The CV / MV-22B convertible is adopted by the US Marine Corps in the 2007 year. This is the only currently operated aircraft, taking off and landing vertically and having a high speed horizontal flight.
Helicopters since their appearance in the French army and air force during the war with Algeria in the 1954-1962 years added a new dimension to the concept of military operations.
The use of helicopters to support vertical maneuver allows you to deliver combat units, not paying attention to geographical obstacles, to the place where your opponent can least expect. This opens up new combat opportunities. Since the time of the Algerian conflict, technical progress and constant improvements in the design of the helicopter have increased its capabilities, in particular, its payload and lift. However, the maximum speed and range of modern medium and heavy multi-purpose helicopters, apparently, reached their upper limits.
For example, the newest model F of Boeing’s CH-47 Chinook multi-purpose transport helicopters has a maximum speed of 315 km / h and an 370 km range. For the CH-47F is the Russian Mi-35M helicopter with a maximum speed of 310 km / h and a range of 460 km. The AgustaWestland / Finmeccanica medium AW-101 helicopter with a maximum speed of 309 km / h, while the new AW-139M medium helicopter of the same generation develops a maximum speed of 306 km / h. As can be seen from this list of maximum speeds, not all modern helicopters can develop a maximum speed of just over 300 km / h.
Cruising speed is important because it affects the "turn" of the aircraft when performing combat missions. The faster the helicopter flies, the sooner it will reach its goal and will soon be able to return to pick up and deliver additional forces and supplies. Rapid build-up of forces on the ground is very important for the success of the air assault. Thus, the ability of an aircraft to fly more flights over a given period of time is extremely useful. Flying at high speed also increases survivability by reducing the time when the aircraft is open to enemy observers and arrows on the ground.
An increased range is also desirable, although it is mainly related to the fuel supply. In the past, special attention was paid to increasing the flight range, which is directly related to the capacity of the fuel tanks. Medium and heavy helicopters, such as the Mi-26 with a range of 800 km and Sikorsky CH-53E with a range of 999 km, need such a range to perform several sorties without refueling. Meanwhile, fuel booms mounted on aircraft, such as the CH-53E helicopter or the MH-60G / U Blackhawk special operations helicopter, allow you to perform long-range tasks in the rear of the enemy. However, the range and cruising speed of flight in terms of practical operational sense are closely related. Although the aircraft may have a range that allows it to reach the landing area hundreds of nautical miles, it is necessary to take into account the return journey and the time spent on it, since this can lead to an increase in the time it takes for the landing forces to rise. In this case, it will not be able to quickly perform round-trip tasks due to the increased flight time. That is, in order to most effectively use a longer range, the aircraft must again fly faster.
Despite initial difficulties and criticism of skeptics, the Bell-Boeing CV / MV-22B Osprey tiltrotor, which began life in 1981 in the framework of the Vertical Take-Off / Landing Experimental (JVX) joint project, changed the concept of operations involving vertical-lift devices. First deployed by the US Marine Corps in 2007 and special forces of the US Air Force in 2009, this convertoplan is currently used not only in military operations (intervention in Iraq and Afghanistan), but also in humanitarian tasks and disaster relief operations, for example he helped out after typhoon Haiyart, which devastated part of the Philippines in 2013. The Marines, in particular, saw in the MV-22B tiltrotor a solution to the problem of delivering troops from ships far beyond the horizon. This task was previously performed by a heavy CH-46E Sea Knight transport helicopter, but its flight time was unacceptable. This helicopter took quite a long time to build up the necessary contingent of airborne forces, while it made several sorties. The limited number of troops remained vulnerable.
The unique characteristics and capabilities of the MV-22B tiltrotor are aimed at solving such problems. He can take off vertically from the amphibious ships, but when moving to level flight and turning the engines down he can fly at a speed of 500 km / h. This is more than twice the speed of the CH-46E helicopter, which means the flight time is reduced to the same landing zone by more than half. Plus, the large 722 km range and higher payload in the 9070 kg cockpit and on the 6800 kg suspension further increase its efficiency. The hands-on experience gained with the MV-22B has increased interest in the convertoplanes as an aircraft type and improved the prospects for the next generation convertoplane. This is especially true given that CV / MV-22B, in fact, uses the technologies, materials and processes of development and production of 70-ies of the last century, which, without any doubt, have advanced significantly over the past three decades.
When developing a promising V-280 Valor convertible, Bell-Boeing takes into account the experience gained with CV / MV-22B and introduces the latest technologies, materials and production processes in order to create a more sophisticated turning screw aircraft.
For the Sikorsky S-97 helicopter, a scheme with two rotors of opposite rotation and a tail propeller is used. This allowed not only to get high speeds, but also the possibility of flying sideways and even back
As noted above, aviation the industry is working to overcome the maximum speed limit of helicopters. The problem of increasing speed is partially connected with the very element that allows the helicopter to make a vertical flight - with the upper rotors. The problems that needed to be solved were related to the aerodynamic drag of the screws and the casing, elimination of air breakage from the blades, reverse air flow, and air compressibility. A discussion of the technical subtleties of these problems could take several pages, but one thing is obvious - they must be solved in one way or another in order to change the dynamics of the helicopter flight. Designers are trying to solve these problems, going in a variety of directions and "groping" for answers there.
For example, Bell Helicopter took the proven concept of CV / MV-22B pivot screws and adapted it for its convertible plane V280 Valor project. According to Steve Matia, director of business development for advanced rotary screw systems: “When creating and producing the V-280, the experience gained and tested on the CV / MV-22B tiltrotor is used, and the most modern development and design technologies are used.” As he explained, one of the most interesting solutions is implemented in the V-280 gondola. At the convertoplane CV / MV-22B, the entire gondola is rotated. With the new V-280, only the screws and gears are rotated, while the gondola and the engine remain stationary. This allows you to safely embark and disembark, since the engine case does not interfere with the landing party, and also reduce maintenance requirements. The V-280 convertoplan, designed to perform various tasks, is smaller than the CV / MV-22B convertiplane. It will have a cruising speed of 520 km / h, combat range over 930 km, will be able to hover at an altitude of 1828 meters and fly at a temperature 32 degrees Celsius with a full combat load, while exceeding existing helicopters in maneuverability. Together with Lockheed-Martin, Bell offers a convertible glider V-280 for the FVL JMR-TD (Future Vertical Lift Joint Multi-Role Technology Demonstration) advanced helicopter program. The companies have scheduled the first flight of their convertible V-280 on August 2017.
Through the use of tail pusher propeller and twin-girder tail stabilizers, the S-97 is already noticeably quieter than traditional helicopters. When there is no need for high speed, but low visibility is needed, the pushing screw makes it almost silent.
A promising X3 helicopter from Airbus Helicopters has short wings, creating lift at speeds above 80 nodes, and two turboprop engines for forward flight. Pilots speak favorably of the maneuverability of an Airbus Helicopter aircraft.
Meanwhile, Sikorsky and Boeing have joined forces with the FVL JMR-TD program to offer the SB-1 Defiant helicopter. They propose to take Sikorsky's X13636 project with coaxial screws of opposite rotation and a pushing propeller as the basis for a new aircraft weighing no more than 2 kg. In this approach, Sikorsky-Boeing has its advantages, since the sample for demonstrating technical solutions X2 Technology Demonstrator weighing 2720 kg made several test flights in 2010 year, in which it reached a record speed of 463 km / h. In 2015, the company Sikorsky presented its prototype of a light tactical multipurpose helicopter S-97 Raider weighing about 5000 kg.
The project of the SB-1 Defiant helicopter companies Sikorsky and Boeing
Chris Van Van Buyten, Vice-President of the Innovation Projects Division at Sikorsky, who heads this project: “Flying farther and faster in a co-axial helicopter is definitely a key requirement. However, with our S-97 project, we want to show the next-generation rotary-wing aircraft, which will be able to surpass traditional helicopters in each operational parameter, especially at low speed and during a hangup. The secret of the coaxial unit X2 is that the main screws with counter-rotation provide lift and forward flight without a tail screw. Above the 150 knots (277,8 km / h) the thrust is provided by a pushing screw, so the main screws do what they do best - provide a lift. ” Van Byuten further made the assumption that the S-97 and SB-1 aircraft "will radically change how military pilots are now flying and fighting in helicopters." By the time the Sikorsky and Boeing team has raised its SB-1 helicopter into the air in 2017, Sikorsky will have the third experimental device X2 in less than 10 years, which can finally confirm the inherent ability of this project to scale to the size of an average multi-purpose UH helicopter -60 Black Hawk.
Sikorsky's X2 Project
The goal of the FVL JMR-TD program is to develop and deploy an aircraft with significantly improved performance and capabilities that can perform a wide range of tasks, ranging from reconnaissance and attack to transporting troops and cargo.
Airbus Helicopters (formerly Eurocopter) is implementing a hybrid approach to developing advanced helicopters using some of the integral elements of traditional aircraft, such as short rectangular wings. This solution significantly increased the flight speed, which in 2012 showed a test flight of the technological demonstrator X3, which reached the speed of 255 nodes (472 km / h) (above the speed record X2). In the X3 project, the top rotor for lifting and hovering and short wings are combined with turboprop engines mounted on them, providing thrust for moving forward (therefore, the term “hybrid” is used here). It does not have a rear propeller; instead, a horizontal stabilizer with vertical tail stabilizers at each end is installed. When flying forward at speeds of more than 80 knots (148 km / h), the wings begin to create additional lift and at high speed provide almost all lift for this aircraft.
Airbus has not yet disclosed its plans for a new military aircraft using the approach shown by the X3 project. However, a company representative suggested that many of the current helicopters could include these constructive solutions. Since the deep-modernized body of the AS-3N365 Dauphin light-duty helicopter AS-3N3 from Airbus Helicopters is taken as the basis for the X3 project, this seems entirely possible. X2019 was shown to the US military, but ultimately did not get into the FVL JMR-TD program. Airbus has indicated its intention to focus on search and rescue tasks and continues to work on an aircraft based on the XXNUMX project, which can take to the air in the XNUMX year.
The Russian Helicopters holding announced in 2009 year that it is developing a promising high-speed aerodynamic helicopter with a retractable landing gear and a proprietary implementation in the rotor design of the local stall suppression system on the retreating blade SLES (Stall Local Elimination System). According to the company, Mi-X1 will have a cruising speed of 475 km / h and a maximum speed of up to 520 km / h. In August, the 2015 of the year at the MAKS Airshow in Moscow Helicopter Plant. Mile showed a RACHEL demo (Russian Advanced Commercial Helicopter - Russian advanced commercial helicopter), advertised as a high-speed helicopter. The helicopter can take on board up to 24 passengers or 2,5 tons of cargo and carry it with a maximum speed of 500 km / h to a maximum distance of 900 km. The holding said that test flights will begin in December, and mass production in 2022 year. In December 2015, the public was presented a deeply modernized Mi-24K with new curved rotor blades. The purpose of this development is to reduce aerodynamic drag, increase stability and speed of flight of the helicopter. The company assumes that the maximum speed of the experimental aircraft will increase from 333 km / h to 400 km / h. According to the company, if it is possible to re-equip another aircraft with curved blades, this will increase the speed by 30 percent.
Russian project of advanced high-speed helicopter RACHEL
The small American company AMV is developing its own high-speed vertical take-off vessel with propellers located on its short wings. The prototypes clearly hint at a combination of a VTOL (Vertical Take-Off and Landing) and a high-speed helicopter. AMV launched its demo X-PLANE into the air and expects its AMV-211 to reach a maximum speed of 483 km / h, a cruising speed of 402 km / h and a flight range of 1110 km. Although the company submitted its proposal for the FVL JMR-TD program, its project was not selected, and the X-PLANE project was not stopped and its development continues.
AMV X-PLANE Concept
Another candidate proposed in the field of high-speed helicopters uses the VTDP patented design scheme (Vectored Thrust Ducted Propeller; a pushing screw with thrust vectoring) mounted in a pipe in combination with bearing wings. The experimental four-bladed X-49 Speed Hawk model with two engines for the first time took off in the 2007 year and reached the speed of 268 km / h. This model was based on the body of the deck anti-submarine helicopter Sikorsky SH-60F Seahawk. The work was initially funded by the US Navy and then by the US Army to demonstrate ways to increase the speed of existing helicopters to 360 km / h. This project was not selected for the FVL JMR-TD program.
The project of the company Piasecki Aircraft on the basis of the deck anti-submarine helicopter Sikorsky SH-60F Seahawk
SB-1 is a further development of the Sikorsky S-97 project and another candidate for the FVL JMR-TD program, which aims to meet the needs of an average multi-purpose helicopter
A number of countries, including the US and NATO forces, will face the challenge of aging their helicopter fleets in the coming decade. Many of the current helicopters were put into service in the 80-s, their lifespan is approaching the 30 years. For example, McDonnell Douglas / Boeing AH-64 Apache combat helicopters began to be supplied to troops in the 1986 year, and despite a number of improvements, they have essentially the same flight characteristics. The UH-60 family is even older; the first helicopters were delivered in the 1974 year. The newest UH-60M helicopters have electric remote control systems, a common architecture, a new powerful and reliable engine, but the speed remains the same. The first task of the FVL JMR-TD program will most likely be the replacement of UH-60 series helicopters, which explains the similarity of the structures of the cabins offered for it.
So, military operators inevitably seek to replace their aircraft. And here they are faced with the question of whether to leave proven designs, albeit with the inclusion of digital electronics and avionics, electrical remote control systems and composite materials, or move to projects that offer a new level of possibilities. The second question is the possibility of developing a universal vessel that could perform a variety of tasks. The US military initially wanted to have a maximum of three aircraft to perform all its intended tasks. This idea has changed several times, and at the moment they are focused on three projects: Light Scout light helicopter (operated from 2030 of the year), medium Medium Light, universal / shock from the beginning of operation from 2028 of the year, and finally heavy Heavy Cargo transport from start of operation from 2035 year. In addition, the US Army is counting on the implementation of the Ultra project, the start of operation of which is scheduled for 2025 year. This is a new vertical take-off truck with characteristics similar to those of transport aircraft with turboprop engines, such as the Lockheed Martin C-130J or the Airbus A400M. But, judging by the results of a briefing by José Gonzales, deputy director of the ground combat and tactical combat systems department, held at the US Department of Defense in January 2016, everything seems to be changing again. A breakdown into categories is proposed, based on necessary capabilities rather than mass. These new categories have not yet been announced.
Even without the “Ultra” option, this concept of new aircraft has not only technical problems, but can also affect the current situation of the US Air Force with its ambition and deadlines. Probably, from an operational point of view in various tasks some projects may be preferable to others. The main issue remains the proportionate funding of such a program and how this may affect other army modernization projects.
The CV / MV-22B tiltrotor operating experience reveals the advantages of this aircraft and points to new ways of using its unique capabilities. Based on this experience, the US command of special operations forces USSOCOM has already expressed interest in increasing the number of CV / MV-22B convertible plans compared to initial requirements. Adequate experience of the X3 project in the framework of the FVL JMR-TD program shows the reality of achieving high speed, increased maneuverability and greater range. Currently, there is a question of determining the viability, expandability and adaptability of high-speed helicopters, as well as their cost, which will allow them to perform the full range of combat missions. High-speed helicopters are already on the horizon, but how soon and in what form is still unknown.