Cessna 172 Empty CGs

[[email protected]]

I'm working with a Cessna 172A, which is the '59 model.

It has a full panel with a pair of KX170s, and an ADF. It has been
modified with the 0-300D engine which supports a vacuum pump.
This is the 6 cylinder engine with Millenium cylinders. I don't think
they add much weight -- but it would be forward if they did.

According to the paperwork, the empty CG is so far forward that
I can barely load it in limits. With one in the front seat, it
requires
a 40# weight in the baggage compartment. With two in the front seats,
I don't think you could put enough weight in the baggage compartment
to get it in limits, tho leaving some gas out does help. With 3 in
the
airplane, it is at gross and in CG but is still close to the forward
limit.

It flies as if the CG is forward. Takes a good effort to really get
it
planted on the main wheels without touching the nosewheel.

It would help me if anyone with an older 172 (or any 172 actually)
would
post their empty weight and CG arm so I can sanity check
the paperwork on this one.

Thanks,
Bill Hale Loveland CO CFI

[[email protected]]

On May 23, 1:53*pm, " >
wrote:
> I'm working with a Cessna 172A, which is the '59 model.
>
> It has a full panel with a pair of KX170s, and an ADF. *It has been
> modified with the 0-300D engine which supports a vacuum pump.
> This is the 6 cylinder engine with Millenium cylinders. *I don't think
> they add much weight -- but it would be forward if they did.
>
> According to the paperwork, the empty CG is so far forward that
> I can *barely load it in limits. *With one in the front seat, it
> requires
> a 40# weight in the baggage compartment. *With two in the front seats,
> I don't think you could put enough weight in the baggage compartment
> to get it in limits, tho leaving some gas out does help. *With 3 in
> the
> airplane, it is at gross and in CG but is still close to the forward
> limit.
>
> It flies as if the CG is forward. *Takes a good effort to really get
> it
> planted on the main wheels without touching the nosewheel.

What is your empty weight and CG? We have four 172s here but
they're all at the airport along with the paperwork so I can't quote
it exactly, but I think the CG is around 38" aft of datum. I'd have to
check.

Are you landing with zero flaps? That'll make the nose heavy
in the flare. Have you looked back while in level cruise to see where
the elevator is? It should be angled down slightly with respect to the
stab if the CG is OK. If yours is streamlined or up a little, you
probably really do have a forward CG. Is the trim properly rigged? Do
you have the trim indicator centered during climb, or is set nose up?
Misrigged controls on old airplanes is distressingly common.

But where would the weight come from" The TCDS for the O-300
indicates that the engine weight for the D is the same as the old A
model, which that airplane started with. The Millenium cylinders won't
be any heavier, at least not enough to notice.

Check your CG range numbers. From the TCDS for your airplane:

C.G. Range Normal (+40.8) to (+46.4) at 2200 lbs.
(+36.4) to (+46.4) at 1733 lbs.
Utility category (+38.4) to (+40.3) at 1950 lbs.
(+36.4) to (+40.3) at 1733 lbs. or less
Straight line variation between points given.
Empty Weight C.G. Range: None

Dan

[Ron Rosenfeld]

On Sat, 23 May 2009 12:53:24 -0700 (PDT), "
> wrote:

>I'm working with a Cessna 172A, which is the '59 model.
>
>It has a full panel with a pair of KX170s, and an ADF. It has been
>modified with the 0-300D engine which supports a vacuum pump.
>This is the 6 cylinder engine with Millenium cylinders. I don't think
>they add much weight -- but it would be forward if they did.
>
>According to the paperwork, the empty CG is so far forward that
>I can barely load it in limits. With one in the front seat, it
>requires
>a 40# weight in the baggage compartment. With two in the front seats,
>I don't think you could put enough weight in the baggage compartment
>to get it in limits, tho leaving some gas out does help. With 3 in
>the
>airplane, it is at gross and in CG but is still close to the forward
>limit.
>
>It flies as if the CG is forward. Takes a good effort to really get
>it
>planted on the main wheels without touching the nosewheel.
>
>It would help me if anyone with an older 172 (or any 172 actually)
>would
>post their empty weight and CG arm so I can sanity check
>the paperwork on this one.
>
>Thanks,
>Bill Hale Loveland CO CFI

You can always get that data, for the unmodified a/c, from the FAA website
collection of Type Certificate Data Sheets.

For the C172A: (see

http://www2.airweb.faa.gov/Regulatory_and_Guidance_Library%5CrgMakeModel.nsf/0/9F56B5DA3FEB757E862574780058E45A/$FILE/3A12.pdf

or http://tinyurl.com/odd9ct





C.G. Range Normal (+40.8) to (+46.4) at 2200 lbs.
(+36.4) to (+46.4) at 1733 lbs.
Utility category (+38.4) to (+40.3) at 1950 lbs.
(+36.4) to (+40.3) at 1733 lbs. or less

Straight line variation between points given.

Empty Weight C.G. Range None

*Maximum Weight Normal category 2200 lbs.
Utility category 1950 lbs.
--ron

[Bill]

The empty arm is 36.5", empty weight 1367#.

Empty CG seems fairly far forward. bH

[Ross]

wrote:
> I'm working with a Cessna 172A, which is the '59 model.
>
> It has a full panel with a pair of KX170s, and an ADF. It has been
> modified with the 0-300D engine which supports a vacuum pump.
> This is the 6 cylinder engine with Millenium cylinders. I don't think
> they add much weight -- but it would be forward if they did.
>
> According to the paperwork, the empty CG is so far forward that
> I can barely load it in limits. With one in the front seat, it
> requires
> a 40# weight in the baggage compartment. With two in the front seats,
> I don't think you could put enough weight in the baggage compartment
> to get it in limits, tho leaving some gas out does help. With 3 in
> the
> airplane, it is at gross and in CG but is still close to the forward
> limit.
>
> It flies as if the CG is forward. Takes a good effort to really get
> it
> planted on the main wheels without touching the nosewheel.
>
> It would help me if anyone with an older 172 (or any 172 actually)
> would
> post their empty weight and CG arm so I can sanity check
> the paperwork on this one.
>
> Thanks,
> Bill Hale Loveland CO CFI

Be sure the the correct datum was used to determine the W&B. I always
thought mine was off and sure enough the wrong datum was used. Refer to
TCDS 3A12 for the correct location. I had to have mine done over. Cessna
used different datums for the Skyhawk.

--

Regards, Ross
C-172F 180HP
Sold :(
KSWI