The USA is planning to take the evolution of the helicopter to the next step with the
Future Long-Range Assault Aircraft Programme. Why was this programme which intents to change
the whole perspective in this field in the next 50 years, needed? What are the important
developments in the FLRAA? And could the programme really do what they promised? As the Weapon
Detective, we are examing this important programme and its two competitors, the V-280 Valor and
the SB-1 Defiant. Please don't forget to subscribe to our channel,
before we start and give us a thumbs up if you like our video.
Competing for the FLRAA Programme, the V-280 Valor and SB-1 Defiant are not just helicopters
superior to their predecessors. They are the game changers which may radically change helicopter
design and military use. That's why FLRAA is a truly special programme.
However, in the 30 years since the end of the First Cold War, we have also witnessed
a large number of such special programmes being stillborn.
There have been some other projects that manage to come to life.
Yet many of them, such as the JSF, still struggle with childhood illnesses that could be fatal.
So although the FLRAA is, in theory, the next step in helicopter evolution, its survival
depends on its performance in overcoming many important problems in practice.
Before analyzing the Valor and Defiant, let's take a look at why the FLRAA Programme started
and what stages it has gone through. The US Army had to use its helicopters five
times more than in peacetime, especially during Operation Iraqi Freedom and Operation Enduring
Freedom. Therefore, the need to replace these rapidly
worn out helicopters arose. At first glance, it seemed a logical step to replace the existing
inventory with the same models. After all, the production lines of the UH-60, AH-64,
and CH-47 were still open. These combat-proven helicopters were still
winning major tenders in the international market.
However, in the last two decades, significant innovations have been made in rotorcraft technologies.
It was feasible in terms of costs to put these new technological leaps into practice to meet
the needs of the US Army which plans to acquire 4,000 new helicopters.
Of course, to develop a new generation helicopter, a more practical reason was needed besides
the excitement of new technologies. China has begun to become a great military
power. So, the US interest has shifted to the Pacific
Region, where many islands spread over a vast area, after Afghanistan and Iraq.
But, the current helicopters in use have a combat radius of approximately 300-350 kilometres.
Therefore, the US Army and the US Special Operations Command need many helicopter groups
and lots of bases to control the Pacific. Furthermore, the US Marine Corps also has
to regularly deploy a great number of amphibious assault ships in the region.
The combat radius should increase to decrease in the number of bases, groups, and ships.
But this is not enough alone. If the range of a UH-60 with a cruising speed
of 280 kilometres per hour doubles, its flight time also doubles. This increases the reaction
time of a quick response team. Besides, the fatigue level of the troops who
travel for a long time would be high when they reach the mission area.
Therefore, the new helicopters have to be almost faster nearly twice than their predecessors.
Thus, the Future Vertical Lift, shortly FVL, Programme started in 2009 to study on the
US Armed Forces vertical lift capabilities, technology development, and retaining long-term
engineering capabilities. The programme goal was the development of
a rotorcraft family to replace, the OH-58 Kiowa scout, UH-60 Black Hawk utility, AH-64
Apache attack, and CH-47 Chinook heavy-lift helicopters.
Members of this family would use the common subsystems as possible.
However, taking into account the complexity and high-cost disadvantages of the Joint Strike
Fighter and Future Combat Systems programmes, the US Army decided on a simpler development
model. Priority was given to utility and attack helicopters.
Thus, while the programme became easier to proceed, a more affordable project cost could
be presented to the US Congress which is complainant about the excessive financial burden of the
F-35. In 2019, the FLRAA Development Programme was
initiated as part of the FLV, a study programme. In the new programme, the decision was made
to continue with the V-280 Valor developed by Bell and the SB-1 Defiant developed in
partnership with Sikorsky and Boeing. For the new helicopter to replace the UH-60,
the US Army demands a continuous cruise speed of at least 460 kilometres per hour. But the
desired speed is 520 kilometres per hour. The minimum requirement of the US Marine Corps
is 510 to 565 kilometres per hour. Its desired speed is 546 to 611 kilometres per hour. Due
to the difference in squad formations, the US Army demands the helicopter to carry 12
troops and the US Marine Corps 8 troops. The range requirement is between 3,195 and 4,520
kilometres. The new helicopter must have low radar and acoustic signatures.
After having a brief look at the FLRAA, let's review the helicopters competing in the programme.
Considering their first flight dates, we will give priority to the V-280.
The V-280 made its first flight on December 18, 2017.
The helicopter has a different tiltrotor design than the V-22. Valor's turboshaft engines
are fixed, not rotating with its entire body like the Osprey's. Only the rotor assembly
rotates for the take-off/landing and cruise. So, the exhausts of the fixed engines do not
rotate downwards during vertical take-off/landing. Therefore the risks of hot air from the exhaust
damaging the ship deck or setting on fire dry grass on land are eliminating.
The constant forward-facing air intakes provide more efficient airflow for engines.
The fixed design makes maintenance and repairs easier than on V-22s.
Also using the experience gained from Osprey, the Bell engineers have managed to reduce
the drag around Valor's engine significantly. The new design also minimizes the wake turbulence
behind the engine during flight. Thus, vibration and fluttering at the wingtips
are reduced. The tiltrotor design provides the V-280 with
a more stable hovering capability. The rotor, which would have lost its drive
in case of engine loss, can be driven by the shaft extending through the wing.
The fuselage of the V-280 is made of the generally composite materials to reduce weight. Aluminium
was preferred for the framework. The wings are made of a single piece of carbon
fibre reinforced polymer. The larger wingspan of the V-280 compared
to the V-22 increases aerodynamic efficiency. These wings are not angled forward like the
Osprey's wings. Thus, it is possible to use simpler mechanical components.
The V-208's V-type tail helps reduce the helicopter's radar and thermal signatures. It also weighs
less than its conventional design and increases manoeuvrability.
Valor's elastomer rotor bearing is resistant to high loads and does not need lubrication.
The V-280's all carbon rotor blades increase reliability, reduce costs and offer higher
aerodynamic performance. Capable of carrying 14 troops apart from the
crew, the Valor is 15.4 meters long, 24.93 meters wide and 7 meters high. The empty weight
is 15,000 kilograms, while the maximum take-off weight is 26,000 kilograms. Two General Electric
T64 turboshaft engines enable the helicopter to reach a cruising speed of 520 kilometres
per hour. With a combat radius of 930 to 1,480 kilometres, the maximum range of the V-280
is 3,900 kilometres. The helicopter has a hover ceiling of 1,800 meters out of ground
effect. Of course, these data belong to the development
model. If the Valor becomes the winner of the contract, its mass production model will
have different general characteristics. The Sikorsky-Boeing partnership shared less
information about the SB-1 Defiant, than its competitor, the V-280. The SB-1 Defiant made
its first flight on March 21, 2019. Most of the technical information about this
helicopter is based on information shared on the X-2 and S-97 Raider.
It is a compound helicopter with rigid coaxial rotors.
It means the SB-1 has an additional system for thrust.
The rotor designs used to date have prevented helicopters from exceeding a certain speed.
On the SB-1, solid rigid composite rotor blades were preferred to overcome the speed limitation
of helicopter aerodynamics. The propellers in the tail are driven by turboshaft
engines that also power the main coaxial rotor. For this reason, the powerplant has an additional
gear-box. As the speed of the helicopter increases,
the speed of the airflow over the main rotors also increases. Therefore, rotor blades provide
more lifting power and pull the helicopter up. To avoid this problem, a special system
is used that automatically activates when the SB-1 reaches a speed of above 148 kilometres
per hour and reduces the angle of attack of the rotor blades depending on the speed. Lowering
the angle of attack is also lowering the lift. Thus, the Defiant gains more stable flight
characteristics. The tips of the rotor blades have a special
design that did not lose its efficiency at transonic speeds.
The counter-rotating coaxial main rotors design makes the lift symmetrical and offers more
stable flight characteristics. Also, compared to conventional helicopter design, it provides
a more stable flight in a crosswind and has 50 per cent better performance in high-hot
hover performance. The rotor head used on the SB-1 has a special
aerodynamic design reducing drag. The rotor blades of the Defiant have a manual
folding mechanism. Metal reinforced composite components are
used for the SB-1's fuselage to reduce the weigh.
Even if one of two engines would have lost, the helicopter can continue its flight at
a speed of 288 kilometres per hour. As we mentioned before, very little information
has been published officially about the SB-1. The helicopter can carry 12 troops apart from
the crew. The rotor diameter is estimated to be around 15 meters. Its empty weight is
around 11,500 kilograms. The Defiant has already reached speeds of 380 kilometres per hour.
The target is to reach a cruising speed of 450 kilometres per hour. It is known that
with the existing turboshaft engines, the SB-1 cannot meet FLRAA criteria for the combat
radius. Now if we compare these two competitors, each
has its own advantages and disadvantages. First of all, especially in high-speeds, the
tiltrotor design has the advantage of less vibrating compared to the coaxial rotor one's.
This is an essential advantage in keeping the fatigues of troops and crew within a certain
limit during long flights. The vibration has also negative effects on
the life of mechanical parts, electronics, and fuselage.
Similarly, against the drag of high speed, the tiltrotor design is more advantageous
in terms of the load on the mechanical parts compared to the coaxial rotor design.
The SB-1 is a more compact helicopter than the V-280.
So, the Valor is an easier target against the ground fire.
Besides, the Defiant has the advantage of being able to land and take-off from narrower
areas than its opponent. Smaller dimension is a factor that facilitates the deployment
of the helicopter to a ship or a forward base. Despite using old turboshaft engines in the
trials that are currently being conducted, the V-280 has achieved the FLRAA requirements.
The SB-1, on the other hand, is waiting for the development of a new engine to meet these
requirements. In the Advanced Tactical Fighter Programme
launched in the 1980s, the fact that the YF-22 had lines similar to the F-15 was instrumental
in its victory over the YF-23. Of course, that was not the main reason. However,
the generals, who are generally more conservative, could have a sense of confidence in the similar
equipment they use. In this aspect, the V-280 has the fuselage
resembling the UH-60 and the proven tiltrotor design with the V-22.
It looks friendly. However, the US Armed Forces are not accustomed
to the coaxial rotor compound helicopter design. This unfamiliar appearance may cause some
anxiety. Bell has not won a major tender from the US
Armed Forces for a while. But its rival in this programme is a consortium
consists of Sikorsky Aircraft, a Lockheed Martin company and Boeing.
The lobbying power of these two defence giants both in the armed forces and in the congress
is extremely high. This power, no matter how successful it may
be, can block off the V-280. Nevertheless, it is also possible for the
US Armed Forces to choose different helicopters for different branches due to the difficulties
experienced in the F-35, which was developed as a single aircraft for all military services.
Over the past 30 years, the USA has introduced many revolutionary projects. However, very
few of them were able to see the finish line. Similarly, although viewed as a groundbreaking
programme, the FLRAA could a victim of budget cuts. However, the V-280 and the SB-1 prove
that future helicopter designs will differ from the current conventional ones'. It is
not a rational approach to step back at this point. Even if this programme could be terminated
after maybe 10 years, a similar one will inevitably come up again after 20-30 years.
Thanks for watching our video. And please don't forget to subscribe to our channel and
give us a thumbs up if you like our video.