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

[Roy Page]

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

[zatatime]

On Thu, 18 Nov 2004 02:34:16 GMT, "Roy Page" >
wrote:

>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.
In the summer, heavily loaded I'd say he's right. In the summer with
obstacles at the end of the runway I'd also say he's right.

>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.
In the winter, or fall with a headwind I'd say he's right. At a field
with no obstacles and fields beyond the end of the runway, I'd also
say he's right.



There is no cut and dry answer to this. You need to learn your
airplane. Look at the POH and make a determination of what you feel
is appropriate for your skill level. It's pretty obvious these two
are fighting for fighting sake since they are arguing over something
that is situationally dependant, and one of the "finer" points of
flying. If you're completely in doubt use the 25 the POH says and you
should get close to what the charts depict for short field performance
assuming a descent engine and airframe.

HTH & Good luck with those two.

z

[BTIZ]

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.

With no data in the POH for a "modified short field technique", then you are
a test pilot and only can reasonably estimate that the required distance to
clear the 50ft obstacle is somewhere between the no flap (normal) departure
and the prescribes short field (2 notch) departure.

I can read the NTSB report now, pilot attempting take off from a short field
did not follow the prescribed takeoff procedure and failed to outclimb the
obstacle on departure. Causal factor: Pilot error.

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
>
>

[Blanche]

And don't forget density altitude!

[Jim Burns]

Try taking the landing and take off distances over a 50 ft obstacle and
doubling them. Anything at or under those distances I'd consider using the
short field techniques.

I just grabbed an old Archer II POH and ran my finger across the table I
come up with a rough guess short field take off over a 50 ft obstacle
distance of 1500 ft from a dry paved runway with 25 degrees of flaps at
standard conditions. Double that and you get 3000 ft. Under 3000 ft I'd
use the short field technique. Flaps up, same conditions takes 1850 feet.
Double that and you get 3700 ft.

Between 3700 and 3000 ft of runway, it would depend more on the
circumstances and conditions.

I'd apply the same rule of thumb to landings.

These numbers may sound way to conservative, but they give you a lot of
fundge factor on the safe side and I'd rather be safe than sorry. Most of
us don't fly factory fresh airplanes and most of us aren't test pilots.

Jim



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[[email protected]]

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 *
************************************************** ***********************

[Mike Rapoport]

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: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.
>
> 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.
>
> With no data in the POH for a "modified short field technique", then you
> are a test pilot and only can reasonably estimate that the required
> distance to clear the 50ft obstacle is somewhere between the no flap
> (normal) departure and the prescribes short field (2 notch) departure.
>
> I can read the NTSB report now, pilot attempting take off from a short
> field did not follow the prescribed takeoff procedure and failed to
> outclimb the obstacle on departure. Causal factor: Pilot error.
>
> 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
>>
>>
>
>

[Mike Rapoport]

"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]

"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
>>
>>
>
>

[Dave Butler]

Mike Rapoport wrote:
> 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.

I don't have any documentary evidence, but this is counterintuitive and contrary
to my unquantified experience. The Cherokees feel like they go up at a much
steeper angle with the flaps. Is it an illusion?

[Mike Rapoport]

"Dave Butler" > wrote in message
...
> Mike Rapoport wrote:
>> 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.
>
> I don't have any documentary evidence, but this is counterintuitive and
> contrary to my unquantified experience. The Cherokees feel like they go up
> at a much steeper angle with the flaps. Is it an illusion?
>

I think so. The Helio Courier flight manual gives different flap settings
for minimium ground run vs. minimiunm 50' obstacle clearance with a lower
flap setting for the obstacle clearance distance. These airplanes have more
sophisticated flaps than a Cherokee (single slotted fowler flaps on the
Helio) so I assume that the Cherokee is even more disadvantaged as the flaps
are deployed since they are creating relatively more drag for each increment
of increased lift. Of course, if the runway is not hard and dry, anything
that reduces ground roll will likely reduce the obstacle distance.

Also, the maximium performance takeoff in a Super Cub is to accelerate with
the flaps retracted and then deploy full flaps to break ground, then to
reduce flaps while accerating in ground effect to Vx and then to climb at
Vx. It is impressive to see someone do this well.

You will need more pitch with the lower flap setting.

Perhaps someone with a newer Cherokee could look in the manual and see if
there are obstacle clearance charts for the different takeoff
configurations?

Mike
MU-2

[Jim Burns]

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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[Mike Rapoport]

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
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.788 / Virus Database: 533 - Release Date: 11/1/2004
>
>

[Jim Burns]

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
> >
> >
> > ---
> > Outgoing mail is certified Virus Free.
> > Checked by AVG anti-virus system (http://www.grisoft.com).
> > Version: 6.0.788 / Virus Database: 533 - Release Date: 11/1/2004
> >
> >
>
>


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[[email protected]]

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 *
************************************************** ***********************

[Newps]

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.

[xyzzy]

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.

[xyzzy]

This is for a pa28-161, so don't know how different the -181 would be
but the answer is no for the -161: Vx is 63 kts. Short field takeoff
technique is with 25 degrees and climb at 52kts, which is also the short
field rotation speed.

Jim Burns wrote:

> 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
>>>
>>>
>>>---
>>>Outgoing mail is certified Virus Free.
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>>>
>>>
>>
>>
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.788 / Virus Database: 533 - Release Date: 11/1/2004
>
>

[Mike Rapoport]

> 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

[[email protected]]

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 *
************************************************** ***********************

[Dave Butler]

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.

[Mike Rapoport]

"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

[Ben Jackson]

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/

[Mike Rapoport]

> 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

[Elwood Dowd]

> 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.

[John Galban]

"Roy Page" > wrote in message t>...
> 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)

[John Clonts]

"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

[PaulaJay1]

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

[BTIZ]

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

[Mike Rapoport]

"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

[Jim Burns]

Archer II
Take off ground roll flaps 25 degrees is about 875 ft standard conditions,
dry, paved, level..... Lift off speed 49 knots, barrier speed 54 knots at
gross weight 1850ft over an obstacle

Flaps up is about 975 ft standard conditions, dry, paved, level.....Lift off
speed 53 knots, barrier speed 58 knots at gross weight, about 1550 ft over
an obstacle



"Jim Burns" > wrote in message
...
> 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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> > >
> > >
> >
> >
>
>
> ---
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> Checked by AVG anti-virus system (http://www.grisoft.com).
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>
>


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[Aaron Coolidge]

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

[Jay Somerset]

On Thu, 18 Nov 2004 15:32:32 -0500, Dave Butler >
wrote:

> 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.

I really have a problem with that, and would like to see some quantitative
evidence. It flies in the face of all the laws of physics that I am
familiar with.

>
> >
> > 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.

[Jay Somerset]

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

[kage]

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
>
>

[BTIZ]

>
> 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.

[Matt Whiting]

Jay Somerset wrote:
> On Thu, 18 Nov 2004 15:32:32 -0500, Dave Butler >
> wrote:
>
>
>>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.
>
>
> I really have a problem with that, and would like to see some quantitative
> evidence. It flies in the face of all the laws of physics that I am
> familiar with.

It doesn't fly in the face of the laws of physics, if you remove the
erroneous part of his comment. More drag doesn't give a greater angle
of climb. The reason you don't retract the gear in most cases is that
the drag of the gear is highest during the retraction process. If you
could retract it instantly, then you would, but given that many
airplanes take several seconds to retract, you don't want that extra
drag between lift-off and the height of the obstacles you are trying to
clear.


Matt

[Dave Butler]

Jay Somerset wrote:
>Dave Butler wrote:
>>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 really have a problem with that, and would like to see some quantitative
> evidence. It flies in the face of all the laws of physics that I am
> familiar with.

OK, I probably shouldn't have inferred the "more drag" statement from the POH
instructions. I retract that. Much as I like flying, into the face of the laws
of physics is not where I like to do it.

Nevertheless, as others have pointed out, Cherokees have a steeper angle of clib
with flaps than without, which supports my original observation.

[Mike Rapoport]

"Dave Butler" > wrote in message
...
> Jay Somerset wrote:
> >Dave Butler wrote:
>>>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 really have a problem with that, and would like to see some
>> quantitative
>> evidence. It flies in the face of all the laws of physics that I am
>> familiar with.
>
> OK, I probably shouldn't have inferred the "more drag" statement from the
> POH instructions. I retract that. Much as I like flying, into the face of
> the laws of physics is not where I like to do it.
>
> Nevertheless, as others have pointed out, Cherokees have a steeper angle
> of clib with flaps than without, which supports my original observation.
>
Didn't you read Jim Burns post? He reported the following:

Archer II
Take off ground roll flaps 25 degrees is about 875 ft standard conditions,
dry, paved, level..... Lift off speed 49 knots, barrier speed 54 knots at
gross weight 1850ft over an obstacle

Flaps up is about 975 ft standard conditions, dry, paved, level.....Lift off
speed 53 knots, barrier speed 58 knots at gross weight, about 1550 ft over
an obstacle

Clearly, if his POH is to be believed, the Archer climbs better with flaps
up.

Mike
MU-2

[kage]

"Dave Butler" > wrote in message
...
>
> Nevertheless, as others have pointed out, Cherokees have a steeper angle
> of clib with flaps than without, which supports my original observation.
>

No.

They do not.

Vx is without flaps. Period!

Karl

[Dave Butler]

Mike Rapoport wrote:

> Didn't you read Jim Burns post? He reported the following:

<sigh> back to my reading comprehension class... Thanks.

[Dave Butler]

kage wrote:

> Vx is without flaps. Period!

OK, my batting average is not very good on this thread, what with flying in the
face of physics and all.

Please explain what your emphatic statement above means. I'm trying to learn
from this, but I'd like a little more detail than just defining Vx by fiat.

[Mike Rapoport]

"BTIZ" > wrote in message
news:lmfnd.106367$bk1.76106@fed1read05...
> >
>> 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
>

This doesn't make sense to me. How can the plane take off shorter if the
rotation is made at the same speed and the plane accelerates slower (with
the flaps down.)

> 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)
>

This sounds more like what I would expect. The question I now have is
whether the distance figures you gave earlier are for the "short field with
obstacle" or without the obstacle. Also the speeds I am interested in are
the speeds at the 50' obstacle.

The basic theory that I am espousing (supported by several POHs) is that a
certain amount of energy is added to the airplane between being stationary
on the ground and being 50' higher and moving at some speed. Since flaps do
nothing except increase the drag on the ground roll and have a lower l/d,
less energy is availible to accelerate and climb with the flaps down. This
is only valid if the speeds at the 50 obstacle are equal.

Mike
MU-2

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

[kage]

"Dave Butler" > wrote in message
...
> kage wrote:
>
>> Vx is without flaps. Period!
>
> OK, my batting average is not very good on this thread, what with flying
> in the face of physics and all.
>
>>> Please explain what your emphatic statement above means. I'm trying to
>>> learn from this, but I'd like a little more detail than just defining Vx
>>> by fiat.


On any standard light aircraft wing, all best climbs (rate of climb Vy, and
angle of climb Vx) are achieved with a clean wing. Adding flaps causes the
climb angle and rate to decrease.

Another way to look at it is the airspeed indicator. Anytime the IAS in the
green range, climb is best achieved with no flaps.

Aircraft that come to mind where this is not true are weird one's like the
DHC-2 Beaver and possibly the MU-2.

Karl


>
>
>
>
>

[Newps]

kage wrote:

>
> On any standard light aircraft wing, all best climbs (rate of climb Vy, and
> angle of climb Vx) are achieved with a clean wing. Adding flaps causes the
> climb angle and rate to decrease.

Not on my 182. The manual says, and I quote...

Using 20 degree wing flaps reduces the ground run and total distance
over the obstacle by approx 20 percent.

And while I certainly don't have accurate instrumentation in the plane
my seat of the pants obsevation tells me that if I have to clear an
obstacle I want 20 flaps. I get off a lot shorter and climb to a given
altitude in a lot less real estate.

[John Galban]

"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)

[Jim Burns]

Over an obstacle figures should be reversed.
1850 OAO with flaps UP
1550 OAO with 25 degrees of flaps
mistake on my part, remainder of the post is correct.

Jim

"Jim Burns" > wrote in message
...
> Archer II
> Take off ground roll flaps 25 degrees is about 875 ft standard conditions,
> dry, paved, level..... Lift off speed 49 knots, barrier speed 54 knots at
> gross weight 1850ft over an obstacle
>
> Flaps up is about 975 ft standard conditions, dry, paved, level.....Lift
off
> speed 53 knots, barrier speed 58 knots at gross weight, about 1550 ft over
> an obstacle



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[Dave Butler]

Jim Burns wrote:
> Over an obstacle figures should be reversed.
> 1850 OAO with flaps UP
> 1550 OAO with 25 degrees of flaps
> mistake on my part, remainder of the post is correct.

Thanks for the correction, Jim! That's more in line with my unscientific
observations.

[Jim Burns]

Mine too. Sorry for the mistake, I had too many things going on when I
looked up that info.
Jim

"Dave Butler" > wrote in message
...
> Jim Burns wrote:
> > Over an obstacle figures should be reversed.
> > 1850 OAO with flaps UP
> > 1550 OAO with 25 degrees of flaps
> > mistake on my part, remainder of the post is correct.
>
> Thanks for the correction, Jim! That's more in line with my unscientific
> observations.
>


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[kage]

"Newps" > wrote in message
...
>
>
> kage wrote:
>
>>
>> On any standard light aircraft wing, all best climbs (rate of climb Vy,
>> and angle of climb Vx) are achieved with a clean wing. Adding flaps
>> causes the climb angle and rate to decrease.
>
> Not on my 182. The manual says, and I quote...
>
> Using 20 degree wing flaps reduces the ground run and total distance over
> the obstacle by approx 20 percent.


Yes over an obstacle. But that is a compromise. On a short strip the
compromise is less climb for shorter takeoff distance.

Your 182 manual NEVER says that Vx is with flaps. NOWHERE!

Vx in a 182 is clean wing. Read the POH.

Karl

[Dave Butler]

kage wrote:
> "Newps" > wrote in message
> ...
>
>>
>>kage wrote:
>>
>>
>>>On any standard light aircraft wing, all best climbs (rate of climb Vy,
>>>and angle of climb Vx) are achieved with a clean wing. Adding flaps
>>>causes the climb angle and rate to decrease.
>>
>>Not on my 182. The manual says, and I quote...
>>
>>Using 20 degree wing flaps reduces the ground run and total distance over
>>the obstacle by approx 20 percent.
>
>
>
> Yes over an obstacle. But that is a compromise. On a short strip the
> compromise is less climb for shorter takeoff distance.
>
> Your 182 manual NEVER says that Vx is with flaps. NOWHERE!
>
> Vx in a 182 is clean wing. Read the POH.

kage,

You've made that statement a couple of times as if it means something. I'm not
saying it doesn't mean anything, but when you've been asked to clarify, you
respond with more authoritarian statements that don't explain. It's as if you
expect us to just accept your authority.

It seems to me that somone can define a term, say Vx, and -define- it to be
whatever he wants. OK, so then you can authoritatively say that that's what Vx
means, but so what?

The part I am missing is: supposing I accept your statement that "Vx is a clean
wing". How am I supposed to reason from that starting point to the place where
you seem to want me to go, that best angle of climb is achieved with a clean wing?

Thanks,

Dave

[Newps]

kage wrote:

> "Newps" > wrote in message
> ...
>
>>
>>kage wrote:
>>
>>
>>>On any standard light aircraft wing, all best climbs (rate of climb Vy,
>>>and angle of climb Vx) are achieved with a clean wing. Adding flaps
>>>causes the climb angle and rate to decrease.
>>
>>Not on my 182. The manual says, and I quote...
>>
>>Using 20 degree wing flaps reduces the ground run and total distance over
>>the obstacle by approx 20 percent.
>
>
>
> Yes over an obstacle.

Well that's what were talking about...what gets me the highest in the
air in the shortest distance over the ground. My owners manual says I
get to 50 feet in 20% less distance than no flaps. Can't be more
clearer than that.


But that is a compromise.

No, it's not. I want to be the highest in the air as possible over the
shortest total ground distance. That will be with flaps 20.

[kage]

"Dave Butler" > wrote in message
...
> kage wrote:
>> "Newps" > wrote in message

I don't see what is difficult to understand.
Vx is defined as best angle of climb. Do you have a hard time understanding
that concept?


The Cessna's and Piper's discussed here have POH's. The older ones have
owners manuals. In each of these documents Vx is listed. It is always listed
as a clean wing speed. Do you have difficulty with "clean wing?"

Thus, anytime you lower flaps, climb angle is reduced. I know you don't want
to believe that, and you are just playing dumb. Are you too lazy to just
look in your POH?

Karl

[kage]

"Newps" > wrote in message
...
>
>
> kage wrote:
>
>> "Newps" > wrote in message
>> ...
>>
>>>
>>>kage wrote:
>>>
>>>
>>>>On any standard light aircraft wing, all best climbs (rate of climb Vy,
>>>>and angle of climb Vx) are achieved with a clean wing. Adding flaps
>>>>causes the climb angle and rate to decrease.
>>>
>>>Not on my 182. The manual says, and I quote...
>>>
>>>Using 20 degree wing flaps reduces the ground run and total distance over
>>>the obstacle by approx 20 percent.
>>
>>
>>
>> Yes over an obstacle.
>
> Well that's what were talking about...what gets me the highest in the air
> in the shortest distance over the ground. My owners manual says I get to
> 50 feet in 20% less distance than no flaps. Can't be more clearer than
> that.
>
>
> But that is a compromise.
>
> No, it's not. I want to be the highest in the air as possible over the
> shortest total ground distance. That will be with flaps 20.

It is most certainly a compromise, since you never accelerate to Vx.

Your speed is just a climb speed to clear close in obsticles, and is not
related to Vx. Once clear of those close in obstacles you will want to
accelerate to Vx and retract flaps if you want to continue to climb at best
angle.

Simple concept.
>

[Jay Somerset]

On Fri, 19 Nov 2004 15:01:57 -0700, Newps > wrote:

>
>
> kage wrote:
>
> > "Newps" > wrote in message
> > ...
> >
> >>
> >>kage wrote:
> >>
> >>
> >>>On any standard light aircraft wing, all best climbs (rate of climb Vy,
> >>>and angle of climb Vx) are achieved with a clean wing. Adding flaps
> >>>causes the climb angle and rate to decrease.
> >>
> >>Not on my 182. The manual says, and I quote...
> >>
> >>Using 20 degree wing flaps reduces the ground run and total distance over
> >>the obstacle by approx 20 percent.
> >
> >
> >
> > Yes over an obstacle.
>
> Well that's what were talking about...what gets me the highest in the
> air in the shortest distance over the ground. My owners manual says I
> get to 50 feet in 20% less distance than no flaps. Can't be more
> clearer than that.
>
>
> But that is a compromise.
>
> No, it's not. I want to be the highest in the air as possible over the
> shortest total ground distance. That will be with flaps 20.

Just can't resist jumping in here. Your climb gradient with flaps will be
lower than with zero flaps. The only reason that you do better over a 50 ft
obstacle is that your ground run is shortened so much (in a 182) that it
more than makes up for the shallower climb to 50 AGL. Most 172's, for
example, are better without flaps, even over a (standard) 50 ft obstacle
(per their POH's).

[Jay Somerset]

On 19 Nov 2004 12:17:45 -0800, (John Galban) wrote:

> "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.

It's because the wheels get out of the grass earlier, and the climb starts
farther from the trees, even if the climb angle is less than optimum.

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

[Ron Natalie]

Jay Somerset wrote:

>
> Just can't resist jumping in here. Your climb gradient with flaps will be
> lower than with zero flaps.

Best angle of climb is determined by what gives you the most excess thrust.
Best rate of climb is determined b what gives you the most excess power.

[One's Too Many]

"Roy Page" > wrote in message t>...
> 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.

At sea level or up to maybe ~ 1500MSL field elevations and at
"reasonable" density altitudes, I'd say short field would in an Archer
would be runways under 2500' long. A few years ago before I got my
PPASEL, I used to ride often with a fellow who operated a Cherokee 140
out of a 2000' private grass strip in the middle of Texas. Even in the
summer time, the 140 had no problems with the two of us on board with
fuel to the tabs. We were nowhere near max gross however, and had no
obstacles to clear at either end of the airstrip.

[Roy Page]

Gentlemen,

I really appreciate all the informed and learned replies to my question.
I know my Archer pretty well, and have flown rental Archers for a number of
years.
The POH is totally clear on the techniques regarding take-off and the use of
flaps.
I did not intend to ask questions which the POH properly covers.
My question is much more simple.
Where can I find the definition for a "Short Field" as referred to in my
POH.
The POH makes no attempt to define the length of the short field.
That's all I need guys, Where can I find either a defined formulae or Piper
specific definition of a "Short Field"

Thanks for all the great input that this question has created.

--
Roy
N5804F - PA28-181



have pored a POH and
"One's Too Many" > wrote in message
om...
> "Roy Page" > wrote in message
> t>...
>> 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.
>
> At sea level or up to maybe ~ 1500MSL field elevations and at
> "reasonable" density altitudes, I'd say short field would in an Archer
> would be runways under 2500' long. A few years ago before I got my
> PPASEL, I used to ride often with a fellow who operated a Cherokee 140
> out of a 2000' private grass strip in the middle of Texas. Even in the
> summer time, the 140 had no problems with the two of us on board with
> fuel to the tabs. We were nowhere near max gross however, and had no
> obstacles to clear at either end of the airstrip.

[Newps]

Roy Page wrote:

> Where can I find the definition for a "Short Field" as referred to in my
> POH.

No such thing.


> The POH makes no attempt to define the length of the short field.

Because it's a moving target. Weight, wind and air density all affect
performance.

[Matt Whiting]

Newps wrote:
>
>
> kage wrote:
>
>>
>> On any standard light aircraft wing, all best climbs (rate of climb
>> Vy, and angle of climb Vx) are achieved with a clean wing. Adding
>> flaps causes the climb angle and rate to decrease.
>
>
> Not on my 182. The manual says, and I quote...
>
> Using 20 degree wing flaps reduces the ground run and total distance
> over the obstacle by approx 20 percent.
>
> And while I certainly don't have accurate instrumentation in the plane
> my seat of the pants obsevation tells me that if I have to clear an
> obstacle I want 20 flaps. I get off a lot shorter and climb to a given
> altitude in a lot less real estate.

Yes, that is my recollection from when I owned a Skylane. It's takeoff
and climb with 20 flaps was impressive and I believe the speed
recommended in this configuration was something ridiculously low like 51
knots. I did this a few times for practice and the deck angle was
scary, but the old girl flew just fine.

I don't know the ins and outs of Vx and Vy, but it may be that they are
simply the best angle and rate with a clean wing, not that a clean wing
produces the best angle or rate. There is a difference...


Matt

[Matt Whiting]

kage wrote:

> "Newps" > wrote in message
> ...
>
>>
>>kage wrote:
>>
>>
>>>On any standard light aircraft wing, all best climbs (rate of climb Vy,
>>>and angle of climb Vx) are achieved with a clean wing. Adding flaps
>>>causes the climb angle and rate to decrease.
>>
>>Not on my 182. The manual says, and I quote...
>>
>>Using 20 degree wing flaps reduces the ground run and total distance over
>>the obstacle by approx 20 percent.
>
>
>
> Yes over an obstacle. But that is a compromise. On a short strip the
> compromise is less climb for shorter takeoff distance.
>
> Your 182 manual NEVER says that Vx is with flaps. NOWHERE!
>
> Vx in a 182 is clean wing. Read the POH.

Yes, but just because a clean wing has a certain velocity that provides
the best rate or angle in that configuration (no flaps), doesn't
necessarily mean that this is the best rate and angle that the airplane
is capable of achieving in other configurations. I don't know why Vx
and Vy are provided only in the clean configuration, but that may simply
be by definition and may not imply that this is the best that the
airplane is capable of.


Matt

[Matt Whiting]

kage wrote:

> "Dave Butler" > wrote in message
> ...
>
>>kage wrote:
>>
>>>"Newps" > wrote in message
>
>
> I don't see what is difficult to understand.
> Vx is defined as best angle of climb. Do you have a hard time understanding
> that concept?
>
>
> The Cessna's and Piper's discussed here have POH's. The older ones have
> owners manuals. In each of these documents Vx is listed. It is always listed
> as a clean wing speed. Do you have difficulty with "clean wing?"
>
> Thus, anytime you lower flaps, climb angle is reduced. I know you don't want
> to believe that, and you are just playing dumb. Are you too lazy to just
> look in your POH?

I believe Newps WAS quoting his POH? What part of that didn't you
understand? You also are aware that Vx and Vy aren't constants, right?
They vary with aircraft weight for one thing. And steady state best
angle and best rate of climb aren't necessarily correlated with the
takeoff regime and clearing an obstacle.


Matt

[Matt Whiting]

Roy Page wrote:

> Gentlemen,
>
> I really appreciate all the informed and learned replies to my question.
> I know my Archer pretty well, and have flown rental Archers for a number of
> years.
> The POH is totally clear on the techniques regarding take-off and the use of
> flaps.
> I did not intend to ask questions which the POH properly covers.
> My question is much more simple.
> Where can I find the definition for a "Short Field" as referred to in my
> POH.
> The POH makes no attempt to define the length of the short field.
> That's all I need guys, Where can I find either a defined formulae or Piper
> specific definition of a "Short Field"
>
> Thanks for all the great input that this question has created.
>

I don't think "short field" is meant to be a definition of an airport.
It is meant to mean a takeoff or landing technique that minimizes either
the ground roll (in the case of no obstacles) or the total takeoff or
landing distance over an obstacle of a given height. It isn't a
specific length of runway as the capability of the airplane will vary
with density altitude, aircraft weight, CG location, etc.


Matt

[BTIZ]

>> 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
>>
>
> This doesn't make sense to me. How can the plane take off shorter if the
> rotation is made at the same speed and the plane accelerates slower (with
> the flaps down.)
>
>> 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)
>>
>
> This sounds more like what I would expect. The question I now have is
> whether the distance figures you gave earlier are for the "short field
> with obstacle" or without the obstacle. Also the speeds I am interested
> in are the speeds at the 50' obstacle.
>
> The basic theory that I am espousing (supported by several POHs) is that a
> certain amount of energy is added to the airplane between being stationary
> on the ground and being 50' higher and moving at some speed. Since flaps
> do nothing except increase the drag on the ground roll and have a lower
> l/d, less energy is availible to accelerate and climb with the flaps down.
> This is only valid if the speeds at the 50 obstacle are equal.
>
> Mike
> MU-2
>
>> I should add that this is from the 1973 PA-32-300, fixed gear, fat wings.
>>
>> BT.

Mike.. like I said, it's a 1973 manual... so details are not very forth
coming.

Previous distances were for normal (10degree flap) and short field (25
degree flap)
Speeds at the 50ft mark based on the text would not be the same.
Normal take off, 10degree flap, plane will lift off at about 65-70 and
allowed to accelerate in climb to enroute cruise climb speed of 115. The
50ft speed should be somewhere between 70 and 115.
Short field, lift off as soon as possible, accelerate in ground effect to 95
(Vx) and maintain Vx until clear of obstacle, so the 50ft speed should be
95.

The distance charts are not easy to interpolate, but the Max GW at Sea Level
differences are not much more than 100ft.

BT

[Mike Rapoport]

"kage" > wrote in message
...
>
> "Dave Butler" > wrote in message
> ...
>> kage wrote:
>>
>>> Vx is without flaps. Period!
>>
>> OK, my batting average is not very good on this thread, what with flying
>> in the face of physics and all.
>>
>>>> Please explain what your emphatic statement above means. I'm trying to
>>>> learn from this, but I'd like a little more detail than just defining
>>>> Vx by fiat.
>
>
> On any standard light aircraft wing, all best climbs (rate of climb Vy,
> and angle of climb Vx) are achieved with a clean wing. Adding flaps causes
> the climb angle and rate to decrease.
>
> Another way to look at it is the airspeed indicator. Anytime the IAS in
> the green range, climb is best achieved with no flaps.
>
> Aircraft that come to mind where this is not true are weird one's like the
> DHC-2 Beaver and possibly the MU-2.
>
> Karl
>

The MU-2 has a conventional wind for an airplane in its speed range and
definately climbs best with flaps up.

Mike
MU-2

[Newps]

Matt Whiting wrote:

>
> Yes, that is my recollection from when I owned a Skylane. It's takeoff
> and climb with 20 flaps was impressive and I believe the speed
> recommended in this configuration was something ridiculously low like 51
> knots. I did this a few times for practice and the deck angle was
> scary, but the old girl flew just fine.
>

And I have VG's so I can climb well below the white arc.

[Matt Whiting]

Newps wrote:

>
>
> Matt Whiting wrote:
>
>>
>> Yes, that is my recollection from when I owned a Skylane. It's
>> takeoff and climb with 20 flaps was impressive and I believe the speed
>> recommended in this configuration was something ridiculously low like
>> 51 knots. I did this a few times for practice and the deck angle was
>> scary, but the old girl flew just fine.
>>
>
> And I have VG's so I can climb well below the white arc.

I fly a 180 HP club Arrow now and boy do I miss the Skylane during
take-off and climb. The Arrow is marginally faster in cruise, but it is
a pig on take-off and climb, especially at lower airspeeds. It doesn't
climb well at all until above 80 knots.


Matt

[Mike Rapoport]

"Matt Whiting" > wrote in message
...
> Newps wrote:
>>
>>
>> kage wrote:
>>
>>>
>>> On any standard light aircraft wing, all best climbs (rate of climb Vy,
>>> and angle of climb Vx) are achieved with a clean wing. Adding flaps
>>> causes the climb angle and rate to decrease.
>>
>>
>> Not on my 182. The manual says, and I quote...
>>
>> Using 20 degree wing flaps reduces the ground run and total distance over
>> the obstacle by approx 20 percent.
>>
>> And while I certainly don't have accurate instrumentation in the plane my
>> seat of the pants obsevation tells me that if I have to clear an obstacle
>> I want 20 flaps. I get off a lot shorter and climb to a given altitude
>> in a lot less real estate.
>
> Yes, that is my recollection from when I owned a Skylane. It's takeoff
> and climb with 20 flaps was impressive and I believe the speed recommended
> in this configuration was something ridiculously low like 51 knots. I did
> this a few times for practice and the deck angle was scary, but the old
> girl flew just fine.
>
> I don't know the ins and outs of Vx and Vy, but it may be that they are
> simply the best angle and rate with a clean wing, not that a clean wing
> produces the best angle or rate. There is a difference...
>
>
> Matt


Maximium rate and angle of climb are both achieved with flaps up at Vx and
Vy. That doesn't mean that the best climb angle or rate at speeds below Vx
are with the flaps up. Take the extreme case where the speed is such that
the wing is stalled with flaps up but not with them down. Clearly in that
case the airplane will climb better with flaps down.

Mike
MU-2

[TMG]

Kage,

I guess it is you who is lazy. Too lazy to read the topic or think about it
straight. The majority will understand the concept of a clean wing and Vx.
But I do hope you understand the difference between the concepts of Vx and
Short Field Take Off, as they most certainly are not the same!

TMG

"kage" > wrote in message
...
>
> "Dave Butler" > wrote in message
> ...
> > kage wrote:
> >> "Newps" > wrote in message
>
> I don't see what is difficult to understand.
> Vx is defined as best angle of climb. Do you have a hard time
understanding
> that concept?
>
>
> The Cessna's and Piper's discussed here have POH's. The older ones have
> owners manuals. In each of these documents Vx is listed. It is always
listed
> as a clean wing speed. Do you have difficulty with "clean wing?"
>
> Thus, anytime you lower flaps, climb angle is reduced. I know you don't
want
> to believe that, and you are just playing dumb. Are you too lazy to just
> look in your POH?
>
> Karl
>
>

[Jay Somerset]

On Fri, 19 Nov 2004 18:15:23 -0500, Ron Natalie > wrote:

> Jay Somerset wrote:
>
> >
> > Just can't resist jumping in here. Your climb gradient with flaps will be
> > lower than with zero flaps.
>
> Best angle of climb is determined by what gives you the most excess thrust.
> Best rate of climb is determined b what gives you the most excess power.

Absolutely correct! Have you ever seen an example where there is greater
excess thrust (at any airspeed) with flaps deployed? I suppose one could
design a wing where this was true, but I have some doubts that any (popular)
GA aircraft exhibits this behavior. Am I wrong?

[Roger]

On Sat, 20 Nov 2004 00:04:45 GMT, "Roy Page" >
wrote:

>Gentlemen,
>
>I really appreciate all the informed and learned replies to my question.
>I know my Archer pretty well, and have flown rental Archers for a number of
>years.
>The POH is totally clear on the techniques regarding take-off and the use of
>flaps.
>I did not intend to ask questions which the POH properly covers.
>My question is much more simple.
>Where can I find the definition for a "Short Field" as referred to in my
>POH.
>The POH makes no attempt to define the length of the short field.
>That's all I need guys, Where can I find either a defined formulae or Piper
>specific definition of a "Short Field"
>
>Thanks for all the great input that this question has created.

"Short field" is any field that feels, or looks short to you. It will
vary with your competency/currency in techniques.

I land my Deb at a friends sod strip and think nothing of it. OTOH I
hear: "You landed on that short little strip? Good Lord, I was
stopped in half the strip length and well over 300 feet above the
trees on the way out without straining".

That was in a conversation with a 172 pilot.
To him it was a short field. To me it wasn't.

Bring in Cherokee in steep at book speeds and it'll use very little
distance to land and stop. Probably a lot less than it'll take to get
out.

Get the book out. Do the weight and take off distance over any
obstacles for the temperature. If the take off distance at the
current conditions is going to require good short field techniques to
get out, then it is a short field. IF you are proficient on short
field techniques (and I don't mean having done them a few times) it's
no big deal, but it will leave little margin for error, or for an
engine not developing full HP.

So there are two definitions of short field. If the field seems short
enough to make the pilot consider it short (whether it is or not), or
if the TO calculations show it to require short filed techniques then
it's a short field.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

[Mike Rapoport]

How about where the speed was between that where the wing would stall flaps
up but not flaps down?

Mike
MU-2

"Jay Somerset" > wrote in message
...
> On Fri, 19 Nov 2004 18:15:23 -0500, Ron Natalie > wrote:
>
>> Jay Somerset wrote:
>>
>> >
>> > Just can't resist jumping in here. Your climb gradient with flaps will
>> > be
>> > lower than with zero flaps.
>>
>> Best angle of climb is determined by what gives you the most excess
>> thrust.
>> Best rate of climb is determined b what gives you the most excess power.
>
> Absolutely correct! Have you ever seen an example where there is greater
> excess thrust (at any airspeed) with flaps deployed? I suppose one could
> design a wing where this was true, but I have some doubts that any
> (popular)
> GA aircraft exhibits this behavior. Am I wrong?
>

[Paul Sengupta]

"Jay Somerset" > wrote in message
...
> 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?

I would guess about 50ft! :-) My observations in a 172 are the same,
you can gain speed then leap up over obstacles...I believe there's a
technique where you can "leap" up over an obstacle, get to less than
the (1g) stall speed while pushing forward over the obstacle to unload the
wing (less-g = lower stall). I don't think I'd really like to try that.

If there's a headwind, wouldn't climbing at less than Vx possibly give you
a better angle of climb as seen from the ground?

Paul

[Paul Sengupta]

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

Mmm, like others have said, I would think this is model specific.
You know when you accelerate for take-off...the increase in speed
takes proportionately longer as you get faster, so you use up much
more runway getting from 55 to 60 knots than 0-5 knots (basic
physics)...thus I would think that (for instance) if you start your
climb by lifting off at 55 knots rather than at 60, you've saved a
fair bit of runway. Usually I would guess that this distance saved
more than compensates for the slight decrease in climb angle with
flaps.

Paul

[Paul Sengupta]

"Matt Whiting" > wrote in message
...
> kage wrote:
> > Vx in a 182 is clean wing. Read the POH.
>
> Yes, but just because a clean wing has a certain velocity that provides
> the best rate or angle in that configuration (no flaps), doesn't
> necessarily mean that this is the best rate and angle that the airplane
> is capable of achieving in other configurations. I don't know why Vx
> and Vy are provided only in the clean configuration, but that may simply
> be by definition and may not imply that this is the best that the
> airplane is capable of.

Indeed. It may be useful to know what the best angle of climb speed
is with 20 degrees (or whatever) of flap.

Paul

[Paul Sengupta]

"Roy Page" > wrote in message
k.net...
> My question is much more simple.
> Where can I find the definition for a "Short Field" as referred to in my
> POH.
> The POH makes no attempt to define the length of the short field.
> That's all I need guys, Where can I find either a defined formulae or
Piper
> specific definition of a "Short Field"

I'd say work out how much you're going to use without flap. If it's over the
distance available, or close, then it's a short field and you should use
flaps!

Paul

[Ron Natalie]

Jay Somerset wrote:
> On Fri, 19 Nov 2004 18:15:23 -0500, Ron Natalie > wrote:
>
>
>>Jay Somerset wrote:
>>
>>
>>>Just can't resist jumping in here. Your climb gradient with flaps will be
>>>lower than with zero flaps.
>>
>>Best angle of climb is determined by what gives you the most excess thrust.
>>Best rate of climb is determined b what gives you the most excess power.
>
>
> Absolutely correct! Have you ever seen an example where there is greater
> excess thrust (at any airspeed) with flaps deployed? I suppose one could
> design a wing where this was true, but I have some doubts that any (popular)
> GA aircraft exhibits this behavior. Am I wrong?
>
I was agreeing with you, just throwing in a little aerodymanic theory to
the argument.

[Kees Mies]

Hi,

There is no such thing as a short field. They simply do not exist.
On the other hand, there are enough too short fields :-(

-Kees

[Matt Whiting]

Paul Sengupta wrote:

> "Jay Somerset" > wrote in message
> ...
>
>>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?
>
>
> I would guess about 50ft! :-) My observations in a 172 are the same,
> you can gain speed then leap up over obstacles...I believe there's a
> technique where you can "leap" up over an obstacle, get to less than
> the (1g) stall speed while pushing forward over the obstacle to unload the
> wing (less-g = lower stall). I don't think I'd really like to try that.
>
> If there's a headwind, wouldn't climbing at less than Vx possibly give you
> a better angle of climb as seen from the ground?

Yes. The V speeds are based on calm conditions.

Matt