Aviator168
Member
In general cruise, what is the AoA of the retreat blade? At what RRPM or fly speed will I see the retreating blade stall?
Looking at the chart. If the blade pitch (static) is lower, it can reduce the stall region of the retrieving blade? Also has delay stall devices (Vortex Generators) been put on blades?Of course ! These results obtains the autorotation steady rpm, with the disk A.o.A required. Here 375 rpm, with disk A.o.A: 8.8 degrees and a1: 2.2 degrees
As said Waspair, lower pitch setting reduces the stalled area and increases the rrpm. However, it also increases rotor drag.Looking at the chart. If the blade pitch (static) is lower, it can reduce the stall region of the retrieving blade? Also has delay stall devices (Vortex Generators) been put on blades?
There is a limit of how much collective pitch can be reduced.Using the collective trim control fitted to some A&S18As, you can slightly reduce collective pitch, (which also leads to an increase in rotor rpm) and thus delay the onset of retreating blade stall to higher speeds. It's useful when flying fast and lightly loaded where the rpm is at the low end of the desired range and the ride gets rough with increasing speed.
The original manufacturer's design did not include it, but an STC was developed by Don Farrington to add it. It used a small electric motor, activated by a miniature switch on top of the cyclic stick, to drive the swash plate up and down (response with fine gearing was too slow to use it for a collective flare at touchdown unless your timing was absolutely perfect). You could easily delay retreating blade stall onset by about 10 knots, at the cost of a big reduction in the available climb rate at full fine-pitch/high rrpm travel, but it was very helpful at low load and high speed.There is a limit of how much collective pitch can be reduced.
Just curious, is this done with a trim on a A&S 18A?
I am wondering how much of the rotor drag is due to simply increase in rrpm and how much is induced by getting to a higher rrpm.As said Waspair, lower pitch setting reduces the stalled area and increases the rrpm. However, it also increases rotor drag.
For example, a rotor like ELA 07 carrying 370 kg with an aerodynamic pitch setting of 3°, the rrpm is 342 steady (at sea level). The drag of the rotor alone is 566 N at 110 km/hI am wondering how much of the rotor drag is due to simply increase in rrpm and how much is induced by getting to a higher rrpm.
So it looks like for very speed a gyroplane flies, there is a most efficient RRPM that goes with it. For a given rotor of cause.For example, a rotor like ELA 07 carrying 370 kg with an aerodynamic pitch setting of 3°, the rrpm is 342 steady (at sea level). The drag of the rotor alone is 566 N at 110 km/h
Now, with an aerodynamic pitch setting of 0°, the rrpm would be 450 steady and the rotor drag alone would be 890 N at 110 km/h.
Are you saying when you pull back the stick, you going to get a pitch down attitude?with this greater disc A.o.A, the attitude of airframe should be corrected, of few degrees nose down.