On Saturday, July 30, 2016 at 11:33:26 PM UTC-4, son_of_flubber wrote:
On Saturday, July 30, 2016 at 8:50:08 AM UTC-4, Tango Eight wrote:
On Saturday, July 30, 2016 at 12:51:25 AM UTC-4, son_of_flubber wrote:
My default procedure is to set spoilers to 50% open, then adjust pattern shape to make my aim point.

I'd like to hear some well experienced CFIGs weigh in on that statement..

What I left unsaid, because I thought it was understood, is that the pilot will first adjust the spoilers moderately, and then if necessary, change the heading of the base leg.

You want a CFIG to weigh in?

To quote Tom Knauff from 'Preventing Launching and Landing Accidents' page 27

"After the turn onto the base leg, the pilot has two plans of action in case the apparent final approach glide angle appears too steep or too shallow. If the slope appears too steep, the pilot uses a plan of action to open the dive brakes and angle away to extend the glide path to lose some altitude. If the glide angle appears too shallow, the pilot will immediately close the dive brakes and turn towards the landing area." Copyright 2004 Knauff and Grove

A schematic figure that shows a non-rectangular pattern follows immediately in the text.

On page 26 "The dive brakes of a typical modern glider will allow the glider to descend anywhere from 5:1 to a very conservative 20:1. The pilot should never be very close to either of these extremes." Copyright 2004 Knauff and Grove

Based on this and other things written by Tom, I conclude that aiming to keep the spoilers near 50% effectiveness gives the pilot the most flexibility (either way) to compensate for things that don't go according to plan. That's my default (goal) as previously noted.

So changing the heading on base leg (non-square pattern) is a Knauff-recommended means to recover from an incorrectly timed turn to base. That said, almost all of my patterns are square, my turns are steep, and my spoilers stay open to about 50% until I touch down.

If my pattern speed needs to be higher to deal with wind and turbulence, I'll delay opening the spoilers, and if conditions are intimidating, I might turn to base a bit early, so that I have more reserve to deal with the possibility of extraordinary sink, and if it turns out to be just ordinary sink, I'll add a little more spoiler on final to get down.

In the last 30 days, I've flown glider on 13 days, and because I think safe and optimal landing is utterly important and merits practice, I've landed 21 times, (and as often as possible in utter crap conditions in order to stay proficient). So if you think I'm a mad anarchist pilot trying to tear down the status quo, then I've communicated poorly and/or you're projecting something that isn't there.

No, I'm not projecting anything. I just wanted to see if the very experienced guys had a different take on your story than I did.

FWIW, putting the *priority* on maintaining spoilers half open, and adjusting the pattern to keep it that way struck me as profoundly odd. In fact I'd rate it right up there with the advice in Joy of Soaring about how to fly the final approach**: it's precisely backwards. Sure, you can make it work. That doesn't make it a best practice.

The normal procedure for correcting glide slope is to use more or less spoiler to capture the desired glide slope for the pattern being flown. Adjustments to the pattern are sometimes necessary or desirable, and the ability to make these adjustments when needed is essential skill for any glider pilot. The passages you've quoted from Tom's books are fine as far as they go, I simply think you've misunderstood the application. Generally, one can make corrections for all but the grossest of errors with spoilers alone. In the case of a really big error (or rotor, or big wind shear or whatever), then you add the pattern variations as Tom describes.

**The Joy of Soaring approach to final approach was this: aim with the nose (in pitch), control airspeed with spoilers.

best,
Evan