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Smart Bombs: Military, Defense and National Security

Defiant X Meets the FLRAA Mission

Defiant X
Defiant X. Image Credit: Creative Commons.

With the U.S. Army just weeks away from a decision on its Future Long Range Assault Aircraft (FLRAA), competition between the final competitors, defense industry titans Bell and Lockheed Martin, is fiercer than ever. In their bids to replace the venerable H-60 Blackhawk, the companies are pursuing radically different approaches. Bell’s V-280 Valor is a smaller version of the V-22 Osprey tiltrotor, while Lockheed’s Defiant X is a clean-sheet design, compound helicopter. Both have their merits and would signal a giant leap forward for Army aviation. But considering attributes regarding lifecycle costs of infrastructure, training, sustainment, and most importantly, mission, the Defiant X is the clear choice. 

Infrastructure and design

The Defiant X has the same footprint as the H-60, meaning it can easily nest within the Army’s existing infrastructure, sparing the costs of adapting facilities – costs that touch on everything from labor to materials. Advocates for the V-280 argue the airframe can be accommodated in current Army attack/assault helicopter hangars. But at 82 feet wide, it’s more than 50% wider than Defiant. There’s a difference between fitting existing hangar and ramp infrastructure like a glove, and barely squeezing in. 

Yet despite its smaller size, the Defiant X has larger rotors than the V-280, with all the benefits that entails. With its two, 53-foot six counter-rotating, coaxial rotors, Defiant X provides more lift than V-280’s 35-foot diameter proprotors. Defiant has significantly more rotor disk area than the V-280, equating to lower disk loading for a given gross weight. Basically, compared to the V-280, the Defiant X can hover higher, lift more, and handle better. It maintains a better visual environment along with greater flexibility.

Training

Selecting the V-280 would increase pilot training requirements for the elemental reason that the V-280 is not a helicopter; it’s a tiltrotor with both helicopter and fixed wing modes. Army pilots don’t receive fixed-wing training in Phase 1 rotary wing common core. Yet most of the flight time in a tiltrotor is spent in airplane mode, significantly increasing Phase 2 training requirements for the V-280 compared to the Defiant X. 

Further, a tiltrotor introduces a control unique in aviation: proprotor tilt. This is a high-inertial control, meaning there’s lag between control input and control response. Speaking from experience as a test pilot, specialized training is necessary to master this control, especially in tight formations and confined landing zones. Conversely, Defiant X’s compound design facilitates an easy transition from Phase 1 to Phase 2 training, making it a “go to war” aircraft.

Sustainment

While advocates argue the V-280 is a helicopter when it comes to training, they insist the same aircraft should be regarded as an airplane in terms of sustainment. Airplanes, after all, have fewer moving parts, which means fewer maintenance costs. 

Past performance does not bear this out. In 2019, only four out of 10 V-22s were found ready for combat. The V-280 has numerous modes – helicopter, airplane, and conversion – all of which are used in flight. All components controlling those modes must work. With a single mode, fixed rotors, and fixed propulsor, the Defiant X is less complex and more sustainable.

Even more concerning, the V-280 confronts a design issue of having fixed the engines to the wing, as veteran defense reporter Richard Whittle wrote in 2016:

“One result of fixing the engines on the wingtips… a gaping hole in the wing facing forward opens up beneath the V-280’s nacelles when they rotate upward…Bell engineers considered trying to close the hole to prevent dust and dirt from entering the nacelle there. … They decided instead to live with what they regard as a minimal risk.”

Experience in the Middle East and Afghanistan demonstrated the impact of sand and dust on the aircraft, with everything from blade erosion to clogged filters and engine degradation, serving as a major driver of sustainment costs in austere environments. Potential corrosion from rain and salt water intrusion also poses a risk. Whether the gaping hole in the V-280’s helicopter mode becomes a sustainment issue remains to be seen. Experience suggests there will be an impact on sustainment unique to the V-280’s configuration. 

Actions and Tactics “On the X”

For Army aviation, the mission is accomplished in the landing zone – “on the X” – and landing is the critical moment in any air assault.

It’s here that Defiant X’s configuration and flexibility are shown to be superior to the V-280. With a similar footprint to the H-60, the Defiant X can maintain the same missions, tactics, and techniques in the same formations and in the same kinds of confined areas as its Blackhawk predecessor. 

While the V-280 can operate in confined areas, it requires changing tactics to do so, as Bell’s own Frank Lazzara, director for FLRAA sales and strategy, explains: “If we were in a confined area we could still land in the same footprint as a UH-60, we [the V-280] might need to land in a different axis.” (Emphasis added.) 

Changing orientation at the critical landing phase adds complexity and risk to the mission for pilots and assault forces. Likewise, a lack of flexibility in formation selection reduces options for V-280 pilots and assault forces precisely where they need it most – on the X. 

To meet the tactical standards defined by the 101st Airborne Division’s Gold Book, the V-280’s design demands that the aircraft separate in what’s known as a trail formation – single file, one after the other.

The trail formation brings serious challenges for tilt-rotor aircraft due to their rotor wake. In April 2010, an Air Force Special Operations CV-22 crashed while flying through the rotor wash of the lead aircraft. The resulting investigation found that “CV-22 wake modeling is inadequate for a trailing aircraft to make accurate estimations of safe separation from the preceding aircraft.”

By design, V-280 is susceptible to this same phenomenon: the spacing between its proprotors allows one to be engulfed in downwash reducing lift while the other continues to provide it, an asymmetry in lift known as an uncommanded roll off. 

The Defiant X does not carry the same design constraints. It meets the separation requirements of the Gold Book without any changes to tactics,and it avoids the risks of changing the landing axis and of uncommanded roll offs. 

Taking Up the Black Hawk’s Mission

The Defiant X possesses the design requirements to pick up the assault mission where the H-60 Black Hawk left off, without requiring costly adjustments to existing facilities, longer and more involved training, and changes in tactics. 

This helps hold complexity at bay. This is important, because amid the worsening security situations in both Europe and the Pacific, the complexity of mission requirements for Army aviation’s foreseeable future will only increase. There’s no doubt Army aviators will meet those challenges as they write their next noble chapter, but they deserve the best tool for that mission: the Defiant X.

Scott Trail is a retired Marine CH-46E helicopter pilot, V-22 developmental test pilot, and a member of the Society of Experimental Test Pilots.

Written By

Scott Trail is a retired Marine CH-46E helicopter pilot, V-22 developmental test pilot, and a member of the Society of Experimental Test Pilots.

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