Preparations for the Joint Multi-Role Technology Demonstration are Underway
By Donna J. Kelly
Igor Sikorsky (1889–1972) once said that the helicopter is “probably the most versatile instrument ever created by man. It approaches closer than any other to fulfillment of mankind’s ancient dreams of the flying horse and the magic carpet.” The next generation of rotorcraft in the works right now will provide even more vertical magic to military crews performing diverse missions worldwide.
In 2008, after years of urgent and repeated requests of both the American Helicopter Society (AHS) International and industry, Congress and the U.S. Department of Defense (DOD) made the move to initiate the long process of conceptualizing, designing, and creating the next generation of vastly superior rotorcraft. These new aircraft will enable aviators to fly faster, longer, quieter, with less vibration, and will embody a host of other improvements designed to overcome the limitations of legacy rotorcraft.
Intense service in Iraq and Afghanistan has resulted in a rapidly aging legacy fleet of helicopters with glaring deficiencies and gaps in needed capabilities. The overarching program to address these needs is being administered by the U.S. Army for all of the military services and is called Future Vertical Lift (FVL). The real powerhouse of the FVL program, however, is the Joint Multi-Role Technology Demonstration (JMR TD). Here, many diverse concepts are being developed and tested that will hopefully find their place in the world of rotorcraft… or maybe not.
The U.S. Army has made it perfectly clear that everything being tested is for evaluation only. Even the two biggest entries of JMR TD, demonstrator rotorcraft Bell V-280 Valor, and the Sikorsky-Boeing SB>1 Defiant, are not guaranteed a production contract if they do not come out at the top in the flight demonstration scheduled for next year.
Since many of the designs and concepts are theoretical and have only been tested at small scale, the U.S. Army is being very thorough in reviewing all of the potential approaches before deciding upon systems. The result may very well end up being an amalgam of several selected ideas presented by different producers. As Dan Bailey, Program Director of the JMR/FVL explains, “the intent of the JMR TD effort is to maximize the knowledge gain and risk reduction toward an anticipated Future Vertical Lift Acquisition Program.”
According to AHS International Executive Director Mike Hirschberg, the FVL Program proposes the creation of a multi-role family of rotorcraft in three overarching sizes and capability sets: Light, Medium, and Heavy. Unifying all three categories will be commonalities in training, cockpit layout, system requirements, reduced overhead, mission flexibility, and the use of common sustainment and maintenance facilities. It is important to note that FVL is a joint initiative between the U.S. Air Force, U.S. Army, U.S. Marines, U.S. Navy, U.S. Coast Guard, and U.S. Special Operations Command, with each branch of the service having input into the requirements needed to fulfill their specific missions.
The U.S. Army’s Center of Excellence at Ft. Rucker, Alabama, collected and analyzed the reported needs of each military service between the years 2009 and 2012. Using those results, the Army created what is called “capability sets.” These are the requirements stipulated for the individual rotorcraft, such as speed requirements and fuel range. An example of the needs of a specific service would be that the U. S. Marine Corps will need bigger seats, and therefore a bigger cabin, to accommodate the troops of the future, who are estimated to weigh a total of 335 pounds each with their equipment.
The first category, “Light,” is designed to include missions such as reconnaissance, security, marine interdiction, surface warfare, direct and close combat attack, close air support, and more. The “Medium” category is split into three different capability sets that vary in nature but include recon, surface warfare, air assault, logistics, humanitarian assistance, and others. The “Heavy” class is proposed to perform missions such as air and amphibious assault, MEDEVAC, and other jobs that would necessitate a larger air vehicle.
Two FVL Contenders
The Bell V-280 Valor and the Sikorsky-Boeing SB>1 Defiant, which will be flight tested next year, were targeted for the original requirements for the Medium class. Under this proposal, these helicopters would fall under Capability Set 3 and would be outfitted for such missions as mine/counter mine, air and amphibious assault, logistics, humanitarian assistance and disaster response, noncombatant evacuation operations, and MEDVAC.
The Bell Helicopter V-280 Valor is a tiltrotor design that was built upon the lessons learned from the Boeing V-22 Osprey. It boasts full-authority digital fly-by-wire flight control systems, flight envelope protection in the form of structural load limiting, and conversion corridor protection. Designed to be manufactured at a low-cost, the Valor uses commonly available broad goods (assembled fibers) for skin lay-up and yoke assemblies, a large cell carbon core, and bonded skin assemblies. It has been designed for performance and meets all Level 1 Handling Qualities for yaw, pitch, and roll quickness.
The Valor is sized to carry eleven to fourteen troops and has a target speed of 280 knots or higher (a gain over the Osprey’s top cruising speed of 250 knots). Its two engines will be fixed horizontally on its wingtips, with the engines housed in nacelles located at the tip of the wing. Vince Tobin, Bell Vice President for advanced tiltrotor systems and leader of the V-280 design team points out, “The troops will have an 8-foot clearance under the wing for field of fire and unfettered ability to egress out of side doors and establish a perimeter.”
The Sikorsky-Boeing entrant in the JMR TD is the SB>1 Defiant. Building on recent flight testing of Sikorsky’s X2 Technology Demonstrator and S-97 Raider light tactical helicopter demonstrator, the SB>1 has been scaled up to meet the requirements of the FVL Medium class of rotorcraft. While the X2 and S-97 development programs were self-funded by Sikorsky and its suppliers, over sixty partners are involved in the Defiant production.
The Defiant features full-authority digital fly-by-wire flight control system and will be configured with a lift offset coaxial rotor, pusher prop, and variable RPM drive system. It is expected to have a cruise speed of 250 knots, and excellent low- and medium- speed maneuverability.
The Defiant demonstrator is being assembled and will be tested at the Sikorsky Development Flight Center near West Palm Beach, Florida, reports Hirschberg. LORD of Cary, North Carolina, has developed an Active Vibration Control Systems (AVCS) that uses Circular Force Generators (CFG) to give the helicopter omnidirectional vibration suppression, rather than linear vibration suppression. Swift Engineering of San Clemente, California, is manufacturing a major part of the SB>1 frame.
Two other rotorcraft companies were not selected for the JMR Technology Demonstration but have been funded for further research and development. AVX Aircraft of Benbrook, Texas, was awarded a Technology Investment Agreement to refine its uniquely designed Compound Coaxial Helicopter (CCH). Under this agreement, AVX will continue with CCH development with design, analysis, and subscale testing to validate the aircraft’s ability to meet expected goals in speed, hover, and cruise efficiency, while also accomplishing a wide variety of military missions.
The AVX features a unique configuration of a conventional coaxial compound rotor, with ducted fans for auxiliary propulsion. According to Hirschberg, “further technology demonstrations will include scaled wind tunnel testing and Computational Fluid Dynamics (CFD), as well as the development and evaluation of control laws to reduce rotor loads, vibration, and vertical spacing of rotors.”
Karem Aircraft of Irvine, California, also is receiving further funding to continue development of a suite of technologies that the company believes will dramatically increase the performance of tiltrotors. Karem has patented what it calls the “optimum speed tiltrotor” (OSTR) configuration. In theory, this approach of greatly varying the rotational speed of the rotor blades from 100 percent at hover to around 50 percent when cruising will provide maximum efficiency in both flight modes and enable the configuration to deliver a speed of over 300 knots.
The Karem lightweight, stiff rotor design will be further evaluated, as will be the multi-speed transmissions and individual blade control with electromechanical actuation. All of these systems will be integrated and checked in a rotor test at the top of a tower.
A Brave New World
Superior vertical aircraft will soon be aloft. New designs with more efficient systems will promote rotorcraft’s use across more areas of aviation. Most important, they will provide the world’s best fighting forces with the world’s best rotorcraft.
Image #1 - The Bell V-280 Valor is conceptualized as a replacement to legacy helicopters, such as the Sikorsky MH-60 Seahawks and Bell UH-1Y Venom and AH-1Z Viper helicopters. (Image courtesy of Bell Helicopter)
Image #2 - The Bell V-280 Valor in production. (Image courtesy of Bell Helicopter)
Image #3 - National Full-Scale Aerodynamics Complex mechanics Rick Mcllmoil and Jose Rosario are shown conducting preflight checks of the Sikorsky UH-60 Black Hawk’s rotor before individual blade control testing in the facility’s 40- by 80-foot wind tunnel. (Image courtesy of U.S. Air Force, Arnold Air Force Base, photo by Jeff Johnson)
Image #4 - In preliminary flight testing, Sikorsky’s hub-mounted vibration sensor, which works in conjunction with LORD’s Active Vibration Control Systems (AVCS), significantly reduces vibration. (Image courtesy of Sikorsky Aircraft)
Image #5 - The cutaway view of the attack configuration shows weapons storage. (Image courtesy of AVX Aircraft)
Image #6 - This illustration shows the OH-58D conversion process. (Image courtesy of AVX Aircraft)
Image #7 - Though not selected to produce a demonstrator for the trials in 2017, this drawing expresses Karem Aircraft’s concept for a Joint Multi-Role (JMR) aircraft. (Image courtesy of the U.S. Army at www.army.mil)