SB1 Defiant
At the end of December, one of the most interesting aviation events of the outgoing year took place: the appearance of a promising multipurpose helicopter with the complex name Sikorsky-Boeing SB1 Defiant (English “daring”, “defiant”, “disobedient”) was presented. The development is based on the promising Future Vertical Lift program, designed to give the American military a whole family of high-speed helicopters.
If you experience a state of déjà vu at the sight of the SB-1, don't be surprised. The Americans have been testing its fellow Sikorsky S-97 Raider for a long time and, in general, very successfully. The new SB1 cannot be called a modification of this car in the full sense of the word. Helicopters are designed to solve completely different tasks: to the extent that the tasks for rotary-wing aircraft may generally differ from each other.
Recall that the S-97 is a relatively small helicopter with a crew of two and the ability to carry up to six troops. This is either a scout, or a light drummer, or a base for a future drone. Most often it is seen as a high-speed replacement for the small Bell OH-58 Kiowa helicopter, which is almost outdated. The S-97 attack helicopter will most likely never replace the Apache: the Americans generally intend to operate the AH-64 almost until the 2050s. Recently, by the way, it became known that the Boeing company wants to remake the legendary helicopter, providing it with a pusher propeller. This, in theory, will increase flight speed by 50 percent. But how it will be in practice, of course, is unknown, because radical alterations are far from always beneficial to old machines, if we talk about their flight and technical qualities. This often leads to an abrupt increase in mass with quite predictable consequences.
By the way, it is the presence of a pusher propeller in the tail section that makes the S-97 Raider and SB1 Defiant so similar. And also the use of a coaxial rotor in the design of both helicopters. But this, as we said, is where the similarities end. The fact is that the helicopter shown now will by default be a much larger machine, capable of performing a much wider range of tasks. Simply put, this is a possible replacement for the famous Sikorsky UH-60 Black Hawk - the main American multipurpose army helicopter. Like him, Defiant is capable of predetermining the appearance of the US Army for many decades.
The importance of the program can hardly be overestimated. For all its merits, the "Black Hawk Down" has speed limitations inherent in any "classic" helicopter, due to the aerodynamic concept itself. The "maximum speed" indicated in open sources for the UH-60L is 300 kilometers per hour at a cruising speed of just over 280. For comparison, the estimated cruising speed of the SB1 Defiant should be 460 kilometers per hour. The difference is huge. And, it must be assumed, the widespread use of the SB1 Defiant will give the American army opportunities that it had never dreamed of before. At the same time, no other country in the world has plans for the massive introduction of high-speed helicopters in the foreseeable future.
Helicopter characteristics
At the heart of the design of the SB1 Defiant is the experimental apparatus Sikorsky X2, which, before the closure of its program, managed to set at least one unofficial speed record, accelerating to 415 kilometers per hour. The very experienced coaxial helicopter with a pusher propeller was built on the basis of the experimental S-69.“The secret to the X2 coaxial is that the counter-rotating main propellers provide lift and forward flight without a tail rotor. Above 150 knots (277.8 km / h), thrust is provided by the push propeller, so the main propellers do what they do best - provide lift,”said Chris Van Buyten, who was vice president of Innovation in 2016. projects at Sikorsky. It is noteworthy that for the SB1, two far from new Honeywell T55 engines were chosen as the basis of the power plant: the same ones are installed on Boeing CH-47 Chinook helicopters. However, they are being modernized specifically for Defiant, and in the future, the helicopter can be equipped with a fundamentally new power plant.
Built on the basis of the SB1 Defiant, the serial vehicle will be able to carry out transport operations, land troops, carry out search and rescue operations, evacuate the wounded from the battlefield and perform a number of other tasks. The crew is four people. On board it will be possible to mark twelve paratroopers or cargo with a solid mass. The use of the SB1 Defiant as an attack helicopter cannot be ruled out, however, as far as can be judged, such a possibility will be purely optional. Do not forget that in addition to Apaches, Vipers and tactical aircraft, the Americans have attack UAVs at their disposal, which can also be effectively used for ground support. And, of course, the A-10, which will serve the United States faithfully for some time until they are replaced, for example, by the F-35A or the F-35B.
Underwater rocks
The SB1 Defiant should not be feared for machines designed for other tasks, but for the Bell V-280 Valor tiltrotor, which, in general, has similar characteristics. This, recall, is a promising tiltrotor, which is already undergoing flight tests. Like the SB1, it will be able to carry more than ten troops, and the speed of the V-280 is even higher - the maximum is 520 kilometers per hour. Of course, the US Department of Defense has enough finances, but it must be assumed that the military will choose one aircraft: either the SB1 or the V-280. And for now, Valor is ahead.
On the way, he may only have a very controversial experience in the operation of tiltrotors by the Marine Corps. "The V-22 looks great … when not idle for repairs," the late Senator John McCain said at the time. Indeed, disasters, technical failures and a low level of combat readiness pursued the V-22 all his life. Do not forget that the Osprey was built in a relatively small series: for the Bell V-280 Valor, which is considered a mass aircraft, such difficulties are completely unacceptable. In general, now it is difficult to say with confidence which option will be the winner. It is very possible that none of the created devices will suit the US military. And they will ultimately remain loyal to Black Hawk.
At the same time, other countries should understand that if revolutionary high-speed helicopters really "shoot", then their more familiar counterparts will ultimately be out of work. And Bell, Sikorsky and Boeing will share the world market of multifunctional rotorcraft. "Boring" option, but so far it looks the most plausible.
