Sikorsky X-Wing (2013) | Hacker News Reader

Sikorsky X-Wing (2013)

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130 pointsjeffreyrogers32 comments

Sikorsky was attempting to bolt a helicopter atop a fixed-wing aircraft. Rather than the best of both worlds they wound up with the worst problems of each. A more interesting idea was the F-104 VTOL concept. Rather than put helo blades on a fighter, take the delta wing of a fighter and spin it like a helicopter blade. Take off with it spinning then fix it in place when flying forwards, potentially at supersonic speeds. The concept was never built but would have avoided the inherent inefficiencies of Sikorsky's approach. And a supersonic rotary-wing aircraft would be very cool.

https://elpoderdelasgalaxias.wordpress.com/2014/03/28/f-104-...

https://www.secretprojects.co.uk/threads/lockheed-f-104-%C2%...

I'm not so sure that F-104 concept would've worked out. It wasn't called the Widowmaker for nothing and the added weight for the rotating wing assembly would've been quite substantial.

As for bolting a helicopter to a fixed wing aircraft, they bolted two rotors to the V-22 and it's working out pretty well, despite early, deadly failures.

Also, both the SB-1 Defiant helicopter and the S-97 Raider are in development for fast helicopters.

But, the X-wing concept looks like the coolest one of them all. I would've loved to see it fly. It could have enabled city to city fast transport without the need for local, urban runways.

>they bolted two rotors to the V-22 and it's working out pretty well, despite early, deadly failures.

my favorite which seems to have worked much better (and one can say was a preview of the minimum what one can expect from the current Cambrian explosion of modern multicopters) yet didn't make it into production https://en.wikipedia.org/wiki/Bell_X-22

Yeah, that's a beautiful aircraft. The ducted fans look more modern and sleek despite being decades older than the V-22.

I'd agree.

Its the transition from rotating blades with little to no forward motion to full forward motion and no rotating blades which appears to be the biggest cost hurdle. I dont think much can beat the Osprey design.

So the metrics/requirements as I see it is. Ascent/Descent speed. Forward flight speed. Carry capacity.

I cant find any VTO data, but the Bell Boeing Osprey has similar properties albeit 30-40knots slower on the forward motion. However, the Osprey can carry alot more which is a factor for these things namely more than 2-3times more weight than the x-wing.

Over the years military equipment weights have increased so you need transporters which can carry more whilst maintaining a good forward motion speed.

A future upgrade path for the Osprey is swapping the rotating blades for jet engines which could increase the forward motion speed a bit more.

The idea is out there on Buzz Light Year ironically!

A similar concept has worked well for drones.[1] That's an electric quadrotor VTOL with wings. It transitions to a fuel-powered prop for ranges in hundreds of kilometers. The two-blade electric props stop pointed fore and aft when in fixed-wing mode, for minimal air resistance. There are multiple manufacturers of such aircraft.

NASA has been trying out variations on this theme.[2] Package delivery up to 25Kg or so should work. Human-carrying designs are possible but may not be practical.

[1] https://youtu.be/eyEW8mAJ5a8

[2] https://ntrs.nasa.gov/api/citations/20205000636/downloads/20...

If you think it’s cool with the .uk site, could you link directly to some of the images in the thread?

They currently require a forum login.

This concept was eventually developed into the S-97/RAIDER X/Defiant line of helicopters..

https://en.m.wikipedia.org/wiki/Sikorsky_S-97_Raider

https://en.m.wikipedia.org/wiki/Sikorsky–Boeing_SB-1_Defiant

This is very much likely to be the template for the US next generation of assault and recon helicopters.

The X-Wing was very different from these concepts. The X-Wing flew with a single fixed main rotor with blowers to attach the flow via the Coanda effect. The S-97 uses two conventional contra-rotating rotors. The X-wing was much more radical whereas the S-97 configuration has been in production usage for decades in the Kamov helicopters.

The innovation of the S-97 and it’s kin isn’t the main rotor but the pusher propellor which allows it to operate at speeds and altitudes far above what a conventional helicopter can achieve but it’s not fast enough for the main rotors to be locked in a fixed wing position, mainly because it’s not a good trade off for the roles which these fill.

It overall it kept quite a few design elements from the X wing such as the rigid wings on the main rotor and that the forward propulsion is achieved by a pusher rotor instead of the jet exhaust on the X wing.

Those aren't new things though, and it's not the crux of what the X wing was. The rigid rotor, the pusher propeller, had all been done already in the 1967 AH-56.The X wing has more in common with the F-35B than the S-97 has in common with the X wing. The S-97 is attempting to succeed where the AH-56 failed; it's supposed to do helicopter things with a helicopter frame and fulfill a helicopter role, but maybe have a little more speed and altitude capability. The F-35B is attempting to succeed where the X wing failed; it's supposed to do jet plane things with a jet plane frame and fulfill a jet plane role, but be able to do so in places and environments where a full sized runway doesn't fit.

https://en.wikipedia.org/wiki/Lockheed_AH-56_Cheyenne

https://en.wikipedia.org/wiki/Eurocopter_X%C2%B3 this is more like it

Not sure you guys get it. The X-Wing could fly with a fully stopped main rotor. The rotor was completely still in forward flight, but then could start rotating for hover flight.

We get it the new Sikorsky helicopters use a rigid rotor just the like the X wing they don’t lock because they don’t fly as fast as the X wing and will operate primarily as helicopters.

They also receive about half of their forward momentum from the pusher motor.

The Defiant is the X wing with better trade offs to serve as helicopter rather than a pure VTOL.

I know it might look like nothing but a Kamov but it’s anything but. The Kamov uses flexible contra rotating rotors and is very much a traditional helicopter the new line from Sikorsky is very different.

I worked at Sik and was a rotorcraft engineer for 8 years, master's concentration in fluid mechanics. A stopped rotor with active flow control is a world and era apart from slowed rotor configurations. Almost none of the engineering overlaps, they're completely different approaches except for an end goal of wanting faster forward flight. Similar vs different is semantic at this point. It's like saying the bicycle gave rise to the hovercraft, which is true in a sense.

Ok I’ll concede to your expertise however I still fail to see how the rigid rotors on the S-97/Defiant are not related to the X-Wing at all.

Well we should know soon, it is the Defiant vs. V280 and is supposed to be awarded this year.

https://en.wikipedia.org/wiki/Bell_V-280_Valor

Thanks for sharing this. I grew up a few miles away from the Sikorsky plant in Stratford, CT. and as a kid remember seeing on a couple of occasions some of the experimental helicopters flying overhead. A lot of my friends parents worked at Sikorsky and sometimes would mention the program, in particular the ABC (advanced blade concept). It was mainly hushed but after what seemed like many years the experimental programs were moved out of Stratford or maybe scrapped. Then all the overhead traffic everyday were from the Blackhawk and Super Stallion programs the company was focused on to keep themselves going.

I still marvel at the Sikorsky Skycrane, IMO one of the most underrated aircraft ever produced. Whenever I see one I'm transported back in time seeing them flying over my neighborhood thinking that it was like a big giant wasp in the sky.

I interviewed at Sikorsky back in the day. Sort of wish I had pursued it, because the factory floor was amazing, but the manager reminded me of a guy from The Sopranos, and then I got into medical school. But that floor, man. Swashplates. Have you ever seen a swashplate, naked and alone on a pallet? Thin wall machining. I mean, goddamn, that was some sexy machine work. But they wanted me to run business analytics for government cost-accounting programs. Fuck. That. Also, medical school.

If you are an 80's kid there was a G.I. Joe toy based on this.

https://www.3djoes.com/skystorm.html

I totally had that toy. The mechanism for extending/retracting the rotor always felt like it was about to finally break the next time you used it.

I guess they worked hard to make it realistic ;)

Likewise! For some reason my clearest memory of the toy was putting the little sticker-decals on.

I’m reminded of the aircraft in The 6th Day movie.

https://youtu.be/7nqo_3kyw8M

I'm not familiar with aviation, so I have no idea what I'm talking about, but that rotor looks to me a lot like the "stealth" helicopter remains from the Abbottabad / bin Laden crash:

https://www.wired.com/2011/05/aviation-geeks-scramble-to-i-d...

Much different than this design:

https://en.wikipedia.org/wiki/Sikorsky_UH-60_Black_Hawk

The first picture shows the tail blade, not the main blade.

Still interesting I would think of the Comanche with the ducted tail rotor.

I'm not an aeronautical engineer or anything... but the downwash from the rotors onto the large fixed undermounted wings on the RSRA test model is some serious WTF, no?

The test aircraft was designed to see whether the coanda effect would produce the lift and controllability they desired. The rotor for that aircraft would be fixed. They didn't intend for VTOL with the model that had fixed wings, they would fly it like a regular airplane and see how she handled.

Ah, that's less crazy, just probably drank fuel really fast (which, test craft, so who cares)

Ok, that's wicked. I guess I'm a kid at heart because I only looked at the pictures :)

Although looking at that render (erm, drawing) at the top it looks like a lot of the thrust of the rotor would be eliminated / redirected by the fuselage. It doesn't look like that later, so I guess that was more a visual effects decision than a design one.

Random tidbit: Robert Williams, the DARPA PM for (at least some of) this, was also DARPA's PM for NASP.

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