Vortex Ring State in gyros?

Ed L

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Hi All correct me if I am wrong. I also thought no way untill I stopped and really thought about it. to create lift there must be a downward flow of air. without a downward flow of air there can be no lift. in autorotation there is a downward flow of air creating lift otherwise we would just drop out of the air.
Doug

Are you saying/thinking for a fixed wing there must therefore also be a “downward flow of air”? I don’t think that’s true. For both there’s an upward vector of lift, caused by the aerodynamic forces at play.

Again, I don’t believe there is a VRS for a gyro and have seen no credible source suggest otherwise.
 

Jean Claude

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I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
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Are you saying/thinking for a fixed wing there must therefore also be a “downward flow of air”? I don’t think that’s true.
Of course it is true: Aft, the angle of deflection is 2 Cl /πA radians with A = Aspect ratio
For example if A = 5 and Cl = 0.5, then Deflection = 3.6 degrees down
Sans titre.png
For the lifting disc of a rotary wing, A = 1.27 and when CL of the disc is 0.5, then Deflection is about 0.25 rad or 14 degrees
For both there’s an upward vector of lift, caused by the aerodynamic forces at play.
It's also true. Just more local. The sum of all the local pressures on the walls produces on the one hand the lift vector, and on the other hand the deflection of the air flow
 
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Burlington Wi
An article at Skybrary states that for a vortex ring state to occur:
The aircraft has to be in powered flight. If the engines are not producing power, the aircraft is in autorotation and the upflow of air (rather than engine power) is being used to drive the rotor motion. It is not possible to enter the vortex ring state whilst the helicopter is in autorotation.
Now it makes sense because one of the ways to get out of VRS was autorotation


Doug
 

Ed L

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Of course it is true: Aft, the angle of deflection is 2 Cl /πA radians with A = Aspect ratio
For example if A = 5 and Cl = 0.5, then Deflection = 3.6 degrees down
View attachment 1146787
For the lifting disc of a rotary wing, A = 1.27 and when CL of the disc is 0.5, then Deflection is about 0.25 rad or 14 degrees

It's also true. Just more local. The sum of all the local pressures on the walls produces on the one hand the lift vector, and on the other hand the deflection of the air flow
Fair enough.
Stepping back, though, it still seems like “we” are trying to rationalize that VRS can occur in a gyro. Best I can tell, the scientific answer still seems to be no. Failing to respect the H/V curve, for example, does not mean a VRS was induced in a gyro.
 
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