compass turns with high mounted compass (Cessna 152)

On 1 Apr 2005 06:26:48 -0800, "paul kgyy" wrote:

I think the problem is that, with a high-mounted compass, you are
looking out the window every time you look at the compass. I'm not
sure how examiners deal with this.

When I took the instrument flight test, I asked the DE about it. He
asked me if I could see out when doing that. I replied, "I wear
bifocals. If you mean can I see any thing the answer is no, but if
you mean can I see light and dark and I could probably figure out
where the horizon was if the conditions were just right. If they
weren't just right I would probably come up with a false horizon". He
said not to worry, he'd just give me readings when appropriate.

Whether he read the vertical card compass on the glare shield for me,
or I read it made no difference to me. Actually it was probably
easier as I didn't have to look up away from the panel. Compasses
that are not very close to your flight instruments are a royal pain in
the real world.

Whether they let you look at it, or not should make no difference to
you. You know how to make timed turns and they are *not* going to
have you make turns while watching the compass. I seriously doubt any
one in their right mind would even ask for it in VFR conditions. They
just want the student to be aware of the quirks of a magnetic compass.
I've never head of them expecting the student to make turns with one.
However if I had to use the compass I'd cheat by getting the heading,
then rolling into the turn and ignoring what the compass was doing.
Just remember that 2 minute standard rate turn, one minute for a 180,
half a minute for 90, 15 seconds for 45. you can interpolate for
anything in between.

Timed turns are not the same thing.

Even VFR you should be looking at the compass to get a heading, make
the turn for so many seconds, roll out and then check the compass
again. If you are VFR, who cares if you miss the heading, you make a
correction and check again.

I had an instructor cover up everything except the TC, air speed, and
altimeter to see how long I could fly a straight course. After five
minutes, he said, never mind...we were still on course. :-))

Now when he had me close my eyes and fly, I lasted about a minute and
a half before "we had to recover". (mainly due to the plane being
well trimmed and rigged and little to do with any skill of mine) He
said he saw very few students who managed more than 15 to 20 seconds.
I admitted I was letting the plane do most of the flying with me just
nudging the controls from time to time.

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

Unrelated response to your specific question.... do they have a dual
com/nav stack in the 152? I ask, because all the 152 trainers I've seen at
my FBO only have one com and one nav. I would think that adding another
stack would only serve to further reduce the marginally okay max load capy
of the 152?

--
--
=-----
Good Flights!

Cecil
PP-ASEL-IA
Student - CP-ASEL

Check out my personal flying adventures from my first flight to the
checkride AND the continuing adventures beyond!
Complete with pictures and text at: www.bayareapilot.com

"I fly because it releases my mind from the tyranny of petty things."
- Antoine de Saint-Exupery -

"We who fly, do so for the love of flying. We are alive in the air with
this miracle that lies in our hands and beneath our feet"
- Cecil Day Lewis -
"Ray" wrote in message
...
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.

- Ray

Unrelated response to your specific question.... do they have a dual
com/nav stack in the 152? I ask, because all the 152 trainers I've seen
at
my FBO only have one com and one nav. I would think that adding another
stack would only serve to further reduce the marginally okay max load capy
of the 152?

Hi Cecil - the plane is 65610 with West Valley out of Palo Alto (
http://www.wvfc.org/craft/65610.html ), and it does have dual nav/com with
glideslope and an inop ADF. All this adds about 80 or so pounds to the
empty weight. The max load is decreased, but the performance is more than
compensated for by the sparrowhawk conversion. I'm a fair bit lighter than
the FAA "standard passenger" - so I can barely fly with my instructor and
full fuel.

After doing my PP in 152's, I had originally planned on doing my instrument
in 172SPs in order to become proficient with the autopilot and GPS
approaches - which I figure I'll be much more likely to use in 'real life'
IFR flight. However, I'm a grad student with a pretty tight budget - and
there's a $50/hour wet difference between the 152 and 172SPs. I told my
instructor that I wanted to spend at least some of my instrument training in
the cheaper 152, and his response was basically "why not do all of it in the
152, after you finish the checkride it'll only take a couple lessons for you
to learn the GPS and autopilot, and this will save you thousands of
dollars." Sound's good to me!

- Ray

Ask the CFI to tell you when you hit the compass heading
you want to start your rollout on. Talk thru your logic for
selecting this heading. (compensating for lead/lag of the
compass)


"Ray" wrote in message
...
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.

- Ray

I'm with Gardner on this one.

compass turns are a complete waste of time and money.

Use a clock. Forget lead, lag, accelerate north, decelerate south,
and all the rest of the anal aviation gobbledygook..





On Fri, 01 Apr 2005 16:28:32 GMT, "OtisWinslow"
wrote:

Ask the CFI to tell you when you hit the compass heading
you want to start your rollout on. Talk thru your logic for
selecting this heading. (compensating for lead/lag of the
compass)


"Ray" wrote in message
...
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.

- Ray

I couldn't agree more with you and Bob. I can turn a lot more accurately
with a stop watch than a mag compass. But his question wasn't about
the merits of each .. it was about using the compass when it's outside
the viewing area of the hood. That would also be a factor when setting
the DG prior to starting an approach. To which I still say .. have the
CFI/safety pilot read it for you.


wrote in message
...
I'm with Gardner on this one.

compass turns are a complete waste of time and money.

Use a clock. Forget lead, lag, accelerate north, decelerate south,
and all the rest of the anal aviation gobbledygook..





On Fri, 01 Apr 2005 16:28:32 GMT, "OtisWinslow"
wrote:

Ask the CFI to tell you when you hit the compass heading
you want to start your rollout on. Talk thru your logic for
selecting this heading. (compensating for lead/lag of the
compass)


"Ray" wrote in message
...
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.

- Ray

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

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