What is a "short field" for a PA28-181

I won't argue with your POH! Does it give the speeds on both takeoffs?

Mike
MU-2

1.2 Vs for both conditions, premature raising of the nose or raising it to
an excessive angle will result in a delayed takeoff. Normal takeoffs are
with 10degree flap settings. At MAX GW, accelerate to 65-70mph, slight back
pressure to let the airplane fly itself off the ground. Accelerate to normal
climb. Enroute climb speed is 115mph, gets the nose down for visibility and
air cooling into the engine and better forward speed.

Short Field no obstacle, 25degree flap settings and lift off at the same
65-70mph at MAX GW. The text does state that with no obstacle, accelerate to
best rate (Vy) 105mph

Short Field With an obstacle, 25 degree flap, lift off at lowest possible
airspeed and accelerate in ground effect to 95mph, (Vx), climb at 95mph
until the obstacle is cleared, then accelerate to 105mph (Vy)

I should add that this is from the 1973 PA-32-300, fixed gear, fat wings.

BT.

Mike is correct. Only "close in" obstacles are best cleared with flaps in
any GA airplane.

That is because all GA aircraft have only one Vx and Vy and they are ALWAYS
attained with ZERO flaps.

Climbing at a lower speed with flaps to clear obstacles is a compromise. In
order to get off the ground in the shortest distance flaps are used. But one
has to then climb at a speed that is lower than Vx. There becomes a point at
which you are better off to accelerate to Vx and retract the flaps. Then you
will be climbing at BEST angle, which is impossible to do with any flap out.

For instance, say you are taking off from a short strip in the Snake River
canyon. There are trees at the end of the runway. Most likely you will use
the short field procedure in the POH for takeoff, which will probably
include flaps. But, once clear of the trees you will want to get rid of the
flaps in order to clear the distant obstacles, such as a ridge five miles
away. Best angle is WITHOUT flaps.

On the kind of Cessna, Piper and Beechcraft airplanes discussed here, Vx and
Vy are "clean wing" numbers. The exceptions are some VERY unusual STOL wings
like on a DHC-2 Beaver, which does use some flap for all normal climbs.

Karl
"curator" Cessna A185F, N185KG


"BTIZ" wrote in message
news:%tcnd.106330$bk1.58516@fed1read05...
Well Mike, I do not have a PA-28-181 POH handy so I checked my old
PA-32-300
At sea level, At Max GW
Normal take off, 10degree flap setting, Ground Roll, 1050ft, 50ft
clearance 1500ft
Short Field take off, 25degree flap setting, Ground Roll, 950ft, 50ft
clearance, 1400ft.

Say again?

BT

"Mike Rapoport" wrote in message
ink.net...
The problem with this logic is that the 50' obstical distance is
genarally greater with the short field flap setting. Only the ground run
is shorter.

Mike
MU-2

"kage" wrote in message ...

For instance, say you are taking off from a short strip in the Snake River
canyon. There are trees at the end of the runway. Most likely you will use
the short field procedure in the POH for takeoff, which will probably
include flaps. But, once clear of the trees you will want to get rid of the
flaps in order to clear the distant obstacles, such as a ridge five miles
away. Best angle is WITHOUT flaps.


Excellent point. I do a lot of flying from high DA, short, canyon
strips with tall trees at each end, and I've found that the POH
directions don't really account for all of the combinations of
conditions. Where I fly, a short field is often also a soft field.
In that case, one needs to get the wheels off the draggy surface as
soon as possible in the ground roll. This requires a combination of
the short (with obstacle clearance) and soft field procedures.

In my Cherokee, flaps definitely make a difference for clearing 75
ft. trees at the end of a grass strip. Whether it's shorter because
it gets the wheels out of the tall grass, or because of a better angle
of climb, I don't know. I do know that without flaps, the trees are
much closer to the wheels as I pass over.

John Galban=====N4BQ (PA28-180)

"BTIZ" wrote in message
news:2VUmd.106033$bk1.85623@fed1read05...
Look at the POH and determine what the take off distance is over a 50ft
obstacle, normal take off (no flaps) Then compute the landing distance
over a 50ft obstacle. This will give you a very conservative Accelerate /
Stop distance estimate. If the runway in use is shorter than that, then
you may not be able to accelerate to rotation speed, chop the throttle and
safely stop. I would use the short field take off procedure.

This is indeed conservative! it is probably twice the accelerate/stop
distance.

Mike
MU-2

jmho
BT

"Roy Page" wrote in message
nk.net...
I have been trying to determine the length of a runway that would be
considered a "short field" for my Archer II.
The two instructors that I work with on occasions disagree on the amount
of flaps to use for takeoff at gross weight.
One guy says my airfield with a 2,800ft runway is a "short field" and I
should use 25deg flaps as per the POH for takeoff at gross weight.
The other says 2,800ft is not a short field and I should use 10 deg flap
at gross weight and that 25 deg increases drag too much.
It does not help that the instructors have a low opinion of each other.
The POH is clear about using 25 deg for a short field but I have failed
to find what runway length puts in a short field category.
These guys also instruct in a PA28-140 based here and you can guess that
some students are using 1 notch of flap, while the other set use 2
notches.

So the question is.
How long is a "short field" for a PA28-181 ? And for that matter how does
that relate to a PA28-140 with 30 less horses.

--
Roy
N5804F - PA28-181

The one I looked at was an Archer II POH.

25 degrees of flaps, standard conditions, dry, paved, level runway was about
1500 ft over 50 ft obstacle

0 flaps, same conditions takes about 1850 ft over a 50ft obstacle

Those were the only two configurations given.

I didn't compare ground roll distances but that would indeed be interesting.

And you are correct, the Super Cub is impressive. I did my tailwheel
checkout in a SC. We never used the flaps off, flaps on, flaps off
technique, but even so, once you break ground you can pull the stick back as
far as you want and it just goes UP!

Jim


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Thanks. Are both takeoffs to Vx?

Mike
MU-2


"Jim Burns" wrote in message
...
The one I looked at was an Archer II POH.

25 degrees of flaps, standard conditions, dry, paved, level runway was
about
1500 ft over 50 ft obstacle

0 flaps, same conditions takes about 1850 ft over a 50ft obstacle

Those were the only two configurations given.

I didn't compare ground roll distances but that would indeed be
interesting.

And you are correct, the Super Cub is impressive. I did my tailwheel
checkout in a SC. We never used the flaps off, flaps on, flaps off
technique, but even so, once you break ground you can pull the stick back
as
far as you want and it just goes UP!

Jim


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I thought of that question also and I'll check tonight when I get home. I
would think that a "normal" takeoff would be to Vy and a short field to Vx.
But then again sometimes "normal" has many definitions!

Jim

"Mike Rapoport" wrote in message
hlink.net...
Thanks. Are both takeoffs to Vx?

Mike
MU-2


"Jim Burns" wrote in message
...
The one I looked at was an Archer II POH.

25 degrees of flaps, standard conditions, dry, paved, level runway was
about
1500 ft over 50 ft obstacle

0 flaps, same conditions takes about 1850 ft over a 50ft obstacle

Those were the only two configurations given.

I didn't compare ground roll distances but that would indeed be
interesting.

And you are correct, the Super Cub is impressive. I did my tailwheel
checkout in a SC. We never used the flaps off, flaps on, flaps off
technique, but even so, once you break ground you can pull the stick
back
as
far as you want and it just goes UP!

Jim


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BTIZ wrote:

Look at the POH and determine what the take off distance is over a 50ft
obstacle, normal take off (no flaps) Then compute the landing distance over
a 50ft obstacle. This will give you a very conservative Accelerate / Stop
distance estimate. If the runway in use is shorter than that, then you may
not be able to accelerate to rotation speed, chop the throttle and safely
stop. I would use the short field take off procedure.

If the POH does not list take off data for 1 notch of flaps, and states to
use 2 notches for a short field. Then I would use 2 notches and not pay
attention to the instructor that says to use only one notch.

I fly a warrior. If I am not doing a short field technique I usually
take off with one notch of flaps. This was suggested by an instructor
and I find that with 1 notch the plane "unsticks" and climbs to 50 feet
much easier. I don't think it improves the performance signficantly but
it's a much smoother and comfortable takeoff.

short field is 25 degrees and 52 kts. And it does get off and clear an
obstacle in less distance that way.

In article , xyzzy wrote:
BTIZ wrote:

I fly a warrior. If I am not doing a short field technique I usually
take off with one notch of flaps.

In the Comanche one notch of flaps makes for a much crisper transition
from rolling to flying. The takeoff angle is noticably steeper, too.

--
Ben Jackson

http://www.ben.com/

In article PM7nd.527035$mD.5173@attbi_s02, (Ben Jackson) writes:

I fly a warrior. If I am not doing a short field technique I usually
take off with one notch of flaps.

In the Comanche one notch of flaps makes for a much crisper transition
from rolling to flying. The takeoff angle is noticably steeper, too.


With my Archer if I put in 2 notches of flaps at 60 knots, I rise like a helo.

Chuck