After spending several hours in this wonderful aircraft, I have the following problem: when I’m descending with a lot of forward speed (approx. 110 knots), the helicopter suddenly rolls to the left and overturns several times before it crash. According to the original manual of the Bell 206 B3, the speed limit should be 130 knots. There is no warning for a limitation of 110 knots.
It shouldn’t be a vortex either, because you “escape” the downwash again due to the high forward speed… or am I completely wrong?
Depends of the altitude…
The higher you are, the max speed decrease.
Yes Altitude, outside air temperature and gross weight.
See original B206 Flight manual.
There is a placard in the Helicopter.
The table with the Max Speeds is known to me so far. What I don’t understand is the aerodynamic background to this behavior. Is the problem that the rotor blades enter the supersonic range and thus get a flow rupture?
Does this happen so abruptly in real life or does the danger slowly become apparent because the helicopter first rolls only slightly to the right??
A good physical explanation is here https://www.flight-study.com/2019/12/forward-flight.html
I don’t know how this effect irl is, I guess every real pilot try to avoid it.
The retreating side of the rotor disc can stall with the relative wind speed
The combination of blade flapping and slow relative wind acting on the retreating blade normally limits the maximum forward speed of a helicopter. At a high forward speed, the retreating blade stalls because of a high AOA and slow relative wind speed. This situation is called retreating blade stall and is evidenced by a nose pitch up, vibration, and a rolling tendency—usually to the left in helicopters with counterclockwise blade rotation.
Pilots can avoid retreating blade stall by not exceeding the never-exceed speed. This speed is designated VNE and is indicated on a placard and marked on the airspeed indicator by a red line.