Can Helicopters fly upside down?

Step N. Mud

Step N. Mud

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Don't know why anyone would want to, but have seen them do loops and barrel rolls on youtube channels. Think it was a movie called 'Blue Thunder' that Roy S. does a loop with a high-tech
chopper. :eek::cool::rolleyes:
 
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I don't believe they can actually fly inverted. The nature of the rotary wing would make that a losing preposition. I suspect they would end up making a messy mark on the ground. Around 1982, I attended an air show in Brunswick, ME. I saw 2 marine Sea Cobra's perform a flip (not a loop, just flipped nose to tail). Off the coast of Korea, in 1986 (Team Spirit) I watched a Marine CH-53 do a slow (and majestic) left hand roll. So I have 2 thoughts: Yes, they can roll/flip; and I have no great desire to fly in a Marine Helo.
 
Short answer: No, inverted flight is restricted by the rotor system which, for conventional helicopters, are designed to take aerodynamic loads in one direction, upward. However, several have tried and succeeded.
Longer answer: theoretically yes, with a newer redesigned rotor that can take loads in both directions as well as providing negative pitch control. Some newer helicopters can do loops with a newer rigid negative pitch rotor system. They are a wonder to watch when handled with skill. They are a smoking hole when not…….
 
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Step N. Mud said:
Don't know why anyone would want to, but have seen them do loops and barrel rolls on youtube channels.
Click to expand...

Theoretically, there is no reason why not. Practically, there are a lot of issues.

Most problems have to do with basic design and loads. The standard helicopter‘s rotor has the fuselage hanging BELOW it; it is optimized aerodynamically for that.

Flying inverted for any length of time, the helo would have to carry the fuselage ABOVE the main rotor, putting entirely different stresses on joints and connectors, and flexing everything in the opposite direction.

You can likely build a special aerobatic helo to handle this, but this would not be an efficient aircraft for any other practical purpose.

I am not a certified helicopter pilot; there are probably other issues, but this would be the most obvious problem.
 
Not a helo, but a C-9. We flew into Wake Island as a maintenance crew for a Marine A6-E squadron. The attack birds were doing some aerobatics as it is unrestricted airspace and giving the advance maintenance crew an airshow. The Crew Chief came through the cabin and was stowing stuff in the overhead compartments and told us to strap in. The next thing we know the plane is doing rolls and stuff. When we got on the ground we asked the Marine Colonel what was he doing!?! His answer was "I just want to show the little fellas (the A6's) that I could do it too, only slower!" Let me tell you it is very interesting to be in a DC-9 upside down!
 
I do know that sitting on a cliff, watching the Tribal Police fly 150-200 feet underneath you is an awe inspiring experience.

No one was wanted, they just flew the backcountry daily cause they could.
 
You can leave a cup of coffee on the dash board of an airplane while a well executed roll is done, and it won't spill, because during the time the airplane is inverted the craft is accelerating downward, pinning the cop of coffee to the dash board. A passenger with his eyes closed would not know the plane just did a roll. I imagine the same would be true of a roll in a helicopter, wherein there's never a negative G-load on the system while inverted, because the loads are the same as right-side-up flight (but pointing in the opposite direction).
 
Can helicopters fly upside down?

To paraphrase Larry, The Cable Guy: Sure! All the way to the scene of the crash! Probably beat the ambulance guys there by 20, maybe 30 minutes.
 
vt_shooter said:
…. I imagine the same would be true of a roll in a helicopter, wherein there's never a negative G-load on the system while inverted, because the loads are the same as right-side-up flight (but pointing in the opposite direction).
Click to expand...

That’s the key difference to actual sustained inverted flight.

In a well-executed aerobatic maneuver the aircraft (fixed or rotary) is never “upside down” aerodynamically, no matter its momentary orientation relative to level flight.

PS: Here’s legendary Bob Hoover demonstrating the principle in a plane.

[ame]https://m.youtube.com/watch?v=V9pvG_ZSnCc[/ame]
 
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