Takeoff flaps & obstacle clearance

[shumway76]

Refering to C172 POH, it is mentioned that for obstacle clearance during takeoff , takeoff is done with flaps UP & rotate climb speed of 56kts until clear of obstacle.

For short/soft field take off, flaps 10 is used with climb speed of 65-70kts.
*The airspeed mentioned above could be wrong, but that's not the point of this topic*
BUT flaps 10 should not be used for takeoff requiring obstacle clearance.

Does this mean that with flaps 10 set for takeoff & climb speed of 65-70kts, your climb angle is actually lesser than flaps UP and obstacle climb speed of 56kts?

[Big Pistons Forever]

You did not specify which model of C 172 you are flying. The POH for C 172 M model specify flap 10 only for short fields with no obstacles in order to shorten the ground roll. But it specifies that they should be up for short fields with obstacles as the aircraft will get to 50 feet in a shorter distance then if the flaps where at 10.

However the POH for C 172 P, R, and S models specify using flap 10 for all short field takeoffs and notes it will reduce both ground roll and the distance needed to get o 50 feet to clear an obstacle by approximately 10 %

When in doubt read the POH :ok:

[Pilot DAR]

The technique specified in the Flight Manual will be based upon testing, and the optimum results being obtained with "average" pilot skill. There are differences in 172's over the years, including installed power. This can result in differing optimum techniques. Obviously to get the best results, you should fly it the way the Flight Manual says. This is not to say that cannot get even better results, but in doing so, you might be sacrificing safety in the case of an unexpected event.

Every aircraft manufacturer wants you to fly safely above all. They will write down the techniques and performance a little, if doing so more assures safety, compliance, and keeps them out of court!