The pilot pulled up abruptly, cleared the obstacle, and suffered a boom strike when he leveled the helicopter. Because the helicopter was still rising at that moment, the rotor was pushed downward into the boom. The pilot was a friend of a friend, who described the incident. It's been a long time, so I probably have some details wrong, but you get the idea.
In theory, a helicopter pilot could roll to an inverted orientation, put the main rotor blades into negative pitch, apply throttle, and climb imverted In practice, there is a very good chance that this would cause an in-flight boom strike. I do think that at some point blade technology will allow for inverted flight, however it will take a tremendous investment to get there.
In addition to blade development, someone will have to rig a helicopter for remote control in order to test this, and they'll need to be willing to risk losing the entire helicopter if the new blades don't live up to their hopes. RedBull seems quite fond of rolling and looping their helicopter, and they can afford the development costs of two F1 teams, so perhaps they'll be the ones to try it first. Can it be done? Red Bull, lots of it. Or at least a sponsorship…. Chuck Aaron is the only FAA certified pilot in the world to aerobatically perform in a helicopter. I have personally seen him perform at a local airshow, and he was very unique indeed.
He has done backflips, loops, barrel rolls, cuban 8s, you name it! It can be done, but the conditions have to be right. A helicopter flies because the rotor blades create lift.
Tilting the blades—the rotor disk—changes the thrust vector to make the aircraft go forward, back, and sideways. The control to accomplish this feat is called the cyclic , because it causes the individual blades to change their pitch—the angle of attack—at different areas of their rotation. There is another control called the collective. This controls the pitch of all the rotor blades the same amount. Flying a rotary wing aircraft inverted for any length of time is essentially impossible, because rolling inverted would cause the lift from the rotor to be pointed to the sky, not to the ground.
In other words, it would augment gravity, rather than defy it. Model helicopters have been able to perform seemingly impossible aerobatic maneuvers including sustained inverted flight for decades. They have a trick, though: This allows the pilot to change the pitch to negative when they perform maneuvers involving inverted flight. Wired Magazine had an interesting article about him several years ago:. A NH performed, but if it has that capability, it was not demonstrated. I was also told by CH heavy lift Super Stallion pilot that the E model had performed a flip, but that is also against regulations.
To the best of my knowledge, the US Armed Forces do not demonstrate these capabilities at any air shows, but Chuck Aaron in the Red Bull Helicopter with titanium rotors performs them at air shows across the US. In Europe, you can see military aircraft demonstrate these maneuvers. Well, you can do a loop or if you like to call it, a backflip. But you cant constantly fly that way, because gravitation would pull the chopper to the side and it will turn back. For example, imagine a chopper is like a balloon, and your hand is a propeller. As you can see, the balloon falls to the side.
Same thing will happen to the chopper. The blades are designed to lift the aircraft. Now can you do a flip or a roll? In some rotorcraft with enough forward momentum you can briefly perform some of these stunts. Think of it like a skateboarder on the half pipe. Is that Spectre helicopter stunt even possible? For short maneuvers like rolls and loops, there are several that can do it. The aircraft has to have a fully rigid rotor head, though. Semi rigid heads run the risk of breaking up with all the differential rotational forces of the rotor system pulling the aircraft through inverted G situations.
As for longer maneuvers like hovering or level flight, no. There are no full size helicopters that can do that. I asked one of the pilots if they could be flown upside down. He repeated that it would be against regulations. I said OK and walked away. Technically yes with negative pitch rotor blades, but that would require a chassis strong enough to withstand the stress as well as pilots who are able to cope with the extreme G-Forces.
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See this video of a talented RC Helicopter pilot making full use of his collective pitch rotors and making his helicopter look possessed! Having minored in Philosophy and having flown the Osage, Irqouis, Kiowa, Blackhawk and Apache helicopters in the Army, I would say it depends on your definition of helicopter, fly, and upside down. Bricks can fly in one meaning of the word, but that is not the same as sustained or controlled flight, whether powered or non-powered.
Also, to fly up-side down is not the same as merely to be upside down. Being up-side down during a controlled flight sequence is different than being up-side down in an un-controlled but recoverable, or uncontrolled and unrecoverable flight sequence. Many fixed-wing aircraft are designed to exert lift opposite gravity whether right-side up or up-side down. But helicopters are not designed or able to sustain inverted flight sequences, whether powered or non-powered. Helicopters are designed to fly suspended from a circular lifting area formed by lifting surfaces that rotates.
In powered flight, the lifting surface is driven by the engine. In non-powered, auto-rotation glide the centrifugal force and momentum of the lifting surface is maintained by air moving up through the system as the aircraft descends. This preserved power can be used to maneuver the aircraft during descent and help control and cushion the landing. Being designed for suspended flight means survivable G-forces are designed to be positive, not negative.
However, as one answer succinctly put it, some helicopter systems are able to withstand small amounts of negative G-forces. However, the load on the system must be carefully controlled throughout the flight sequence, from entry to exit to return to normal flight. Otherwise components not designed to endure those loads will fail and flight will no longer be able to be sustained or controlled.
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At which point the helicopter will assume the flight characteristics of a brick. Reversing the direction of blade rotation would be like flying a fixed wing aircraft backward. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site the association bonus does not count.
Would you like to answer one of these unanswered questions instead? Home Questions Tags Users Unanswered. Can a helicopter stand on the ground upside down on its rotor head? In short, can a helicopter do something like this? PTwr 1 3 7. That would be one hell of a joy-ride.
It's just a model. And there were technologies to create scenes like this as special effects besides green-screen. Compositing and matting could both be used. Perhaps the biggest give away is that it's rotating the wrong way. Simon or from Australia, maybe? KorvinStarmast The rotor of an MD turns clockwise, therefore the fuselage, when inverted, with the blades prevented from turning, the fuselage would rotate clockwise.
Stand on its rotor head? Fuel flow isn't going to work either, to the engines. I would be amazed if it managed even half a revolution. Total destruction would be the outcome. KorvinStarmast How is that? The engines are right below the rotor, and the fuel is in the tail and below "above" the passenger compartment; wouldn't gravity help? Or do you mean the centrifugal force will prevent it from flowing? When you turn it upside down, you quickly end up with air in the fuel lines.
Fuel tanks are not pressurized, the fuel feed is pressurized once the pumps suck the fuel into them from the tank. The capability of the rotor head to support the helicopter when upside down is not an open question. It cannot do it, the flapping hinges won't support this with a rotor that is not spinning. This looks like a model that was carefully set up to spin. The rotorcraft must be designed for— a A limit maneuvering load factor ranging from a positive limit of 3. Look at the drawing of the Hughes C , the type used in the clip, below: Hughes three-side view picture source Clearly, the tail extends above the rotor plane, so something must be broken first before the fuselage is free to spin around.
From the linked page: There is a huge difference between inverted flying and rotating standing on the rotor: Inverted flying is mainly about one thing: By moving the rotor head, not the center of gravity. When standing, that does not work, obviously. Yes, that is what I meant with stability and balancing a broom on a fingertip.
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Its Escape to Witch Mountain Great find, thank you! I've never had known without your hint! Your answer can be correct for a model, however the question is about a real helicopter. Update Bearingless rotor heads have flexing beams instead of pure hinges, so the rotor head has some inherent stiffness to keep a fuselage upright when the helicopter is upside down. Actual rotor head of the Hughes Check where the flapping hinge is.
I am pretty sure I've read helicopter capable of negative Gs is not possible and thinking about it I believe the flapping hinge will cause exactly the same problem as on the ground—the rotor is tilted by shifting lift with cyclic and the body hangs underneath it, so at negative Gs, the body would topple. They can withstand -1 g but in a normal position only, with the rotor on top: Possible exception may be a hingeless rotor head, with a body balanced on top where nobody makes any wild movements.
PTwr No this is from an EC demonstrator. The reference book I have lists the Hughes as having a hinge offset ratio of 12 cm: Koyovis, the position does not matter. It can withstand -1G, so a sudden turbulence won't break it, but it can't fly that way for more than a second or two, because it would topple. You have neglected to account for how drive systems work.
KorvinStarmast 2, 11 A sprag clutch would have no problem engaging upside down, because for sprag clutch, the only thing that matters is the relative rotation and torque between the two elements, not which is actually turning and which is static. And the engine still turns the same way relatively to the gearbox. A centrifugal clutch would care, but helicopters don't use that it behaves differently. Of course the bearings will probably fail because those have different strength against load in different direction and the load will then break or dislodge the drivetrain that normally does not need to bear it, but that is different from the problem you describe.
JanHudec Hmm, did I reverse direction on my little sketch with vectors and rotation? I did a quick 'back of the napkin' estimate.
However, with a lot riding on the aircraft investments, facilities, payroll and a slight downturn in student enrollment, the company only lasted five years in operation. By the time Everything Flyable closed, Kono had obtained the remaining ratings he needed and being hired soon after graduating as a CFI. The job required flights on bank runs that performed by helicopter from airports and off-site locations in Van Nuys, Fullerton, John Wayne, El Monte and others.
The process seemed tedious, but eventually, all added up, and pilots for the bank run duty became the next PIC candidates, selected from the pool of pilots based on their skill and experience.
Rotorhead: The Life and Times of an Early Helicopter Pilot - Robert A. Close - Google Книги
Kono explains, at that time, it was a difficult time to secure full-time pilot positions. Vietnam-era helicopter pilots still occupied many flying positions.
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Kono took his second hiatus from a flying role to pursue ground-based employment that paid more. His eventual return to flying required a move to Louisiana, taking him into oil and gas work, flying for Tex-Air Helicopters. The company was a family owned business that serviced the oil and gas industry before being run primarily by the two major oil and gas players in the area today, PHI and Era.
The company also operated the first generation of the EC for larger transports into the oil fields. Kono stayed in the Gulf for a year and a half, amassing a significant amount of hours and experience before finally returning to Los Angeles for good. It was upon his return that he again found himself working for Helinet Aviation, now under new management by Alan and Kathryn Purwin, previously of West Coast Helicopters. The company that Kono left had made a total degree turn since his last stint, he recalled.
It was a different time, the pay was better, as were the aircraft and morale with the new ownership. Where, a short time later, one of the worst news helicopter crashes in history occurred when two pilots covering the same event lost spatial awareness of each other, coming into contact and crashing to the ground in downtown Phoenix. The accident occurred in full view of a third pilot still on the way to the story location in another news helicopter capturing the event as it happened while trying to remain composed and report on the crash. This crash, although not a direct causal factor, began to spike conversations about combining helicopter news operations.