Perlan 2 Glider Beginning Final Flight-test Campaign

 - May 3, 2023, 1:18 PM
The Perlan 2 glider has broken its own world subsonic altitude record three times since its debut flight in 2015. (Photo: The Perlan Project)

Airbus is preparing to shoot for a world record with another flight of the Perlan 2 pressurized, high-altitude glider. After setting a subsonic altitude record at over 76,000 feet (23 kilometers) in 2018, the Perlan 2 mission team will attempt to reach 90,000 feet (27 kilometers) during a flight-test campaign that will kick off in Argentina on July 22, the team announced on Tuesday. 

According to the Perlan Project, the nonprofit organization behind the record-breaking mission, the Perlan 2 glider set sail from the U.S. on May 1 to begin its journey to El Calafate, Argentina, where the flight-test campaign will take place. During the flight tests, a tow airplane will carry the piloted Perlan glider to an altitude of 40,000 to 45,000 feet. The Perlan glider, which has no engines, will then soar to double that altitude by taking advantage of a rare atmospheric phenomenon known as “stratospheric mountain waves,” which form when mountain winds are boosted by the polar vortex. 

“The polar vortex swings around the South Pole and bounces off the Andes Mountains, so we're going to a place—El Calafate—that's almost as far south as you can go in Argentina,” Morgan Sandercock, the Perlan Project’s chief engineer, said Tuesday during a media briefing. “It's on the downwind or eastern side of the Andes mountain range, where these waves that are triggered by the mountains get pushed up into the stratosphere by the polar vortex, so that each layer of winds stacked on top of the lower layers pushes the wave a little bit higher.”

The Perlan Project has successfully flown gliders to high altitudes using this concept in the past. The team set its first world subsonic altitude record in 2006 with Perlan Mission 1, in which the pilots glided to an altitude of more than 50,000 feet (15 kilometers) over the Southern Andes Mountains. Following the success of the first glider, the team built a second, pressurized glider optimized to fly near the edge of space. The Perlan 2 glider made its debut flight in 2015. It surpassed the Perlan 1 glider’s altitude record in 2017 and continued to shatter its own records three times with subsequent flights in 2018. 

Following the success of that flight test campaign, the team planned to fly to 90,000 feet in 2019, but a series of unfortunate circumstances delayed that flight. First, a stratospheric warming event disrupted the polar vortex in 2019, which decreased the size of the stratospheric mountain waves. Then in 2020, the team’s plans were foiled by the Covid-19 pandemic, during which they were unable to travel to Argentina. By 2021, Argentina was still fairly locked down. The shipping industry had also been disrupted by the pandemic, so the team was unable to ship its glider to Argentina in time to take advantage of the polar vortex. 

In 2022, with plans to fly in Argentina still on hold, the Perlan Project brought its glider to EAA AirVenture in Oshkosh, Wisconsin, for a flight demonstration. “I think Oshkosh was a really, really positive experience for us,” Perlan Project pilot and simulator programmer Tim Gardner said during the briefing. “Even though we weren't flying in Argentina, we did continue one of the things that we're always doing, which is fundraising.” Gardner added that Airbus has been a great sponsor since it partnered with the Perlan Project in 2014. “We have a number of other great corporate sponsors, but we rely a lot on private donations as well, so Oshkosh was a chance for us to connect with some of those donors.”

Now that the world has somewhat recovered from the effects of the Covid-19 pandemic, the Perlan Project is once again ready to head to Argentina to set its next record.  

“The number-one goal for the Perlan Project during this year's campaign in Argentina is to prove that the [stratospheric mountain] waves are as strong and that the waves go as high as our forecasts say they do,” Jim Payne, chief pilot and chairman of the Perlan Project, said during the briefing. Sandercock added that the team has calculations showing that stratospheric mountain waves can reach altitudes higher than 130,000 feet. “But for the glider that we've built, we think its maximum altitude is going to be around 90,000 feet,” he added. When soaring at this altitude, the Perlan glider will experience an air density similar to the atmosphere of Mars.

The Perlan 2 glider is equipped with instruments to measure things like turbulence, ozone, and ultraviolet radiation at high altitudes. A new instrument added this year is the GPS Radio Occultation instrument, supplied by the Airbus Acubed program, which will monitor the paths of GPS radio signals passing through the atmosphere. 

“Through the processing that they're able to do on that, it's able to measure humidity at ranges up to 100 kilometers away from the glider,” said Sandercock. “In fact, the clouds at these altitudes are not even made out of water. They're nitric acid crystals. So being able to take those kinds of measurements is a really exciting thing for us.” Sandercock added that this instrument could one day be installed on commercial airliners to improve weather forecasts, “because there’s a lot more airplanes up there than there are weather balloons doing these measurements.”

Also hitching a ride to the stratosphere on board the Perlan 2 glider will be some student-built science projects in the form of CubeSats, or small experiments enclosed in 10-centimeter cubes. “The experiments that we have flying come from the interest of the students,” said Perlan Project CEO Ed Warnock. “We have everything from Geiger counters flying that are going to be measuring radiation coming in from space [and] one that's measuring biological material that's been carried up into the atmosphere.” Another experiment will measure chemical pollutants at the high-level ozone. “It turns out that the acidic clouds that Morgan mentioned actually caused the ozone hole…so we're carrying student-built ozone detectors.”

During the flight tests in Argentina, the Perlan Project will live stream its telemetry data online in what the team calls a “virtual cockpit,” which will allow the students involved as well as the general public to follow along with the mission in real time. “It shows our altitude, our airspeed, and some of the consumables that we have in the cell plane such as oxygen and so on, so you can watch it as we fly and be there virtually,” Warnock said. 

Warnock explained that this flight test campaign will be the end of the Perlan 2 mission, but the team will continue to conduct atmospheric research using new innovations with its partners. “We think that the mission has been accomplished, so we probably aren't going to keep flying the Perlan for scientific research afterward,” he said, adding that the Perlan glider may end up in a museum once the campaign is over.