FLYING took the opportunity to see what’s on the horizon in terms of both traditional helicopters and the red-hot powered-lift and eVTOL categories ahead of the Helicopter Association International’s HeliExpo in February at Anaheim, California.

Bell 525

The Bell 525 (at right) proposes to bring the first fully digital, fly-by-wire rotorcraft to the civil market, and Bell Helicopter has been hard at work getting the program to the finish line down at its headquarters in Fort Worth, Texas.

So what does that mean? The FBW design logic on the 525 is different from an aftermarket add-on autoflight system such as the GFC 600H. In this case, Bell’s partnership with Garmin has translated to the G5000H flight deck.

Tim Evans, business development manager on the 525 program, gave FLYING a special update ahead of Heli-Expo.

“Broadly speaking, flight testing is continuing very nicely, with the good relationship we have with the FAA,” said Evans. “Last year, we were able to complete nine TIAs towards certification, and by the end of February, we should have only five events left. Two of them we’re already into, and the other two [should be complete] by midyear.”

• READ MORE: Bell 360 Invictus Prototype Advances with T901 Engine Delivery

At that point, all of the delegated activities that Bell is responsible for will be finished—and the team will turn things over to the FAA. From there, functional and reliability testing is the last milestone to cross, with 150 hours of flying with the FAA, putting the 525 through its operational paces.

As with similar Textron Aviation aircraft programs, Bell engaged its Customer Advisory Board, which gave a clear message.

“The overwhelming response?” said Evans. “It’s automation that will bring a level of safety seen commensurately on the fixed wing side—the redundancy will be game-changing to how the civil market functions.”

According to Bell, the 525 will deliver what the customer feedback told it was needed: “When you pull it into a hover and get to 20 to 30 feet—with no pedals—it will hold that attitude, essentially hands off.”

Pilots can also turn into an angle of bank, with no pedal inputs, and the 525 will do a full 360 at the input bank angle.

“The control laws are able to anticipate and calculate the pilots’ inputs,” said Evans, noting that the 525 also benefits from a level of redundancy not seen before in this class of rotorcraft. “We’re shaping some of the requirements in Part 29, so the FAA required a triple redundancy—three computers, three hydraulic [systems]—so [it’s] a safer aircraft at a foundational level.”

Several markets that Bell shaped the 525 for include offshore, VIP/head of state, and SAR/parapublic/Coast Guard—so Bell built certain provisioning into the airframe itself, though kitting will take care of the details. Bell has multiple launch customers and is in active negotiations, though it can’t say yet who those first deliveries will go to.

In closing our briefing, Evans also wanted to highlight the green side of the design.

“If you compare the 525 to others in the medium space, it’s going to be 30 percent more efficient than a [Sikorsky] S-92. That’s one we’re pretty proud of. We’ve also flown it on SAF fuel, a 30 percent blend, but capable of up to 100 percent.”

Leonardo AW09 and AW609

Two projects from Leonardo Helicopters have also been winding their way through the certification process along the European Union Aviation Safety Agency (EASA) track—the modern-yet-standard AW09 helicopter and the AW609 tiltrotor design.

The single-engine AW09 was originally developed by Kopter Group, a company acquired by Leonardo in 2020. Proposed as a multimission solution for VIP transport, emergency medical services, utility operations, and security teams, the AW09 will carry up to eight passengers.

A five-blade, all-composite rotor system will translate into smooth flight characteristics and a high degree of maneuverability. Up front, the Garmin G3000H flight deck offers pilots next-generation glass. The Safran Arriel 2K powerplant has dual channel FADEC with an auxiliary backup system. Projected retail pricing begins at $3.9 million.

• READ MORE: Leonardo Tests AI-Enabled Visual Awareness System for Rotorcraft

A year ago, on March 16 and 17, Leonardo began familiarization flight testing with EASA on the tiltrotor AW609, following on to FAA testing in February. The company plans dual certification, so it is moving through the process with both agencies concurrently. Leonardo pursues this strategy in hopes of making up for some lost time, as the AW609 began life in the 1990s as a joint project between Bell and Agusta, called the BA609.

That’s probably why it bears some resemblance to the more commonly known Bell V-22 Osprey. The AW609 similarly enters the powered-lift category with its ability to take off vertically and fly at high cruise speeds with props tilted forward—up to twice the speed of normal helicopters, according to the company. The expected service ceiling will be 25,000 feet msl.

Its projected certification timeline remains in the distance, with a proposed retail price beginning at roughly $24 million.

Up Next for Robinson?

Robinson continues to set the pace on the light GA end of the market with its line of piston-powered R22s and R44s, and turbine R66 helicopters.

• READ MORE: Airworthiness Directive Issued for Robinson Helicopters

While the Lycoming O-320-powered R22 is well known in training, the R44—with its O-360 engine—crosses over into the recreational and light transportation markets with the Raven and Raven II variants. The R66 fulfills a variety of roles, with added cruise speed—up to 110 knots—extra passenger capacity, and turbine reliability from its Rolls-Royce RR300 engine.

As of press time, the company indicated news on the horizon that it would be sharing at Heli-Expo—including the updated empennage for the R44—so stay tuned into FLYING’s reporting from the event.

eVTOLs Next?

As we gear up for Heli-Expo, we know that the show floor will host an entire flight line of eVOTLs in various stages toward initial FAA certification. While we covered Joby Aviation’s prospects in detail in our “First Look: Joby’s eVTOL Future” piece in this issue, it is far from the only player in town.

Archer Aviation’s Midnight has recently passed its Phase 1 flight testing program, hot on Joby’s heels. The company announced in late January that it would be ready for the beginning of for-credit flight testing with the FAA later in 2024. The Midnight cuts a similar profile to the Joby aircraft—carrying one pilot plus four passengers—but with six fixed rotors in a forward flight position and six fixed for vertical flight. The test unit has yet to make the transition from vertical to forward flight as of press time, but we expect this to come soon.

Beta Technologies launched its program with a conventional takeoff and landing (CTOL) aircraft

called the Alia to test its electric propulsion system in a more traditional airframe before moving forward into the powered-lift space. As of late January, Beta had conducted multiple flights with the U.S. Air Force and U.S. Department of Defense in both on-base and cross-country ops as part of the Agility Prime program. While it tests the applicability and cost reduction

possible—using electric aircraft in missions including casualty evacuation to go operational in 2025—Beta hopes to take what it learns and produce an eVTOL version by 2026.

Overair’s Butterfly eVTOL is also coming up quickly, as the Southern California-based company signs on several new customers in South Korea as well as Houston-based Bristow Group. Overair is now working through its G-1 Stage III means of compliance documentation with the FAA, with testing of the full-scale, six-seat prototype to begin later this year.

Meanwhile, south of the equator, Eve Air Mobility recently saw Brazilian aviation authority ANAC release the proposed airworthiness criteria for its design, along with bringing a list of key suppliers on board. Eve broke ground on its manufacturing facility in Taubaté, Brazil, earlier this year as well.

Many other players, including Volocopter, Lilium, and Jump Aero continue to chug along—and the race is really heating up as to who will make it to certification first. Oh, wait—that honor already belongs to EHang, which obtained CAAC’s blessing for its EH216-S in China in late 2023—and made the first commercial demonstration flights with it by December.

This feature first appeared in the March 2024/Issue 946 of FLYING’s print edition.

The post Rotor Roundup: What’s on the Horizon for Helicopters and eVTOLs? appeared first on FLYING Magazine.

Now, it’s all about electricity. Electricity is an unlikely way of propelling airplanes—you can store enough of it to go either far or fast, but not both—yet hundreds of projects are currently in development. A lot of them are in the electric vertical takeoff and landing or eVTOL category, for which electric power is, if anything, even less appropriate. A list of eVTOL proposals takes up several pages online at evtol.news/aircraft. Several surprising names pop up. Cadillac? Aston Martin? Really? Good luck trying to tell the sheep from the goats.

Electric aircraft fall into several broad categories:

1. Conventional Transports

These are the most likely to enter service within a few years. They use runways. Electric motors replace piston or turbine engines on existing airframes (or, in a few ambitious cases, novel ones). Power may be supplied entirely by batteries or fuel cells, or by fuel-burning motor-generators supplemented by batteries providing excess power for takeoff and climb. The putative virtues of fuel-electric hybrids are: a) reduced cruising fuel flow through optimal matching of engine size to cruise requirements; b) use of a relatively cheap and clean grid power to charge batteries on the ground; and c) adaptability to non-fossil fuels, including hydrogen.

2. VTOL with Wings

These have wings for efficient cruise, supplemented by multiple rotors for vertical takeoff and landing. VTOL is difficult: If the lift/drag (L/D) ratio of an airplane is 12:1, it takes 12 times as much thrust to hover as to cruise. Projects fall into two categories—and some have one foot in each:

a. Fixed Rotor: Lift rotors and their motors are fixed in place, typically on booms mounted along the wingspan. In cruise, the lift rotors are feathered and/or stowed in a low-drag position and one or more cruise motors produce thrust. This arrangement has the advantage of mechanical simplicity, but the boom and rotor structures become deadweight and drag in cruising flight.

b. Vectored Thrust: The thrust axes of some or all of the lift rotors rotate to the horizontal to produce cruising thrust. Wings may or may not rotate with them. Aerodynamic efficiency is greater than for stowed-rotor types, but at the cost of additional weight and mechanical complexity.

3. Multirotor

These are scaled-up variations on the self-stabilized quadcopter hobby drone. Proposed configurations involve various numbers and placements of ducted or open rotors. Difficulties include the high power requirement of hovering flight, which limits duration and range; the impossibility of autorotation; and, particularly for unpiloted versions, collision and obstacle avoidance in busy urban airspace where they are imagined to replace taxi cabs.

The fundamental problem for an electric aircraft is how to make the most of its energy supply. The classical answer is to have a large wingspan and to fly at the speed for least drag. That speed is unfortunately quite low, but it increases with wing loading, and so, to be fast and efficient at the same time, the airplane should have as small a wing area as it can, consistent with an acceptable stalling speed.

Here are some numbers, partly published and partly my estimates, for one of the better-publicized projects,the Beta Alia-250: gross weight, 7,000 pounds; wing-span, 50 feet; wing area, around 200 square feet. Two mid-span booms each carry two fixed motors with stowable rotors of about 12 feet in diameter. The fuselage pod seats six and has a single pusher prop on the tail.

Based on these specifications, the most efficient speed at gross weight would be around 110 kias, and would require around 200 hp (150 kW) continuous at 1,000 feet msl. The airplane would need at least 800 hp to hover at gross weight. Notably, it is very large and heavy for a six-seater, for a simple reason: batteries. At current specific energies for commercial lithium batteries—6 pounds of battery yields 1 hp for an hour—it would require 1,200 pounds of batteries per hour of cruise, plus maybe 500 pounds more for vertical takeoff and landing and an additional 900 pounds for IFR reserves, go-around, and holding. A hybrid power system would go a long way to alleviate the weight problem, but would compromise the “pure electric” nature of the project.

Fuel-burning general aviation airplanes (with the exception of jets) regularly fly at speeds far above their best L/D speed. An electric airplane has that option too, but for the Alia to cruise at say, 175 knots at 10,000 feet, would more than double its power consumption. That might be acceptable for short trips, but it’s on long trips, not short ones, that high speed is wanted.

The FAA has already adjusted engine certification criteria to encompass electric motors and their controllers, so certification of electric retrofits to already approved airframes should be comparatively simple. But the FAA has chosen to see the essence of winged eVTOLs as not their airplane-ness but their dual nature, part helicopter and part airplane, with special piloting challenges during transitions between vertical and horizontal flight, and so, it will not be possible to certificate them as airplanes under Part 23.

The small, wingless multi-rotor hovercraft that are envisioned for short-range “urban mobility” confront a dense regulatory thicket. While there is nothing logically impossible about swarms of autonomous hoverpods using crowd-sourced collision avoidance, the concept will take a long while to migrate from the TV screen to the real world.

Huge as the number of electric airplane projects is, and despite their magical ability to attract investment, there is a mirage-like quality to the whole business. There are too many press releases hailing first flights that fail to occur, too many speed and range claims that are incompatible with simple arithmetic, and too many implausible promises to be in commercial service in 2024. Perhaps these claims are meant to buoy the spirits of impatient investors; or perhaps the teams of young idealists who create these interesting prototypes just have no idea of the purgatory that lies ahead. But it is certain that most of the current projects will fail, and those that get through the gantlet of certification will change and evolve. In at least one respect, delay is desirable. It gives battery technology time to improve.

The Leonardo AW609, a pioneering tilt-rotor business airplane similar in concept to the V-22 Osprey, is claimed to be “close” to FAA certification. The process has taken 20 years so far. The 609 has no doubt suffered greatly from being the first of its kind. Nevertheless, I think it may be another 20 years before the best configurations for electric aircraft, the best applications for them, and the definitive standards for their certification are completely settled.

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