Fly Farther, Stop Less, Save More
Making a wing more efficient with a winglet comes from more evenly distributing the aerodynamic loading on the wing to reduce drag; but this always introduces more bending load in the wing. In other words, the greater the benefit provided by the winglet design, the more wing load is increased. This means that there are compromises that must be made to ensure that the wing can carry the worst case flight loads. This is actually addressed by Boeing in their description of the 737 winglet design. The 737 winglet is detuned from an efficiency standpoint in order to reduce the amount of structural reinforcement that would be required to carry the worst case flight loads. The purpose of ATLAS™ is to actively reduce the bending load in the wing in conditions that produce worst case flight loads. This means a Tamarack winglet can be designed for peak efficiency without compromise for structural considerations.
Structural considerations in this context means high potential for reduced weight with an ATLAS™ winglet; and reduced time for engineering design and testing. If a wing must be made stronger it means there must be more metal for reinforcement -which is an obvious weight penalty for a passive winglet. Less obvious is the engineering time required for engineering design and testing.
Increased design loads introduced by a passive winglet extend from the fuselage to the winglet. Design of structural reinforcements in the original wing can be costly and time consuming because it often requires reverse engineering the original structure for the entire wing to identify the weakest areas in addition to designing the reinforcements. An ATLAS™ equipped winglet only increases the loads near the tip which dramatically reduces the engineering work required to ensure that the original structure will be strong enough. Likewise, it takes much less time and engineering resources to certify increased loads only near the tip than it does to certify increased loads over the entire span of the wing.
Airworthiness authorities, either FAA or EASA, require that the structure can carry the worst case flight loads (Limit Load); and also require that the structure can carry the worst case flight loads with a factor of safety of at least 1.5 (Ultimate Load). Of course, the purpose of the safety factor is to reduce the probability of a structural failure which can also be accomplished with very reliable systems such as ATLAS™. Existing regulations (EASA CS-25.302) allow a reduced structural factor of safety via a load alleviation system as long as the probability of a structural failure is extremely improbable. ATLAS™ has been designed with this in mind in order to leverage this benefit for customers.
This goes back to the engineering benefits of the ATLAS™ equipped winglet because the reduced factor of safety is applicable to the entire wing. This provides opportunity for increased gross weight (or other mission changes) in a modification; or a new, lighter wing that is designed with ATLAS™ in mind from the outset. These are opportunities that are not available with a passive winglet design.
The orange surfaces that look like little ailerons on the extension near the winglet are called TACS. TACS is short for Tamarack Active Camber Surfaces. The TACS, extension and winglet comprise the ATLAS™ Active Winglet system. The extension and winglet on the CJ 525 and its variants adds 6’ to the total wingspan. For the CJ 525B, the wingspan increases by 8’.