On Saturday, July 4, 2015 at 12:58:28 PM UTC-7, wrote:
On Saturday, July 4, 2015 at 11:38:55 AM UTC-4, Jonathan St. Cloud wrote:
The mixer is actually very different and Schleicher spent much time on this. So is the lay up schedule for the spar, and an extra layer of carbon on the wing. Wing root airfoil is different and the outboard sections of airfoil have been changed. The empty weight of a 29 compared to a 27 both at 15 meters is about 80 pounds.

Interesting to read this. When the '29 came out I heard there was a new outboard airfoil and wanted to modify my '27 with it. I pulled templates off a friend's '29 and lo and behold there was no perceptible difference. Certainly the winglet changed but we had done that in 2000. The winglet is very similar to what we did for the '27 back then with thicker, more conservative airfoil.
Obviously the structure changes when you go to 18M.
UH

I am a bit perplexed as well.

The Schleicher mixer seems to be designed to assure that in landing flap the ailerons go to negative so the tips don't stall with the flaps at ~40 degrees. This doesn't strike me as something that requires a lot of fine-tuning, compared to (for example) making sure that the flap handle positions correspond to the correct flap angles so the pilot can set the correct flap position to match the airspeed and wing loading, per the Operating Manual. However, that exercise has more to do with matching the flap handle detents to the correct calculated/derived flap angles as part of manufacturing for each production unit more than anything to do with the mixer per se. It seems even less plausible if the airfoil sections are in fact the same.

9B