"Brien K. Meehan" wrote

Okay, this post contradicts the previous post, and the way I learned it
is more like this post.

... but somewhere along the way, the 172 book changed from saying that
10 degrees would decrease climb performace, to indicating that it would
increase climb performance (in terms of reduced distance to clear a 50
foot obstacle).

When did the change occur? What physically changed on the aircraft?

Bigger engine. When Lycoming upgraded the O-320 from 150 hp to 160 hp.
The 1959 manual that I quoted reflected the 145 hp Continental O-300.
I posted that data to refute George's post about "all 172's before
1964" used 20 degrees of flaps.

Bob