On Thursday, February 16, 2017 at 7:26:51 PM UTC+3, 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.

Of course you shouldn't find yourself unexpectedly needing a slip -- at least not more than once in a few hundred landings due to a headwind a circuit altitude turning into a tail wind on short final, or something like that (e.g. on an outlanding).

That doesn't mean you shouldn't practice it. I often fly approaches in the DG1000 (or Janus before it) with perfectly standard heights turning base and final, but using only slip and no brakes/flaps at all until at maybe 50 ft and in the normal place at the normal speed and height.

I don't know whether those count as "high performance" for you -- I don't fly single-seaters a lot and maybe they're different. A slip is relatively ineffective, but it's comparable to half brakes. If you add it to full brakes instead of using it instead of brakes then you can come down really quick..