmer art, and keeps his collection of rare guitars (including instruments signed and given to him by Keith Richards and Pete Townshend) in a dedicated room of the apartment he shares with his Thai wife, Lek.

But Selby’s greatest passion is building hyper-realistic scale-model planes. “Building and tinkering is so far from what I do work-wise, it takes my mind off it,” he says. “Also, it’s part of my attempting not to grow up.” It is a pursuit that has become increasingly sophisticated over the past five years. For those like Selby, with plenty of resources, ambition and technical savvy, high-tech com-posite materials and miniaturized controls have enabled higher strength-to-weight ratios, and telemetry and digital engine-management systems have given RC pilots more power and control. Model kits are more realistic and reliable than ever before, and super-modelers like Selby, who build their own from scratch, are taking on larger, more ambitious projects.

“Around the world,” Tiano says, “there’s a niche group of maybe 2,000 people who have as much dedication

the obsessives

and Davidson rendezvous in Bangkok to shake out their latest flying machine, party, and prepare for Top Gun.

Even though Selby’s team has never won the overall Team class at Top Gun, Selby has won more Critics’ Choice awards—bestowed each year by the judges and a panel of “guest artists” for exceptional craftsmanship —than anyone else. In 2001 (the first year Johns and Selby flew together), they won it with an F7 Grumman Tigercat, a late-1940s fighter. In 2004, a Brewster Buffalo (which now hangs at the Naval Aviation Museum in Pen-sacola, Florida) brought them another, and in 2005 and 2006 it was a Vought Vindicator SBU-2 (a carrier-based dive bomber developed for the U.S. Navy in the 1930s). Last year, their Tucano was so impressive that even after crash-ing, it was still named a runner-up.

This year’s plane is an ambitious choice. The real-life A-10 Thunderbolt II, a.k.a. the Warthog, was the first

inside The hangar

HALL Of fAMeselby’s past winners line the walls of his enormous Bangkok workshop.

sOPHIsTIcATed On THe InsIdeThe pneumatic landing-gear drive, like everything else, is a hand-built system.

rUdder And sTIcKsince there’s no tactile feedback, flying models is harder than flying big planes.

inside The WarThog

Battery stack Light control

Sequencer unit for landing gear

Plumbing

Compressed air tanks Turbine control

Canopy servo

Power box

Kerosene tanks

Gyroscope

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Air Force jet specifically designed for close air support of ground forces. Its distinguishing characteristics make it an especially difficult plane to model. The A-10 weighs in at 30,000 pounds, and its engines produce 18,000 pounds of thrust. True to its nickname, the fighter, all bumps and protrusions, isn’t sleek. Rather, it’s built to take—and inflict—a beating. From a cockpit pro-tected by a titanium “bathtub,” a pilot can drop up to eight tons of bombs or fire a 30-millimeter Gatling gun at 4,000 rounds a minute. “On a battle-field,” Davidson says, “there’s probably nothing more intimidating than an A-10 coming at you on a strafing run.”

But the flight characteristics of the A-10 make it a tremendous engineer-ing challenge. At Top Gun, a model must not only be built to scale, it must fly to scale as well. “They’re judging realism in flight,” Selby explains. “If

the real airplane makes bombing runs at 300 knots, a smaller plane has to do its bombing runs at a much slower speed, or else it won’t look realistic. You’ve got to duplicate whether it climbs steeply or gradually, whether it turns quickly like a fighter jet or sluggishly like a heavy bomber. The A-10 is a tough one, because it’s known to have excellent maneuver-ability at low air speeds and altitudes, so we’ve got to make that happen.”

Although Selby’s A-10 Warthog is strictly a hobbyist project (albeit an expensive one), it has the tacit support of the Pentagon, where his work has high-placed admirers. “A couple of years ago,” Johns recalls, “[Air Force chief of staff] General Buzz Moseley was challenging us to fly an Air Force plane, instead of the Navy planes we had been flying for the past few years. It wasn’t exactly

an order, but he said he was getting impatient. He wanted to know when we were going to get around to put-ting one of our birds into the air.”

In the Team class at Top Gun, competitors replicate a particular air-craft, rather than just a type. Selby’s team settled on an A-10 flown by Captain P.J. Johnson, who is now a colonel based in a Pentagon office just down the hall from both Johns and Davidson. The plane, built in the early 1980s and painted in the Air Com-bat Command’s Flying Tigers color scheme, is based out of Moody Air Force Base in Georgia. In the first Iraq war, in 1991, Johnson’s A-10 wing was partially blown off in combat. Remark-ably, he managed to land safely.

In early May, Davidson traveled

deATH frOM ABOVe Modeled after a specific plane, the A-10 has it all, from a spinning Gatling gun to a figure dressed like the real pilot, Captain P.J. Johnson.

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the obsessives

the flight characteristics of the a-10 make it a tremendous engineering challenge, and a team of judges checks the look of the model against photos of the actual plane.

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to Pope Air Force Base in North Caro-lina and took walk-around photos of another full-size A-10 for reference, and Selby dug up a book of photos of Johnson’s A-10. He also unearthed schematics and official guides to mark-ings and heraldry. In the “static” part of the Top Gun competition, a team of judges meticulously checks the model’s lines, markings and weathering against photos of the actual plane, right down to the scratches and dings. It must be an exact copy of that moment in the A-10’s career. “If there’s a defect on the real plane,” Tiano says, “you’d better have the same defect on your model, or you’re going to lose points.”

sMALL BUT POWerfULSelby’s model will be the first A-10 to fly in competition, and probably the largest jet ever to fly at Top Gun. About 85 percent of Top Gun com-petitors build from kits, but Selby designed and built nearly everything on Johnson’s A-10 from scratch in his 1,500-square-foot workshop, just off the parking deck of his 30-story apartment building. The shop is a tech geek’s dream, outfitted with a laser-cutting machine, computer numerical control mill and lathe, 3-D laser scan-ner, and plastic vacuum former.

A scale modeler’s biggest chal-lenge is building a functional model that will look like the real plane, while using different materials and construction techniques, and keep-ing thrust-to-weight and lift-to-weight ratios within practical limits. “A plane with an overloaded wing will fly like a powered brick,” Selby says. “In low-speed situations, you can run into stalls and control problems, and the sink rate on the plane is quite high.”

Starting with Davidson’s photos and the original Fairchild Republic drawings of the A-10’s wing, Selby scaled the wing down and modified the control surfaces, using design and airfoil-analysis software. The A-10’s fuselage, wing and control surfaces are made of lightweight fiberglass, carbon fiber and Kevlar. To make the

skin look authentically weathered, Selby bound pastels into the paint and then rubbed it with steel wool—a particularly impressive feat consider-ing that he’s partially color-blind.

Real A-10s are equipped with turbofan engines, which drive a fan that feeds extra air into the burner, but to stay aloft, model jets typically use lighter and simpler single-stage axial turbines. Unfortunately, most single-stage turbines take several seconds to accelerate from idle to full throttle. This lag time can sometimes make the difference between being able to abort a landing, and crashing.

Selby and Saechour’s Bangkok-based scale-jet company, PST Engines, boosts its miniature jet engines’ acceleration by adding extra vapor-izers in the combustion chamber and sophisticated digital fuel controls. Built out of heat-resistant superalloys and kitted out with full ceramic bearings, the A-10’s engines rev up to 120,000 rpm and develop up to 29 pounds of thrust—more thrust for their weight, Saechour claims, than anything else on the market. With both wings attached, Selby’s 5.5:1-scale A-10 stretches 10 feet across and weighs 65 pounds at takeoff. Inside the fuselage, carbon fiber snakes like spaghetti around five Kevlar fuel tanks, which hold 8.5 liters of jet fuel, enough for about 15 minutes of flight.

Selby designed the plane’s electri-cal system with enough redundancy to make NASA proud. A power box distributes signals from the two radio receivers to 24 servo motors, which operate the control surfaces. The redun-dant radio system calculates which receiver has a stronger signal and constantly switches back and forth. Two separate electrical systems run the microswitches and small microcomput-ers that handle sequencing, and backup lithium-polymer batteries guard against catastrophic loss of power.

Selby also built a high-pressure pneumatic system to handle the land-ing gear, gear doors and braking system. He designed and machined his own hydraulic shock absorbers out

Selby and company will be up against the most sophisticated and dedicated RC-jet makers in the world.

eneMy ForMaTionsahead

cAMerA-MOUnTed sPOrT jeTTop Gun founder frank Tiano takes in-flight pics with this nimble craft.

f-4 PHAnTOMThe colors of Tim redelman’s 200mph fighter orient the pilot at a distance.

f-18 sUPer HOrneTjorge escalona built 50 pounds of thrust into the jet’s turbine engines.

MIG-15johnny Hernandez’s 1:6-scale russian fighter weighs only 24 pounds.

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of aircraft-grade aluminum and even molded his own rubber tires. Up front, there’s an onboard replica of the A-10’s Gatling gun.

When the A-10’s canopy opens, it reveals an action figure wearing a jumpsuit meticulously sewn by a Bang-kok dressmaker to match P.J. Johnson’s. On the tiny plastic control panel, each instrument is laser-engraved; the panel even pulses and appears to acquire a target. “There are no extra points awarded for cockpit detail,” Selby says, “but if you’re going to go to this much trouble, you might as well take it all the way.”

sMALL PLAne, BIG rIsKConsidering the time, craftsman-ship, dedication and money that has gone into this airplane, it’s a wonder that Selby can summon the guts to send it into the air. But that’s the nature of the Top Gun competition: Build a complex, delicate machine, and then risk destroying it.

Selby and Johns suspect that radio interference might have caused their Tucano’s crash at Top Gun last year. If that’s the case, the “radio hit” must have come from somewhere off-field, since all other competitors’ radios are impounded and disabled during competition. But according to Top Gun organizer Tiano, radios have become so sophisticated that they are rarely the cause of crashes anymore. “When we do have equip-ment failures,” he says, “it’s usually a problem with fuel or with batteries. But even those are getting more rare.”

Tiano, who was standing next to Johns when the Tucano went down, thinks the plane probably didn’t have enough airspeed as it entered a turn, causing it to stall and plunge to the ground. “It looked a little slow to me,” Tiano says. “But we’ll never know for sure.”

Selby has learned his limits the hard way, losing several planes over the years. Although he was once a com-mercially rated multiengine pilot, Selby claims he doesn’t have the right stuff

to fly the model planes he builds for competition. “I’d probably consider it,” he says, “if my best friend didn’t hap-pen to be one of the world’s best pilots.”

Ray Johns made his first solo flight at 16 and studied the certification of commercial aircraft for military applications while getting his mas-ter’s degree. As a flight instructor, he’s flown most of the Air Force’s fighter and air-to-ground jets and was the chief test pilot for an Air Force One project in 1990 in which the military radically modified a Boe-ing 747-200 for presidential use.

Johns got into model airplanes as a kid, and he continued the hobby as an adult in the Air Force, wherever his duties took him. On a visit to Sin-gapore in 2000, the deputy American ambassador introduced him to Selby. As a three-star general and deputy chief of staff for strategic plans and programs, Johns rarely has the chance to fly in a single-seater plane like the

A-10. So he gets his fix in miniature. To hear him describe it, it’s in many ways more difficult and more satisfying.

“Flying a model is actually much harder than real flying,” Johns says. “For starters, when you have a new plane, you don’t have any idea about what speed it will take off, land, or stall. When you get it in the air, you don’t have the direct feedback that pilots rely on to stay oriented. You only have control when the plane’s in your line of sight, and your perspec-tive is usually all wrong. For instance, when you’re landing and you’re look-ing at the plane coming toward you, the controls are reversed. You need to remember to push the stick left to go right, and right to go left.”

fIre UP THe enGInes“The trick when testing airplanes,” Johns says as our caravan of three vehicles pulls up to the airstrip for the second day of flight time, “is

johns is critical of his own flying. “the high-speed pass was too high,” he says. “the immelmann was sloppy, and that was a wussy split s.”

MAsTer BLAsTer Pornchai Saechour, who designed the jet’s 120,000rpm engines, runs PST, a scale-jet business in Bangkok, with Selby.

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to expand the envelope a little at a time.” Only one part of the process should be unknown at any given time, he explains, “so if you screw up, you have room to recover. That’s the same whether you’re testing Air Force One or one of Mike’s models.”

The airstrip is deserted on this hot Saturday morning. This is flat, green, fertile country, in the heart of the rice belt just outside Bangkok’s sprawling eastern suburbs. We unload to the sounds of chirping birds and lowing buffalo, and Selby and Saechour care-fully spread their tools and parts out on bird-marked tables in the shade of a wooden pavilion. As their team-mates assemble the plane, Johns and Davidson go out to walk the runway.

Selby and Johns are constantly on the move, chewing gum or, in Selby’s case, smoking a cigar. Bill Davidson, a larger man, provides an anchor-ing presence, moving as required, his large glasses hiding soft eyes that offer few hints of the intrigue that he has known in his career at the Pentagon and, earlier, in two decades

as an agent of the Air Force’s secre-tive Office of Special Investigations.

“You know how people say, ‘If I told you that, I’d have to kill you’?” Johns had commented to me earlier. “There are guys who are just playing around—and then there are guys like Bill.”

When Johns and Davidson return from their runway inspection, the A-10 is assembled and fueled. Saechour clears everyone from the area behind the plane—the turbines exhale gases at a toasty 1,1000F—and starts the engines with a butane/propane mix. Once the engines reach a stable rpm and temperature, the fuel supply switches over to the pure Jet A formula in the internal tanks. After Johns and Selby double-check the pneumatic pressure, control surfaces and radio, Johns takes the controls, taxiing the plane out to the runway for the day’s first takeoff.

If yesterday’s first takeoff was a lit-tle wobbly, today’s is rail-straight—but the landing is downright harrowing. Just before touchdown, a gust catches the A-10’s double rudders and yaws it

sideways. The plane veers to the left, then back to the right. As the tires catch the pavement, the plane darts toward the edge of the runway, where Davidson is videotaping the flight. Davidson keeps his cool as Johns works the stick frantically and gets it redirected, and the A-10 skids sideways to a bootlegger’s stop a few feet from Davidson. There’s a long silence. “You had me holding my breath,” Selby says finally, letting out a sigh. “And I think you had Bill wetting his pants.”

sMOOTHInG IT OUTAfter the day’s first flight at Bang Nam Prio, Selby and Johns decide to wait out the crosswind gusts and do some trou-bleshooting. On his control console, Johns modifies the A-10’s stick move-ment to “soften up the middle” and make the controls less touchy. Selby and Saechour try to figure out why the nose wheel keeps fouling on its hatch when retracting, and eventually trace the problem to the fake hydraulic cap on the side of the nose structure. “You get so involved in

fIGHTer cOMMAnd Johns, Selby and Davidson go over their calculations after the Warthog’s inaugural flight.

Did Selby’s Warthog win the honors at Top Gun, or did it crash and burn? Find out at popsci.com/rcjet.

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the obsessives

putting these little tchotchkies on to make it look real,” says Selby, as he lies down on the cement floor under the landing gear, “that you can forget that it needs to reliably function and fly.”

The A-10 takes off again and, as it climbs, the landing gear functions flawlessly. Johns sends the A-10 into a steep climb and then pulls it into a half-loop and rolls it 180 degrees—a rapid-reverse maneuver known as an Immelmann turn. Johns brings the plane around for a low-level pass over the runway. As it roars past us at palm-treetop level, it couldn’t look or sound any more realistic. Stand-

ing in his jeans and topsiders, Selby smiles and whistles, starting to relax.

On the next flight, the A-10 carries four fiberglass “bombs,” but during the bombing run, they fail to release. For Selby and Johns, the situation brings back memories of the 2006 Top Gun competition. “We were sitting in first place with our Vindicator when Ray brought it in for the run. He called out, ‘Bomb drop.’ But nothing happened. We would have won overall Team, but we came in second—only two tenths of a point behind the winner.”

Between flights, Selby and Saechour shorten the release pins, while David-

son and Johns review the video. Johns is critical of his own flying. “The high-speed pass was too high,” he says. “The Immelmann was sloppy, and that was a wussy split S—but at least the landing flare was better.”

fInAL PAssThere’s time for one more flight today, and then the men and their wives will head off to the islands for some beach-side R&R. In the few weeks before Selby airfreights the plane to Florida, he will do some cosmetic work on the aerial-refueling hatch and add a GPS-based telemetry system. The system

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as the plane coasts to a stop, the canopy opens, as if the pilot-in-miniature were seeking some breezy relief from the tropical sun.WING MEN

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will include a voice synthesizer that will call out various data points, such as altitude, airspeed, and engine rpm and temperature. “That way,” he says, “Ray can plot his turns and we can figure out the stall speed, which will allow us to land slower, which will look more realistic and more to scale.”

Johns taxis the A-10 back out to the runway. “Let’s make sure that we don’t go home with more pieces than we came to the field with,” he says. He pushes the throttle forward, looking confident as the A-10 screams down the runway and into a steep, arcing climb. He brings it around for the

bombing run. This time, the bombs release and come down in a perfect trajectory, sinking deep into the mud at the opposite side of the runway.

He takes the plane through a mili-tary roll and a split S, then an attack approach and a half-reverse Cuban eight—maneuvers he will attempt at Top Gun to wow the judges. Selby is beaming. “Next, General Ray’s going to show you the Jimi Hendrix maneuver!” he says. “First he’ll fly it behind his back, then with his teeth.”

Johns brings the plane in for a perfect landing and taxis it over to the tarmac. As it coasts to a stop,

the canopy opens, as if the pilot-in-miniature were seeking some breezy relief from the tropical sun. The tur-bines shut down, and Davidson pulls the video camera’s viewfinder from his eye. He walks over to Johns and Selby, his normally impassive face stretched into a grin. Looking around at his partners and then at the plane, he quietly delivers his verdict.

“Flies like an A-10,” he says.

Contributing editor Tom Clynes pro-filed Arctic climatologist Konrad Steffen in the August 2007 issue.