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

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.

"Dave Butler" wrote in message
...
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.


More drag, by itself, can't improve angle of climb. They must have had
another reason.

Mike
MU-2

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/

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

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.

I did some extensive testing in a Beech Sierra and discovered that gear
up or down makes extremely little difference below Vy. Less than I
could reliably notice.

"Roy Page" wrote in message ink.net...
I have been trying to determine the length of a runway that would be
considered a "short field" for my Archer II.

Whether or not a field is short depends quite a bit on the density
altitude. A 2800 ft. runway at sea level and 69F isn't a short field
for the Archer. The same runway at 7,500 ft. and 100F is probably to
short even for the short field procedure.

Basically, the POH takeoff calculation for the particular runway
will tell you how much runway you'll need for a particular
runway/altitude/temperature combination. Do the calculation, add a
fudge factor, then decide whether or not the POH short field procedure
should be used.

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

"Mike Rapoport" wrote in message
nk.net...

"Dave Butler" wrote in message
...
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.


More drag, by itself, can't improve angle of climb. They must have had
another reason.


I agree. Our C210 POH specifies the same (retract gear AFTER obstacle
clearance), and my understanding is that it's because the transition to gear
up involves the opening of the doors, etc, which causes a momentary INCREASE
in drag.

Cheers,
John Clonts
Temple, Texas
N7NZ

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

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

"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



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

Mike
MU-2