Flight in turbulence.

rwdreams

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I found the discussion of flying in turbulence of great interest in the 0 g thread. I was hoping to start a discussion on other experiences that might be helpful. In particular there was a comment about the danger of updrafts when close to Vne. I hope this could be expanded upon. Thank you.
 

Vance

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I found the discussion of flying in turbulence of great interest in the 0 g thread. I was hoping to start a discussion on other experiences that might be helpful. In particular there was a comment about the danger of updrafts when close to Vne. I hope this could be expanded upon. Thank you.
This is a big subject so pleas ask questions if there is anything you need more information on.

I fly along the coastal hills of Southern California.

I have experienced 1,200 feet per minute sink, 1,000 rising air and a 20kt wind shear.

Don’t be hesitate to say “unable” if air traffic control restricts you above an altitude you are unable to maintain.

Most descending air does not go all the way to the ground unless it is a microburst or a collapsing thunderstorm.

Mountain Wave activity should be avoided if practical. The descending air can easily exceed the capability of a gyroplane.

The Pilot’s Operating Handbook of most gyroplanes advises you to slow down in turbulence. I follow that advice.

Most low time gyroplane pilots over control in turbulence.

I recommend just letting her rock and roll and sort of heard her if her path becomes divergent from your desired path.

Different gyroplanes respond to turbulence in different ways.

If I encounter anything beyond moderate turbulence I land as soon as possible.

Pay attention to pilot reports and understand what the reporting criteria for Moderate, Severe and Extreme are. The information is in the

Aeronautical Information Manual. http://www.faraim.org/aim/aim-4-03-14-475.html

I stay 25 miles away from thunderstorms and further from a collapsing thunderstorm.

I stay 15 miles away from virga.

In my opinion gusts are the biggest challenge to elegant takeoffs and landings and a gust limit should be a part of your wind limits.

Try to imagine what the wind is doing particularly in relation to ground obstructions such as buildings, trees or mountain ridges.
 

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loftus

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I recently experienced the most severe turbulence on landing that I have yet felt, and that is a characteristic of the runway. Staniel Cay MYES in the Bahamas is a17-35, well know for strong crosswinds particularly in February. On the East side of the runway, there is a hill with homes on it. Towards the Northern end the hill rises to about 100 feet, as it extends South it gets lower and further away from the runway.
Approaching 17 with winds at at approximately 90 degrees to the runway 270 @ 20kts gusting to 25 or more, the turbulence was almost unmanageable close to the ground, requiring a go-around. My second approach was as difficult but managed to land safely. Essentially the extreme burbel coming of the hill was responsible for the turbulence of course compounding the gusty crosswind conditions. The third aircrcraft in our group, after watching number one and number two struggle, decided to approach on 35 from the South to avoid the burbel from the hill even if there was a small resulting tail wind. They had a much easier time. Lesson learned of course is that the hill close to the runway was quite treacherous in crosswind situations, and rather land with a slight to moderate tailwind than approach from the side where the hill is close to the runway. Had I not been able to put her down, I would have flown 5 miles South to the next island runway which has an East-West runway. Here's a little vid taken by the first guy to land of my second, fortunately successful attempt. This is also a situation where I think it would have been much safer to land on the ramp perpendicular to the runway, particularly in a gyro.
 

Tyger

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In particular there was a comment about the danger of updrafts when close to Vne. I hope this could be expanded upon. Thank you.
In rotorcraft with semi-rigid rotor sytems (almost all gyros and many light helos), flying at Vne will have the rotor teetering near its physical limits (the "stops") because of dissymmetry of lift (DoL) between the advancing and retreating blades. If you then encounter a sudden updraft, the angle of attack on the blades will be momentarily increased. This would require more teetering, which you will not have available if you are actually at Vne. If you exceed the teeter limit, even momentarily, BAD things happen.
Have a look at this video:
At minute 4:50 of this video (the last clip of a very good series on DoL) he discusses flying in turbulence and why you must only fly near published Vne in smooth air.
 
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Tyger

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This is also a situation where I think it would have been much safer to land on the ramp perpendicular to the runway, particularly in a gyro.
Ya, those kind of days/situations you're going to be MUCH happier in a gyro.
I cannot tell you how many blustery days I've happily gone up when the airplane guys are all hunkered down on the ground.
 

Eltor74

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Updraughts and vne dont go hand in hand. You get an updraught you go up faster, not forward faster
 

Doug Riley

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Exceeding your teeter limits in a tilt-spindle gyro is certainly not a good thing. It's not quite as dangerous as it is in a helicopter with a swashplate control system, though. In the helo, you get mast bumping: the shock loads of the blades contacting their stops pass into the (fairly rigid) mast/driveshaft/engine unit. In a tilt-spindle system, these same loads are transmitted back to the stick, through the pushrods and other connecting components. Momentary teeter-stop contact and, the consequent stick slap, is actually not that unusual when performing quick reversals of bank direction (e.g. rapid S-turns) in a gyro with heavy blades.

This kind of metal-to-metal shock loading can break things and is to be avoided but, again, a tilt-spindle gyro is a little more forgiving in this regard than a swashplate rotorcraft.

As for turbulence, there are huge differences in the appropriate pilot technique among experimental gyros.

Gyros having good static stability in pitch are best handled (in my experience) by holding the stick still. The entire airframe will react appropriately, nosing up into a downdraft and vice versa.

OTOH, in a gyro with a Bensen-type* offset gimbal head but an airframe with negative static stability in pitch, it's better to adopt a very loose stick grip ("float the stick"). This allows the rotor head to move in response to the stabilizing forces created by the gimbal head. If you hold the stick firmly, you lock the head and defeat its stabilizing function. In such a gyro, the (unstable) airframe will often pitch the wrong way: up in an updraft and down in a downdraft.
___________________________________
* By "Bensen-type," I mean a head with more offset than is needed to counteract the effects of rotor blowback. The excess offset (often 1") is zeroed out by a long adjustable spring.
 

WaspAir

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If the conditions, including wind, wind shear, thermal activity, turbulence, visible moisture, and storm activity, are such that I would not be comfortable standing (unbelted, of course) in a hot air balloon, I won't take a gyro anywhere near Vne (as in never exceed, anywhere, anytime, any circumstances). While the issues are different for different categories, most aircraft have some sort of Va (maneuvering) or Vra (rough air), or Vb (speed for max gust), or Vno (normal operations) speed, all of which are well below Vne, and there's a message in that. From my safety conservative viewpoint, considering turbulence at Vne strikes me as much like asking how many amps of AC can you safely handle in your bathtub. Just don't go there.
 

Vance

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In rotorcraft with semi-rigid rotor sytems (almost all gyros and many light helos), flying at Vne will have the rotor teetering near its physical limits (the "stops") because of dissymmetry of lift (DoL) between the advancing and retreating blades. If you then encounter a sudden updraft, the angle of attack on the blades will be momentarily increased. This would require more teetering, which you will not have available if you are actually at Vne. If you exceed the teeter limit, even momentarily, BAD things happen.
Have a look at this video:
At minute 4:50 of this video (the last clip of a very good series on DoL) he discusses flying in turbulence and why you must only fly near published Vne in smooth air.
The posted video is accurate about helicopters and in my opinion doesn’t apply well to gyroplanes.

A free spinning fixed pitch semi rigid rotor operates very differently than an engine driven variable pitch rotor.

I have not flown a gyroplane that appears to me to be near its teeter stops as it approaches Vne.

I agree that a pilot should slow down in turbulence in a gyroplane. If there is not a particular rough air speed listed in your pilot’s operating handbook the minimum power required speed might be a good place to start for a different reason.

Most of the gyroplanes I fly have a thrust line well above the center of gravity. In my experience any reduction in power required reduces the power/pitch coupling.

The common error I see flying a gyroplane in turbulence is over control and stabbing at the controls. A gyroplane rotor is slow to respond to the control inputs so in my experience the control response will generally not happen in a timely way. Just let her rock and roll and apply gentle steady pressure if she is not going where you want.

I use the rudder to maintain coordinated flight (yaw string straight back).
 
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