I'm not generally one to take my own advice (knowing the source as I do) but
I decided to make an exception in this case.

I took our 172 N (160 hp, 1966 lbs as loaded) out up 3400 foot density
altitude and set up in approach configuration with 20 degrees of flaps. When
I reached mid flare speed, I put in full power. Trimmed as for my usual
landing (I trim at midfield and leave it alone as I like a bit of pressure
on the yoke to work against) there was enough pitch up that speed could
bleed off pretty fast if you were flying by yoke feel and not really on top
of it.

If you are one of those who trim all pressure off on short final, you'd have
even more yoke pressure to deal with. 500 fpm climb was achieved pretty
quickly but at enough lower airspeed that the climb gradient would be a
concern in a marginal situation.

I climbed up 2000 feet without seeing any significant drop off in vertical
speed. The plane was quite controllable and easy to handle once some nose
trim was rolled in. Then I set it up again with 30 degrees of flaps.

There was more pitch up with 30 degrees and the need to hold the nose down
to pick up airspeed. It took a long time for the airspeed to come up to
where I could establish a good climb rate. A mid length runway would
disappear real fast. Once I had the speed, I could get back to 500 fpm climb
and had no trouble doing a climbing turn up another 1000 feet. You wouldn't
want to be doing this in a tight spot among hills though.

With 40 degrees of flaps, the plane didn't climb at all when the throttle
was pushed forward. A slight relaxation of the yoke as you might do when
starting a go around with that much yoke pressure caused the airspeed to
drop instantly. Pushing the nose over to build up speed created an immediate
20 foot sink followed by a painfully slow building of airspeed. I must have
used up a couple of short field lengths before I got enough speed to work
into a climb and had to roll in a good bit of nose trim.

250 fpm was the best climb I could manage. There was a noticeable buffet at
60 knots and dropping the nose didn't change the airspeed much. I was able
to climb 500 feet and turn but it would have hair raising with terrain
around.

If you lose flap function at the 40 degree setting going into a short and
obstructed field, you are going to have to make some very rapid lifestyle
choices. Go into the tree trunks at the speed you can slow down to in an
emergency abort or into the softer tops at 60 knots might be the two best
picks. You have two seconds to make up your mind.

Flap failure at 30 degrees in these conditions would be still be enough
excitement for any day.

This is one of those things that makes you realize how much is sometimes
riding on toy quality components assembled in third world countries by bored
workers. If there is any doubt about your flap function at all (just being
in a post 1976 Cessna could qualify for that) aggressive slipping with 10
degrees of flaps into tight fields has a lot more to recommend it than I
thought previously.

--

Roger Long



"Roger Long" wrote in message
...
One of the more experienced pilots in our club scared himself climbing out
of a touch and go during which he didn't notice that the flaps had frozen
at
20 degrees on our 172.

I've been investigating the flap system on Cessna's and am impressed how
easily a bit of fluff or corrosion in just one switch can let the flaps go
down but then fail to retract.

This leaves me convinced that CFI's and all of us should be drilling in
the
glance over the shoulder to verify retraction on all touch and goes and go
arounds. Practicing climb outs from minimum airspeed with all flap
settings
is a very neglected part of airwork and probably as important to safety as
doing stalls.

--

Roger Long