On Fri, 1 Apr 2005 02:33:35 -0800, "Ray" wrote:

I'm just starting out my instrument training in a Cessna 152 that has a
compass mounted at the top of the windshield. Here's a sample picture for
those who have never seen it, http://www.airliners.net/open.file/643201/M

Can anyone tell me if it's still possible to do compass turns under the hood
with this kind of setup? I've seen a lot of planes with high mounted
compasses, so I imagine this isn't a new question.


What is a compass turn?

I've done timed turns, (my instructors wouldn't even let me call it a
compass turn) but you can't do a turn while under the hood or in
actual while watching the compass. It'll even go the wrong way at
times and it'll change directions when you speed up or slow down when
on anything other than a north or south heading.

You look at the compass, figure how long to make a standard rate turn
(3 degrees per second), figure how many degrees to turn and then how
many seconds. Make the turn for how ever many seconds, roll out and
then check the compass to see how close you came to getting it right.

Short hand method... standard rate is 360 degrees in 2 minutes, 180
degrees in one minute, 90 degrees in 30 seconds, 45 degrees in 15
seconds and 10 degrees in roughly 3 seconds, or 30 degrees in 10
seconds. If you memorize these basic numbers you will be able to work
out any turn time in your head.

If you are referring to flying with a DE and will they let you use the
compass mounted way up there, the odds are no, but they will give you
the heading at the start and stop of the turn.

BTW, I find a vertical card compass "on the glare shield" to be great,
but the ones mounted at the top of the windshield to be a royal pain
when under the hood. They aren't quite so bad in actual, but I prefer
the compass closer to the rest of the instruments.

The new glass panels with all the flight instruments are great and
very easy to use although some pilots just can't seem to get used to
them. I find them to be natural. OTOH I don't think we'll see many
150s with glass panels soon :-)) They'd be worth more than the
airplane.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
- Ray