That TLAR doesn't look right

OK, I think we have (at least) two different ideas being discussed here, attached to the 45 degree value.

If you look at the article (which I have) one 45 degree reference is to the angle from the base-turn corner looking back to the touch down point. This is a common reference for almost any rectangular pattern described in a myriad of training manuals. It works pretty well for locating the base turn position, provided that enough altitude remains to complete the pattern.

There is the second reference to 45 degrees, which places the glider above the touch down point at the same distance laterally. This is the point (pun intended) where I think we have a few differences of opinion, mainly due to differences in altitude on the downwind. A lower performance (also slower) glider can easily be at 600' lateral displacement and have time and altitude to make corrections on the base leg due to the slower speed.

A faster, higher L/D glider needs a lot more distance/time to dissipate energy and being 600' laterally abeam the touch down would create a significant challenge, both with the turns required to intercept final and the 45 degree base base turn reference.

The article covers the extended downwind as a function of glider performance and clearly explains the need for adjustment.

Having said all that, at our field both a higher and wider pattern is typically flown and I believe the reference angle abeam the touchdown point is often closer to the 30 degrees noted by others.

MB

On Sunday, July 12, 2015 at 5:31:27 PM UTC-6, SoaringXCellence wrote:

A faster, higher L/D glider needs a lot more distance/time to dissipate energy and being 600' laterally abeam the touch down would create a significant challenge, both with the turns required to intercept final and the 45 degree base base turn reference.


Not really. EASA CS-22 paragraph 22.75 under which most high performance gliders were certificated says:

"It must be shown that the sailplane has a glide
slope not flatter than one in seven at a speed of
1·3 Vso with air brakes extended at maximum weight."

So basically all JAR-22/CS-22 gliders have less than 7:1 L/D with the spoilers open.

I've done several 45 degree angle of depression approaches with an early model DUO and it worked out fine.