C172 Flaps up or 10 degrees for takeoff

Grubertm,

So what's the best procedure for a sand strip, 4000AGL, 50ft obstacle ?


Don't go? Seriously, you probably want to get out of the sand ASAP. After
that, you want to climb as best as you can, but that only gets important
once you have left the ground. So, do the soft field procedure to start
with.


--
Thomas Borchert (EDDH)

Mike

That's simple enough that every one should be able to understand.

John
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On Sat, 13 Aug 2005 04:05:57 GMT, "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
roups.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 believe that some 172s only have 30deg of flaps availible. Full flaps
produce *some* additional lift even if there is a large drag increase. Keep
in mind that you are trading aerodynamic drag against the drag of the tires
in sand. On my airplanes MU-2 and Helio Courier minimium ground roll is a
function of weight, flaps and power availible.

In the Helio:

At normal density altitudes and light weights minimium ground roll is with
full flaps (40deg). This use of full flaps increases obstacle clearance
distance but reduces ground roll.

At some high density altitude and high weight the airplane won't climb out
of ground effect with full flaps without using a tremendous amount of
distance and a reduced flap setting is required.

The Helio is not that different from the 172 in terms of flaps. Both have
single slotted fowler flaps.

In the MU-2

Take off with flaps 20 uses less ground roll than flaps 5deg. Flaps 40deg
used even less distance but isn't used because the airplane becomes airborn
below Vmc and can't climb on one engine with flaps 40.

My guess is that a 172 at light weights and low density altitude will use
less runway with more than 10deg of flaps and the more powerful the engine
the more pronounced this difference. It would be interesting to see if the
new 172s have a full set of takeoff charts showing all altitudes, temps,
weights and flaps settings

Mike
MU-2


"David Rind" wrote in message
...
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

Okay, this post contradicts the previous post, and the way I learned it
is more like this post.

.... but somewhere along the way, the 172 book changed from saying that
10 degrees would decrease climb performace, to indicating that it would
increase climb performance (in terms of reduced distance to clear a 50
foot obstacle).

When did the change occur? What physically changed on the aircraft?

"Brien K. Meehan" wrote

Okay, this post contradicts the previous post, and the way I learned it
is more like this post.

... but somewhere along the way, the 172 book changed from saying that
10 degrees would decrease climb performace, to indicating that it would
increase climb performance (in terms of reduced distance to clear a 50
foot obstacle).

When did the change occur? What physically changed on the aircraft?

Bigger engine. When Lycoming upgraded the O-320 from 150 hp to 160 hp.
The 1959 manual that I quoted reflected the 145 hp Continental O-300.
I posted that data to refute George's post about "all 172's before
1964" used 20 degrees of flaps.

Bob

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.

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.

I fly an N-model and would agree with all of the above. In a soft-field
situation there may be a moderate advantage to 10deg particularly at
lighter loadings. Based on my runnings of the numbers though the
difference looks likely to be lost in the detail.

NB- 10 degrees is standard for a 172N on floats, which I suppose is the
ultimate "soft field" situation.

-cwk.

Bob Moore wrote:

I posted that data to refute George's post about "all 172's before
1964" used 20 degrees of flaps.

I did not mean that. What I meant was that any aircraft with manual flaps can
get the shortest ground run by dumping in full flaps just above stall speed and
hopping up into ground effect. All 172s prior to 1964 had manual flaps and can
use this technique.

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.

On Thu, 11 Aug 2005 00:26:56 GMT, Michelle P
wrote:

An interesting dilemma.
The manual for the 172 N tells you that 0-10 degrees is acceptable for
takeoff.
What do you all think?
Michelle

I hate giving an unscientific opinion, but piloting is a part of that.

Every Cessna (150 through 337) that I've flown just "feels better"
with 10 degrees of flaps on takeoff.

Mike Weller

Big John wrote:
[snip]
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.
[snip]

Ok, I never know whether to believe such stories or not. Here's a
similar one I liked so much that I posted it on my blog:

http://www.livejournal.com/users/clu...ter/25412.html

-C.

"Mike Rapoport" wrote in message
nk.net...
I believe that some 172s only have 30deg of flaps availible.

Yes, P series only has 30°.


--
Hello, my name is Mike, and I am an airplane addict....