On Sun, 28 Sep 2014 11:33:34 -0400, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
On Sun, 28 Sep 2014 01:04:43 -0400, "Jim Wilkins"
wrote:


"Ed Huntress" wrote in message
...
On Sat, 27 Sep 2014 23:52:00 -0400, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
om...
On Sat, 27 Sep 2014 23:16:42 -0400, "Jim Wilkins"
wrote:


Instructor, to budding 17-year-old pilot Ed, who is under the
hood
on
his first IFR training: "Do you feel like you're flying straight
and
level?"

Ed: "Yes, sort of. It feels like I'm pulling out of a stall,
though;
everything feels heavy."

Instructor: "Lift your hood."

[Ed lifts hood, realizes he's in 20-degree controlled turn,
losing
altitude.]

Ed levels out visually: "I think there's something wrong with
the
artificial horizon." [Horizon says wings are level; it hasn't
budged
through the turn or afterwards.]

Instructor looks at artificial horizon, takes the stick, banks
left
and then right: "Holy ****!"

g What happened was that new/old instruments had just been
installed
in the Cessna 152. They had been removed the day before from a
Beech
Musketeer that had stalled and crashed, at the end of Princeton
airport, through the roof of the Pontiac dealership across the
street.

Anyway, the instruments checked out OK, and they no longer had
the
Musketeer for IFR training, so they put them in the Cessna. But
they
weren't OK. I had my eyes glued to the horizon and the airspeed
indicator, hardly noticing the compass.

If someone had taken off on a real IFR flight in that plane that
day,
he probably would have died.

It was a great lesson to me. I abandoned IFR training and
decided
to
stick to flying in nice weather. d8-)

--
Ed Huntress

The Buddy Holly crash may have been caused by an unfamiliar
artificial
horizon that read the reverse of normal. Think of an ordinary
gyroscope whose rear edge would rise as you climbed and drop as
you
descended.
-jsw

Hmm. Interesting. I don't get why it would read in reverse, but
that's
OK. I don't even like to think about artificial horizons. I still
get
a chill thinking about it.

http://www.fiftiesweb.com/cab.htm
"The Sperry F3 gyro also provides a direct reading indication of the
bank and pitch attitude of the aircraft, but its pictorial
presentation is achieved by using a stabilized sphere whose
free-floating movements behind a miniature aircraft presents pitch
information with a sensing exactly opposite from that depicted by
the
conventional artificial horizon."

"Since Peterson had received his instrument training in aircraft
equipped with the conventional type artificial horizon, and since
this
instrument and the attitude gyro are opposite in their pictorial
display of the pitch attitude, it is probably that the reverse
sensing
would at times produce reverse control action."

CFIT, Controlled Flight Into Terrain.

Aha. That reminds me of the virtual trackball orientation of
Ashlar's
3D CAD program Vellum -- the first, wireframe version IIRC -- that
worked like that. It drove me nuts for a while.

The Sperry version is mechanically simpler, just the single floating
sphere, and I assume intended to be more reliable. I wrote the
gyroscope explanation to see if I could improve on the vague
description in that article.

Here's what the F3 looks like, with the dark ground on top and the
light sky on the bottom
http://www.lets-go-fly.com/safety-one.html
-jsw


Hmmm.. That looks familiar somehow.

BTW, the premise of that website is somewhat undercut by the lead
sentence:

"Safety begines with knowlete."

I'll take their word for it. g

--
Ed Huntress