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.

On Wednesday, February 15, 2017 at 11:51:27 AM UTC-8, wrote:

If the pilot has the skills and judgement to use S turns on final without reducing safety margins, he or she most likely would have the skills and judgement to not need them.
UH

Heh, heh. Irony.

If I have a lot of room before touchdown (and even more than a lot of height in this scenario) and I need to make space I'll extend a leg or two in my pattern or make a circle. If I'm on short final I really want my velocity vector pointed at the runway and not a lot of bank on. I especially don't like the idea of a lot of maneuvering, reversing turns, etc when I'm close to the ground and needing to focus on a dozen other really important things. A stabilized approach makes a lot of other potential problems less problematic. It should be sufficient to use spoilers, landing flaps if you got 'em and an aggressive slip (which also guards against spin entry since it's the opposite of a skidding turn). Maybe there is a place for S-turns between turn to final and short final if you are ridiculously high and flying a really slippery glider with weak spoilers and no flaps. Fortunately, I don't fly one of those.

9B

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.

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

On Thursday, February 16, 2017 at 8:26:51 AM UTC-8, Sean Fidler wrote:
With the very high degree of spoiler effectiveness on most gliders, if "said pilot" is regularly "forced" to slip or S-turn in order to make their intended touch down point, there is probably something else wrong "upstream" in said pilots landing pattern decision making process. Also, the majority of sailplane landing patterns appear to me to be rather high (again, IMO)..

I commented here only to state (I'll say it again now) that slipping a high performance glider is almost useless (IMO). It requires such an aggressive slip angle (in order to result in any measurable increase in descent rate) that it is uncomfortable (and unnecessary) for me, personally (IMO). I'm surprised to hear otherwise, but that certainly doesn't change my opinion or practices. Perhaps their fuselages are the "slab sided" ASG29 version ;-). Perhaps I am a poor pilot. Perhaps this is a skill I need to work on. Oh well, for now, I don't slip unless absolutely necessary. I prefer docile S turns, but can only really recall one time I have done this. I have never needed a slip in my ASG29 or (ex) Lak17a (in the execution of many, many land-outs)

That said, slips are an important skill in glider pilot training. To need to use them on a regular basis (or even rare basis) is perhaps indicative of some other concerns or areas of potential landing pattern/planning skill improvement. The need to slip or S-turn means that to that point in the approach, the pilot has misjudged the approach extremely high in terms of altitude and/or total energy, requiring a last resort maneuver (slip or S-turn) in order to bleed it off. Desperate. Poor planning. Poor energy management. This is how people get hurt.

For those who have not yet flown higher performance glider, when you do, I would strongly suggest practicing slips at high altitude before trying (or being forced to exectute) a true, aggressive (full rudder) slip, with full spoilers (and perhaps 25-30% water remaining, simulating real world stress, for example) and at low (minimum possible) final approach speed while at very low altitude into a short land-out field (perhaps with tall trees on both ends and in some wind).

I strongly prefer striving to execute consistent, well managed, stable approaches without big transitions from slip to non slip (close to the ground, at the last moment), especially when flying in a high performance glider (in which I feel slips are ineffective). Gliders have outstanding glideslope control with spoilers (and perhaps flaps). My goal is to fly the entire approach (from midfield downwind to near touchdown) with a set pitch, set flap setting, set speed and set spoiler setting (33%, I have a mark I use).. The exact same approach every time. This takes significant practice. I prefer focusing on precisely controlling my energy (not too fast, not too high, good base turn decision) as early as possible in every approach. That is the critical moment in the approach for me, not the final leg. Everything flows from this mindset of setting the approach up with great precision and getting stable early.. If necessary, I prefer managing my glideslope with spoilers (only) and in a very smooth, controlable manner. If I must use them, I try and minimize adjustments rather than making constant adjustments (unstable). If I ultimately need to S turn, or slip, it means I have really (enormously) misjudged the approach and/or the landing area (perhaps the height of the trees on the approach end, wires I didn't see, or the usable length of the field (perhaps identifying a rock or a post on final)). If I started experiencing gross errors in general landing pattern decisions regularly (landouts or normal landings at an airport), requiring slips or S-turns to make the touchdown point (and stress), I would schedule some meaningful time with a respected flight instructor and sort myself out.

Perhaps I'll be having a talk with one about slips in my 29 in fact. So, thanks for this discussion.

Sean
7T

Sean the 29actually slips well and really increases sink rate. Yes, it can be uncomfortable until you are comfortable flying them. A slip can be very valuable if you have a rope break at 100' and need to use an aggressive slip to put it on remaining runway. Slip is a maneuver that is essential to have in a quiver of mastered skills.

I have used slips in helicopters, war birds, gliders, never came across an aircraft that was not effective in a slip. Probably the only time I really needed the slip was one flight in a helicopter.

On Wednesday, February 15, 2017 at 6:44:26 PM UTC-5, Casey wrote:
"S" turns were taught to me in early stages of hang glider training. It is used as inexperience to judging height when too high on final. Most I saw used on first few flights then used a more standard approach. From the ground it really looks like an inexperienced pilot, but the judgement for approach was right on for those that I saw using it. I think there were a lot of hang glider pilots that did/do not have any other type of flight training and so no good judgement of height, and I think the tendency of new hang glider solo would tend to be high on final.

I have never been taught "S" turns in glider training. I would much rather track slightly away on downwind, and or extend, than to have to "S" turn on final.

If that video is from the 40's, I wonder when this was stopped being taught.

As a hang glider pilot for 38 years I agree Casey.... but we didn't have air brakes on Hang Gliders. I still used pattern approaches then but I landed in small fields surrounded by trees most of the time.

Dennis.... DC

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

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.

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.

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.