C172 Flaps up or 10 degrees for takeoff

I would guess (low time pilot warning here, wait for someone else to
comment) that soft field takeoff would be the best bet here, except
climbing out at VX instead of VY after accelerating out of ground
effect. That way, you're not dealing with the friction of the sand for
as long.

Ben Hallert
PP-ASEL

Some flaps (maybe even full flaps) until airborn, accelerate in ground
effect and then climb. If you are interested in this stuff, read F.E. Potts
book on bush flying.

Mike
MU-2


"grubertm" wrote in message
oups.com...
So what's the best procedure for a sand strip, 4000AGL, 50ft obstacle ?
I can see the advantage of 10 deg. flaps for a mud strip, but I am not
sure whether the increased friction due to sand is worth the decrease
in climb rate..

- Marco

Mike Rapoport wrote:
Some flaps (maybe even full flaps) until airborn, accelerate in ground
effect and then climb. If you are interested in this stuff, read F.E. Potts
book on bush flying.

Mike
MU-2


"grubertm" wrote in message
oups.com...

So what's the best procedure for a sand strip, 4000AGL, 50ft obstacle ?
I can see the advantage of 10 deg. flaps for a mud strip, but I am not
sure whether the increased friction due to sand is worth the decrease
in climb rate..

- Marco

I haven't been following this thread that closely so I may have missed
something, but "full flaps"? I thought that once you got to 40 degrees
of flaps on a 172 you were just adding drag without any appreciable
reduction in stall speed. I can't see how that would get you into ground
effect any quicker....

--
David Rind

David Rind wrote:

Mike Rapoport wrote:

Some flaps (maybe even full flaps) until airborn, accelerate in ground
effect and then climb. If you are interested in this stuff, read F.E.
Potts book on bush flying.

Mike
MU-2


"grubertm" wrote in message
oups.com...

So what's the best procedure for a sand strip, 4000AGL, 50ft obstacle ?
I can see the advantage of 10 deg. flaps for a mud strip, but I am not
sure whether the increased friction due to sand is worth the decrease
in climb rate..

- Marco


I haven't been following this thread that closely so I may have missed
something, but "full flaps"? I thought that once you got to 40 degrees
of flaps on a 172 you were just adding drag without any appreciable
reduction in stall speed. I can't see how that would get you into ground
effect any quicker....


He said maybe. Some aircraft do use full flaps for takeoff. The Cessna
does not. You want 20 degrees to break ground quickly, accelerate to 80
mph and milk the flaps up and then climb. If you have an obstacle then
you accelerate to 60 mph with the flaps down and keep it there and climb
above the obstacle. Once above the obstacle accelerate to 80 and get
the flaps up.

For which Cessna model is that procedure recommended? Certainly not
any version of the 172.

David Rind wrote:

I haven't been following this thread that closely so I may have missed
something, but "full flaps"? I thought that once you got to 40 degrees
of flaps on a 172 you were just adding drag without any appreciable
reduction in stall speed. I can't see how that would get you into ground
effect any quicker....

With an aircraft which has the ability to dump the flaps quickly (about anything
with a "Johnson bar"), you can get a remarkably short ground run by accelerating
with no flaps until just past the full flap stall speed. Drop the flaps down,
use a little elevator to yank it into ground effect, immediately put the yoke
forward to keep it a few feet above the runway, and milk the flaps up in ground
effect.

Obviously you aren't going to be able to drop the flaps that rapidly with a
172N, but the full-flaps stall speed is only 51 mph. Perhaps accelerating to
about 55 with the flaps down wouldn't incur much of a drag penalty?

Note that you *do* get a hefty drag penalty while the flaps are down, so your
distance to clear the traditional 50' obstacle is likely to be longer than a
normal takeoff.

It's a fun technique to try when there's no pucker factor involved. I used to
almost always spoil the effect by banging the tailwheel getting off the ground.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

Brien K. Meehan wrote:
For which Cessna model is that procedure recommended? Certainly not
any version of the 172.

Any 172 made prior to 1964.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

George Patterson wrote:
Brien K. Meehan wrote:
For which Cessna model is that procedure recommended? Certainly not
any version of the 172.

Any 172 made prior to 1964.

Ah, I haven't had the pleasure. Thanks!

George Patterson wrote
Brien K. Meehan wrote:
For which Cessna model is that procedure recommended? Certainly not
any version of the 172.

Any 172 made prior to 1964.

From my 1959 Cessna 172 Owner's Handbook:

For unusually short field takeoffs, apply 10 degrees
flaps (first notch) prior to takeoff. An alternated
procedure ofapplying 10 degrees just before the airplane
is ready to leave the ground may be used in lieu of the
above method of leaving the flaps in the 10-degree
position throughout the entire ground run. Four further
discussion of the use of wing flaps for take-off, see
page 3.2

Wing Flap Settings
For Normal takeoff Up 0 degrees
For Shortest takeoff 1st Notch 10 degrees
For Landing 2nd Notch 20 degrees, 3rd Notch 30 degrees,
4th Notch 40 degrees
-------------------------------------------------------
F. TAKE-OFF.
NORMAL TAKE-OFF.
(1) Flaps 0 degrees (retracted).
-------------------------------------------------------
MINIMUM GROUND RUN TAKE-OFF.
(1) Wing flaps 10' (First notch).
(2) Apply full throttle while holding brakes.
(3) Release brakes.
(4) Take-off slightly tail low.
OBSTACLE CLEARANCE TAKE-OFF.
(1)Wing flaps 0 degrees (retracted).
(2) Apply full throttle while holding brakes.
(3) Release brakes.
(4) Take-off slightly tail low.
(5) Level off momentarily to accelerate to best angle
of climb speed (60 MPH).
SOFT OR ROUGH FIELD TAKE-OFF WITH NO OBSTACLE AHEAD.
(1) Wing flaps 10-degrees (First notch).
(2) Apply full throttle and raise nosewheel clear of
ground with elevator control back pressure.
(3) Takeoff in a tail-low attitude.
(4) Level off momentarily to accelerate to a safe airspeed,
(5) Retract flaps slowly as soon as a reasonable altitude
is obtained. (see "Take-off paragraph on page 3-2)
----------------------------------------------------------
TAKE-OFF
Normal and obstacle clearance takeoffs are performed with
flaps retracted. The use of 10 degrees flaps will shorten
the ground run approximately 10%, but this advantage is
lost in the climb to a 50-foot obstacle. However, if 10
degrees of flaps are used in the ground runs, it is
preferable to leave them extended rather than retract them
in the climb to the obstacle. The exception to this rule
would be in a high altitude takeoff in hot weather where climb
would be marginal with flaps 10 degrees. Flap deflections of
30 degrees and 40 degrees are not recommended at any time for
take-off. General rules for flap operation during take-off
are as follows:
Don't under marginal conditions leave flaps on long enough
that you are losing both climb and airspeed.
Don't release flaps with airspeed below flaps up stalling speed.
(See stalling speed table on page 3-3). Do slowly release the
flaps as soon as you reasonably can after take-off, preferably
50 feet or more over terrain or obstacles.
-----------------------------------------------------------

War Story

In late 1949/early 1950 I had a P-80A on cross country headed east,
can't remember where. This early version of the P-80 had the small
engine in it and the under slung tip tanks.

It was middle of summer and I stopped at Biggs AFB (El Paso) to
refuel. Full internal and full tips.

Taxied out for a TO on R/W 21 (over 13K feet long). R/W 21 had a cross
R/W about 4K down it. I released brakes and accelerated very slowly in
the heat and altitude. When I hit the cross R/W there was a slight
bump that threw me in the air and I caught it. Wasn't accelerating
very fast so pulled the gear (flaps were still down 30 degrees) to
reduce drag.

Guess what, no climb (and no gear to land on remaining R/W). R/W
heading was over Fort Bliss and I went over it about 5 feet above the
TV antennas on the barracks (could count the elements on them) and
just missed the flag pole.

Next obstacle was the hill west of El Paso toward which I was pointed
with a snow balls chance in hell of clearing.

Used some rudder and gently skidded the nose toward the south enough
to miss the hill.

Was then over Mexico and dodging cactus and blowing sage brush.
Started milking flaps up. Would get 25 or so feet altitude and retract
flaps 2-3 degrees and when I sank would rotate the nose up to keep
from hitting ground and again fly in ground effect.

After about 20 miles into Mexico I got the flaps up and was able to
gain a little airspeed which let me climb and accelerate.

1. I was a dam good pilot in those days.
2. I was also lucky as hell which we always said was the most
important aspect of flying.

On occasion, I still wake up and see in gory color that flight in high
density altitude and temp ( Sure made a believer out of me.

Big John
`````````````````````````````````````````````````` ``````````````````````````````


On Fri, 12 Aug 2005 16:40:49 -0000, wrote:

john smith wrote:
Greg Farris wrote:
There is another reason to use 10? flaps - training.
Many students are not learning to fly a 172, but using a 172 to learn to fly
airplanes. If you are anticipating transitioning up ASAP (as in career
oriented students) it's good to get into the habit, because your next
airplane may require flaps on takeoff, and the one after that certainly will.

Cherokee Six calls for minimum 10-degrees flaps for all takeoffs.
If you try a no-flaps takeoff, your takeoff roll is significantly longer.

All correctly stated by each... however, I suggest it is better to
"learn to fly the current aircraft proficiently in the current weather
and environment" before "attempting to learn to fly the next
aircraft".

Best regards,

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