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Sikorsky-Boeing Defiant X

Compound Helicopter Proposal [ 2030 ]

The Defiant X is being presented by the Sikorsky-Boeing joint venture as the refined form of its earlier SB-1 Defiant demonstrator.

Authored By: Staff Writer | Last Edited: 03/21/2022 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

In January 2021, the Sikorsky-Boeing Joint Venture team revealed its contender for the United States Army's "Future Long-Range Assault Aircraft" (FLRAA) requirement - the "Defiant X". The Defiant X compound helicopter is built atop the proven framework of the existing SB-1 "Defiant" technology demonstrator detailed elsewhere on this site. In testing, the demonstrator has exceeded speeds of 232 knots (266.98 mph) in a dive and 211 knots (242.8 mph) in level flight - exceptional performance for a rotorcraft. The FLRAA competition is currently (2021) down to offerings from Bell (by way of the tilt-rotor V-280 "Valor") and Sikorsky and seeks a capable successor the Army's storied and ubiquitous Sikorsky UH-60 "Black Hawk" multi-mission helicopter.

Both the U.S. Army and USMC services are actively involved.

Defiant X is being marketed with exceptional performance from its "compound" rotor arrangement, this seeing 2 x Four-bladed main rotors seated over the fuselage and a multi-bladed "pusher" prop positioned at the extreme aft-end of the design. Combined, the helicopter is able to achieve speeds more common to fixed-wing aircraft while retaining the hovering capabilities and low-altitude maneuverability/agility of a conventional helicopter. The new aircraft is envisioned with an operational range double that of the existing UH-60 types while being able to accomplish all of the Black Hawk's current over-battlefield roles and more; these include general transport, maritime patrol, troop insertion/extraction, Search and Rescue (SAR), scouting, fire support, and MEDEVAC.

The twin main rotors are defined as co-axial and is a design element typical of many Soviet-era and modern Russian helicopters originating from Mil of Moscow. In the Defiant X, the blades are of composite construction and rigid, delivering the needed hover and agility capabilities. Spinning in opposite directions, the main rotors negate the need for a traditional tail rotor unit to offset torque effects, leaving the tail unit free for the mounting of a "pusher" prop solution to give the helicopter unprecedented maneuverability and enhanced straight-line speeds compared to other rotary-wing types in this category. In the Defiant X arrangement, the pusher prop will also be used to quickly decelerate the helicopter when coming out of high-speed envelopes.

The fuselage is set to feature lightweight-yet-strong composite construction for in-the-field durability and general survivability. The helicopter is being completed with attention paid to vibration and corrosion reduction when operating in more unforgiving environments such as over-water. Large, rectangular sliding doors will be featured along the fuselage sides, fitted well-forward of midships.©MilitaryFactory.com
The cockpit will sport all-modern systems such as Fly-by-Wire (FbW), digital engine controls, touchscreen MFDs, and stability/control assistants to help reduce crew workloads on long missions. An eye towards the future is being cast in the form of autonomous operation. The passenger cabin will seat up to twelve combat-ready troops or be equipped to carry upwards of 3,700lb of cargo should the mission require it. Externally, transport of cargo via sling will come into play. Optional wingstubs fitted high along the fuselage sides will host Anti-Tank Guided-Missiles (ATGMs) for the assault role - current concept art showcasing four missiles to a fuselage side (eight total) - this in addition to onboard machine guns/miniguns operated by the crew and personal weapons carried by troopers.

The undercarriage will be retractable (three-point tricycle) unlike the UH-60's fixed tail-dragger configuration. This will help to reduce drag at high flight envelopes and keep the aerodynamics of the aircraft streamlined for high-speed endeavors.

In a typical mission setting, the FLRAA will be required to fly low and fast in and out of contested environments, most likely over uneven terrain, through canyons, and across urban settings. As such, maneuverability and speed play a large role in the Army's ultimate selection for the requirement. Helicopter specialist Sikorsky (backed by parent company Lockheed Martin) and defense powerhouse Boeing have an inside advantage is having supplied rotorcraft to the service for decades including produces such as the AH-64, UH-60, and CH-47.

While visibly similar to the SB-1 technology demonstrator, the Defiant X will be given certain new qualities consistent with military operational helicopters. The engine exhaust ports will be shrouded to reduce the aircraft's InfraRed (IR) signature and the undercarriage reinforced for the rigors of military service. The vertical stabilizers have been reworked to enhance general performance. Overall dimensions are comparable to both the in-service UH-60 and the developmental SB-1 form - as such, existing Army solutions in terms of transporting fleets of UH-60 helicopters can remain largely as-is.

An official Request-for-Proposal (RFP) is expected to arrive from the Army in 2021. The contract is expected to be awarded sometime during 2022 with fielding of operational-level units occurring before 2030.©MilitaryFactory.com
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January 2021 - The refined Defiant X form was officially presented by Sikorsky-Boeing for the U.S. Army's Future Long-Range Assault Aircraft (FLRAA) program.

March 2022 - The Honeywell HTS7500 turboshaft engine has been selected to power the Defiant X. The engine offers a 42% power improvement over the originally-planned T55-714A arrangement.


Sikorsky-Boeing Joint Venture - USA
United States (possible)
Operators National flag of the United States
Service Year
United States
National Origin
Project Status

General transport functionality to move supplies/cargo or personnel (including wounded and VIP) over range.
Surveil ground targets / target areas to assess environmental threat levels, enemy strength, or enemy movement.
Aircraft developed for the role of prototyping, technology demonstration, or research / data collection.

Houses, or can house (through specialized variants), radar equipment for searching, tracking, and engagement of enemy elements.
Survivability enhanced by way of onboard electronic or physical countermeasures enacted by the aircraft or pilot/crew.
Survivability enhanced by armor allocated to protect pilot / crewspaces and / or critical operating systems.
Incorporates two or more engines, enhancing survivability and / or performance.
Dual main rotors arranged in co-axial mounting, negating traditional torque-neutralizing tail rotor unit.
Defensive gun positions for engagement / suppression.
Features partially- or wholly-enclosed crew workspaces.
Features retracting / retractable undercarriage to preserve aerodynamic efficiency.

36.1 ft
(11.00 meters)
8,940 lb
(4,055 kilograms)
Empty Weight
11,023 lb
(5,000 kilograms)
Maximum Take-Off Weight
+2,083 lb
(+945 kg)
Weight Difference

2 x Honeywell HTS7500 turboshaft engines developing 7,500 horsepower each to drive 2 x Four-bladed main rotors in co-axial arrangement over the fuselage and 1 x Six-bladed tail rotor arranged in "pusher" configuration.
295 mph
(475 kph | 256 knots)
Max Speed
9,843 ft
(3,000 m | 2 miles)
280 miles
(450 km | 243 nm)

MACH Regime (Sonic)
RANGES (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hi-Hypersonic: 7673-19180 | Reentry: >19030

Proposed with support for 7.62mm/12.7mm machine guns and miniguns for general fire support / fire suppression.

Up to 8 x "Hellfire" (or similar) Anti-Tank, Guided Missiles (ATGMs) on optional external wingstubs along the fuselage sides.


Hardpoints Key:

Not Used

Defiant X - Base Project Designation.

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Image of the Sikorsky-Boeing Defiant X
Image from official Lockheed Martin press release.


Developments of similar form and function or related to the Sikorsky-Boeing Defiant X...

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