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S-turns on final



 
 
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  #1  
Old February 16th 17, 10:17 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
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Default S-turns on final

Eh, I get twitchy getting uncoordinated anywhere low with partial water. While a slip is considered aerodynamically coordinated, not sure water in the wings would agree.
  #2  
Old February 17th 17, 01:17 AM posted to rec.aviation.soaring
Steve Leonard[_2_]
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Default S-turns on final

On Thursday, February 16, 2017 at 4:17:08 PM UTC-6, Charlie M. (UH & 002 owner/pilot) wrote:
Eh, I get twitchy getting uncoordinated anywhere low with partial water. While a slip is considered aerodynamically coordinated, not sure water in the wings would agree.


Crabbing is coordinated. Slipping is not. By any book, stretch of the imagination, or even alternate fact. It may be aerodynaimcally "balanced", as there is no steady state pitch, roll, or yaw RATE. But, not coordinated.
  #3  
Old February 17th 17, 03:17 AM posted to rec.aviation.soaring
CindyB[_2_]
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Default S-turns on final

On Thursday, February 16, 2017 at 5:17:58 PM UTC-8, Steve Leonard wrote:
On Thursday, February 16, 2017 at 4:17:08 PM UTC-6, Charlie M. (UH & 002 owner/pilot) wrote:
While a slip is considered aerodynamically coordinated, not sure ...


Crabbing is coordinated. Slipping is not. By any book, stretch of the imagination, or even alternate fact. It may be aerodynaimcally "balanced", as there is no steady state pitch, roll, or yaw RATE. But, not coordinated..


Thanks, Steve. I was getting twitchy on this one (but not pitchy). But hey,
Charlie M. wasn't the only one to say a slip was 'coordinated' in this thread.
Youch.

A fair range of opinions, and fewer with some slipping experience at altitude that then allows application at lower altitudes with familiarity and confidence.
I find it pretty common that pilots will lower their nose "a bunch" when slipping and then getting down to the chosen angle and unslipping to find they have ~ten more knots than they wanted.

Pretty soon it will be the "Silly Season". This sounds like a good topic for spring brush ups with a CFI - doing slips in 32:1. Balanced slips ( on a track), turning slips, and doing either with no speed change on entry and recovery. Can you tell your CFI what descent rate you can manufacture with your slip in your ship in calm air? It's a helpful data point, rather than conjecture.

My alternative aerodynamics fact is to be happy with pilots who slip, crab, S-turn, buttonhook, angle in or out, min sink loiter, full-spoiler parasitic drag plummet or even make a perfectly coordinated circle to address spacing and slope to satisfy the situation in a pattern. If it is done well, there are lots of ways to 'approach'. Adaptability is a good thing.

Best,
Cindy B
  #4  
Old February 17th 17, 03:17 PM posted to rec.aviation.soaring
Dan Marotta
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Default S-turns on final

Dammit, Steve and Cindy! You should never interject knowledge,
experience, and logic into a discussion on RAS!

On 2/16/2017 8:17 PM, CindyB wrote:
On Thursday, February 16, 2017 at 5:17:58 PM UTC-8, Steve Leonard wrote:
On Thursday, February 16, 2017 at 4:17:08 PM UTC-6, Charlie M. (UH & 002 owner/pilot) wrote:
While a slip is considered aerodynamically coordinated, not sure ...

Crabbing is coordinated. Slipping is not. By any book, stretch of the imagination, or even alternate fact. It may be aerodynaimcally "balanced", as there is no steady state pitch, roll, or yaw RATE. But, not coordinated.

Thanks, Steve. I was getting twitchy on this one (but not pitchy). But hey,
Charlie M. wasn't the only one to say a slip was 'coordinated' in this thread.
Youch.

A fair range of opinions, and fewer with some slipping experience at altitude that then allows application at lower altitudes with familiarity and confidence.
I find it pretty common that pilots will lower their nose "a bunch" when slipping and then getting down to the chosen angle and unslipping to find they have ~ten more knots than they wanted.

Pretty soon it will be the "Silly Season". This sounds like a good topic for spring brush ups with a CFI - doing slips in 32:1. Balanced slips ( on a track), turning slips, and doing either with no speed change on entry and recovery. Can you tell your CFI what descent rate you can manufacture with your slip in your ship in calm air? It's a helpful data point, rather than conjecture.

My alternative aerodynamics fact is to be happy with pilots who slip, crab, S-turn, buttonhook, angle in or out, min sink loiter, full-spoiler parasitic drag plummet or even make a perfectly coordinated circle to address spacing and slope to satisfy the situation in a pattern. If it is done well, there are lots of ways to 'approach'. Adaptability is a good thing.

Best,
Cindy B


--
Dan, 5J
  #5  
Old February 17th 17, 04:12 PM posted to rec.aviation.soaring
Don Johnstone[_4_]
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Default S-turns on final

Time was when we used to teach S turns, both for final approach and
launch failures, and this was fine in slow, wooden open cockpit gliders.
We also taught slipping. Pitching nose down 10 or even 20 degrees in
a T21 when side slipping was not a problem, doing the same in a
modern glass glider certainly is, especially when you stop the slip, the
glider will accelerate rapidly, unlike the T21 which did not understand
acceleration.
The difference is between what we teach, which has very little do do
with what is possible to do. Modern teaching tends towards getting the
circuit right so that the "emergency" procedures are not needed.
Modern airbrakes tend to be so good that even if you get it wrong they
are all that is needed.
S turns and sideslips are perfectly valid solutions, just not something
you want to teach a low hours pilot, concentrating on getting the
circuit right and effective use of airbrake is much safer.
I still fly a T21 and sideslip a lot. I sideslip very little in glass ships
as
proper use of airbrake, at the correct speed, is much more effective.

  #6  
Old February 17th 17, 06:42 PM posted to rec.aviation.soaring
John Cochrane[_3_]
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Default S-turns on final

I think the main point against S turns is that they will not actually lose that much altitude -- unless you turn 90 degrees or more. If you are so high that full flap spoiler and slip are not going to work, then try to do S turns, but get nervous about it and don't head the nose more than 45 degrees away from the runway, you're just not going to get down that fast, and the runway will still slide along below you.

Then there is always the Marty Eiler special: Full spoiler, point the nose at the ground, go VNE to 5 feet off the deck. Even accounting for the float in ground effect, it uses up gobs of altitude.

John Cochrane.
  #7  
Old February 17th 17, 07:16 PM posted to rec.aviation.soaring
[email protected]
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Default S-turns on final

Then there is always the Marty Eiler special: Full spoiler, point the nose at the ground, go VNE to 5 feet off the deck. Even accounting for the float in ground effect, it uses up gobs of altitude.

John Cochrane.


Any video links to this technique? Heard of it before, don't doubt it works, just like to see it. No, I'm not going to teach it to myself.
  #8  
Old February 17th 17, 10:57 PM posted to rec.aviation.soaring
JS
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Default S-turns on final

On Friday, February 17, 2017 at 10:42:13 AM UTC-8, John Cochrane wrote:
I think the main point against S turns is that they will not actually lose that much altitude -- unless you turn 90 degrees or more. If you are so high that full flap spoiler and slip are not going to work, then try to do S turns, but get nervous about it and don't head the nose more than 45 degrees away from the runway, you're just not going to get down that fast, and the runway will still slide along below you.

Then there is always the Marty Eiler special: Full spoiler, point the nose at the ground, go VNE to 5 feet off the deck. Even accounting for the float in ground effect, it uses up gobs of altitude.

John Cochrane.


I was running the line at Mountain Valley one day when Rich Benbrook wanted to demonstrate to a student that you could not be too high on final. I relayed to the tow pilot "2000' at the end of the runway behind you". They released, lined up with the runway, full airbrakes and PUSH.
Looked like a Space shuttle landing in a Twin Grob. Rolled casually to the start line.
But I wouldn't try that in a Nimbus 3 or even a Duo.
Jim
  #9  
Old February 17th 17, 11:20 PM posted to rec.aviation.soaring
[email protected]
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Default S-turns on final

I think the main point against S turns is that they will not actually lose that much altitude

Agreed. I guess originally they were used to control descent but for me they're a way of "loitering" at the approach end. I was on a high downwind at New Castle landing to the north a few years ago when a guy called in much lower and behind me to ask if I could either turn in immediately or let him go first. I responded: "__, you go first, JB will hold." I'd always wanted to say that.

I didn't want to circle or extend the downwind leg much farther (IIRC, this was NC on a rough ridge day, one reason I was pretty high) so I turned onto a high base and just continued beyond the normal base-to-final point. Turned slightly more than 180 degrees and made a couple of figure eights with short straight segments, "parked" out there still on high base. I could see the glider behind me (plus any more traffic) as well as the gliderport at all times. When I saw him touch down, I turned onto a (still) high final, announced my intention, and made my normal final approach.

Yeah, there were alternatives. But because S turns were part of the curriculum when I learned how to fly back in the dark ages and because I've used them a few times to check out fields just ahead where I didn't have enough altitude to fly to them and still do a full pattern, I thought it was safe. When the pilot asked me later how I'd managed the "hold", I realized S turns weren't universally known.

I've tried the full-brakes-and-dive-for-the-earth technique, though not to VNE. Seems to work but everything happens pretty fast so I'll stay with the slips-and-dive-brakes-in-a-high-pattern approach I've been using for decades in Std. Class gliders. Do I NEED slips? Probably not, and I usually end up holding the slip and using partial dive brakes to get the desired angle. But I like having that skill just in case.

Of course, no one should be experimenting with slips or S turns down low the first time. I slipped my ASW 24 at altitude when I got it both to verify there weren't any odd issues as well as whether the sink rate was worth doing it (it was).

Just to stir the pot up, I might offer that not being skilled in slips because you shouldn't ever need them if you fly a correct pattern is sort of like saying you shouldn't need to know how to recover from a spin because if you fly correctly, you'll never enter one. But that analogy might be stretching things....

Since it was mentioned, I can offer that I have slipped down a long final approach with partial water and not noticed a bit of difference in the way the glider handled. It was unintentional. I didn't realize I'd forgotten to dump ballast (after a very busy, crowded finish) until the glider rolled and rolled and rolled. I wouldn't try it again, though.

I did unwittingly land my LS-3 one time with water in one wing but not the other (failed valve actuator) and didn't notice anything amiss until the last few knots when the wing went down hard.

Chip Bearden


  #10  
Old February 19th 17, 05:04 AM posted to rec.aviation.soaring
Mike the Strike
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Posts: 952
Default S-turns on final

On Friday, February 17, 2017 at 9:15:13 AM UTC-7, Don Johnstone wrote:
Time was when we used to teach S turns, both for final approach and
launch failures, and this was fine in slow, wooden open cockpit gliders.
We also taught slipping. Pitching nose down 10 or even 20 degrees in
a T21 when side slipping was not a problem, doing the same in a
modern glass glider certainly is, especially when you stop the slip, the
glider will accelerate rapidly, unlike the T21 which did not understand
acceleration.
The difference is between what we teach, which has very little do do
with what is possible to do. Modern teaching tends towards getting the
circuit right so that the "emergency" procedures are not needed.
Modern airbrakes tend to be so good that even if you get it wrong they
are all that is needed.
S turns and sideslips are perfectly valid solutions, just not something
you want to teach a low hours pilot, concentrating on getting the
circuit right and effective use of airbrake is much safer.
I still fly a T21 and sideslip a lot. I sideslip very little in glass ships
as
proper use of airbrake, at the correct speed, is much more effective.


Last time I slipped in a T21 my hat and sunglasses blew off. S turns are more comfortable in an open-cockpit!

Mike
 




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