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Sorry to say, but James reply is incorrect. A KAP140 single-axis
autopilot is optional equipment on all new C172R and C172SP (NAVII
package). I doubt that there are many without the autopilot.
There is a bit more to the relation between the three axes of an
airplane and how an autopilot works. First of all, there is no
universal definition of “x-axis” autopilot. The simplest one is
a “wing leveller”. As the name suggests, it does nothing but level the
wings, i.e. roll control, and does not hold heading or anything else.
A single-axis autopilot does NOT provide pitch control! In fact, pitch
in GA airplanes is not automatically controlled at all – you do that
normally with the throttle!
A single-axis autopilot provides in addition to the roll control some
form of an “automatic” heading holding function. This can be by
just “following” the heading bug on the DG or by coupling it to a NAV
instrument like VOR, LOC or GPS. The interaction between these
instruments (DG, NAV and autopilot) is very complicated.
A single-axis autopilot does NOT provide altitude control or “altitude
hold mode”. That is done by an autopilot usually called two-axis
autopilot. The better ones even have an “altitude preselect” mode
where the airplane levels itself after reaching the preselected
altitude from above or below. These autopilots have often a mode where
you can select a constant climb or sink rate in fpm. Again, a two-axis
autopilot also does NOT provide pitch control!
Then there are autopilots that can “capture” the localizer AND
glidescope indications from an ILS. The autopilot controls the (1)
roll, (2) heading and (3) descend angle. That is why some people call
these “three-axis” autopilots. That’s mostly it for GA airplanes.
There is MUCH more to commercial airplanes, like autothrottle (for
speed) or RNAV Roll Steering or really neat stuff for ILS CAT IIIc
approaches that can be flown totally automatically until the airplane
stops on the runway.
Have fun flying,
> An autopilot is not standard equipment on a Cessna 172 to the best of
> knowledge. An airplane has three axis (pitch, yaw, and roll). A
> axis autopilot will control one axis (typically pitch). More
> autopilots will control 2 or 3 axis.
> Not that any of this will matter to you. As a student pilot, it is
> that you will even touch the autopilot.
> Your english is great.
> Bernhard Stößel <email@example.com> wrote in message
> > Hello,
> > Im from Germany and I am going to start with my Privat Pilot
> > in spring next year. The flight school in Nuremberg uses several
> > mostly Cessna 172 Skyhawk. They also use one Cessna 182 and two
> > airplanes.Ive heard that the Cessna 172 Skyhawk has an KFC 150
> > (single-axis ???) installed. But now I have two questions:
> > Firstly, is the autopilot standard equipment with the Cessna 172 or
> > have to pay for this extra? (I dont know if the airplanes in the
> > school have the KFC 150 installed ...)
> > Secondly, I have read several aviation magazines (for
example "Plane and
> > Pilot" and others) and I would like to know: whats the differenze
> > "single-axis-autopilot" and the other kinds of autopilots, which
> > of these autopilots are there? Do you know also "double-axis-
> > and do they work different?)
> > Sorry if my english isnt 100% perfect.
> > Greetings from Germany
> > Bernhard
> > You can also send e-mail to firstname.lastname@example.org if you dont
> > post into this group.
> > Thank you, merci, and have a good day
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Before you buy.
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