Glider Pilots: Approach Speeds.

Factual Questions
1

There has recently been some debate in the group with which I fly about the proper approach speed to use when landing a glider.

Of course, most of us know about the whole 1.3 times the stall speed business, but what if there are winds involved?

I was raised in the school of thought that the approach speed would be set at, say, 50 mph for my craft. (this is approximately equal to both the Best Lift/Drag Ratio and 1.3 Times the Stall Speed). To this, add 1 mph for every mph headwind, so that the approach groundspeed is consistent. Of course, this increases the rate of descent, so the final approach should be initiated 100 feet higher for every 10 mph of wind.

A new idea has been proposed. It holds that the approach speed will again be set at 50 mph for solo flight, and at 55 mph for dual flight. However, no speed will be added due to winds, unless the headwind is greater than 15 mph. In this case, 5 mph is added to the approach speed.
I’m in favour of the first argument. It’s always worked for me, and The extra speed provides not only safety above the stall, but greater control when encountering performance-decreasing wind shear (wind gradient on approach). The extra speed also makes it easier to flare on landing, and to hold-off. The extra groundspeed makes it more likely that you wont land short.

So, who’s right?

For the very interested: My craft stalls at 31-35 mph, seats two, best L/D 45-52 mph, manoevring speed 65 mph, max headwind component 28 mph. The ordinary operation involves a circuit joined at 1000 AGL, base turn 500+100 ft per 10 mph wind, final turn 300+100 ft per 10 mph wind

2

What are you trying to achieve? If it’s just endurance, then wind speed doesn’t matter. But if you want to cover the most distance, you need to fly at your best angle speed, and adjust it based on the headwind.

You don’t need any extra stall margin, because the airframe only responds to airspeed. There was an old myth about how you could stall an airplane by making a ‘downwind turn’, but to the airplane, a turn is a turn.

3

And adjust it how, exactly? Add the headwind, or just 5 mph?

Thanks for the reply. I’m surprised there’s only one knowledgeable glider pilot on the Board.