S-turns on final

At 19:16 17 February 2017, wrote:
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.

The Vne approach is an interesting idea that I won't be trying
without 6000 feet of runway available! How do you get rid of
all that speed 5 feet off the ground? It must produce an
incredibly long float?

Here in France "S" bends on approach are the standard
method taught for microlights, but they all tend to be a lot
dragger than even the poorest glider. Seems to me to be a
valid idea (like the side slip) assuming it's done correctly; any
method that doesn't involve flying through the far hedge/wall
must be good.

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

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

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:
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.

Well spoken buy the guy who owns an ASW-12!

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.

On Friday, February 17, 2017 at 3:45:08 PM UTC-6, Dave Walsh wrote:
At 19:16 17 February 2017, wrote:
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.

The Vne approach is an interesting idea that I won't be trying
without 6000 feet of runway available! How do you get rid of
all that speed 5 feet off the ground? It must produce an
incredibly long float?

When I took the glider acro course at Estrella back in the early 90s, one of the "party tricks" was to dive at Vne to the deck on entry to downwind, then fly the whole pattern in ground effect - you had to climb to turn base and final - aiming to be near the approach end of the runway, 10 ft over the desert, at about 60 knots. Then you just cracked the spoilers and landed.. Interesting, to say the least!

It did teach you that once in ground effect, a little speed would take you a LONG WAY.

Helps to have an airport out in the middle of nowhere (then); at my local field there would be too much dodging of houses, water tower, trucks on the interstate, etc..! (although I have tried it in Condor and it still works).

Kirk
66

And then there are gliders where side slipping with full air
brakes makes the glide angle better! Apparently.

On 2/18/2017 3:26 PM, Dave Walsh wrote:
And then there are gliders where side slipping with full air
brakes makes the glide angle better! Apparently.


Definitely true in my S/N 3 Zuni with full flaps on...

Bob W.

P.S. And a hearty "I second those sentiments!" found in the posts of Dave L.
and Cindy B. earlier in this thread. Always good to have Plans B, C, & D
ready-to-go...and the skills to implement 'em, too.

On Saturday, February 18, 2017 at 4:21:21 PM UTC-8, Bob Whelan wrote:
Always good to have Plans B, C, & D
ready-to-go...and the skills to implement 'em, too.

This thread on s-turns or slipping is all about airman skills that we should all posses or should learn enough to be comfortable with these skills. S-turns may be used in another application unforeseen, same for slips. You never know which skills or experiences you might have to apply to another situation to bring you home save. It is part of being a good airman. Often we fly precise, but that does not teach you the corners of your flight envelope.

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