Simple weight/balance question

[Frode Berg]

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

[Steve Foley]

Your calculations are probably correct. I cannot sit in the front of my
Cherokee 140 with a passanger unless I put some weight in the back.


"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
>
>

[Jay Honeck]

> It seems on the old numbers that me and my wife cannot ride in the front
> seat together when fully fueled....

Well, there is "should not" and there is "cannot." Obviously, it is
possible to fly an Arrow with two adults in the front seat with full fuel.
It's done every day, all over the world, safely.

That said, you may be a bit out of CG range -- which is obviously computed
rather conservatively.

Just put a sand bag in the luggage compartment, and you'll discover that
flaring to land is MUCH nicer.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Kevin]

Steve Foley wrote:
> Your calculations are probably correct. I cannot sit in the front of my
> Cherokee 140 with a passanger unless I put some weight in the back.
>
>
> "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
>>
>>
>
>
>
Far better to be nose heavy than tail heavy.

[Kyler Laird]

"Jay Honeck" > writes:

>Just put a sand bag in the luggage compartment,

Sand?! I thought that was something only renters did. Don't
owners have plenty of junk in the luggage compartment(s)
already? With the "oh, ****!" gear and extra engine and turbo
oil I usually carry, I've got no need for dead weight

Hmmm...has there been a "what stuff do you have tucked away
in the recesses of your plane" thread? (I'm not sure where
to start with a search.)

--kyler

[Jay Honeck]

> Sand?! I thought that was something only renters did. Don't
> owners have plenty of junk in the luggage compartment(s)
> already?

For sure! Although, I just cleaned it out (to carry my Mom-in-law's and
Aunt's luggage) the other day, so I'm probably WAY nose-heavy now!

(Back to the original poster: If you think an Arrow is nose heavy with two
in the front seats, try flying a Cherokee with a 6-cylinder engine! We're
always nose heavy, unless we've got two in the back seat, or a case of oil
in the way-back...)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Maurice Givens]

"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



I have a PA28R-200, Arrow II. With 370 lbs in the front seat, I am
well within the CG limits. From what I can tell (a friend has a
PA28R-180) the CG envelope for the PA28R-180 is not that much
different than mine, and I can't imagine that you have that much gear
in the panel that the CG would move so as to be out of the envelope.


Maurice Givens

[RJ]

"Jay Honeck" > wrote in message news:<lWn_b.380048$xy6.2073697@attbi_s02>...
> > Sand?! I thought that was something only renters did. Don't
> > owners have plenty of junk in the luggage compartment(s)
> > already?
>
> For sure! Although, I just cleaned it out (to carry my Mom-in-law's and
> Aunt's luggage) the other day, so I'm probably WAY nose-heavy now!
>
> (Back to the original poster: If you think an Arrow is nose heavy with two
> in the front seats, try flying a Cherokee with a 6-cylinder engine! We're
> always nose heavy, unless we've got two in the back seat, or a case of oil
> in the way-back...)

One other thought...

Most pilots are smart enough to do a pre-flight W&B calculation prior
to launching, which is great. There are two additional numbers you
want to calculate: 1) what's happening to my CG as burn my planned
fuel?, and 2) What's my CG with zero fuel? The latter becomes
important if you get caught in bad weather, or have to make an
unplanned diversion. In the case of my Bonanza, the CG moves aft at a
good rate as I burn fuel. The last thing we want to do is land an
outside-the-envelope airplane when the going gets tough.

My flight planning software package taught me this trick, as it always
spits out the zero fuel CG number when it computes weight and balance.

Rob

[[email protected]]

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. Ever notice how all the
Cessnas on the field have their nose in the air after a snow but the Pipers never do.

Another note is moving the CG further aft gives a non-trivial speed increase
for a Cherokee. I've seen almost 10 mph with three 200 lb people in a Cherokee 150
from front/front/rear -> front/rear/baggage. Tough to climb over that back seat,
BTW.... :)

-Cory


Frode Berg > wrote:
: 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



--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

[Aaron Coolidge]

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.

Also note that there is a Piper service bulletin that extends the forward
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).

Me? I keep a tool box in the baggage compartment.
--
Aaron Coolidge (N9376J)

[Blanche]

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!

[[email protected]]

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

[Aaron Coolidge]

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.

[Aaron Coolidge]

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)

[[email protected]]

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

[Don Tuite]

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

[Roger Tracy]

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
>
>