On Wednesday, May 7, 2014 7:20:33 AM UTC-6, Vaughn wrote:
On 5/7/2014 2:55 AM, Bruce Hoult wrote:

On Wednesday, May 7, 2014 1:20:44 PM UTC+12, Bill D wrote:

I can assure you that the higher a glider's performance, the safer

it is. It's the old, low L/D gliders that can run out of altitude

before getting lined up with the runway.

I agree with you. I'm shaking my head every time I read this thread.



In a modern glass glider (such as the DG1000's I instruct in) with a

40 knot stall speed and being towed at 70 knots you should be able to

execute a safe 180� turn with*zero* loss of height.



The comparison isn't quite as simple as just looking at L/D. Turn

radius also has a lot to do with your chances of making it back to the

field, and turn radius is proportional to the SQUARE of airspeed.



Compare your example (40 knot stall) with a (horrors) 2-33. The highest

stall listed for a 2-33 is around 30 knots. If you do the math, you

will find that your DG1000 has nearly double the turn radius of the

slower glider.



Vaughn

You're exaggerating the stall speed differences. Regardless of what the 2-33 "manual" says, no 2-33 ever got as slow as 30 knots. 35 knots is a practical minimum speed. The flight test stall speed for a DG 1000 is 37 knots..

However, no one should consider a turn back at stall speed. Virtually all gliders will be at 50 - 55 knots so the turn radius will be essentially the same.

8 knots sink? That's a straw man argument. While extreme air movement is always possible, most PT3 incidents are in relatively benign conditions. In extreme conditions a turn back is probably moot anyway.

The point is when conditions allow, a pilot should know how to turn back safely.