Review Article Open Access

“Defiant”, a Today Unique Helicopter in the World

Relly Victoria Virgil Petrescu1
  • 1 Bucharest Polytechnic University, Romania


You do not see helicopters like this every day. Sikorsky-Boeing SB1 Defiant in his first demonstration flight showed that it is much more than just a fancy design on paper as he could initially think, with a first relevant flight demonstration. The initial flight lasted less than 30 min, enough time for Defiant to prove he can climb and descend easily, move back and forth and turn left and right with extraordinary ease and maneuverability. Companies have described this action as a low-speed flight maneuver and a short film has revealed that the helicopter can also operate in the area of about 10 to 20 m of land successfully. His first start in the inaugural flight test was held at a Sikorsky airport in West Palm Beach, Florida. SB1 Defiant has an unusual design that instantly conquers you. If most helicopters have one main rotor for vertical lifting, "Defiant" has a pair of coaxial rotors, one rotating clockwise and the other rotating trigonometrically (counterclockwise) to achieve a balancing the dynamics of the couple - that is, to prevent it from overturning one side or another. This means that the aircraft no longer needs the standard rotor at the helicopter tail. Instead, it has a new, distinctive, rear-wheel drive, which has the role of getting Defiant's zoom along the high-speed horizontal flight. "Defiant" is designed to fly at almost twice the speed of classic helicopters while maintaining the best low speed and hover performance of conventional helicopters. Coaxial design can also be found in some Russian military helicopters but without a propeller. Sikorsky used the project earlier (with the propeller) in the experimental X2 helicopter and the next S-97 Raider. The Defiant Project is considered by the United States Army for the Future Lift Vertical program, which intends to find a replacement for many of the US military helicopters used today (Finally, as in the early 2030s, where Defiant's rival in that area is the Bell V-280 Valor, which is not a helicopter, but rather a V-22 Osprey-like tiller-like aircraft used by US marines. The V-280 has been able to improve flight quality since its first flight in December 2017). The Sikorsky-Boeing team will then analyze the flight data recorder and film on this first demonstration flight with the aim of establishing a plan for several "Defiant" test flights in the coming weeks and months to confirm other important features of the new helicopter, before making a complete presentation, for massive future production orders. Sikorsky and Boeing have long been working on this high-speed military helicopter project and have released the first images of what is expected to become a very efficient utility helicopter of the United States Army sometime in 2030. SB1 Defiant is a technology demonstrator with Future Lift technology, built around the Sikorsky X2 platform, using two counter-rotating blades at the top of the plane to eliminate the problem of a 150 km/h traction rotor (~ 240 km/h).

Journal of Aircraft and Spacecraft Technology
Volume 3 No. 1, 2019, 92-106


Submitted On: 27 March 2019 Published On: 15 April 2019

How to Cite: Petrescu, R. V. V. (2019). “Defiant”, a Today Unique Helicopter in the World. Journal of Aircraft and Spacecraft Technology, 3(1), 92-106.

  • 0 Citations



  • Boeing
  • Sikorsky
  • SB1 Defiant