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In the SCP Foundation story "Over/",1 the protagonist and his fiancée get kidnapped by some terrorists looking for information, who eventually throw the two of them out of a CH-148 (with parachutes, fortunately). Immediately after the two exit, a mirror monster linked to the protagonist causes the copter to roll hard over; as the helicopter rolls towards inverted, one of the terrorists loses her grip and is finely minced by passage through the main rotor. Protagonist and fiancée land safely, and the fiancée says that they'll need to run, because the remaining terrorists had managed to land the helicopter nearby.

I would not have expected a helicopter (CH-148 or otherwise) that'd taken an adult human through the main rotor while rolling through inverted to be capable of landing successfully, for a number of reasons:

  • Helicopter-main-rotor blades do not tend to react well to large, heavy objects passing through them, and chopping up an entire adult human would probably do some pretty nasty damage to the blades.
  • Helicopter main rotors are also fairly intolerant of mass imbalances resulting from blade damage; even a fairly-small section of one blade missing can result in an immediate loss of control of both the main rotor and the helicopter itself (often followed within seconds by the unbalanced main rotor tearing itself free of the helicopter altogether).
  • Finally, rolling rapidly through inverted would put all sorts of new and interesting forces on the main-rotor assembly in directions it was never designed to have force applied to it in (especially if, as seems to have been the case here, positive G was not maintained through the roll), potentially causing the main-rotor blades to strike the fuselage or the main-rotor mast to strike the adjacent structure2 (either of which would result in loss of control and main-rotor separation, not necessarily in that order) and certainly exacerbating the blade damage from an adult human going through the main rotor.
    • As just one example of this, in order for someone who loses her grip on the helicopter to pass through the main rotor, the main-rotor blades on that side of the helicopter would have to have a downward-pointing (in the chopper's frame of reference) lift vector (if the terrorist loses her grip while the main rotor is above her, then that side of the rotor has to accelerate downwards faster than the freefalling soon-to-be-mincee in order to catch up with her, necessitating that it be generating lift in the downwards direction; if she comes loose while the main rotor is under her, that side of the main rotor has to accelerate downwards slower than she does, requiring that it be generating lift in the upwards direction, which, as the main rotor being below its meal corresponds to the helicopter being inverted, requires that it be generating lift in the downwards direction from the helicopter's point of view). This, like any other situation involving a helicopter's main rotor generating downwards-in-the-helicopter's-frame-of-reference lift, would cause the main-rotor blades on that side of the helicopter to cone downwards, towards the rest of the helicopter, and potentially collide with other helicopter structure.

Is it realistic that an S-92-family helicopter - or, for that matter, any helicopter - could (assuming no anomalous augmentations to the helicopter) roll hard through inverted, taking an adult human through the main rotor in the process, and still recover from the upset and make a safe emergency landing?


1: Not a typo.

2: While the S-92 family uses a fully-articulated main rotor, which is not normally susceptible to mast bumping, the extreme lateral forces that would be generated by a rotor disk tilted sufficiently to produce the roll rates involved in this situation might still damage the mast of even a fully-articulated main rotor, and mast bumping would still be an issue for many other types of helicopter in this sort of scenario.

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  • $\begingroup$ All the human has to do is to grab on to the blade. Then they will whirl around with it and not be minced. ; ) $\endgroup$ Feb 6, 2023 at 19:23

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No. I suspect having a human body come in to direct contact with the rotor disk 1) would not “finely mince” a person but instead cause severe blunt force trauma followed by flinging the body or body parts from the disk like a rag doll. 2) The impact would cause severe damage to one or more rotor blades, most likely causing separation of a blade from the base and gross imbalance of the rotor system. This could eventually tear the aircraft apart in a manner similar to uncorrected ground resonance. 3) While (some) helicopters with fully articulated rotor systems are capable of limited inverted flight under positive loading, I don’t think an S-92 can do this.

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A partial answer: some helicopter rotor blades are extremely fault tolerant. Just look at the grin on this lucky aviator and the blades on the chopper he has landed just a few a hours before: Ryan Schwend - Chinook

More to read on the incident here: The Army Bestows This Rare Award to Pilots Who Crash Like Professionals

Alas, while the blades may survive the scenario, it is otherwise extremely unlikely, involving some very James Bond -like physics.

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    $\begingroup$ [reads article] HOLY CARP. $\endgroup$
    – Vikki
    Feb 5, 2023 at 14:47
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    $\begingroup$ That's a Chinook, though, which has 2 lift rotors on it. From the looks of it, only the rear one was damaged? If that happened to a standard 1-rotor helicopter, it would be far less likely to be able to land safely. $\endgroup$ Feb 6, 2023 at 19:07
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    $\begingroup$ @DarrelHoffman Chinook will fly just as poorly with one rotor as, say, a Blackhawk with no rotor. $\endgroup$
    – Jpe61
    Feb 6, 2023 at 22:47
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    $\begingroup$ Yeah, but the point once the damage occurs isn't to fly it, but just to land safely. With one rotor still working, I'd think you'd still have at least a bit of lift to soften the landing. With no rotor, you'd drop like a stone... $\endgroup$ Feb 7, 2023 at 14:34
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    $\begingroup$ If we assume a single rotor would suffer same kind of damage as the featured Chinook, we can safely assume the controllability would be similar as in the Chinook's case. If we totally take away the only rotor, a helicopter will not fly at all. If we take away one of two rotors, the helicopter will not fly, at all, unless the rotors were coaxial, in which case the helicopter will fly very very poorly. In Chinook's case, losing one rotor will lead to such a great imbalance, the remaining rotor will be totally unusable. $\endgroup$
    – Jpe61
    Feb 8, 2023 at 11:46

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