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  #1  
Old April 23rd 15, 08:29 PM posted to rec.aviation.soaring
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Default Chukar's own account

The "let go of the stick" part is probably a souvenir of the period (some 50 years ago) when gliders had airbrakes that kept the speed below Vne even in a vertical dive (this used to be specified in the standard class rules, before the Libelle/Cirrus/ASW-15 generation came up - see the Schweizer stories about vertical dive test flights). The technique you found in many gliding (teaching) manuals was indeed: "trim fully forward, airbrakes fully open, let go of the stick and rudder". At least here in Europe.

With modern gliders, the Vne limit will be reached long before a vertical dive position even with airbrakes fully deployed (I seem to remember that a 30° dive is sufficient with some open class self launchers or fully ballasted gliders). So it is probably common sense to try to hold the stick steady in pitch after trimming forward.
  #2  
Old April 24th 15, 09:32 AM posted to rec.aviation.soaring
Don Johnstone[_4_]
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At 19:29 23 April 2015, wrote:
The "let go of the stick" part is probably a souvenir of the period (some
5=
0 years ago) when gliders had airbrakes that kept the speed below Vne

even
=
in a vertical dive (this used to be specified in the standard class

rules,
=
before the Libelle/Cirrus/ASW-15 generation came up - see the Schweizer
sto=
ries about vertical dive test flights). The technique you found in many
gli=
ding (teaching) manuals was indeed: "trim fully forward, airbrakes fully
op=
en, let go of the stick and rudder". At least here in Europe.

With modern gliders, the Vne limit will be reached long before a vertical
d=
ive position even with airbrakes fully deployed (I seem to remember that

a
=
30=B0 dive is sufficient with some open class self launchers or fully
balla=
sted gliders). So it is probably common sense to try to hold the stick
stea=
dy in pitch after trimming forward.


Benign spiral does work in most gliders. It involves trimming the glider to
say 55kts and then making sure that you do NOT move the stick against the
trim, in other words you maintain neutral stick input. It is a technique
that will allow you to descend through cloud if you do not have blind
flying instruments. A few important caveats. It would be difficult if not
impossible to set up while in cloud, the idea is that you set up while
clear of cloud. The original concept was to recover if the cloud gaps
closed beneath you, NOT if you are already in cloud. The other caveat is
that if you have given your airframe a really cold soak, when you descend
into the cloud you will pick up ice, clouds tend to have moisture, which
may be a complete game changer.

  #3  
Old April 24th 15, 10:54 AM posted to rec.aviation.soaring
krasw
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On Friday, 24 April 2015 11:45:06 UTC+3, Don Johnstone wrote:
The other caveat is
that if you have given your airframe a really cold soak, when you descend
into the cloud you will pick up ice, clouds tend to have moisture, which
may be a complete game changer.


Gliders fly pretty well with ice. You get ice in pretty much every climb to FL80-FL100 in my latitudes, most of the time there is few centimeters of rime ice on leading edges. You notice this while climbing as the airspeed starts to creep up while maintaining same turn rate and pitch attitude. I have only once noticed unusual friction with controls, and that was actually outside cloud. Cloud was apparently bit warmer and water droplets ran to aileron gap, and then froze outside cu in colder air. TE probe usually is the first to get ice, and if you don't have a variometer with electric compensation you probably loose the thermal soon. Pitot probe icing means it's time to open airbrakes and get out of the cloud asap. But at that point you have ice all over wings. It should be obvious that glider with icy wings glides like a brick, and in cold airmass ice melts sometimes at disturbingly low altitude (bug wipers are very good for wiping melting ice).
 




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