On Sun, 01 Apr 2018 07:26:59 -0700, davidlawley wrote:

Libelles suffer from a lack of rudder authority when rolling quickly at
low speed, but are easy to rig.
They also have balsa core wings, rather than foam.

Roger easy to rig. I haven't particularly noticed any lack of rudder
authority, but you're wrong about them all having balsa in their wing
skins. Whether they have balsa of foam depends on age, with the change-
over being spread over approximately 100 airframes:

s/n 1 - 84 had balsa/glass skins on all flying surfaces. There was a
gradual change from balsa to foam from s/n 85 to s/n 182, starting with
just the wings on s/n 85 and gradually progressing to all surfaces.

Other known differences a

s/n 1 - 94 had top and bottom surface airbrakes.
s/n 95 was the first to have only top surface airbrakes.

At some point the tailplane changed, with increased chord and a thicker
section, but I don't know what this happened - possibly s/n 182, which
was the first H.201B Std Libelle.

At s/n 321 an AD allowed all Std Libelles to be recertified as
B-series. This was a flight manual revision: there were no other changes.


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