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S-turns on final



 
 
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  #1  
Old February 19th 17, 01:29 PM posted to rec.aviation.soaring
[email protected]
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Posts: 478
Default S-turns on final

For what is worth the the technique works in Condor. Application to meat world may vary.
  #2  
Old February 19th 17, 08:53 PM posted to rec.aviation.soaring
krasw
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Default S-turns on final

On Sunday, 19 February 2017 13:33:25 UTC+2, Martin Gregorie wrote:
On Sun, 19 Feb 2017 02:11:37 -0800, krasw wrote:

The irony of reading this, and then discovering link to something called
"soaringsafety" below.

No irony: there's nothing dangerous about using brakes to scrub off
excess height - its easy-peasy in a Discus 1 or K21: just follow Eric's
excellent directions if you haven't done it before. Just make sure that
you're not trying it for the first time on a short runway. You shouldn't
need the extra length but it makes a nice comfort blanket.

I haven't tried it yet in my Libelle because I haven't needed to:
slipping one brings it down like a sack of anvils what with all the extra
drag from pushing its razor-back tail boom sideways.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |


Sorry, speed control in approach has been ironed to my skull. Sure you can do anything you want, land inverted if you like, but what is the point? We have brakes and slip which both get you you down with safe approach speed.
  #3  
Old February 19th 17, 09:10 PM posted to rec.aviation.soaring
Dan Marotta
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Default S-turns on final

I look at S-turns on final as a way to increase your time aloft (at
minimum sink speed), perhaps to wait for an obstruction to be cleared
off the runway (like a takeoff or a short landing). To lose altitude on
final, I'll do a slip (almost) every time. And yes, I can fly at
minimum sink and below without stalling...

But what about a gust or gradient or blah, blah... Training and practice.

On 2/19/2017 1:53 PM, krasw wrote:
On Sunday, 19 February 2017 13:33:25 UTC+2, Martin Gregorie wrote:
On Sun, 19 Feb 2017 02:11:37 -0800, krasw wrote:

The irony of reading this, and then discovering link to something called
"soaringsafety" below.

No irony: there's nothing dangerous about using brakes to scrub off
excess height - its easy-peasy in a Discus 1 or K21: just follow Eric's
excellent directions if you haven't done it before. Just make sure that
you're not trying it for the first time on a short runway. You shouldn't
need the extra length but it makes a nice comfort blanket.

I haven't tried it yet in my Libelle because I haven't needed to:
slipping one brings it down like a sack of anvils what with all the extra
drag from pushing its razor-back tail boom sideways.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Sorry, speed control in approach has been ironed to my skull. Sure you can do anything you want, land inverted if you like, but what is the point? We have brakes and slip which both get you you down with safe approach speed.


--
Dan, 5J
  #4  
Old February 20th 17, 04:53 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Default S-turns on final

krasw wrote on 2/19/2017 12:53 PM:
On Sunday, 19 February 2017 13:33:25 UTC+2, Martin Gregorie wrote:
On Sun, 19 Feb 2017 02:11:37 -0800, krasw wrote:

The irony of reading this, and then discovering link to something called
"soaringsafety" below.

No irony: there's nothing dangerous about using brakes to scrub off
excess height - its easy-peasy in a Discus 1 or K21: just follow Eric's
excellent directions if you haven't done it before. Just make sure that
you're not trying it for the first time on a short runway. You shouldn't
need the extra length but it makes a nice comfort blanket.

I haven't tried it yet in my Libelle because I haven't needed to:
slipping one brings it down like a sack of anvils what with all the extra
drag from pushing its razor-back tail boom sideways.


Sorry, speed control in approach has been ironed to my skull. Sure you can do anything you want, land inverted if you like, but what is the point? We have brakes and slip which both get you you down with safe approach speed.


I didn't recommend you keep the high speed all the way to ground - just long
enough to get on a good glide path. I have used slips many times, but find the
"dirty dive" is a quick, easy, and safe way to get rid of a lot of altitude. No
turns required, no uncoordinated flight, no airspeed instrument inaccuracies.

I suggest you try it enough times to have some competence and confidence in it
before you make any judgement about it. Or go up with someone that can demonstrate
it for you.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf
  #5  
Old February 20th 17, 03:25 AM posted to rec.aviation.soaring
jfitch
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Posts: 1,134
Default S-turns on final

On Saturday, February 18, 2017 at 8:35:49 PM UTC-8, Eric Greenwell wrote:
wrote on 2/17/2017 11:16 AM:
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.

The technique is simple and easy to learn. Just don't start out with the
extreme version John related! Basically, you are just increasing the
rate of energy/altitude loss by 2 or 3 times normal by using full
spoiler at high speeds. Try this for starters:

-enter the pattern at least 1000' AGL
-fly the pattern all the way until after you've turned final...NO
spoilers or sideslip
-continue down final without spoilers or side slip until it seems you
are almost too high to get down to your aim point with full spoilers
-open the spoilers fully, point the nose down until you are going 80-90
knots (but NO MORE than the max allowed speed for your landing
configuration - flap setting is the usual thing limiting the allowed speed)
-When the angle to your aim point looks about right for a half-spoiler
approach, pull the nose up gradually to maintain that angle
-when your speed drops to the desired speed on final, retract the
spoilers to one-half
-proceed with a normal landing

Use the technique a few times, and it won't seem very extreme at all.
The altitude loss is very rapid with full spoiler, gear down, and high
speeds, and it's very effective at dumping excess altitude.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf


The "fast and dirty" approach works better, the dirtier you can get. On a flapped glider, full landing flaps and spoilers, point the nose down and you pick up some speed, but you lose energy much faster.

There are landing sites where this makes a lot of sense (including the one at which I fly). One reason is you are flying through the gradient and boundary layer turbulence at well over stall speed and can withstand a 40 knot gradient without stalling.

On my ASH26, this works really well. On the Duo Discus I owned and flew at the same site, not so well - wasn't dirty enough in landing configuration to lose the energy.
  #6  
Old February 17th 17, 10:57 PM posted to rec.aviation.soaring
JS
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Posts: 1,384
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
  #7  
Old February 18th 17, 01:30 AM posted to rec.aviation.soaring
Bruce Hoult
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Default S-turns on final

On Saturday, February 18, 2017 at 1:57:34 AM UTC+3, JS wrote:
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


At Foxton airfield (NZ) there are some very high pine trees exactly 100 metres before the boundary fence. Most people approach around the end of the trees and then make a 30 degree turn at 50 ft -- including the guys with the Pitts. I decided to try approaching over the trees one day in the DG1000. I started my final from well back at 1000 ft. When I could just see the fence over the top of the trees I opened full brakes. That wasn't enough, so I also nosed down. It turned out to need 95-100 knots to maintain the visual picture and just clear both the trees and the fence (standard farm cattle fence). I whizzed past the folks and gliders assembled at the launch point and took about 400 metres to slow down to landing speed, plus of course another 100 to stop without the wheel brake.

That was still before the official displaced threshold for landing over the trees.

A slip (with brakes) would probably have let me achieve the same descent angle at a lower speed, but I haven't had a chance to try it.
  #8  
Old February 17th 17, 11:20 PM posted to rec.aviation.soaring
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Posts: 580
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


 




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