Captmatt Posted October 5, 2004 Report Share Posted October 5, 2004 I have been reading as much as I can on the Kmax and helicopters like the Hormone with dual rotor masts. I dont find anything on retreating blade stall. Or at least I am not looking in the right spot. Is that something that is still a problem with helicopters like the Kmax? And also, what about the effects of gyroscopic precesion? Any thoughts or links anyone could point me to on theses subjects?I would imagine it wouldnt be something to worry about, that is if the advancing blades were on the outside and they counter rotated.Anyone? Quote Link to comment Share on other sites More sharing options...
RDRickster Posted October 5, 2004 Report Share Posted October 5, 2004 I don't believe the KMax or other counter-bi-rotor systems are susceptible to RTB. Quote Link to comment Share on other sites More sharing options...
Captmatt Posted October 5, 2004 Author Report Share Posted October 5, 2004 so what would the limiting factors be for how fast it could go? Wind resistance? Quote Link to comment Share on other sites More sharing options...
eriknymoen Posted October 5, 2004 Report Share Posted October 5, 2004 the kmax have retreating blades doesnt it? and it needs more power and more pitch to go faster right?its not possible to get RBS in the R22 because it doesnt have enough power, but I'm sure the kmax does! so I'm sure it will stall at some point, but then you have to rotors so where is it gonna roll? Quote Link to comment Share on other sites More sharing options...
RDRickster Posted October 5, 2004 Report Share Posted October 5, 2004 RTB is only possible with one main rotor system.The KMax counters the potential because of the opposing blades. Quote Link to comment Share on other sites More sharing options...
Captmatt Posted October 5, 2004 Author Report Share Posted October 5, 2004 I would imagine the retreating blades do stall, yet, since there are two advancing blades on opposite sides of each other the helicopter, it would not roll to one side or the other because of the counter rotating blades. Quote Link to comment Share on other sites More sharing options...
Heli-Ops Posted October 5, 2004 Report Share Posted October 5, 2004 I have sent emails off to a couple of friends of mine that fly Kmax's and asked them to visit and post their responses so keep an eye out for them soon. Heli Ops Quote Link to comment Share on other sites More sharing options...
Captmatt Posted October 6, 2004 Author Report Share Posted October 6, 2004 Muchos gracias Heli-ops. ::2thumbsat:: Quote Link to comment Share on other sites More sharing options...
flingwing206 Posted October 6, 2004 Report Share Posted October 6, 2004 ...speaking purely theoretically... RBS is a phenomena of reducing airspeed and increasing AOA on the retreating side of the rotor disk, combined with the increased reversion zone on the inside portion of the retreating blade. As the blade loses effective lifting area fom the root side and overall lift from the reduced airspeed, downflapping increases which increases AOA. The stall happens when the downflapping pushes the blade past critical AOA. The Kmax is in no way immune to this- it has flapping blades. The symptoms will manifest differently, as the loss of lift will be symmetrical in respect to the airframe. In this case, the blades are "retreating" on the outboard side of the pylons. I can't speak to the mechanical ramifications of extreme downflapping and the Kmax. Quote Link to comment Share on other sites More sharing options...
Captmatt Posted October 6, 2004 Author Report Share Posted October 6, 2004 Shamless bump back to the top Quote Link to comment Share on other sites More sharing options...
Azpilot Posted October 6, 2004 Report Share Posted October 6, 2004 I think the reason this is not touched on very often is the VNE of a Kmax is 100 knots and I think it would need to go a bit faster than this to get into RBS. The helicopter is not immune to RBS for sure, but I am unsure where the # falls on it. Quote Link to comment Share on other sites More sharing options...
AllJeep Posted October 7, 2004 Report Share Posted October 7, 2004 BTW, The R22 is susceptible to retreating blades stall if you exceed Vne. It is just not a common problem. Quote Link to comment Share on other sites More sharing options...
Azpilot Posted October 7, 2004 Report Share Posted October 7, 2004 Unless the Kmax is at GWT, I think it would be very difficult to induce RBS. R-22s run around withing 100lbs of gross weight all the time so you need more pitch to keep it aloft than you do a Kmax. Quote Link to comment Share on other sites More sharing options...
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