Perpetual Defense Thread (Defense & non-commercial Space Nerds ITT)

pauli said:

Next-gen helo engines delivered to Sikorsky for Black Hawk integration

Sikorsky has received two Improved Turbine Engine Program engines and will begin integrating them into UH-60 Black Hawks in the coming months.

www.defensenews.com

Wait, they're actually making progress on this?

Slowly but surely, I guess.

Hopefully it can deliver.

Over in Europe, a press release: https://www.navalnews.com/naval-new...-first-ship-trial-campaign-with-italian-navy/



It's weird to see someone else going after a tilt rotor, in a world where they can look at how Osprey development and deployment have gone.

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There’s a reason it’s been almost 40 years since first flight of the Osprey.

Note that essentially none of the Osprey’s issues were because there’s any fundamental issue with tiltrotors, per se. Making a tiltrotor to the Marine’s specs in the 1980s was ahead of the technology curve.

Technarch said:

True, but when Osprey isn't crashing it has range and speed specs that no other VTOL aircraft can match. And perhaps a clean-sheet tiltrotor can avoid some of the design flaws of the Osprey, like the bad clutch design or the extremely high rotor disc loading or the need to aim the engine exhaust directly at the ground at point blank range.

Also the Osprey has a bit of an unfair rap--on a per-flight-hour basis it's way safer than a Blackhawk.

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My understanding is that Blackhawk flight hours include conditions that ground Osprey, or at least have done so historically.

As for a clean sheet design... AW609 may be Leonardo now, but it started as a Bell Boeing project. Lots of lessons learned, I'm sure, but there's certain to be a lot of common thought.

I thought Leonardo AW609 was based on the original prototype demonstrator of Bell XV-15? The ones they used to convince USMC to develop V-22? In fact looking at the Wikipedia pages of XV-15 and AW-609 specifications, there are many similarities. I'll hold of my optimism on 40 years of lessons learned and technology progress.

A lot of the Osprey issues either wouldn’t be applicable to civilian transport or would certainly have been fixed as lessons-learned.

In order of when they popped in my head:

The Osprey cannot autorotate, because the rotors don’t carry inertia well enough. This was a known compromise among the flight profile, weight constraints and being able to fit the aircraft on amphibious carriers with the rotors folded up. The AW609 can autorotate, and has already demonstrated it.

The early Osprey crash that was a result of vortex ring state was the result of the pilot flying well outside the flight envelope in helicopter mode. The Osprey is actually more resilient to vortex ring state than a typical helicopter. A later crash was also found to be the result of flying outside the envelope. They believe the pilot might have been hotdogging for the GoPro he had set up on the flight deck. The Osprey flight envelope would not be particularly constraining to a civilian flight profile, as I understand, and any aircraft can crash if you deviate too far from the envelope.

A few Osprey incidents have resulted from ingesting dust into the engines. Military rotorcraft have been battling this issue since the beginning of helicopters, while civilian helicopters mostly manage to avoid such conditions. No reason that same solution shouldn’t be similarly effective for AW609 as it is for helicopters in general.

The Osprey was designed with finicky 5,000 psi hydraulics, to save weight. The AW609 went with a standard 3,000 psi system.

The Osprey has had problem with equipment fit/routing within the nacelles. It’s tight in there and they had wires and hydraulics rubbing against each other, causing wear. Also, leaking hydraulic fluid would pool in the nacelle and then flow onto hot surfaces as the nacelle tilted. Some of this was fixed by providing extra drainage, providing better fire protection for critical structures within the nacelle and re-routing some of the wires/hydraulics. Never seen anyone address these concerns directly about the AW609, but with the much smaller power plants, different hydraulics and different electronics, I’d be willing to bet stuff hasn’t had to be haphazardly crammed into the nacelles, as seems to have been the case during the Osprey’s development.

They had two individual cases of mis-installed wiring causing mishaps in the Osprey. Not sure we’d expect that to be any more of an issue for an Osprey-derivative 30-40 years later than to any other airframe.

The Osprey has had issues with clutch plates that have deteriorated faster than expected. This one I’m actually not sure how well they fixed it for the Osprey, or if the AW609 has similar clutches. The AW609 is dealing with much less total power shunting around than the Osprey is, though. Each engine has about one-third the hp.

There doesn't need to be an overt change in Wikipedia-visible specs to take advantage of 40 years of engineering and material sciences advances.

A lot also comes down to desired capabilities. For example the Osprey needs to have it's compact storage mode, which adds a lot of complexity to the design, because the US wanted it to fit into their global force projection strategy, and hence operate it from carriers in large numbers.

But what if you're not really in the carrier-based global force projection game? If you don't even have carriers, or accept that if you operate it from your carrier you'll have to deckpark it and only in limited numbers?
Suddenly you have a much simpler craft that can still fill a lot of the desired "rotorcraft-type VTOL/STOL with range and cruise speed of a turboprop" mission profile.

It should be noted that the US Army recently selected a tiltrotor the Bell V-280 Valor for the FLRAA program to replace the Blackhawk. It seems to address many of the issues that plagued the Osprey including only the rotors tilting rather than the entire engine pod. The Osprey had problems absolutely, it was also probably ahead of its time and there have been many lessons learned as a result of the program. That organizations that aren't the Marines are evaluating and selecting tiltrotors for service says, to me, that a lot of the issues that the Osprey has/had have been resolved to some satisfactory degree. I suspect that, if it doesn't get canceled (it is an army program after all) the V-280 will be fairly successful in service.