Rotorcraft for civil and military purposes are capable of solving tasks that are inaccessible to any other type of aircraft and modern technology in general. Their main and perhaps the only drawback is their relatively low speed. The average speed of the helicopter does not exceed 220 km/h. Today, many helicopter manufacturers say that the time for records has come!
Why do helicopters need high speeds?
As in the performance of military operations, and in the implementation of many tasks of a peaceful nature, there are situations when the success of the mission depends entirely on the speed performance of the helicopter. These include:
- Evacuation of the seriously wounded and sick from the centers of hostilities and hard-to-reach places to large medical institutions.
- Urgent delivery of specialists (doctors, epidemiologists, law enforcement officers) to emergency areas.
- Express delivery of vital (medicines, food, special equipment) and bulky goods to places far from the developedinfrastructure.
Despite the many advantages of rotorcraft (minimum landing surface requirements, maneuverability, the ability to hover in the air), until recently, the speeds of an aircraft and a helicopter were incomparable.
Maximum helicopter speed
Until recent years, the official speed record for classic rotorcraft was 400.9 km/h, set in 1986 by a modified version of the British Westland Lynx multipurpose vehicle. The fact is that even theoretically, the maximum speed of a helicopter cannot exceed this threshold.
This state of affairs is explained by the fact that at higher speeds, the range of oscillatory movements of the main rotor blades dangerously increases. which in turn leads to flow separation from their extremities. The phenomenon is especially characteristic for azimuths of 270-300° (the angle of the blade relative to the longitudinal axis of the machine), i.e. for retreating blades. What design and technological innovations will allow developers to overcome the cherished milestone?
First records
One of the ideas to increase the speed of the helicopter is to use an additional "push" propulsion. This design feature is by no means new. Back in 1967, the creators of the American device Lockheed AH-56 "Cheyenne" installed in the tail section of the machine to increase the speed characteristicsthree-bladed propeller.
The 407 km/h (407 km/h) demonstrated during test flights looked very impressive at the time. It was planned to produce 375 helicopters for the US Air Force, but due to numerous difficulties in serial implementation, the project was closed after the production of only ten aircraft.
Of course, it's one thing to get closer to the cherished figure, but it's quite another to surpass it significantly.
European Hybrid
The next record holder - the X3 Hybrid was developed by the European corporation Eurocopter. First took to the skies from the site of the military base Istres - Le Tube (France) in 2010. After a year of test flights, the creators managed to bring the cruising speed of the helicopter up to 430 km/h.
Further improvements in design and performance allowed the European aircraft to set an unofficial speed record for rotorcraft - 472 km/h in level flight and 487 km/h in a dive. Why unofficial? Yes, because the Eurocopter X3 is not really a helicopter.
The production model EC155 Dauphin served as the basis for the creation of the machine. The designers supplemented the "source" with two gas turbine aircraft engines with pulling propellers located on small wings. Thus, the Eurocopter X3 is rather a hybrid of a helicopter and an airplane. The project is in the final test phase and the developers claim that mass production will start soon.
A little more theory
The use of pulling or pushing screws frees the main rotor from the need to create horizontal thrust for the forward movement of the aircraft. Specialists from the American aircraft and helicopter manufacturing company Sikorsky have developed a promising ABC technology (Advancing Blade Concept), which in Russian translation is called the concept of an advancing blade.
The essence of the development is that the angle of inclination of the advancing and receding rotor blades must always provide maximum lift. Thus, the main rotor will be able to maintain the required flight altitude at a much lower rotational speed. And this is almost the determining factor in increasing the speed of the helicopter.
ABC technology allows the aircraft, even after the disappearance of the lifting thrust on the retreating blades, to continue acceleration.
Competition as an incentive
The concept has already been proven. An experimental helicopter of the Sikorsky-69 concern, equipped with two pusher turbojet engines, demonstrated a maximum speed of 518 km/h.
Helicopter manufacturers on both sides of the ocean are well aware that, other things being equal, the manufacturer whose characteristics of the helicopter model will have higher speed performance will be the winner.
In addition to the emergence of new technological solutions, modern materials science provides developers with ample opportunities to improve flight performance. Many production models are already equippedscrews made of composite materials. To reduce aerodynamic drag, the propeller hubs are covered with fairings.
How fast are helicopters flying today?
Industry leaders
The concern's device, implemented as part of the Sikorsky X2 project, became a logical development of the concept of the Sikorsky-69 model. The helicopter significantly increased in speed and efficiency, but retained all the advantages inherent in rotorcraft: excellent maneuverability at low speeds, the possibility of stationary hovering, vertical takeoff and landing, and autorotation. The cruising speed of a coaxial helicopter with one pusher propeller is 460 km/h (maximum -474 km/h), range - 1300 km.
Proven technologies have been continued in the new generation helicopter S-97 Raider, the model of which with estimated flight characteristics was presented to the public by the designers of the enterprise. The developers claim that the cruising speed of the helicopter will be at least 500 km/h. Units and assemblies of the future leader are undergoing ground tests. There is no reliable information about the date of the first flight of the American Ryder yet.
And what about Russian Helicopters?
But what about domestic helicopter manufacturers? We can say that the plans of the employees of the Kamov and Mil design bureaus are no less ambitious. Back in 2013, the leaders of the Russian Helicopters holding company initiated the PSV program to develop a promisinghigh speed helicopter. Within the framework of this project, the specialists of the Plant named after Mile in 2015, a demonstration model of the Rachel helicopter was presented. The speed of the helicopter, according to the assurances of the developers, is not a priority for this model, but for another promising Mi-1X aircraft, it can reach 520 km/h.
"Kamovtsy" almost a decade ago presented the concept of a very fantastic aircraft Ka-90. According to the idea of the designers, the helicopter, having reached a speed of 400 km / h with the help of a main rotor, folds the blades into a streamlined case, and further acceleration continues with jet engines. Moreover, the developers do not consider the parameter of 700-800 km/h to be the limit.
