Thread: Bohli Compass
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Old November 1st 15, 06:59 AM posted to rec.aviation.soaring
Chris Rollings[_2_]
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Posts: 133
Default Bohli Compass

At 19:04 31 October 2015, krasw wrote:
lauantai 31. lokakuuta 2015 16.16.26 UTC+2 Dan Marotta kirjoitti:
I truly don't know what it's worth, if anything.
=20
=20
=20
I've read that, properly set up, it can be used to fly in

clouds.=A0
I've also read that it was banned in contests in the US for just
that reason.=A0 It would be fun to have as a toy, just like that

J-8
attitude indicator that I've had in a box for close to 40 years.


I've flown with Bohli compass and it's main use is same as directional
gyro=
's. When IMC (or VMC, of course) you can straighten your turn to correct
he=
ading right away if compass is tilted correctly. With normal Airpath
compas=
s procedure inside cloud is to straighten to any direction, wait 15-30

sec
=
to get compass reading, then calculate how many seconds to make 30sec (or
1=
min) standard rate turn to correct heading. This takes easily couple of
mi=
nutes in all. These days any modern GPS gives you track reading at 1 hZ,
wh=
ich makes Bohli compass totally obsolete. You can not fly IMC with only
Boh=
li compass, that has to be some misunderstanding.


You can fly IMC (ie climb in thermals in cloud and straighten up on a
heading) on just a Bohli, ASI and slip ball, I have done so in the past to
prove the point. It is very high workload and taxed me near to the limit
and I have far more cloud flying experience in gliders than most pilots.