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

PaulaJay1 wrote:
: 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.

Ditto with my Cherokee 180 (straight wing Archer).
--
Aaron Coolidge

On 18 Nov 2004 22:28:49 GMT, (PaulaJay1) wrote:

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.

For how long?


Chuck

Roy Page wrote:
: 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.

I fly a Hershey-bar PA28-140 with a 180hp engine, so it's probably somewhere
between the two. If your POH is anything like mine, I understand your apprehension
about what the "true numbers" are. Piper was particularly awful in the older books
WRT some things. For instance, I routinely fly my plane on grass strips with
3000-4000' DA, but I have no guidance from the POH on grass. I would also like
partial loading characteristics, since I almost never fly at gross (for a -180).
Neither of these are present.

I think that the poster who suggesting adding the takeoff (w/ or w/o obstacle
clearance) + the landing distance ground roll makes a very reasonable, yet not overly
conservative estimate. For mine at 3000' DA, that'd be 2200+600 over a 50' obstacle
from a paved runway. Given the safety factor of generally being under gross by
200-300 lbs, that's a very reasonable number.

WRT 1 notch or two, the decision is clear. You're either doing short field
by the book or you're not. While adding 1 notch may help some, you have no
substantive reason to know how much... thus, I wouldn't do it where I wasn't
comfortable with a normal takeoff.

All that said, from what I've gathered by looking through a number of POH's
(not Pipers') and other references, I've come up with the following "rules of thumb"
to keep from being overly aggressive/conservative:

"good" grass: adds 10-20%
"bad" grass: adds 20-30% - not yet tried...
10% under gross: decreases 10%
nonstandard DA: By the book

YMMV
-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

"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


Keep in mind that the short field settings shorten the ground run but
generally increase the distance to clear a 50' obstical.

Mike
MU-2

Mike Rapoport wrote:
: Keep in mind that the short field settings shorten the ground run but
: generally increase the distance to clear a 50' obstical.

Isn't that the *point* of short field technique... to get off and over in the
shortest distance? There would appear to be a logical flaw to that statement.

I would agree that it will take more *time* to get to a given altitude at
(e.g. 50' obstacle clearance)... Short field performance is defined to give the best
obstacle clearance per *distance*. I would agree that soft-field technique will
increase distance, but short is short.

Am I missing something?

-Cory



--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote:
Mike Rapoport wrote:
: Keep in mind that the short field settings shorten the ground run but
: generally increase the distance to clear a 50' obstical.

Isn't that the *point* of short field technique... to get off and over in the
shortest distance? There would appear to be a logical flaw to that statement.

No, a short field is not necessarily an obstructed field. I fly my 182
into a buddies 1000 foot strip. The only obstacle is a barbed wire
fence at the ends, that's 3 feet.

wrote in message
...
Mike Rapoport wrote:
: Keep in mind that the short field settings shorten the ground run but
: generally increase the distance to clear a 50' obstical.

Isn't that the *point* of short field technique... to get off and over in
the
shortest distance? There would appear to be a logical flaw to that
statement.

I would agree that it will take more *time* to get to a given altitude at
(e.g. 50' obstacle clearance)... Short field performance is defined to
give the best
obstacle clearance per *distance*. I would agree that soft-field
technique will
increase distance, but short is short.

Am I missing something?

Maybe :-) If the short field takoff is using a higher drag, higher lift
configuration (more flaps) to get off the ground at a lower speed (shorter
roll) it then takes longer (in both time and distance) to make the climb
over the obstacle because of the higher drag configuration. I hope this
makes sense.

In the Helio, the shortest ground roll is with 40 degrees of flaps but the
shortest distance over a 50' obstacle is with 30 degrees of flaps.

Mike
MU-2
Helio Courier

Mike Rapoport wrote:
: Maybe :-) If the short field takoff is using a higher drag, higher lift
: configuration (more flaps) to get off the ground at a lower speed (shorter
: roll) it then takes longer (in both time and distance) to make the climb
: over the obstacle because of the higher drag configuration. I hope this
: makes sense.

: In the Helio, the shortest ground roll is with 40 degrees of flaps but the
: shortest distance over a 50' obstacle is with 30 degrees of flaps.

: Mike
: MU-2
: Helio Courier

OK... I'll buy that. My experience with performance charts is with a 172 and
a PA-28. The latter is sorely lacking in much relevant detail. I would imagine much
more precision and other ways to figure how to eek out the maximum poop from your
Helio POH... that's what the plane's FOR!

My PA-28 book makes no distinction. Just says, "Max effort, 25 degree flaps
over 50'" It might not matter, but I don't info one way or the other.

-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote in message
...
Mike Rapoport wrote:
: Maybe :-) If the short field takoff is using a higher drag, higher lift
: configuration (more flaps) to get off the ground at a lower speed
(shorter
: roll) it then takes longer (in both time and distance) to make the climb
: over the obstacle because of the higher drag configuration. I hope this
: makes sense.

: In the Helio, the shortest ground roll is with 40 degrees of flaps but
the
: shortest distance over a 50' obstacle is with 30 degrees of flaps.

: Mike
: MU-2
: Helio Courier

OK... I'll buy that. My experience with performance charts is with a 172
and
a PA-28. The latter is sorely lacking in much relevant detail. I would
imagine much
more precision and other ways to figure how to eek out the maximum poop
from your
Helio POH... that's what the plane's FOR!

My PA-28 book makes no distinction. Just says, "Max effort, 25 degree
flaps
over 50'" It might not matter, but I don't info one way or the other.

-Cory

Actually the Helio manual is abysmal compared to the MU-2 manual which I
attibute to the age of the Helio (1974) to the MU-2 (1982). The Helio
manual does devote a lot of space to STOL techniques though. Manuals keep
getting thinker and thicker as time goes on...the FAA and lawers love paper!

Mike
MU-2

Mike Rapoport wrote:
wrote in message
...

Mike Rapoport wrote:
: Keep in mind that the short field settings shorten the ground run but
: generally increase the distance to clear a 50' obstical.

Isn't that the *point* of short field technique... to get off and over in
the
shortest distance? There would appear to be a logical flaw to that
statement.

I would agree that it will take more *time* to get to a given altitude at
(e.g. 50' obstacle clearance)... Short field performance is defined to
give the best
obstacle clearance per *distance*. I would agree that soft-field
technique will
increase distance, but short is short.

Am I missing something?


Maybe :-) If the short field takoff is using a higher drag, higher lift
configuration (more flaps) to get off the ground at a lower speed (shorter
roll) it then takes longer (in both time and distance) to make the climb
over the obstacle because of the higher drag configuration. I hope this
makes sense.

Yes, it makes sense, but I don't think it always holds up in practice. For
example, in my Mooney, the recommended obstacle clearance technique is to not
retract the gear until the obstacle is cleared. More drag gives a greater
-angle- of climb.


In the Helio, the shortest ground roll is with 40 degrees of flaps but the
shortest distance over a 50' obstacle is with 30 degrees of flaps.

It seems the configuration for best angle is model-specific.