C172 Flaps up or 10 degrees for takeoff

"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.