Moshe Braner wrote on 1/14/2021 11:39 AM:
On 1/14/2021 1:43 PM, John Galloway wrote:
...

Another huge advantage, is they don't have that all-flying tail, which
was quickly designed out of the Nimbus line, for good reason.

The late models DG100G, LS1F and Grob built Std Cirruses have conventional tailplanes.
Earlier variants of those 3, and the ASW 15 have all flying tailplanes.


OK, but what is so bad about the all-flying tail?* I know some models had a reputation for no
"feel" in the pitch control.* Others less so. Is it the all-flying tail, or some details of its
design?* Where the hinge is placed along the chord of that tail would make a big difference,
no?* And spring trim added to the system would make it behave better when hands-off?

For example, Dick Johnson was regularly flying a Nimbus 2 IIRC, when he did the flight test of
the original Janus (both with all-flying tails). *He commented that "The well-balanced,
all-movable horizontal tail (on the Janus) provided good longitudinal stability at all speeds
and was a great improvement over the smaller poorly balanced Nimbus and Std. Cirrus tails. It
did, however, cause the longitudinal control to be fairly sensitive to control stick position."

My Ka6e and Std Cirrus both had all-flying tails. Based on those gliders and comments from
other pilots in different gliders, I'd say "did cause the longitudinal control to be fairly
sensitive to control stick position" is what's wrong with all-flying tails, especially at high
speeds. Over 75 knots, I held the Std Cirrus stick in both hands, ditto for the Ka6e at some
slower speed I don't remember. I very much liked both those gliders, but it was a deep pleasure
to leave those gliders for the H301 - so steady at high speeds.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1