C172 Flaps up or 10 degrees for takeoff

An interesting dilemma.
The manual for the 172 N tells you that 0-10 degrees is acceptable for
takeoff. However it does not tell you what affect it has at low altitude
300 feet MSL Density altitude around 2500 MSL. It only states that it
will have a detrimental affect at high altitude on a hot day. It also
does not give an airspeed for Vy flaps 10 degrees.

In talking to another pilot who has an 172 L has states that his manual
says if 10 degrees flaps are used it will decrease ground roll and
decrease climb rate. Having an overall detrimental affect.

The only definitive number the 172N manual states for flaps 10 degrees
is Vx.

First hand experience seems to confirm what the 172 L manual says.

What do you all think?
Michelle

"Michelle P" wrote in message
nk.net...
An interesting dilemma.
The manual for the 172 N tells you that 0-10 degrees is acceptable for takeoff. However it does not tell you what
affect it has at low altitude 300 feet MSL Density altitude around 2500 MSL. It only states that it will have a
detrimental affect at high altitude on a hot day. It also does not give an airspeed for Vy flaps 10 degrees.

In talking to another pilot who has an 172 L has states that his manual says if 10 degrees flaps are used it will
decrease ground roll and decrease climb rate. Having an overall detrimental affect.

The only definitive number the 172N manual states for flaps 10 degrees is Vx.

First hand experience seems to confirm what the 172 L manual says.

What do you all think?
Michelle


1975 C172M manual...

"Normal and obstacle clearance take-offs are performed with wing flaps up. The use of 10° flaps will shorten the ground
run approximately 10%, but this advantage is lost in the climb to a 50-foot obstacle. Therefore, the use of 10° flaps is
reserved for minimum ground runs or for take-off from soft or rough fields. If 10° of flaps are used for minimum ground
runs, it is preferable to leave them extended rather than retract them in the climb to the obstacle. In this case, use
an obstacle clearance speed of 65 mph. As soon as the obstacle is cleared, the flaps may be retracted as the aircraft
accelerates to the normal flaps up climb speed of 80 to 90 mph.

During a high altitude take-off in hot weather where the climb would be marginal with 10° flaps, it is recommended that
flaps not be used for take-off. Flap settings greater than 10° are not recommended at any time for takeoff."

The Take-off checklist has a normal and a maximum performance set of items. Both say Flaps up. The only real difference
is the brakes are held until full power is applied and the run is with the tail slightly low for the max performance
T-O...

The old C-172A book says pretty much the same thing.

From my experience the use of flaps should be reserved for those really rough or rain soaked grass fields with low
obstacles.

based on this, I was always told that 10degree flaps on take off where to
get up off that wet grassy runway and accelerate in ground effect, slower
climb rate to be expected, so make sure there are no trees at the other end.

BT

" Blueskies" wrote in message
. ..

"Michelle P" wrote in message
nk.net...
An interesting dilemma.
The manual for the 172 N tells you that 0-10 degrees is acceptable for
takeoff. However it does not tell you what affect it has at low altitude
300 feet MSL Density altitude around 2500 MSL. It only states that it
will have a detrimental affect at high altitude on a hot day. It also
does not give an airspeed for Vy flaps 10 degrees.

In talking to another pilot who has an 172 L has states that his manual
says if 10 degrees flaps are used it will decrease ground roll and
decrease climb rate. Having an overall detrimental affect.

The only definitive number the 172N manual states for flaps 10 degrees is
Vx.

First hand experience seems to confirm what the 172 L manual says.

What do you all think?
Michelle


1975 C172M manual...

"Normal and obstacle clearance take-offs are performed with wing flaps up.
The use of 10° flaps will shorten the ground run approximately 10%, but
this advantage is lost in the climb to a 50-foot obstacle. Therefore, the
use of 10° flaps is reserved for minimum ground runs or for take-off from
soft or rough fields. If 10° of flaps are used for minimum ground runs, it
is preferable to leave them extended rather than retract them in the climb
to the obstacle. In this case, use an obstacle clearance speed of 65 mph.
As soon as the obstacle is cleared, the flaps may be retracted as the
aircraft accelerates to the normal flaps up climb speed of 80 to 90 mph.

During a high altitude take-off in hot weather where the climb would be
marginal with 10° flaps, it is recommended that flaps not be used for
take-off. Flap settings greater than 10° are not recommended at any time
for takeoff."

The Take-off checklist has a normal and a maximum performance set of
items. Both say Flaps up. The only real difference is the brakes are held
until full power is applied and the run is with the tail slightly low for
the max performance T-O...

The old C-172A book says pretty much the same thing.

From my experience the use of flaps should be reserved for those really
rough or rain soaked grass fields with low obstacles.

Michelle P wrote:
In talking to another pilot who has an 172 L has states that his manual
says if 10 degrees flaps are used it will decrease ground roll and
decrease climb rate. Having an overall detrimental affect.

I have a 172S manual It's my understanding that, in terms of flaps and
related performance, all models after L are exactly the same.

My manual says that "using 10 degrees of wing flaps reduces the ground
toll and total distance over an obstacle by approximately 10 percent."
For a short field takeoff, that would be an overall beneficial affect,
not detrimental.

It's my experience that, at low airpseeds, 10 degrees of flaps
increases my climb performance substantially.

On 11 Aug 2005 00:11:51 -0700, "Brien K. Meehan"
wrote:

Michelle P wrote:
In talking to another pilot who has an 172 L has states that his manual
says if 10 degrees flaps are used it will decrease ground roll and
decrease climb rate. Having an overall detrimental affect.

I have a 172S manual It's my understanding that, in terms of flaps and
related performance, all models after L are exactly the same.

The newest (G1000) 172S manuals and checklist (and factory transition
training) say 0-10deg is approved, but 10deg is preferred to flaps up
in all conditions due to the decreased ground roll and increased climb
performance, and specifically called for when doing soft/rough field.

Michelle,

I have always read the manual to mean that 10 degrees is useful for all
situations where the ground roll should be minimal, e.g. soft fields.
Since we almost only use soft fields here in Germany, I have always
used 10 deg when I flew 172s. It got me some funny looks, though.

--
Thomas Borchert (EDDH)

Are you sure that was due to the flaps? ;-)

Michelle P wrote:
An interesting dilemma.
The manual for the 172 N tells you that 0-10 degrees is acceptable for
takeoff. However it does not tell you what affect it has at low altitude
300 feet MSL Density altitude around 2500 MSL. It only states that it
will have a detrimental affect at high altitude on a hot day. It also
does not give an airspeed for Vy flaps 10 degrees.

In talking to another pilot who has an 172 L has states that his manual
says if 10 degrees flaps are used it will decrease ground roll and
decrease climb rate. Having an overall detrimental affect.

The only definitive number the 172N manual states for flaps 10 degrees
is Vx.

First hand experience seems to confirm what the 172 L manual says.

What do you all think?
Michelle

I used to rent a 172L a lot many years ago, and used 10 degrees to
reduce the takeoff roll but for me it *increased* the rate of climb
slightly at airspeeds between Vx and Vy. Any more than 10 degrees and
it certainly hindered climb rate, but on really soft or muddy turf
strips, I'd use a little more than 10 degrees by carefully bumping the
flap switch down in short spurts during the takeoff roll until it felt
better and got the mains off the ground, then once a positive rate of
climb was established I'd carefully retract the flaps a small amount at
a time until the airplane was happier. A lot of the other renters hated
the spring-loaded up/down flap switch in the 172L because you had to
keep it pushed up or down to run the flap motor, but I liked being able
to 'fine-tune' the flaps to what felt best in a given takeoff situation.

wrote:
I used to rent a 172L a lot many years ago, and used 10 degrees to
reduce the takeoff roll but for me it *increased* the rate of climb
slightly at airspeeds between Vx and Vy.

I suspect that you were NOT at max gross weight. Were you at that
state, I expect you would find that the POH was EXACTLY correct.

We face similar problems with flaps and density altitude in Colorado.

What you experienced is exactly why we teach in the mountain flying
course to fly 10% below max gross weight... because any reduction in
load translates directly into improved performance.

Please consider coming to Colorado for the mountain flying course some
time:

http://www.coloradopilots.org/

Yes, we fly a normally aspirated C172 ("N" model) into Leadville,
Colorado at 9,927 MSL. Pattern altitude is 11,000 MSL. FUN!

Best regards,

Jer/ "Flight instruction and mountain flying are my vocation!" Eberhard

--
Jer/ (Slash) Eberhard, Mountain Flying Aviation, LTD, Ft Collins, CO
CELL 970 231-6325 EMAIL jer'at'frii.com WEB http://users.frii.com/jer/
C-206 N9513G, CFII Airplane&Glider, FAA-DEN Aviation Safety Counselor
CAP-CO Mission&Aircraft CheckPilot, BM218 HAM N0FZD, 231 Young Eagles!

wrote in message ...

http://www.coloradopilots.org/

Yes, we fly a normally aspirated C172 ("N" model) into Leadville,
Colorado at 9,927 MSL. Pattern altitude is 11,000 MSL. FUN!

Best regards,

Jer/ "Flight instruction and mountain flying are my vocation!" Eberhard



How long is the runway and what does the approach/departure zones look like?