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UMR Researchers Tailgate At 37,000 Feet To Gather Data

January 12, 1998
University Of Missouri-Rolla
No head room. No leg room. No reclining seats. No magazines. No peanuts. No flight attendants. No temperature control. Turbulence, however, can be expected. Such are the flights that researchers from UMR's Cloud and Aerosol Sciences Laboratory must endure in order to study aircraft exhaust emissions in the North Atlantic Flight Corridor.

ROLLA, Mo. -- No head room. No leg room. No reclining seats. No magazines.No peanuts. No flight attendants. No temperature control.Turbulence, however, can be expected. And all flights end at the same airport where they begin.

Such are the flights that researchers from UMR's Cloud and AerosolSciences Laboratory must endure in order to study aircraft exhaustemissions in the North Atlantic Flight Corridor.

Despite the conditions, Ray Hopkins considers it an honor to be on thespecially equipped German Dassault Falcon plane. He's one of only a handfulof international researchers who can say, "Been there. Done that."

Based out of Shannon, Ireland, this tour of duty beats the one Hopkins had26 years ago as a gunship pilot during the Vietnam War. His training there,however, has proven beneficial for his job today as a CASL researchengineer at UMR. Nothing shakes him -- even when he's riding in atwin-engine jet just 150 meters behind an European Airbus cruising at37,000 feet over Germany.

A test flight begins after Hopkins and four other researchers board analready crowded research aircraft. Ducking through a narrow passageway,past a hive of equipment, Hopkins settles into what will be his home forthe next four hours -- a small, crowded corner just in front of the plane'srestroom. There, he will hover over a computer and a rack of sophisticatedequipment to gather aircraft exhaust emissions in the most heavily traveledairways of the world. The data he and other international scientists gathermay one day be used to set new emissions standards for aircraft exhaust.

Space aboard the Falcon is at a premium, and scientific equipment takesprecedence over human comforts. Cabin temperatures soar as the equipmentmotors generate heat. Outside the cabin it's -40 degrees Fahrenheit.

Inside, temperatures can reach 90 degrees Fahrenheit. While most passengerswould only want to survive such a flight without having to reach for thelittle white bag, Hopkins must analyze atmospheric particle samples. Heprobes the outside air and determines the size of the ultrafine particlesemitted by aircraft.

"It takes four to six minutes to get one size sweep," Hopkins says. "Welook at the size distribution from 10 to 200 nanometers (billionths of ameter). We do as many sweeps as we can because it gives us a profile of theevolution of the particles."

He does take notice, however, when a wing tip catches a wake from awide-body jet.

"Updrafts, downdrafts and gusts pale in comparison to getting a wing tipcaught in the wake of a wide-body jet at 150 meters," Hopkins says.

While right behind a wide-body jet may be an ideal place to gatheraircraft exhaust data, it's a risky proposition to fly there. It wasespecially so the first time, because no one knew for certain if the planecould withstand the air turbulence created by the jet's exhaust.Based on their models, calculations and predictions, the German AerospaceResearch Establishment, DLR, determined that the Falcon could safely flybetween 50 and 150 meters behind a wide-body jet. Modelers reasoned that ajet's exhaust is like the wake of a boat: to travel immediately behind itwould be safer than farther back. They knew, however, that the sameaircraft following between a few hundred meters and five miles would beripped to pieces.

Dr. Jonathan Paladino, a postdoctoral fellow in chemistry at UMR, was onthe Falcon the first time it dove behind an Airbus at 150 meters. It wasMarch 1996.

The risks were staggering: The plane's wings could get ripped off. Anengine could flame out. Anything was possible.

"I don't remember thinking about what could happen that first time,"Paladino says. "If I thought about it, I probably wouldn't have done it."Paladino's confidence in pilot Frank Roessler compensated for the riskfactors he faced on this maiden test flight.

"He's an outstanding pilot who has logged thousands of hours in this typeof aircraft," Paladino says. Once Roessler announced he was going up into the exhaust plume, silencefollowed.

"When we first entered the plume, it was like driving down a country road-- it was bumpy, but there were no tremendous jerks," Paladino says.

Data counters shot up.

"The samples saturated our counters," Paladino says. "No one was preparedfor the strength of the signals."Nor were they prepared for what happened next.

In a flash, the aircraft flipped to a 60-degree angle.

"We got caught in the jet's vortex, and I was hanging from my seatbelt,"Paladino says. "That part was scary, and I was white-knuckled through therest of the flight."

While the flight was rough, the plane and its passengers stayed intact,and a new era of aircraft exhaust emissions study was born. Paladino, bythe way, continues to participate in these flight campaigns.

"We can do all the modeling on Earth that we want, but the only way toprove or disprove these models is to test the actual exhaust," says Dr.Philip Whitefield, associate professor of chemistry and CASL seniorinvestigator, who along with Dr. Donald Hagen, professor of physics andCASL senior investigator, leads this research at UMR. "It is very importantfor us to go up into the atmosphere to gather the exhaust samples, so thatintelligent decisions can be made about aircraft exhaust emission standards."

The international team already has proven that aircraft exhaust emissionscan build up in heavily traveled airways, says Hagen. In September, theteam took advantage of an occasional atmospheric phenomenon called ananticyclone to study emission buildups. Anticyclones, caused byhigh-pressure air masses, are ideal for exhaust studies because the sameair re-circulates several days over the same area, allowing aircraftemissions to build.

"Every time an aircraft passes through the anticyclone, emissions areadded," Hagen says.UMR's preliminary data indicates planes leave behind a trail of sub-micron particles that results in a four-fold increase in an anticycloneover a period of a few days.

UMR's team of researchers will continue to test aircraft exhaust for theforeseeable future. Their research results will be shared by the UnitedStates and European nations and are to be included in a United NationsReport, "Aviation and Global Atmosphere," commissioned by the UN'sIntergovernmental Panel on Climate Change. The report is scheduled forpublication in 1998.

In the meantime, there's no shortage of air travel. Aircraft make up to2,000 crossings daily in the North Atlantic Flight Corridor between NorthAmerica and Europe. Unlike the researchers, most passengers on thoseflights get head room, leg room, reclining seats, magazines, peanuts,flight attendants and comfortable temperatures.

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University Of Missouri-Rolla. "UMR Researchers Tailgate At 37,000 Feet To Gather Data." ScienceDaily. ScienceDaily, 12 January 1998. <>.
University Of Missouri-Rolla. (1998, January 12). UMR Researchers Tailgate At 37,000 Feet To Gather Data. ScienceDaily. Retrieved April 29, 2017 from
University Of Missouri-Rolla. "UMR Researchers Tailgate At 37,000 Feet To Gather Data." ScienceDaily. (accessed April 29, 2017).