Carter Copter Breaks Mu-1 Barrier

tyler_larson writes "Just over a week ago, Jay Carter's CarterCopter managed to break a significant rotorcraft barrier, traveling at a mu ratio of 1. This 1-to-1 ratio (sometimes called the mu-1 barrier) represents a condition where the forward speed of the craft is the same as the speed of the tip of the rotor. This means that at a certain point, the tip of the retreating blade is "standing still" relative to the wind and producing no lift, while the rest of the blade is actually moving backwards through the air. Such a condition is normally impossible for a rotorcraft, and so the forward speed of a helicopter is limited by the the speed of the rotors. This accomplishment by the CarterCopter, which some insisted couldn't be done, proves that this new craft is not subject to that limitation."

Comments

they cheated

[Anonymous Coward]

I fly radio controlled helicopters all the time and worked for Bell for quite some time. Although this is a great accomplishment, it doesn't really break the mu-1 barrier because it is a hybrid between a helicopter and an fixed wing airplane. This is like saying "fixed wing aircraft don't need a runway" when the harrier came out. Regardless, mu-1 will always be here for the purists.

Its a bird, its a plane, its a helicopter...

[rossdee]

They cheated! It has wings.

One other way of dealing with the asymetric lift in high speed rotorcraft is to use 2 contra rotating rotors, for example the russian Kamov helicopters.

Re:Its a bird, its a plane, its a helicopter...

[sl3xd]

Even the worst fixed-wing hangar queen doesn't need near the maintenance of its helicopter equivalent.

Isn't that redundant? Isn't the equivalent of the most maintenance-intensive aircraft therefore the most maintenance-intensive helicopter?

Not that the meaning is lost: The most maintenance-intensive airplane still doesn't need much compared to a helicopter that needs the least maintenance.

Which also brings up why a helicopter needs more maintenance: Unlike an airplane, a helicopter is several thousand parts trying despearately to get away from each other.

Re:Its a bird, its a plane, its a helicopter...

[lawrencekhoo]

For those who want pictures:

http://www.x-plane.org/home/mf70/Current&Future.ht m
http://eaa.aviationuniversity.com/multimedia/img/e aa/CarterCopter-27-eaa.jpg
http://www.davidpride.com/AirVenture2002/images/AV 2_64.jpg

Re:mu and swimmers

[tanveer1979]

Its because they use their legs.

Geometry lesson

[JohnPM]

This means that at a certain point, the tip of the retreating blade is "standing still" relative to the wind and producing no lift, while the rest of the blade is actually moving backwards through the air. Such a condition is normally impossible...

Actually such a condition is completely impossible. If the tip of the blade is stationary and the rest of the blade is moving backwards, then the axle/chopper is moving backwards. Clearly the chopper and blades are screaming forwards except for the tip of the blade on one side which is stationary.

Re:Further explaination...

[Council]

what they have achieved is limiting the flutter associated with the approach of mu = .75

Yeah. From TFA: the CarterCopter, which some insisted couldn't be done, proves that this new craft is not subject to that limitation."

So they're not saying "this breaks the helicopter record" so much as "these new copter thingies are really cool."

Tip of the wing ... not the entire wing !

[Gopal.V]

I think the point is that the wing goes around . So the forward velocity varies depending on what angle the rotor is at that point. It also should be remembered that the wing tips move both ways (forward and backward). The whole point of that being - it will hop from side to side when it touches mu-1 (no, I am not a physics professor). These guys have been near mu-1 for about ~20 seconds.

Also I think the mu-1 ratio has always dealt with the fact that most modern helicopters deal with rigid wings and the lift generated is from around 3/4th distance from the central point. I don't know if that's going to hold for the future (just like moore's law when quantum computers come... sheesh ).

Insult me if I'm wrong. And TFA is slashdotted already . Can't more people use greasemonkey cacher ?.

Re:Wait, what?

[ValentineMSmith]

I think that they phrased things poorly. I think what the poster meant was:

1: The airspeed of the blade increases as you get closer to the blade tip and further away from the rotor hub.

2: The tip of the blade has a 0 airspeed ( is "standing still" relative to the wind).

3: Given 1 and 2, the rest of the blade must have a negative airspeed. Or, maybe a better way of saying it is that the trailing edge of the blade is actually meeting the air, not the leading edge. From the way they worded what they were saying, it looked like the poster was saying that the blade was moving backwards relative to the aircraft, not to the air.

From the picture I've seen, the one thing this is NOT is a helicopter. It looks more like a gyrocoptor with wings. Call me back when they've broken mu-1 with a pure helicopter.