Though you may not have heard of them, an Idaho-based company called Tamarack Aerospace Group has been making some noise in aviation circles for the last few years with startling performance claims for a compound active winglet system, called ATLAS, that it has installed on Textron-Cessna business jets.

Conventional passive winglets, the kind you see on airliners like the 737 NG, are generally agreed to be good for a 3% to 4% decrease in induced drag and corresponding increase in fuel efficiency when installed on aircraft with large, cruise-optimized wings. The Seattle firm Aviation Partners, which was founded by the late Joe Clark, popularized the addition of fuel-saving winglets to business jets and then to airliners in the late 1990s.

Since then, winglets have become ubiquitous in commercial and business aviation with OEMs like Boeing, Airbus and Gulfstream all designing their own. The generally accepted 3%-4% fuel savings associated with different winglet designs may seem small, but it’s significant for airlines and fleet operators for whom fuel is a major, variable operating cost.

So when Tamarack received a Supplemental Type Certificate from the European Aviation Safety Agency (EASA) for its ATLAS active winglet system for Textron-Cessna’s CitationJet CJ, CJ1 and CJ1+ series business jets in 2016, its claim that ATLAS could reduce fuel consumption by 33% was met with amazement and not a little skepticism.

The noise around Tamarack grew a little louder in the spring of 2019 when its ATLAS system came under scrutiny following reports of flight attitude departures from which pilots then had to struggle to regain control. In April 2019, EASA issued an airworthiness directive noting that the active load alleviation system (ATLAS) appeared to have malfunctioned.

The FAA issued a corresponding AD on May 24, immediately grounding affected airplanes. Five loss of control incidents including a fatal accident were noted by the FAA which, along with EASA, required changes to Tamarack’s ATLAS system. However by July 2019, the FAA accepted Tamarack’s proposal for compliance to the AD, terminating the groundings. A month later, Tamarack received a fresh commitment of investor funding.

The grounding led Tamarack into Chapter 11 bankruptcy in early June 2019, a process from which it is about to successfully emerge, according to company executives.

“We’re almost completely out of the Chapter 11 process at this point,” says Tamarack President Jacob Klinginsmith. “We’re in good health and we’ve continued sales through this process, even through the grounding. Things are looking pretty good for the rest of this year.”

Reports of ATLAS-equipped flight control departures were overblown, Klinginsmith contends, a view he says was shared by the NTSB investigator in charge of the probe of the fatal crash.

“One of our customers filed a false pilot report early last year, reporting a failure of our system. He claimed the outcome of the failure was more dramatic than it actually was.”

Investigators found that that the reporting pilot did not have the active winglet system serviced as Tamarack recommended, according to Klinginsmith. Meanwhile, the company has repaid all of its creditors, has continued to service its customers, and secured a confirmed reorganization plan this past spring.

So the small Sandpoint, Idaho, company appears set to continue in business. It has installed the ATLAS winglets system on over 100 CitationJets covering the entire series from CJ, CJ1, CJ1+ to M2, CJ3 and CJ3+. Despite those sales, it still has a sales job to do on its performance claims.

Active Winglets

How can the addition of winglets generate a 33% reduction in fuel burn? By doing more than a pair of passive winglets, Tamarack says. ATLAS is a system that combines the vortex reduction of traditional winglets with real-time aerodynamic load alleviation, light weight and increased climb performance.

“We have a lot more explaining to do,” Tamarack founder, Nicholas Guida admits. “When we come out of the box setting an [informal] world record on our first flight [a claimed 1,853 nautical miles in the company’s CJ], given what’s been claimed [for winglet efficiency], we have to train everybody to realize it’s about getting to altitude quickly and being efficient at altitude.”

ATLAS is comprised of a wing tip extension, a highly tuned winglet, wing loading sensors (located in the aircraft’s fuselage) and a moveable load alleviation surface. The latter looks like a small aileron at the junction of the wingtip and winglet. It’s used to essentially “turn-off” the winglet during short gust or maneuvering events, alleviating loading on the wing and thus the requirement for a beefed-up wing structure that passive winglets impart.

Guida says he came up with the idea while returning from a Steely Dan concert in 2009. Prior to that he’d spent years as a consulting aerodynamic/loads engineer at Aviation Partners working for Joe Clark.

“I worked on the [API] passive winglets for Hawkers and Gulfstreams,” Guida says. “The whole time I was doing it, I realized that there had to be a better way. I saw all the disadvantages of winglets, not just the good parts.”

Among those was the weight generated in the form of structural reinforcement to the wing to handle the aerodynamic loads that winglets create. On a 767 that works out to almost 3,000 pounds of additional metal, according to Guida.

“My idea was that we don’t need to take the winglet up to the [maximum] limit-load of the airplane. The gust maneuvers [that a wing experiences] are short lived events. Why do we need to take the whole wing up to the [maximum load] levels during one of these [brief] events?”

The small aileron at the wingtip deflects when load sensors detect vertical loads on the wingtip/winglet, countering the force of those loads and the aerodynamic affect of the winglet itself. This momentary “load alleviation” means that the wing does not have to be strengthened, saving weight. It also allows Tamarack to add more span to the CJ wing, increasing its efficiency.

“We extend the wing and add a winglet,” Guida says. “That’s why we have three to four times the savings [in fuel] as a passive winglet.”

The added span (five feet in total) also allows the stock aircraft to climb to higher altitudes, further increasing its efficiency.

“If you take a CitationJet fill it up with fuel and fly, you should be back on the ground within three hours and 900 nautical miles or else you’re going to be nervous. With a Citation with active winglets you can fill it with fuel, fly for over four hours and go 1,350 nautical miles,” Guida asserts.

Bizjets won’t be the only beneficiaries Tamarack says. The company’s analyses of the 737 and A320 show an 18% to 20% fuel efficiency increase with the ATLAS span extension/active winglets. Pursuing the commercial aircraft market is obviously part of Tamarack’s long-term plan but it has other targets first, including those who have difficulty digesting its claims.

Convince Us

Textron-Cessna acknowledges supplying Tamarack with baseline wing/engineering data for the CJ but told this reporter it has no active relationship with the ATLAS maker. Textron adds that it has not validated Tamarack’s performance data for the CJ series. Whether Tamarack has asked for such validation or not, Textron won’t say.

For its part, Tamarack says that it has had aerodynamicists from potential clients review its data. But the company can point to no formal third-party validation of its claims. Tamarack says it has 30 patents related to ATLAS and points to numerous testimonials by the 100-plus customers it has done conversions for. Validating and certifying ATLAS data is expensive and time consuming, Guida points out but common sense would suggest that it’s a necessary step for the company’s growth.

For the nearer term, Klinginsmith says the Bombardier Challenger and Cessna Citation XLS series are likely candidates for Tamarack’s ATLAS conversions. But so are other aircraft, particularly those that require good hot-high altitude performance and significant range/loiter time. Both the military and unmanned air vehicle OEMs have aircraft with such needs.

Guida affirms that the company has been approached by UAV customers looking for extra altitude/loiter performance for their drones, though he declines to say who. Tamarack also claims to have had formal and informal discussions with the U.S. Air Force regarding potential ATLAS modifications for the C-130. Given that ATLAS works entirely independently (including actuation/control) of OEM systems, presumable obstacles from Lockheed Martin or others could be surmounted.

But Tamarack won’t identify any Air Force officials it has spoken with. When asked whether the company has spoken with any DoD acquisition authorities, Guida and Klinginsmith will say only that they’ve had discussions “at the Pentagon” and possibly with the Department of Energy. When these took place is unclear. The company’s spokesman mentioned meetings with congressional representatives who expressed interest in ATLAS but offered no names.

That’s an issue for Tamarack, which may have an exceptional product but one that has yet to produce verifiable performance numbers beyond initial sales success.

“The problem with having the best winglet system in the world right now,” Guida offers, “is that you almost discredit yourself by making all the claims we’ve made.”

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