New Sikorsky hybrid-electric (HEX/VTOL) designs

[VM325]

Just announced by Sikorsky (https://news.lockheedmartin.com/2024-02-27-Sikorsky-Looks-to-Future-Family-of-VTOL-Systems?utm_source=facebook&utm_medium=social&utm_campaign=hai_heliexpo&utm_term=global|aircraft_-_rotary_wing|aircraft_-_unmanned|rms_-_sikorsky|rms_-_matrix&utm_content=news_release&linkId=100000245108519&fbclid=IwAR3dDAbRPTl6ZXLZwJZu3LYkC8lYEEl11wZeYzWmYgad1SKS4Iw _oBYv_1w)


ANAHEIM, Calif., Feb. 27, 2024 – Sikorsky, a Lockheed Martin company (NYSE: LMT), today unveiled its plan to build, test and fly a hybrid-electric vertical takeoff and landing demonstrator (HEX / VTOL) with a tilt-wing configuration.

The design is the first in a series of large, next generation VTOL aircraft — ranging from more traditional helicopters to winged configurations — which will feature varying degrees of electrification, and an advanced autonomy system for optionally piloted flight.

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“We never stop innovating at Sikorsky,” said Sikorsky President Paul Lemmo. “Autonomy and electrification will bring transformational change to flight safety and operational efficiency of large VTOL aircraft. Our HEX demonstrator program will provide valuable insights as we look to a future family of aircraft built to the scale and preferred configurations relevant to commercial and military customers.”

The HEX program will put a premium on greater than 500 nautical mile range at high speed, fewer mechanical systems to reduce complexity, and lower maintenance costs.

Sikorsky Innovations, the company’s prototyping group, and GE Aerospace are finalizing designs to build a hybrid-electric power systems testbed with a 600kW electric motor. The testbed is a first step to evaluate hover performance of the follow-on HEX demonstrator — a 9,000-pound maximum gross weight aircraft with 1.2MW-class turbogenerator and associated power electronics.

“Within Sikorsky’s electric pillar, we are designing electric motors, power electronics and our own vehicle management hardware and actuation,” said Igor Cherepinsky, Sikorsky Innovations director. “HEX will integrate these components, showcase the growing maturity of our MATRIX™ autonomy suite (https://www.lockheedmartin.com/en-us/products/sikorsky-matrix-technology.html), and the potential for maintenance-free systems. Seeing the results will lead us to more efficient overall designs.”

[atakacs]

So the engines are electric with an onboard ICE ?
Looking forward to the demonstrator !

[SplineDrive]

Notice what's missing? An X-2 configuration. Sikorsky management must realize that after a billion+ dollars invested in a dead end technology, they need to play catch up on winged configurations with tilting rotors. They've done concept work with rotor blown tilt wings before, we'll see if this is a viable path in and of itself, or just a stepping stone to a tilt rotor. No pitch fan in the tail indicates these rotors have cyclic and probably flapping, so it's not a traditional tiltwing and that's a good thing. The hybrid business is green washing, the real point of the project is the rotor / tiltwing configuration.

[TURIN]

Doesn't the hybrid part simplify the power train? Until we know more about fuel consumption I'm not sure how this classes as 'greenwashing'.

[skadi]

Doesn't the hybrid part simplify the power train? Until we know more about fuel consumption I'm not sure how this classes as 'greenwashing'.

The ICE is more efficient when used as electrical generator

skadi

[SplineDrive]

My point is that the point of the aircraft is more about the aero-elastic, mechanical, and performance characteristics of a wing and flapping rotor rather than a hybrid power system. They’re 50+ years behind the competition.

[Bravo73]

they need to play catch up on winged configurations with tilting rotors.

They don't just seem to be going for tilt rotors - they are going full hog with tilt wings.

What would that do to the lift as the aircraft decelerates whilst it converts from aeroplane to helicopter mode?? The angle of attack on the wing would get pretty extreme, pretty quickly. :sad:

[SplineDrive]

They don't just seem to be going for tilt rotors - they are going full hog with tilt wings.

What would that do to the lift as the aircraft decelerates whilst it converts from aeroplane to helicopter mode?? The angle of attack on the wing would get pretty extreme, pretty quickly. :sad:

Having the rotor diameter similar to the wing span can help with the deep stall and drag, depending on the rotor wash velocity. Still, there are other reasons tilt wings haven’t been successful. Marrying one with a flapping rotor will help with control authority, so that’s one set of problems addressed. You’ve identified drag in conversion. Despite more control authority than a traditional tiltwing, it’s still a barn door in pure hover, so maneuvering in a 35 knot side wind, for example, will take a lot of power. The disk loading looks higher than a traditional tiltrotor, so I suspect the power requirements are higher than a tiltrotor of the same gross weight, despite the reduced download on the wing. In any case, what they learn will inform the next aircraft, whether it’s another tiltwing or they convert to a full tiltrotor configuration.

[Tango and Cash]

The ICE is more efficient when used as electrical generator

skadi

And I'm no engineer, but running a big thick electrical power cable from the 'engine' through the tilting mechanism out to the motor on the wing has to be a lot simpler than tilting the entire engine (V-22) or having the tilt mechanism as part of the gearbox (V-280).

[TURIN]

The ICE is more efficient when used as electrical generator

skadi
Indeed, which is why I don't understand the greenwashing comment.

[asianj0e]

My point is that the point of the aircraft is more about the aero-elastic, mechanical, and performance characteristics of a wing and flapping rotor rather than a hybrid power system. They’re 50+ years behind the competition.

Tilt wing technology died in the 1960s, mostly for good reason IMO, and while a hybrid power system opens up a few new options, I don’t think that is enough to bring tilt wings back from the dead. This is an odd design choice.

One other negative about tilt wings not yet mentioned in this thread is that it’s hard to make the tilting hinge stiff enough in torsion such that it doesn’t strongly limit the whirl flutter speed (and therefore the maximum speed) of the aircraft. Having large rotors on the wing only makes that problem worse. I wonder if Sikorsky didn’t choose a tilt rotor because they don’t want to give tacit approval to Bell that tilt rotors are decent sometimes (only half joking here…)

[SplineDrive]

Downfall: The FLRAA Edition (https://www.captiongenerator.com/v/2284390/hitler-reacts-to-the-bell-v-280-winning-flraa.)

Prescient for late 2022... watch the strategizing at the very end.

(Warning... harsh language in text, audio is in German)