Planes can fly in a blizzard because they are tested in this indoor one first
At McKinley Climate Lab, researchers create fearsome weather to test cars and planes.
ON AUGUST DAYS IN THE FLORIDA PANHANDLE, the tropical heat steam-cooks everything. UPS drivers slap wet bandannas to their foreheads. Pirate-themed mini-golf parks, shimmering like mirages, lay deserted. But a few miles from the Gulf motels and sandy beach malls, engineers like Kirk Parrish face the worst snowstorms of their lives. Sheathed in parkas, they cold-start their pickups and drive straight into stinging, minus-40-degree whiteout blizzards. Indoors.
“It’s absolutely crazy seeing an indoor snowstorm,” says Parrish, a diesel engineer at Ford Motor Company whose job is to make sure your F-150 can start and run in Prudhoe Bay extremes. To prove it can, and tweak things if it can’t, he treks each summer to the McKinley Climatic Laboratory at Eglin Air Force Base. Sprawled over several buildings, the lab is the largest indoor-weather testing facility in the world and can conjure nearly any meteorological hazard: ice storms, corrosive fog, driving rains (up to 27 inches per hour), 165-degree heat, jungle humidity, and 40-mile-per-hour sandstorms.
The lab has been operating since 1947, when the U.S. Army Air Corps (now the Air Force) began assessing warbirds there. A few years later, it opened its doors to the rest of the military and, in the late 1980s, to private companies. It has since served as a proving ground for all sorts of consumer goods, from Ford trucks to Goodyear snow tires to Google’s Internet-beaming Project Loon balloons. It’s the last stop for most commercial jets seeking FAA certification. And the lab has tested just about every warplane in the U.S. arsenal, including Northrop Grumman’s B-29 bomber, Lockheed Martin’s C5 Galaxy transport (which barely cleared the ceiling), and the F-35 Joint Strike Fighter. “I cannot tell you of a military aircraft that hasn’t been through here,” says lab chief Dwayne Bell, who has seen hundreds of jets roll through in his 26-year tenure.
On a mid-April day, Bell was juggling logistics for at least a dozen products of every make and size. They were coming, going, or begging for a slot in his schedule. Later this year he expects to see the Bombardier Global 7000, a new ultra-long-range business jet. “The fact is, we get requests for all manner of things,” he says. “We’re talking to a company that makes offshore-drilling equipment. I got a call yesterday from one that wants to bring in a snow blower.”
A LOT OF BUSINESSES WHOSE PRODUCTS NEED TO HOLD UP IN NASTY WEATHER subject their boots, tents, gloves, planes, boats, and trucks to Mother Nature’s direct assault. But waiting for her to rain down her worst—and apply it evenly to your prototype in remote places like the Arctic or the Amazon—is a huge time chew. And it clips the R&D budget. Plus, it’s really hard to accurately measure results and track problems in harsh conditions, and then hit repeat. And isn’t that, after all, the essence of the scientific method: to replicate an experiment, to offer skeptics rock-solid proof that your stuff works?
That, in fact, was the shrewd insight of a little-known World War II-era U.S. Army Air Corps commander: Lt. Col. Ashley McKinley. Stationed at Ladd Field, Alaska, the former pilot—who had photographed American explorer Richard Byrd’s Antarctic expeditions in 1928 and 1929—ran the Army’s Cold Weather Test Detachment. With a global war on, the military had to operate in many extremes, from Arctic tundra to Far East rainforests. McKinley found hauling material to Alaska expensive. And testing in the variable outdoors yielded spotty results. He figured it would be more effective and efficient to create weather on demand and test under controlled conditions at one-tenth the cost. In September 1943, the cold-test program moved to the easily accessible Eglin Field air base, on northwestern Florida’s Gulf Coast. Four years later, the newly built Main Chamber began punishing its first planes. And over the next 50 years, the lab tested some 300 aircraft and 2,000 other pieces of equipment, including missiles, bombs, Howitzers, and Humvees.
An airplane’s torture chamber
In the early 1990s, the lab’s engineers, welders, and electricians embarked on a $100 million, ground-up rebuild to accommodate larger aircraft and to install updated refrigeration and heating machinery, as well as electrical and steam equipment. When the retooling finished in 1997, the center expanded its commercial-client roster. As military equipment became more sophisticated, it took longer to get to the testing phase. So commercial clients, Bell says, “help pay the bills.”
Today, the lab has six chambers. Two of the most extreme rooms were added in the early 1970s to meet the military’s global portfolio. In the Salt Test Chamber (50 feet by 16 feet wide, and 16 feet tall), technicians can spray metal-eating sodium chloride to test for corrosion resistance. The Sun, Wind, Rain and Dust Chamber (50 feet by 50 feet, and 30 feet tall) has fans that can blow 40-mile-per-hour sandstorms, the kind you see U.S. Army grunts in Afghanistan posting on YouTube. And to better simulate doing time in a Middle East gulf state, techs can switch on heat lamps set as high as 165 degrees to bake tanks, radar systems, missile launchers, aircraft tugs, and Army transports. The crew at McKinley recently vetted a new Army generator that will sit outside “little tent cities,” says Bell, to power air, filtration, and electrical systems.
The main attraction at McKinley, however, is its Main Chamber. At 252 feet wide, 260 feet deep, and 70 feet tall at its highest point, its size allows the lab to test extremely large planes. The most notable ones to roll through its 200-ton steel-sheathed doors include Boeing’s 787 Dreamliner, which earned its foul-weather wings there in 2010, and Lockheed’s C-5M Galaxy transport, the largest plane ever to enter the U.S. fleet.
The Main Chamber’s primary modes are hot and cold. During heat testing, crews can use lamps to bake an aircraft or switch on steam vents to also bathe it in humidity. The lamps can mimic a 24-hour solar cycle, coming on at dawn, peaking in a 140-degree sizzling heat, and then gradually sunsetting. Engineers will also check to make sure the plane’s aviation and communications electronics hold up. “Most electrical is happy when it’s cold, not when it’s hot,” says Tom Sanderson, manager of research and technology for Boeing, who also served as a flight-test director for the 787.
Freeze, then bake
The lab’s closed-loop cold mode was created for the other end of the thermometer. To create a deep freeze, the system works just like your home air conditioner. It cools a liquid refrigerant, sends it through some coils, and then blows air over them. Then it recycles the cold indoor air to chill things down even more. But this is no window unit. McKinley’s supersize compressors can run at 1,200 horsepower (like having a Bugatti as your power source). Its six primary cooling coils stand 10 feet tall, with 100-horsepower ducted fans that can move 78,500 cubic feet of air per minute. It can take Bell’s crew around 12 hours to drop the chamber’s mercury to minus 40, the preferred temperature for simulating an overnight stop on tarmacs in the Canadian Arctic or Siberia. After cold-soaking its 787 for 12 hours, Boeing’s engineers went through a textbook restart: draining fluids, servicing hydraulics, and using an auxiliary-power unit to warm the cabin, just like they would if they were preparing for boarding passengers.
McKinley’s staff doesn’t actually test planes or anything else that rolls through its doors. That’s the job of the corporate employees and test pilots. Because these machines are prototypes, they’re rigged with thousands of sensors and are often accompanied by as many as 30 to 40 engineers, a dozen of whom might sit inside a craft during assessments. McKinley can run a cable from the jet to an instrumentation booth where the lab’s technicians can record findings for the client. “It’s just raw data to us,” Bell says. “We don’t know whether the numbers mean it passed or failed.”
How well does your antifreeze work?
THE REAL FUN ENGINEERING STARTS WHEN A PLANE IGNITES its engines inside the Main Chamber. The physics of air pressure say that doing this could destroy the building and everything in it. A jet engine can suck in 1,000 pounds of air mass per second. Without precautions, that force would pull down the walls of the hangar. Thus Bell’s team must feed air into the hangar at the same rate the engines devour it. They achieve this feat—and maintain the target temperature—via what they call an air-makeup system.
For cold testing, engineers super-cool a powerful refrigerant known as R30, or methylene chloride, to minus-70 degrees or lower. They then send this potion through a set of coils while fans blow fresh air over them, generating a powerful wind that travels through ducts and enters the Main Chamber slightly below the target temperature of minus 40. There, the jet engines draw it in and blast it back into the world via an exhaust duct.
“There’s no automation to the system,” says Bell. “We have a refrigerator operator on a headset with the pilot in the cockpit. As the pilot advances the throttle, he’s telling the air-makeup operator, getting permission to proceed, and our guy is speeding up our air-makeup fans to match the mass of his airflow, and manipulating valves to control how much fluid goes back and forth so we can control the temperature.”
McKinley took on one of its most challenging tests ever on September 24, 2014, when a small tug pulled Lockheed’s F-35B into the Main Chamber for six months of harsh weather. “That was a major, major test for this facility,” says Bell. “The things we had to do to prepare were the same as always, but on a much grander scale.”
The setup was a brain-bender. The center’s maniacal weather-makers would have to hurl every climatic extreme at the F-35B while its engine and turbofan blasted at hover and flight speeds—putting out 40,000 pounds of thrust—without actually hovering or flying.
The F-35B had to sit 13 feet off the floor to accommodate its exhaust pipe, which can swivel 90 degrees and allows the fighter to take off and land vertically. McKinley’s crew anchored the jet to the cement floor by attaching pipes to the landing struts and connecting them to an I-beam frame. Welders had built a custom duct system to collect all of the über-jet’s exhaust.
After engineers spent several weeks evaluating the craft under temperature extremes, test pilot Billie Flynn climbed aboard for the flight test. No one had ever started an F-35B inside a building. Dozens of engineers and government officials huddled in a portable cabin just off the plane’s wingtips to monitor hundreds of data feeds as Flynn went through the preflight checklist. “I wouldn’t say I ever get scared,” says Flynn, “but I was really, really anxious to figure out what it would be like to turn this jet on in a building where there was nowhere to eject.” With a footprint of 4,000 square feet, the test platform was the largest setup ever assembled at McKinley. When Flynn fired up the engine and pushed the throttle, he felt the usual surge of flight, but the plane—and the building—stayed put. “When you feel that and you’re chained to a platform,” he says, “that is a pretty darn cool trick.”
Flynn sat in the cockpit for several days, testing the engine in minus-40-degree Arctic chills and ice storms conjured by 20-foot-tall spray bars, each with 300 water-atomizing nozzles. “We had to make sure ice didn’t build up in the lab’s wind tunnel,” says Marc Thompson, a Lockheed engineer who took part in the test. “You want to make sure a big chunk of it doesn’t come flying at your plane.”
Over the remaining months, hundreds of the F-35B’s system parameters were tested across dozens of foul-weather scenarios. The engineers examined the oil, which turns viscous in the cold, making sure it would be able to move deep into the engine at minus-40 degrees. They tested the pilot’s display, making sure it didn’t get wonky in 120-degree heat, still allowing its operator to lock in an enemy target 100 miles in the distance.
You’d expect anyone working on a $100 million stealth plane to be evasive about what they learned, but Flynn and Thompson swear they’re being candid—and that the jet performed better than expected. “The computational models were good,” says Thompson. “We really didn’t get surprised during this test.”
The price tag for all this was reportedly as much as $25,000 a day, which Flynn considers better than the alternative: chasing bad weather around the globe and hoping for the best. “This is the only place in the world where we can control all conditions to the nth degree. And do it again and again, like in a controlled science experiment.”
Or maybe he’s just grateful for the expertise that enabled him to throttle the engine without collapsing the building and crushing everyone inside it. “I remember thinking,” he says, “if something goes wrong, this is not what I want to have in my obituary.”
This article originally appeared in the Extreme Weather issue of Popular Science.