Pilot Jim Payne was ready when a relatively rare favorable weather window over Nevada’s mountains on June 10 created an opportunity to break a 24-year-old sailplane distance record in a one-of-a-kind aircraft.
Payne was very familiar with the previous record, having set it himself, flying with his brother, Tom, 24 years and two days before the June 10 launch. Payne claimed the new records after sailing more than 1,000 kilometers (nearly 600 nautical miles) on a triangular route that began and ended at his home base in Minden, Nevada. The latest record claims, supported by data from the flight, include distance around a triangle and speed around a triangle in a two-seat, open-class sailplane flown in the United States, along with a new record that did not yet exist in 1996: free distance around a triangle.
The long, thin wings of this 28-meter sailplane custom-designed by Iscold at the request of (and funded by) Brazilian aviator and businessman Sergio Andrade first flew in 2019. While they appear perfectly straight when the sailplane is at rest on the ground, the thin airfoils flex and bend in flight to a degree that not every pilot would be comfortable seeing. Iscold’s first attempt at creating the wing ended with a structural failure during ground testing, and that, in turn, led to Iscold getting his aerospace engineering students at Cal Poly involved with the fabrication of a new set of wings.
Payne, who was honored in 2018 by the Society of Experimental Test Pilots with the Iven C. Kincheloe Award, for his record-setting work on the Airbus Perlan Project, which produced a sailplane that shattered the sailplane altitude record, was not dissuaded by that early setback for the Nixus Project, and said the ultimate result was an aircraft that performed to perfection.
“Paulo’s done an amazing job,” Payne said during a video conversation with AOPA and Iscold on June 16. “We’ve had essentially no major problems with the whole system.”
While the Perlan 2 sailplane was optimized for altitude, Nixus is made for distance and duration. Payne, Iscold, and the university students continue to fine-tune that with test flights that will validate the optimum flap settings calculated by Iscold.
Like other open-class sailplanes, the Nixus Project glider (Nixus means “pushing forward” in Latin) has flaps that can be set at positive or negative angles to increase efficiency in various phases of flight. Unlike other sailplanes, however, the flaps and ailerons are controlled through a fly-by-wire computer system, which is a first, and reduced Payne’s workload during the June 10 flight, though the system’s contribution to the aircraft’s efficiency was less significant than it otherwise might have been because, Iscold noted, the computer was programmed to deploy the various control surfaces less aggressively than it could have been.
“Since the airplane is so new, we don’t have a very aggressive strategy on the computer to drive those flaps,” Iscold said of the fly-by-wire system, which interprets control inputs from the pilot and translates them into actuation. “We’re still studying it and trying to understand if it’s really the optimum strategy. I don’t think it is, but at least it reduces his workload.”
Payne said fly-by-wire technology, long since deployed on air transport and military aircraft, does make the sailplane a little easier to handle on long flights.
“It’s kind of like flying an open-class sailplane with power steering,” Payne explained, noting the stick force required to roll an aircraft with wings that extend 50 feet from each side of the fuselage is much reduced from what would be required without the automated assistance. The fly-by-wire system also enables Nixus another way, he added, by reducing the mechanical complexity of the control system. There is precious little space inside a wing as thin as this one is.
Payne has his steely eye on other records, including the longest distance covered in a sailplane. His personal best exceeded 2,900 kilometers, and there’s a nice, round number ahead of that which Payne believes he could achieve with some help from the same kind of mountain waves that produced Perlan’s high-soaring feats.
“One of our goals is to fly over 3,000 kilometers in one flight in the wave … that’s a huge optimization problem there,” Payne said. “You need an airplane that’s very efficient at near-redline speeds… Nixus is going to fit that bill.”
Iscold continues to work with Payne and others on getting the best performance possible out of Nixus, and hopes that it will serve to inspire other engineers to bring fly-by-wire into light aircraft.
“I really believe Nixus will be this very first seed on putting fly-by-wire [into], I don’t want to say general aviation, but maybe small aviation, small airplanes,” Iscold said. He has begun drafting scientific papers about Nixus for publication, and looks forward to continuing its development with help from his Cal Poly students. He teaches them to let dreams be their inspiration.
“I dream with the speeds, I dream with the long wing. I keep dreaming,” Iscold said. “Why not?”
He allowed that he might not dream up such a long, thin wing again, however. It’s a bit much for one engineer to tackle alone, though he might be persuaded: “Let’s see what the students think.”