Next generation of V/STOL machines builds on proven tech innovations
Tiltrotor, coaxial, hybrid aircraft, advanced rotor blade configurations and antitorque devices have been adopted and accepted into new designs.
AgustaWestland's revolutionary "Project Zero" is an all-electric tiltrotor technology demonstrator. Revealed to the public in Mar 2013, it has been flying since Jun 2011.
Tiltrotor technology has proved itself on the battlefields of Iraq and Afghanistan. The Bell/Boeing V22 Osprey got off to a rocky start in the development phase—but, through aircraft improvements and system redesign, the aircraft being fielded today are far superior to the first tiltrotors.
V22s have logged over 170,000 flight hours with more than 200 aircraft in the field so far. CV22s configured specifically for USAF special ops missions are deployed around the world today.
AgustaWestland is proceeding full speed ahead with certification efforts on the AW609 tiltrotor. Few people can argue against an aircraft capable of taking off from a small LZ, climb to 25,000 ft in pressurized comfort and cruise at speeds up to 275 kts. AgustaWestland's plans include AW609s serving in the search-and-rescue, law enforcement, deepwater offshore and corporate mission areas.
A recent addition to the tiltrotor scene and the newest proposal for the FVL program is the Bell V280 Valor. Breaking free from Boeing, which teamed with Sikorsky for the S97 Raider coaxial aircraft, Bell is going forward with its own tiltrotor technology to meet future military needs.
With 55 years of tiltrotor experience under its belt, Bell is into its 3rd generation of tiltrotor aircraft, with the XV15, BA609, V22 and now the V280 Valor. Bell Helicopter is also pursuing the tiltrotor UAS market with the smaller Eagle Eye.
AVX Aircraft, located in Fort Worth TX, proposes its patented technology to create a coaxial rotorcraft with directional dual ducted fans. Combining these 2 proven technologies produces an additional 15% power available for vertical lift because the drive train does not power an antitorque system.
Additional efficiencies are gained by the mutual integration of coaxial rotor systems, resulting in a 6% increase in lift at sea level, increasing to possibly 20% during hot-and-high operations.
The AVX proposal will use lower rotor RPM during high-speed flight to minimize compressibility and decrease the aircraft's noise signature. Dual ducted fans will provide forward thrust and offload the lift requirement of the coaxial rotor system in forward flight.
During a hover, the fans use differential thrust to pivot the aircraft about the vertical axis for hovering turns. The AVX rotorcraft will obtain greater speed, fuel efficiency, payload and range than today's conventional helicopters.
Beyond vertical lift
If the FVL program were not enough, manufacturers and DARPA continue to push for engineers to stretch beyond the current limitations and imagine what is next. Fixed-wing aircraft are fast but cannot land in tight LZs, while helicopters fly low and slow, which leaves them vulnerable to attack.
Fixed-wing development over the past 50 years has seen airplanes exceed the speed of sound and now enter the very fringes of space.
Rotorcraft and VTOL development have failed to produce similar quantum results. This is why DARPA has launched the VTOL X-Plane program—to overcome this "flatline" VTOL progress. DARPA Program Mgr Ashish Bagai says the agency launched the program "to challenge industry and innovative engineers to concurrently push the envelope in 4 areas—speed, hover efficiency, cruise efficiency and useful load capacity."
Bagai continues, "We have not made this easy. Strapping rockets onto the back of a helicopter is not the type of approach we're looking for. We're looking for true cross-pollinations of designs and technologies from the fixed-wing and rotary-wing worlds."
If AgustaWestland was not busy enough with its AW139/169/189 family and the AW609 tiltrotor, it continues to push the envelope by introducing the "Project Zero" effort. This new tiltrotor R&D demonstrator, flying since Jun 2011, is an electric tiltrotor using 2 integrated rotors capable of tilting forward 90° in flight.
The aircraft has long sleek wings and resembles a fixed-wing aircraft more than a traditional helicopter. According to CEO Daniele Romiti, AgustaWestland "strongly believes in the tiltrotor concept as the future of high-speed rotorcraft flight, as it offers much greater speed and range than compound helicopter technology."
With Project Zero and the VTOL X-Plane on the horizon, pilots can expect some great rotorcraft advances over the next few decades. With demonstrators like the Sikorsky X2 and Eurocopter X3 already flying, future rotorcraft advances aren't that far away. Faster, further and more lift capability is the order of the day—and manufacturers seem ready and willing to deliver.
Jay Chandler has written for Pro Pilot magazine since 1995 and has flown for the FAA, military and Part 91 and 135 operators.