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Settling with Power
#11
ted, you have made the point beautifully! We can talk about issues in theory and get a decent understanding of them but applicative experience is where the correlative learning actually takes place. Simply put, you don't really understand it until you experience it and make some mistakes.

bryancobb and everyone else, using power to get out of SWP is a big no-no because all power does is exaggerate the vortex ring state destroying more and more lift until the helicopter is literally propelled out of the air in a column of destroyed lift almost like a vacuum.
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#12
this brings up a great point. practice, practice, practice. go up to altitude and explore settling with power. see what it takes to get into it then remove one of the three things, power or slow speed, descent rate will not be able to decrease. during my training we would go forward cyclic and fly out of it. have fun, be safe, practice helo flying. so much to do and learn to be proficient. turbo
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#13
turbo,

I get your point but I don't really think it's a great idea for a pilot to go out in Mosquito and get into SWP to learn SWP recovery all on their own. That's pretty dangerous especially if the pilot has never had SWP demonstrated with an instructor. SWP is very avoidable. I have never been in SWP and I have never had it demonstarted to me. The best way to deal with SWP is to know how to never get into it. I don't think there is much to be gained by practicing getting into SWP much the same way there is no real benefit to doing autos all the way to the ground. You can perfect autos by doing them to a power recovery without the need of going all the way to the ground and risking breaking yourself or your aircraft. Let's really think about what we advise these guys to practice on their own. I know they need to get some real experience but slow, steady, methodical and very, very conservative is the way they need to go. We, as the experienced guys need to set the conservative pace for these guys and reassure them of the best way. By the time I started flying the Mosquito I had around 3,700 hours and I still hovered for 5-6 hours before I ever went through ETL and I had a blast just hovering.
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#14
Er. Perhaps getting a little off-topic here, but bryancobb, you touched on the subject of high humidity as a cause of low air density.
And I seem to recall performance figures for the Bell 47 Flight Manuals having columns for
"High Humidity" and "Low Humidity". So I was always more careful in high humidity.

Until I started to fly helicopters on instruments. And then I found that when I entered cloud:
The helicopter did not lose height, speed or RRPM. Torque and temps stayed the same.

Presumably the humidity in a cloud is 100%. So why did the helicopter not falter and wimp on down out of the sky?
Could it be that "High Humidity" is just another "urban myth"? Or should that be "aerial myth"?

Rob1
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#15
mark, you have a good point there, it should be demonstrated with an instructor. i did swp during my training and practice in now and then. thanks for your input. 
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#16
It should also be noted that a similar phenomenon is possible with the tail rotor.
It is usually called "Loss of Tail Rotor Effectiveness" (LTE), and one of causes
of LTE is a tail rotor vortex ring state. This is basically settling with power
on the tail rotor.

When winds are approx. 210 to 330 degrees,
"Winds within this region will result in the development of the vortex ring state of the tail rotor. As the inflow passes through the tail rotor, it creates a tail rotor thrust to the left. A left crosswind will oppose this tail rotor thrust. This causes the vortex ring state to form, which causes a nonuniform, unsteady flow into the tail rotor. The vortex ring state causes tail rotor thrust variations which result in yaw deviations. The net effect of the unsteady flow is an oscillation of tail rotor thrust. This is why rapid and continuous pedal movements are necessary when hovering in left crosswind."

Nick
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#17
nbrand, true LTE is another thing to worry about and no helicopter is immune to SWP or LTE but the Mosquito has a very powerful tail rotor and LTE will be difficult to encounter. If you will notice the Mosquito tail rotor spins opposite the direction of most tail rotors (the advancing T/R blade arcs downward with the main rotor downflow not up into it) and I still have never had a problem with LTE regardless of the wind angle. I have even flown in steady 25 mph wind and subjected the Mosquito to all 360 degrees and still never had a problem. The tail on the Mosquito is crazy powerful but once again, I'm not saying it's immune to LTE I just have never been able to get it into LTE as hard as I've tried.
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#18
UH-60Pilot - 9/17/2010 10:03 AM

nbrand, true LTE is another thing to worry about and no helicopter is immune to SWP or LTE but the Mosquito has a very powerful tail rotor and LTE will be difficult to encounter. If you will notice the Mosquito tail rotor spins opposite the direction of most tail rotors (the advancing T/R blade arcs downward with the main rotor downflow not up into it) and I still have never had a problem with LTE regardless of the wind angle. I have even flown in steady 25 mph wind and subjected the Mosquito to all 360 degrees and still never had a problem. The tail on the Mosquito is crazy powerful but once again, I'm not saying it's immune to LTE I just have never been able to get it into LTE as hard as I've tried.

The TH-55 T/R spun the same direction as the Mos.
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#19
I did my Commercial ride and IFR ride with the Chief Pilot from Boeing Helicopters, Rich Lee. Two years ago, he had 48,000 hours of helicopter time with much of that in Test Pilot mode. He flew Apaches behind C130's and CH53 helicopters putting out water to do inlet ice testing on the Apache. His big thing is icing. He was showing photos of ice formation that was caused by a helicopter hovering over wet asphalt.

This would be one concern with humidity in helicopters. He said the helicopter can cause enough temp change in the air to produce fog if temp and dew point are close. Same with ice. Fascinating photos.

Not much of a concern here in AZ but must be recognized in those areas where freezing occurs.

Darwin N. Barrie
Chandler, AZ
XET on order
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#20
When the temp and humidity get high here in Texas we drink ice tea.
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