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Hybrid RotorWing Design Transitions From Fixed To Rotary Wing Mid-Flight

samzenpus posted about a year ago | from the pivoting-propellers dept.

Australia 86

cylonlover writes "Attempts to combine the vertical take-off and landing (VTOL) capabilities of a helicopter with the high-speed flight and long range capabilities of a fixed-wing aircraft have been tackled in a number of different ways – from tiltrotor designs, such as the V-280 Valor and Project Zero, to fixed rotor aircraft that transition from vertical to horizontal flight, such as the SkyTote and Flexrotor. Australian company StopRotor Technology has taken a different approach with its Hybrid RotorWing design concept which features a main rotor that switches from fixed rotor to fixed wing in mid air."

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86 comments

Harrier? (1)

satuon (1822492) | about a year ago | (#43515211)

Is this like the Harrier, where the motor switches from vertical to horizontal?

Re:Harrier? (4, Informative)

Trepidity (597) | about a year ago | (#43515313)

A bit different. The rough rotor equivalent of the Harrier is a tiltrotor design, where the rotor rotates from a position where it generates vertical thrust (for takeoff) to one where it generates horizontal thrust (for flight).

This design instead stops the rotor when in horizontal flight, fixing it at an angle perpendicular to the fuselage so it becomes a wing generating lift. Then forward thrust is provided by separate, flight-only engines mounted in a conventional manner. When the plane wants to land again, the rotor stops being a wing, and starts spinning again in a helicopter style, to provide vertical thrust.

Re:Harrier? (4, Informative)

dj245 (732906) | about a year ago | (#43515395)

A bit different. The rough rotor equivalent of the Harrier is a tiltrotor design, where the rotor rotates from a position where it generates vertical thrust (for takeoff) to one where it generates horizontal thrust (for flight).

You are thinking of the V-22 Osprey. [wikipedia.org] The Harrier uses a jet engine and ducting to direct the jet blast downward. There are no tilting rotors.

Re:Harrier? (0)

Anonymous Coward | about a year ago | (#43515695)

A bit different. The rough rotor equivalent of the Harrier is a tiltrotor design, where the rotor rotates from a position where it generates vertical thrust (for takeoff) to one where it generates horizontal thrust (for flight).

You are thinking of the V-22 Osprey. [wikipedia.org] The Harrier uses a jet engine and ducting to direct the jet blast downward. There are no tilting rotors.

Yes, he was taking about the Osprey. He was saying the Osprey design is the rotor equivalent of the Harrier in that the same engines have their angle of thrust changed between vertical and horizontal.

Re:Harrier? (2)

EasyTarget (43516) | about a year ago | (#43516423)

I think his original comment made it clear he knows the difference; that's why he called the Tiltrotor a 'rotor equivalent to' the Harrier.

Re:Harrier? (0)

Type44Q (1233630) | about a year ago | (#43517421)

The rough rotor equivalent

Me thinks you fail to grasp simple english... :p

Re:Harrier? (1)

Yo_mama (72429) | about a year ago | (#43516403)

Actually, it does *NOT* stop the rotor in horizontal flight. They put it into a controlled fall and use that period to transition the airfoils.

For that reason, I don't think it will "fly" as a passenger vehicle. Maybe for larger drones, but I've met few people who like a fall during their commute.

Re:Harrier? (-1)

Anonymous Coward | about a year ago | (#43517679)

-1... moron...

Re:Harrier? (1)

MichaelSmith (789609) | about a year ago | (#43519649)

It still has wings so maybe it just descends while the rotors transition.

As seen in 6th Day movie (0)

Anonymous Coward | about a year ago | (#43519607)

Maybe not the best sci-fi movie (more entertaining than anything, given it's a Schwarzenegger action flick), but definitely had some interesting ideas. The concept helicopter in the movie is pretty much an idealized form of what the real-life experimental helicopter being developed does in its transition.

Scene from the movie featuring the hybrid rotorwing helicopters. [youtu.be]

Re:Harrier? (1)

RivenAleem (1590553) | about a year ago | (#43524921)

When a harrier does this so well, why would you want to make a rotor equivalent? Is there a problem, or do they want a plane that can operate like a helicopter (be nimble, hover at will, move sideways) for one occasion, but then change to a fighter for another occasion?

Is the goal just a new form of VTOL, or is it expected to operate in both settings?

Re:Harrier? (5, Informative)

dj245 (732906) | about a year ago | (#43515367)

Is this like the Harrier, where the motor switches from vertical to horizontal?

No, it is a helicopter where you stop the rotor and then use it as a wing for flying straight ahead with a traditional propellor. There is a typo in the summary.

This design would necessitate that the airfoil be symetrical along the long axis. Think VW Beatle shaped [wikipedia.org] rather than teardrop-shaped like a typical NACA airfoil [wikipedia.org] . This is probably a lot less efficient than a normal airfoil. Locking the airfoil would also be tricky- The rotor must come to a stop, so upwards lift is basically 0. At the same time, there is no wing for the front propeller to work on. Or worse, a wing oriented in the wrong direction. If they make a full-scale version, I hope the test pilot is single without any kids.

Re:Harrier? (1)

Anubis IV (1279820) | about a year ago | (#43516121)

According to the article, it engages in a free fall to provide it with the time it needs to stop the rotor and lock it in place as a wing, as well as to procure the air speed it needs to have upward lift. As you said, I hope the test pilot has no family.

Re:Harrier? (1)

Anonymous Coward | about a year ago | (#43516129)

I think this looks like an ~excellent~ drone-only technology.

Re:Harrier? (4, Interesting)

dywolf (2673597) | about a year ago | (#43516213)

Been done. S-72 and X-50 prototypes. Its very unstable. The bring a rotor to a controlled stop thing is easy, existing rotor brakes can be geared to align it fairly precisely when it comes to a stop. The lift transition is the issue. It's not just that lift is basically 0. It's that one half of the rotor disc (the theoretical abstract describing the lift forces) has to completely reverse the airflow of the lifting surface.

Its essentially an expanded case of the Retreating Blade Stall problem.

But the retreating half of the rotor disc has to, as some point, go from generating lift from a retreating motion through the air (moving backwards relative to airframe, due to rotation) to generating lift from an advancing motion through the air (moving forwards, relative to airframem though no longer rotating). The easiest way to think about it isnt to think of it as going from rotating to fixed, but rather think about a rotor that is simply being reversed in direction (simplfies a lot of math).

So at some point in the middle there, half the rotor disc will fall below stall speed, and experience a stall similar to the effect of a Retreating Blade Stall. Worse, won't regain sufficient lift until its now going ~100 KIAS in the opposite direction. Think of it as stalling between -100 and +100 KIAS (example number) as it crosses the transition.

The only craft I can see being able to cross that boundary zone would be a very small, very lightweight rotor that is able to make extremely fast accelerations, and thus cross the zone before it's able to affect the craft much. A full scale craft would simply have too much inertia/momentum to be able to make the transition fast enough, without tearing itself to pieces. Likewise for any craft trying to stop the rotor and use forward motion to generate the lift.

Re:Harrier? (2)

jklovanc (1603149) | about a year ago | (#43517411)

They have a way to get around the rotor stall issue. While none of the videos had a shot of a transition it looks like the aircraft stalls, ceasing forward movement, and while it is falling through the air the rotor spins up or spins down. The then use the conventional control surfaces to translate the vertical movement into horizontal movement. That could require quite a bit of a drop depending on how fast the rotor can change speed.

It looks like quite a carnival ride during transition..

Re:Harrier? (1)

dywolf (2673597) | about a year ago | (#43538471)

i saw the part where they add what basically seems like an autorotation transition to the mix. i didnt talk about that, simply the general idea and engineering problems of slowing/stopping a rotor in flight.

Autorotation itself is interesting because it's another transition of forces. Whereas autogyros use autorotation by default, at all times, a helo does not. a helo effectively (but not precisely, because airfoil lift is more complex than simple "fan pushes air") directs air downward, or stated another way, air tends to flow down through the rotor. and in autorotation, the opposite occurs: the rotor is forces to continue rotating (providng some measure of lift) by air being forces up through it as the helo descends.

So another transition phase to consider, going from one set of dominant forces, to another. And helo pilots that I've met generally dislike autorotation training, so it could be interesting to ge the, onbaord with making it an intentional part of normal flight. Heh.

Re:Harrier? (1)

slinches (1540051) | about a year ago | (#43518053)

The only craft I can see being able to cross that boundary zone would be a very small, very lightweight rotor that is able to make extremely fast accelerations, and thus cross the zone before it's able to affect the craft much. A full scale craft would simply have too much inertia/momentum to be able to make the transition fast enough, without tearing itself to pieces. Likewise for any craft trying to stop the rotor and use forward motion to generate the lift.

There is another solution. With coaxial rotors there's less of a stability problem because the lift can remain symmetric even if the retreating blades are completely unloaded. The Sikorsky X-2 (and S-97 Raider) use this configuration along with a pusher prop to achieve a 250 knot forward airspeed, but I don't think they drop the rotor speed all the way to zero.

Re:Harrier? (1)

dywolf (2673597) | about a year ago | (#43538377)

Right, and the S-69 before them, though it also never got to the point where they reduced rotor speed. Something about too much airframe stress. Slowing down the rotor would allow a higher forward speed with the same total force on the rotor, but the combined forces on the airframe as a whole, particularly in the support structure (rotor/body interface), could be an issue.

X-wing (0)

Anonymous Coward | about a year ago | (#43522523)

Yes, we've been here before. The one I remembered was the four-bladed "X-wing" (no relation) concept from the 70s/80s. Same challenges. Sikorsky were building a prototype at one point, but (according to Wikipedia, at least) the program was canned before the prototype got a chance to fly. The approach on that occasion was to use blown-air shaping on the rotors to get the desired effective lift surface shapes.

I must admit, the idea in this case, that the way to transition between modes is to plunge the airframe into a fall, doesn't exactly sound like they've found an ideal solution yet.

Re:Harrier? (1)

Jonathan_S (25407) | about a year ago | (#43533303)

een done. S-72 and X-50 prototypes. Its very unstable. The bring a rotor to a controlled stop thing is easy, existing rotor brakes can be geared to align it fairly precisely when it comes to a stop. The lift transition is the issue. It's not just that lift is basically 0. It's that one half of the rotor disc (the theoretical abstract describing the lift forces) has to completely reverse the airflow of the lifting surface.

Its essentially an expanded case of the Retreating Blade Stall problem.

But the retreating half of the rotor disc has to, as some point, go from generating lift from a retreating motion through the air (moving backwards relative to airframe, due to rotation) to generating lift from an advancing motion through the air (moving forwards, relative to airframem though no longer rotating). The easiest way to think about it isnt to think of it as going from rotating to fixed, but rather think about a rotor that is simply being reversed in direction (simplfies a lot of math).

So at some point in the middle there, half the rotor disc will fall below stall speed, and experience a stall similar to the effect of a Retreating Blade Stall. Worse, won't regain sufficient lift until its now going ~100 KIAS in the opposite direction. Think of it as stalling between -100 and +100 KIAS (example number) as it crosses the transition.

The only craft I can see being able to cross that boundary zone would be a very small, very lightweight rotor that is able to make extremely fast accelerations, and thus cross the zone before it's able to affect the craft much. A full scale craft would simply have too much inertia/momentum to be able to make the transition fast enough, without tearing itself to pieces. Likewise for any craft trying to stop the rotor and use forward motion to generate the lift.

Theoretically couldn't it work if the craft had enough sufficient fixed wings to provide most of the lift necessary for level flight at transition speed?

Then you should be able to trim the rotor disk to near zero lift (beginning a relatively mild decent) before braking it to a stop. Once stopped, retrim it for forward lift and level off.

Mind you those big wings would likely do ugly thing to the airflow in vertical lift mode...

I love the details! (1)

Quakeulf (2650167) | about a year ago | (#43515215)

All that tape, cables and patchwork. It looks like a real garage project. :3

Re:I love the details! (1)

fuzzyfuzzyfungus (1223518) | about a year ago | (#43515311)

Hey, they have to leave room for the awesome crashing action that their pro-level competitors over at the V-22 project have been delivering so aggressively...

Re:I love the details! (0)

Anonymous Coward | about a year ago | (#43515409)

The problem with the V-22 lies solely in poorly-trained pilots going into vortex ring state after completely ignoring the design specification.

So thats what it was (0)

Anonymous Coward | about a year ago | (#43515221)

Looks like one of those UFO rods.

The 6th Day (5, Funny)

BlacKSacrificE (1089327) | about a year ago | (#43515223)

Someone has been watching it.

"Convert to da choppa!" - Arnold Schwarzenegger

Though at least these guys seem to have worked out how to stop the thing from sinking like a stone during rotor transition though, which is a welcome feature.

Re:The 6th Day (0)

Anonymous Coward | about a year ago | (#43515375)

What? how'd you work that out. It pulls up, stalls, drops like a rock, stabilizes with no forward motion, unlocks the wing assembly, and seems to use the read engine to power out into an auto gyros flight characteristics.

Looks like a great re-think of flight profiles for robots to do but humans? I'm not so sure.

Re:The 6th Day (4, Informative)

j-beda (85386) | about a year ago | (#43515441)

Though at least these guys seem to have worked out how to stop the thing from sinking like a stone during rotor transition though, which is a welcome feature.

I don't know, the flight path from their simulation video looks a lot like it drops like a stone for a while:
1) Fly along in "airplane mode" with the rotor fixed perpendicular to the body, acting like a wing - regular amount of lift being generated
2) lift the nose until the airflow is perpendicular to the bottom of the rotor - not much lift being generated now
3) unlock the rotor so that the wind can start it rotating like an autogyro - starts to provide significant amount of lift
4) apply power to the rotor and get into helicopter mode - regular amount of lift being provided.

Step #2 looks a bit like falling.

Going the other way
1) Fly in helicopter mode, moving forward at a fast clip - regular amount of lift being provided
2) Lift the nose to get airflow perpendicular to the bottom of the rotor -
3) Stop the rotor and get it fixed perpendicular to the body - not much lift being generated now
4) drop the nose to get the airflow over the now fixed wing - regular amount of airplane lift.

Step #3 looks a whole lot like falling.

Re:The 6th Day (1)

GameboyRMH (1153867) | about a year ago | (#43515525)

D'oh, beaten. But they didn't work out how to stop it from diving during transition, the video shows it going into a huge stall when transitioning from fixed-wing to rotorcraft mode.

It's just an autogyro (1)

DrHeasley (1059478) | about a year ago | (#43515285)

The working prototype is a helicopter with an added prop on the front.

This is not a new concept. Autogyros are very old tech.

Re:It's just an autogyro (3, Informative)

ozmanjusri (601766) | about a year ago | (#43515305)

Autogyros are very old tech.

From TFA "The design features a powered main rotor" so no, not an autogyro.

Re:It's just an autogyro (2)

BlacKSacrificE (1089327) | about a year ago | (#43515347)

FTFA;

The Hybrid RotorWing can operate in five different flight modes.

Fixed Wing Flight: where the RotorWing is locked to operate as a fixed wing
Rotary Wing Flight: The RotorWing rotates like a helicopter rotor providing sustained hover capability
Compound Rotary Wing Flight: where the rotors requirement to produce lift and thrust is off loaded to other lifting surfaces or propulsion engines
Autogiro Flight: a form of rotary wing flight where the rotor is driven by the relative airflow and not directly by the engine
Transition Flight Mode: where the conversion from fixed to rotary or rotary to fixed wing flight occurs

Autogyro mode is one of 5 flight modes. To call this an old concept is like saying tyres are not a new concept because we have spoked wagon wheels. Its existing tech, but better.

Re:It's just an autogyro (1)

GameboyRMH (1153867) | about a year ago | (#43515591)

I wonder if autogyro mode could be used to transition between fixed wing and helicopter-like flight without the huge stalls. The wing could be unlocked and a little power applied to start auto-rotation, then it would be a matter of metering in more rotor power and tail rotor thrust to transition to helicopter mode. Heli to fixed wing would be the reverse. I can't imagine autogyro mode is too useful when you have fixed wing mode...maybe good for short takeoffs and landings.

Not an autogyro [Re:It's just an autogyro] (1)

Geoffrey.landis (926948) | about a year ago | (#43515417)

The working prototype is a helicopter with an added prop on the front.

This is not a new concept. Autogyros are very old tech.

No, it's not. First, it's not an autogyro, although it apparently can operate in autogyro mode. But, more important, once it has forward motion, the rotor stops rotating and becomes a wing.

check some of the images here http://www.gizmag.com/hybrid-rotorwing-stop-rotor/27092/pictures [gizmag.com]

Re:It's just an autogyro (0)

Anonymous Coward | about a year ago | (#43517827)

It autogyro's are your thing then I think the guys at cartercopter are doing a better job.

Smashed together a plane and heli (1)

a_big_favor (2550262) | about a year ago | (#43515307)

You will get no applause from me.

Man is that thing ugly (2)

BitwizeGHC (145393) | about a year ago | (#43515315)

It's interesting engineering and all, but I was kind of hoping that when someone finally built a helicopter that transformed into an airplane, it'd look cooler. This thing looks like a flying cigar with toothpicks coming out of it. As it is I think I'd rather fly in that autogiro made of crates, whose rotor was Pippi Longstocking spinning a pair of brooms, than this thing.

Re:Man is that thing ugly (0)

Anonymous Coward | about a year ago | (#43515845)

As it is I think I'd rather fly in that autogiro made of crates, whose rotor was Pippi Longstocking spinning a pair of brooms, than this thing.

Considering that that would be the bestest aircraft ever I'm not surprised that you would prefer that version.

Saw this in Popular Science 15 years ago... (1)

moosehooey (953907) | about a year ago | (#43515325)

Everything that's old is new again.

Saw this in Popular Science 25 years ago... (4, Informative)

Ken_g6 (775014) | about a year ago | (#43515457)

Yep, I remember this too. I even found the site of someone who claims to have created it. [nemontel.net] But you and he are off by 10 years - it was July 1987. [google.com]

Re:Saw this in Popular Science 25 years ago... (2)

dywolf (2673597) | about a year ago | (#43515835)

http://en.wikipedia.org/wiki/Sikorsky_S-72 [wikipedia.org]
The sikorsky S-72 demo prototype. Never actually made the conversion from rotary to fixed flight mid-air, but did fly in both configs seperately.

Re:Saw this in Popular Science 25 years ago... (1)

dywolf (2673597) | about a year ago | (#43515883)

they also followed on a few years ago with http://en.wikipedia.org/wiki/Boeing_X-50 [wikipedia.org]

It actually made the transition....or tried to. Both prototypes crashed.

Re:Saw this in Popular Science 15 years ago... (0)

Anonymous Coward | about a year ago | (#43516339)

Boeings Dragonfly is the only one I was aware of...

http://en.wikipedia.org/wiki/Boeing_X-50_Dragonfly

Nevah been done befo' (0)

Anonymous Coward | about a year ago | (#43516973)

This guys [cartercopters.com] built a much prettier chopper-airplane hybrid vehicle. [google.com]

They assembled it in my hometown and I got to watch it fly in person.

Mattel to sue (1)

kannibal_klown (531544) | about a year ago | (#43515343)

In other news, Mattel to sue StopRotor for copying its various GI Joe and Cobra toys from the 80s

Re:Mattel to sue (1)

Isaac-Lew (623) | about a year ago | (#43515825)

Isn't GI Joe made by Hasbro?

Re:Mattel to sue (1)

kannibal_klown (531544) | about a year ago | (#43515947)

Isn't GI Joe made by Hasbro?

Darn it, you're right. I get those old companies confused.

Balderdash (0)

Anonymous Coward | about a year ago | (#43515385)

This has to be one of the most ridiculous things I've ever seen. The forces on a set of rotor blades are phenomenal, and the additional hardware required to make them a controllable item would have to be slung around with the blade. A rotor hub is already an obscenely complicated, high-tolerance device even without active components adding weight. There have been attempts to make dynamic rotors, and the results have been hard-won, with the only intention being expanding the operational range of the craft. Trying to completely change the layout mid-flight is crazy, not to mention the brown-trousers experience of piloting such a thing. The V-22 had enough problems due to pilot error; with this I shudder to think. As has been stated previously, the only operational demonstrator is fundamentally an autogyro, and even a working model would do very little to suggest that this could be meaningfully scaled up.

Re:Balderdash (1)

GameboyRMH (1153867) | about a year ago | (#43515615)

Maybe the wing has no control surfaces. It could use control blending on the elevators and canards.

Re:Balderdash (1)

BitZtream (692029) | about a year ago | (#43518285)

It wouldn't have any control surfaces, nor would it need any.

Just like in normal rotary flight, you simply change the pitch of the rotor blade. The entire wing is an aileron, not any small portion.

The entire layout change consists of ... rotating the receeding rotor 180 degrees (if they even bother to do that) so that its shape is the most aerodynamic. You could just leave it and compensate for the additional drag and lower lift using other control surfaces if you wanted to reduce complexity and remove the ability to rotate a rotor blade 180 degrees on its hub.

From a control perspective, theres no reason to modify the rotor head if you don't do that, cyclic inputs will work exactly as expected in roll, yaw and pitch would need alternate controls not on the rotor as the rotor is no longer in a position to apply torque to pitch or yaw the craft.

And for reference, my R/C helicopter has a rotor head far more complex than anything these guys are working on unless you count the complexity of putting a radar dome on top of the rest of that mess as the military does. Rotor heads aren't complex really, just precise.

The control style of the aircraft wouldn't change either, though heli pilots tend to 'pilot' more than fixed wing pilots so it wound't be something that you could just step into and fly unless you were made aware of the transition phase issues.

The V-22's problems were media and congress. If you think the V-22 shouldn't be flying you have no idea how incredibly hard to control the stealth aircraft are. A v-22 pilot actually flies his aircraft, no F-22, F-35, F-117, or B2 bomber would make it very far past the end of a runway if it wasn't for the computer that ACTUALLY flies the aircraft. The pilot just points the thing in a direction and the computer makes it happen. The V-22 has no where near that sort of fly-by-wire system. The V-22 as it was tested required the pilot to actually be in control of the aircraft, not just pointing it in a direction and letting the computer do the work.

Spend 1/3rd as much on avionics for the Osprey as was spent on any one of the stealth fighters or bomber electronics and you'd never hear of another Osprey mishap. (well, you won't anyway since they aren't flying) It could have easily been made as flyable as it wasn't even completely devoid of static stability like all the Stealth aircraft are.

I'm not sure what you're going on about with the completely changing the layout (geometry is the word you're looking for btw) of the rotors in flight. You do realize that you can already do that in even the most basic of rotor heads, right? (Short of rotating one blade 180 degrees by itself), Its trivial to change any one blade without effecting the others. No one does that because theres no reason to, but the added 'complexity' isn't there.

Helicopters are not ridiculously complex machines. They are more complex than an fixed wing aircraft in some ways, others not so much.

Re:Balderdash (1)

T-Bone-T (1048702) | about a year ago | (#43522783)

If you think the V-22 shouldn't be flying you have no idea how incredibly hard to control the stealth aircraft are. A v-22 pilot actually flies his aircraft, no F-22, F-35, F-117, or B2 bomber would make it very far past the end of a runway if it wasn't for the computer that ACTUALLY flies the aircraft. The pilot just points the thing in a direction and the computer makes it happen. The V-22 has no where near that sort of fly-by-wire system. The V-22 as it was tested required the pilot to actually be in control of the aircraft, not just pointing it in a direction and letting the computer do the work.

It sounds like you haven't heard anything about the V-22 in a couple decades. The V-22 is extremely high-tech. It has a glass cockpit and triple-redundant fly-by-wire-system and is currently in Operational status and flying all the time. I watched a pair of them doing fast-roping exercises a few days ago.

Everything old is new again (0)

Anonymous Coward | about a year ago | (#43515393)

See also: http://en.wikipedia.org/wiki/Sikorsky_S-72

ATM this is effectively just a large R/C model, we'll have to see how it scales and with what useful cargo load. All sorts of interesting design work on R/C models because of the power/weight that is possible at this scale.

To Simplify the complex description... (0)

Anonymous Coward | about a year ago | (#43515445)

This is a two blade helicopter that has a jet engine in the back. When the jet engine fires, the two blade lock into position perpendicular to the jet engine, and act as a wing.

Everything else they talk about are the complex things that need to be done to make it work.

Also note, they made it in small drone sized scale. That might be to save money, or it might be that we don't have the technology to scale it up to human sized (material strengths might not be up to the task).

No video? (0)

Anonymous Coward | about a year ago | (#43515491)

Are you kidding me?

New job? (1)

ArcadeMan (2766669) | about a year ago | (#43515535)

I wasn't aware that Stephen Hawking was doing narration for videos.

What's a fixed rotor? (1)

wonkey_monkey (2592601) | about a year ago | (#43515567)

How do you define "fixed rotor"? Is there such a thing as an unfixed rotor in comparison?

Re:What's a fixed rotor? (1)

ISayWeOnlyToBePolite (721679) | about a year ago | (#43515841)

I'm guessing fixed as opposed to freespinning rotor, aka autogyro.

Re:What's a fixed rotor? (1)

Endo13 (1000782) | about a year ago | (#43516075)

Fixed, as opposed to tiltrotor. You know, like the summary says.

Re:What's a fixed rotor? (1)

nedlohs (1335013) | about a year ago | (#43516155)

A rotor that isn't a tiltrotor or mounted on a tiltwing?

Sure, usually you'd just say "rotor" but when talking about the domain where a tiltrotor is one of the most well known techniques they might have felt the need to make a distinction.

You mean... (1)

rossdee (243626) | about a year ago | (#43515659)

They finally got the V22 Osprey to work?

Re:You mean... (1)

Yo_mama (72429) | about a year ago | (#43516417)

Try and keep up ;)

Who will try this thing? (1)

ygslash (893445) | about a year ago | (#43515681)

Will you be the first one to try flying one of these things? Oh no, don't look at me. No way.

Re:Who will try this thing? (0)

Anonymous Coward | about a year ago | (#43517907)

that's kinda what I was wondering. That and when they DO find someone, how is he going to fit his GIANT TESTICLES in the cockpit.

Seriously, it looks from the video like they basically let it stall while they transition.

Re:Who will try this thing? (1)

BitZtream (692029) | about a year ago | (#43518315)

If I could certify it in X-Plane and make it fly, I'd hop in.

You don't actually think engineers go fly this aircraft with pilots who have no idea what its going to be like, do you?

Bell helicopters has pilots 'certified' for new aircraft before the aircraft has finished the production line. This isn't the 80s anymore man, we simulate before we do the real thing. Hell, even Space Ship One and Two pilots are certified on X-Plane before they go fly a brand new experimental orbital craft.

Challenges of Rotorary Aircraft (0)

Anonymous Coward | about a year ago | (#43515771)

Well, looks like Bell trying make new product get another military contract. I remember them selling their civilian rights to their european partners. V-22 Osprey been having troubles since the 80s with various problems with the mechanical break downs to pilots having problems.

V-280 Valor almost looks like a Blackhawk helicoptor with V-22's Rotorary setup. CGI promotion films makes look bit too think and smaller than the Osprey.

Is this a good solution (2)

91degrees (207121) | about a year ago | (#43515781)

Seems there will have to be a few design compromises

The rotors need a drive mechanism. This is dead weight when in level flight.
The rotors will need to be symmetrical, making them less efficient as wings and as rotors.
The whole system is more complex than either a plane or a helicopter. Makes building and maintaining it more expensive.

What are the advantages over a vectored thrust approach?

Re:Is this a good solution (1)

Bearhouse (1034238) | about a year ago | (#43516721)

Probably less fuel consumption, (if it works).

The only successful vectored thrust aircraft, the Harrier (in it's various guises), had severely-reduced range if its VTOL capabilities were used.
That (and loading considerations) mean that normal takeoff procedure was STOL, optionally using a ski-ramp.

http://en.wikipedia.org/wiki/AV-8_Harrier_II [wikipedia.org]

Re:Is this a good solution (1)

BitZtream (692029) | about a year ago | (#43518433)

You must be British. No one outside of Britain thinks the Harrier is a success.

Re:Is this a good solution (1)

BitZtream (692029) | about a year ago | (#43518425)

The rotors need a drive mechanism. This is dead weight when in level flight.

The turbine power plant would work in all phases of flight, this is trivial and already accomplished.

The rotors will need to be symmetrical, making them less efficient as wings and as rotors.

And? Most heli's already use symmetrical airfoils. Of course, the receding blade still needs to be rotated 180 degrees so its 100% efficient compared to rotary flight but its not a requirement.

The whole system is more complex than either a plane or a helicopter. Makes building and maintaining it more expensive.

Yes, but this has the potential to land at a hospital helipad, as well as go super sonic. We currently can not design helicopter rotors that are able to deal with sustained entry/exiting from supersonic speeds as it rotates. Remember, the forward moving blade has its rotational speed PLUS your airspeed moving it over it. If the rotor tip speed is 300mph, you can't go more than 400 or so without the rotor having only parts of it repeatedly enter and leave supersonic flight.

Going with that, at 400 forward speed, your right side of the rotor disk has a airspeed of roughly 700mph, where as your left side is dealing with about 100mph. Dealing with the dissymetry of lift alone is enough to ruin your day, throw in the whole 'a sonic boom above your head 30 times a second' tends to just make it impossible for us to build.

Stop the rotor from spinning and you've solved the biggest problem with high speed rotary aircraft.

This is about landing on your hospital roof then immediately leaving there and going supersonic to your destination, and again landing on a roof without any runway.

Efficiency is a secondary concern here.

Comfort much? (1)

asylumx (881307) | about a year ago | (#43515901)

I'm glad they're working on something and especially glad that they are starting with hobbyists because they've got a reasonable chance of commercial success there, and hopefully it will lead to some eureka moment that can effectively be transferred into full-scale passenger flight.

That said, I would NOT want to be a passenger in that thing! Even the computer model gets bounced around a hell of a lot during transition and that, I'd imagine, is modeled in calm weather. Not to mention, a lot of free-fall is involved. A lot of passengers have a hard enough time stomaching CTOL. These transitions should come with a warning that says "For roller coaster enthusiasts, only."

Will it beat the X2? (1)

tlhIngan (30335) | about a year ago | (#43516043)

Sikorsky unofficially holds the record on fastest helicopter (the Sikorsky X2 [wikipedia.org] ) which while not stopping the rotors, use them to generate a little lift for high-speed flight. It too uses a pusher prop and wings...

Airwolf, at long last!! (0)

Anonymous Coward | about a year ago | (#43516261)

Glad I'm not the only one who remembered it.

Stopped-rotor design new -- in 1976 (1)

DragonWriter (970822) | about a year ago | (#43516313)

See the Sikorsky "X-Wing" modification of the S-72 RSRA [wikipedia.org] .

What will be news is when someone builds something that goes beyond "concept" to "flyable aircraft that demonstrates in-flight transition between rotary- and fixed-wing flight.) But a stopped rotor concept is not much in the way of news.

Points of failure? (1)

Kozar_The_Malignant (738483) | about a year ago | (#43516335)

This is very interesting, but it seems quite complicated. I wonder how many points of failure there are that transition it to brick mode.

So basically (0)

Anonymous Coward | about a year ago | (#43516675)

So this is basically trying to create in reality the aircraft from "The 6th Day", where they act as a helicopter part of the time, but can convert to a "sleek" jet for long range flight. Sounds neat, but there have to be some serious issues with weight & efficiency. Judging from the prototype images they have a long way to go.

seems super practical (1)

dirtyhippie (259852) | about a year ago | (#43516701)

One of the videos shows the transitions between rotary and fixed phases, during which the vehicle is essentially in free-fall. How long does it have to stay in transition, spinning up/down the wing/blades before it can complete the transition? You can definitely rule passenger flight out, and will ikely be less reliable than the V-22 by an order of magnitude - and that's saying something.

Re:seems super practical (1)

Rich0 (548339) | about a year ago | (#43518969)

Yeah - that thing would have just about anybody puking and screaming for their mothers from the look of it. Sure, it might be safe in theory, but so is the vomit comet.

Airwolf (1)

Gothmolly (148874) | about a year ago | (#43516907)

Isn't this what Airwolf did when it went supersonic?

X-Plane VTOL (0)

Anonymous Coward | about a year ago | (#43519033)

Personally I like my concept better......
http://www.youtube.com/watch?v=ep4nQAoL9FM

Drone only (1)

Goonie (8651) | about a year ago | (#43519825)

It seems to me that the transition between rotary and fixed wing modes is a bit "exciting". Can't imagine that you'll get pilots prepared to try it, let alone passengers. Maybe it'll be useful for drones, if anybody needs a VTOL drone with a long-range cruise mode.
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