By Eric Tegler
In 2022 the Army will choose a new aircraft to replace its Reagan-era UH-60 Black Hawk helicopter. Two contenders from Sikorsky-Boeing and Bell will battle it out to become the winner of the Service’s Future Long-Range Assault Aircraft (FLRAA) program and the Army’s next combat helo when it deploys in 2030.
But “helicopter” isn’t even the right word to describe these two aerial beasts.
Bell’s V-280 is actually a tilt-rotor, similar to the V-22 Osprey currently flown by the Marine Corps, Air Force, and Navy but smaller and with a V-tail. Rather than relying on a single large main rotor for lift in forward flight and vertical takeoff and landing (VTOL) like a helicopter, it tilts two large rotors (called prop-rotors) at each of its wingtips 90 degrees from horizontal to vertical and back. It’s essentially an airplane in forward flight and twin-rotor helicopter in VTOL flight.
The V-280 gets lift from its wings as well as its proprotors, adding another dimension Bell test pilot, Ernie McGuinness says. “Below 120 knots (138 mph) it flies like a helicopter. Beyond 120 it flies like an airplane.”
The traditional cyclic is moved to the pilot’s right hand in sidestick fashion in the V-280. Since the Valor is a tilt-rotor, it acts a bit more like an airplane control yoke in cruise and a cyclic in vertical flight. Bell replaces the collective with what it calls a “power lever.” It controls the thrust of Valor’s twin proprotors and the power of the twin engines but has shorter travel than a collective.
The V-280 has a thumb-wheel located on the power lever. Roll the wheel (like the one on your computer mouse) forward and the 35-foot-diameter proprotors tilt forward and down, accelerating the aircraft. Roll it backward and they tilt back and up, decelerating the V-280 hard. In hover or at slow speed the foot pedals rotate the nose left or right by commanding differential pitch between the proprotors. At speed, the pedals actuate rudders on the V-tail.
Meanwhile, Sikorsky-Boeing’s SB-1 might look like a normal helicopter, but it’s actually a “compound helicopter,” including stacked, counter-rotating main rotors, a pusher propeller, and aircraft-like rudders. The pusher-propeller can provide significant forward thrust, relieving the need to tilt its main rotor for forward flight. Counter-rotating main rotors give extra lift, stability and smoothness. This gives the SB-1 speed, climb, and VTOL advantages over normal helicopters.
“In a helicopter when you want to turn really hard, you slow down,” says Sikorsky-Boeing test pilot, Ed Henderscheid. “In the SB-1 you can turn as hard as a fixed wing airplane and the prop will maintain your speed. It allows the pilot to manipulate the flight path in ways we’ve never been able to before.”
The SB-1 is more traditional with a cyclic and collective similar to the Black Hawk but moves the cyclic to the pilot’s right hand in sidestick fashion. It also adds a thumb-wheel and two buttons on the collective to control its pusher-propeller. Rolling the wheel forward with your thumb increases propeller pitch, speeding the aircraft up. Rolling it backward decreases pitch/thrust, slowing things down.
A “zero thrust” button automatically puts the prop in negative pitch, dramatically slowing the Defiant. A clutch button engages or disengages the propeller. Rather than a tail rotor, the foot pedals command opposite pitch on each stacked main rotor, making Defiant rotate left or right at slow speed or in hover. At higher speeds the pedals actuate Defiant’s rudders like an airplane.
Their designs stem from the Army’s desire for a multi-mission VTOL aircraft that flies much faster and farther than the workhorse Black Hawk. In fact, the Army wants its UH-60 replacement to be capable of a top speed of 230 knots (265 mph) or more, one-third faster than the 159-knot (183 mph) twin-engine Black Hawk.
Despite being more than 40 years old, bettering the Black Hawk won’t be easy. The helicopter has been built in two dozen variants for the Army alone and operated by 30 global militaries
“The Black Hawk is a tall bar,” says Army veteran helicopter pilot and Sikorsky test pilot Bill Fell. “We’ve been building them for over 40 years. In my view it’s the greatest helicopter the world has ever known.”
New Designs, Different Controls
Both prototypes have already logged real-world flight hours. Bell’s V-280 has accumulated 170 hours of flight test time and even performed a flight demonstration at the 2019 Fort Worth (TX) Alliance Air Show. As for the SB-1, it has over 13 flight hours under its belt and made its first public flight in late February
But the way they fly is different. Their respective tilt rotor and compound pusher-helicopter designs allow their pilots to manipulate thrust in multiple axes at once, giving them agility a UH-60 can’t match.
In a traditional helicopter like the Black Hawk, the pilot has three primary flight controls. There’s the cyclic, a stick between the pilot’s legs. Move it left or right and the helicopter rolls left or right. Move it forward or backward and it pitches the nose up or down. The collective is a lever by the pilot’s left thigh. Pulling it up increases lift from the main rotor and increases engine power, making the helicopter climb. Lowering it decreases lift/thrust and the aircraft descends. Anti-torque pedals control the tail rotor. Step on the left pedal and the nose rotates to the left, press the right pedal and the nose rotates right.
Defiant and Valor employ programmable fly-by-wire digital flight controls, allowing engineers to tune pilot inputs and feedback.
Lifting Off and Climbing Out
Flying the Valor or Defiant is a new experience for any pilot, including veteran Bell and Sikorsky-Boeing test pilots, but there are two common themes—power and speed.
Lifting off vertically and flying away in either machine is an eye-opener test pilots say. Despite both aircraft weighing around 30,000 pounds, they leap into the air far more aggressively than a 12,000-pound Black Hawk.
The competing Defiant and Valor teams won’t offer VTOL rate-of-climb/acceleration numbers but they easily surpass the UH-60 and are expected to do so with a dozen soldiers inside.
Transiting To Target
As a medium-lift helicopter replacement, a Valor or Defiant would have to haul soldiers, weapons, or gear to battle just like the UH-60. Both teams affirm they can do so faster and more comfortably.
So far, the SB-1 has achieved around 140 knots (161 mph) top speed in flight testing. Bell says it has exceeded 300 knots (345 mph) with the V-280.
Fast Approaches and Hovers
Given sophisticated anti-aircraft threats, the Army reckons its FLRAA aircraft will need to fly fast and low, figuratively slamming on the brakes as late as possible to slow to a hover or touch down in a hot landing zone (LZ).
Though they do this differently, Defiant and Valor improve markedly on the UH-60.
Survivability was a concern when the UH-60 was designed in the early 1970s, and it’s a challenge that’s only gotten tougher. Whichever FLRRA contender is selected, it will have to survive at the “X”—defined by the Army as the terminal area where it actually has to go deliver troops, conduct reconnaissance, or pull off the attack mission.
The New Black Hawk: A Difficult Choice
The tradeoffs between the two FLRAA aircraft will make the Army’s decision a tough one. Speed, agility, survivability, maintainability, cost, and manufacturing capability among others will tip the balance. Bell already has a tilt-rotor in service with the other Armed Forces. Sikorsky already supplies the Army with the Black Hawk.
Whatever selection the Army makes, it won’t fly like any helicopter before it.