Simple weight/balance question

Aaron Coolidge wrote:
CG envelope a moderate amount, so that the situation of 2 * 200 lb front
seat passengers + fuel + no rear seat pax or baggage is within the CG
envelope. It is purely a paper change, you get a new CG envelope sheet.
It came with my Cherokee 180, and I believe that it applies to straight-wing
Arrows too (ie, PA-28-180 and PA-28-200).

Aaron:

Do you happen to know the number of the SB from Piper?

And I keep an 8 gallon (with only 7 gallons in it) water tank in
the baggage area. Works perfectly!

On 24-Feb-2004, wrote:

That sounds about right. Our Cherokee 180 is right at the edge of the
forward envelope with 400 lbs (marginally fatso pilot + copilot) at full
fuel. I
can tell flying it there, because the elevator trim barely runs out on a
slow short
final to landing (80 mph IAS or so). That's part of the reason a bit of
power in
the flare on these Cherokees helps keep the nose from "plopping" on
landing.

I've run the math with a matlab script that implies it's virtually
*impossible* to aft-load the thing. Put a 120 lb pilot, enough fuel for a
spin around the patch, the maximum of 100 lbs in the baggage compartment,
and enough
fat-asses in the back seat to gross... still not outside the aft limit.

Of course, your plane may vary so do your own W&B.

snip

As you suggest, while there is a lot of family similarity among PA-28 models
they do vary quite a bit in W&B. Two primary factors are the varying engine
weights and in particular the 5 inch "stretch" given Arrows and 180/Archers
in the mid-'90s. That stretch moved the back seat and baggage compartment
considerably farther from the center of lift, making CG more sensitive to
different loadings.

In our Arrow IV, most common-sense loading situations put CG comfortably in
the middle of the envelope. You CAN get the CG forward of the limit, but it
takes something like two 240 lb hulks in front with full fuel and no other
loads. Much easier to screw up the CG in the aft direction. For instance,
250 lbs in the front seat, 200 lbs in back, 100 lbs in the baggage
compartment (of 200 lbs max capacity), and 300 lbs of fuel will put CG right
at the aft limit. The solution: as with most light planes. fill the front
seats with the heaviest people before putting anyone in the back seat. Of
course, if the pilot is very small and the passengers very large, this can
create a problem.

-Elliott Drucker

wrote:

: As you suggest, while there is a lot of family similarity among PA-28 models
: they do vary quite a bit in W&B. Two primary factors are the varying engine
: weights and in particular the 5 inch "stretch" given Arrows and 180/Archers
: in the mid-'90s. That stretch moved the back seat and baggage compartment
: considerably farther from the center of lift, making CG more sensitive to
: different loadings.

Not to pick nits, but this stretch happened in 1973 for the Cherokee 180
(which became the "Cherokee Challenger") and 1974 for the Arrow. In 1974
the "Challenger" was named "Archer". 1975 gave the Archer the "Warrior"
wing, and changed the name to "Archer 2". This is from Bill Clarke's "Piper
Indians" book.

Blanche wrote:
: Aaron:

: Do you happen to know the number of the SB from Piper?

It is referenced in the TCDS (2A13) for the airplane. The relevant info
is in Note 15, with the graphs of the CG envelope on page 2:

The Model PA-28-180, S/N 28-671 through 28-5859, may be operated to the
expanded C.G. envelope:
(a) For S/N 28-671 through 28-3072 by the installation of P/N 65280-00
tube - Landing Gear Strut Piston in accordance with Piper Service
Letter 567 and in accordance with FAA approved Airplane Flight Manual
Supplement No. 2, dated September 14, 1970, for Model PA-28-180
(Piper Report VB-261).
(b) For S/N 28-3073 through 28-5859 in accordance with FAA approved
Airplane Flight Manual Supplement No. 2, dated September 14, 1970,
for Model PA-28-180 (Piper Report VB-261).

--
Aaron Coolidge (N9376J)

On 25-Feb-2004, Aaron Coolidge wrote:

Not to pick nits, but this stretch happened in 1973 for the Cherokee 180
(which became the "Cherokee Challenger") and 1974 for the Arrow. In 1974
the "Challenger" was named "Archer". 1975 gave the Archer the "Warrior"
wing, and changed the name to "Archer 2". This is from Bill Clarke's
"Piper Indians" book.

You are absolutely correct, of course. Guess I had a "senior moment" while
typing.

-Elliott Drucker

Can anybody tell me what Piper Report VB-274 says about expanding the
CG envelope for a '67 PA-28-235 without sending me to New Piper for a
copy?

(Please)

Don

Frode ..

You're probably right with your figures. Run some sample W&B scenarios and
print them out and keep them with you. That saves recalculating it all the
time.





"Frode Berg" wrote in message
...
Hi!

I am part owner of an Arrow 180 hp.

We haven't had a weight and balance done in a while, and I was wondering
one
thing.
It seems on the old numbers that me and my wife cannot ride in the front
seat together when fully fueled....

I weigh in at around 100 kg (approx 220 lbs) and wife is around 70 kg
(around 150 lbs)

Is this normal for this plane, or am I doing something wierd with the
figures? I would think that two adults should be ok in this plane with
full
tanks? Its an arrow for goodness.....hehe....no?

Any input appreciated.
I will be doing my nigh rating next week, and would be nice to know if my
instructor and I will be legal flying around in the dark with full
tanks....

Frode Berg
Norway