Tiltrotor and other V/STOL for future urban aviation

While large airports will always exist, flight to city centers is inevitable.

USMC MV 22B Osprey of VMM263 squadron flies over Al Anbar Province in Iraq during a mission out of Al Asad AFB in Nov 2007.

Bell/Agusta is sure to take a very hard look at market projections for its civil tiltrotor before deciding the financial feasibility of continuing the program. Regardless of efficiency, if the cost is too high, corporate operators and potential “tiltrotor airlines” will never be convinced to use such an aircraft.

Many tiltrotor proponents consider construction of new dedicated landing facilities crucial. If tiltrotor aircraft are forced to use existing airports and operate within the current ATC system, particularly in IFR operations, the advantage of the technology is largely lost and the airplane remains a less expensive and equally efficient choice.

A major advantage of the tiltrotor-and one frequently quoted in marketing strategies is that it eliminates time consuming airport operations and subsequent ground transportation.

An executive in New York could leave his/her corporate offices right from a dedicated pad, fly to a business meeting in Boston MA, continue to Philadelphia PA for a second meeting, include a third stop at a suburban corporate office and return to his/her New York country home without going near an airport or needing any ground transport.

This would certainly make for a productive and profitable day. In similar fashion, tiltrotor airlines could emerge, flying travelers between destinations at higher speeds than current helicopters.

For example, the BA609 could do the downtown New York–Washington trip in about 45–50 min. Published performance figures for the BA609 give a 275-kt maximum speed, 265-kt cruise speed and 750-nm range.

The aircraft is designed with anti-ice systems for flight into known icing and can operate at altitudes up to 25,000 ft to enjoy the benefit of fuel savings. The BA609 will be outfitted with 2 Pratt & Whitney Canada PT6 engines.

Building pilot experience

There is also the consideration of who will fly the tiltrotor. Dual rated airplane and helicopter pilots seem like the natural choice, but does that experience necessarily translate well to the tiltrotor aircraft?

Sikorsky S76D made its first flight on Feb 9, 2009. Tiltrotors will compete with helicopters in the 200-mile mission but will bring advantages in speed and high-altitude operations.

Even the 2 tiltrotors currently being produced or nearing certification-the V22 Osprey and the BA609-have different power controls. The V22 uses a thrust control lever (TCL), which closely resembles conventional airplane engine controls, while the BA609 uses a control lever more closely related to the helicopter collective lever.

But it’s unlikely that only former US Marine Corps (USMC) pilots who have flown the V22 will be experienced enough to fly their civilian cousin. One dual rated USMC pilot found the transition to tiltrotor relatively straightforward and believes that any properly qualified pilot could make the transition.

“Just as there are peculiarities in any aircraft, I found my tiltrotor transition was the same. Once you got used to it, it was fine. The feeling of going from a hover to 250 kts is strange at first, but no other aircraft can do it so it’s pretty cool!” Mike McCormack has experience flying the V22 in the USMC.

He recalls that transitioning pilots faced no major challenges, no matter what their background. “I attribute that to the stability of the airplane,” he says. “The FBW, flight control computers and AFCS work great, and not having a tail rotor makes it very stable in a hover.

Finding the infrastructure necessary to support continuous tiltrotor operations in major cities remains a challenge to their widespread introduction.

Initially I thought the FW guys would have trouble in a hover but, again, the stability makes learning to hover pretty easy for them.” McCormack notes that helicopter rated pilots do face a minor challenge: “One thing that takes a bit of getting used to for helo guys is the TCL,” he notes.

“This takes the place of a collective and moves fore and aft like a throttle vice up and down. For the FW guys it’s old hat, but most helo guys have a few moments where they instinctively push forward on the TCL mimicking the downward motion for a collective and the airplane pops up into the air.

This usually occurs when you touch down a bit wobbly and the instinct is to plant the collective but instead the Osprey jumps back up. It only takes 1 or 2 of those and you break the habit very easily I haven’t done it again in nearly 400 hours!” One flight department manager, who chooses to remain unnamed, sums us his feelings.

“On paper it’s a wonderful concept,” he says, “but, until the tiltrotor is proven and is not just an afterthought in the ATC IFR system, I think it has significant challenges.” It may be that, while the tiltrotor concept is widely accepted as sound, the challenge will lie in making it a reality.

The advantages of vertical-lift technology in the 200-mile mission are obvious and clear. It is a matter of price, efficiency, capital heliport improvements and operational capability that will determine if the 200-mile mission is the ultimate proving ground for vertical-lift technology.

Ken Solosky retired from the New York City Police Dept Aviation Unit as chief pilot after 21 years of service. He is currently chief pilot for the Newark (NJ) Police Aviation Unit.


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