Can helicopters do loops and rolls?
Dear Straight Dope:
Can a helicopter perform such classic aerial maneuvers as the roll and the loop?
Seemed like the obvious thing to do was to ask some of the propeller heads at work, so that's what I did. In the classic "yes and no" tradition, Lukys, the answer is "some can, some can't." It all depends on the design.
Some helicopters are built with what's called a "semi-rigid" rotor design, wherein there's a substantial degree of flex in the rotor blades. Push those babies too far--trying to do a roll or a loop, for example--and they'll flex far enough to hit the back end of the helicoptor. As you might guess, this can have a negative impact on the machine's ability to stay aloft.
Other helicoptors employ a "fully-rigid" rotor design, wherein there's little flex in the rotor blades. When the pilot gets daring, the rotor blades happily comply, taking the chopper upside down without cutting off the tail, just like in the cartoons.
Even if your uncle bought you a helicoptor with a fully-rigid rotor system for your birthday, however, you should take a few lessons in how to fly the thing properly before trying loops and rolls at home. And read the owner's manual: even if the rotors are right, the aircraft may not have been designed to withstand the stresses that such maneuvers create.