Airbourne prematurely

[taxistaxing]

And should also say, there's no way I'd feel comfortable monkeying around with the flap settings during the takeoff roll at my current level of experience. One to leave to the bush pilots for now

[The500man]

Looking at the C172S POH it does actually say in the normal procedures section for short field takeoff with flap 10:

6. Elevator control - SLIGHTLY TAIL LOW
7. Climb Airspeed - 56 KIAS (until all obstacles cleared)
8. Wing Flaps - RETRACT SLOWLY (when airspeed is more than 60 KIAS)

For a normal takeoff:

4. Elevator Control - LIFT NOSEWHEEL AT 55 KIAS
5. Climb Airspeed - 70 - 80 KIAS
6. Wing Flaps - RETRACT (at safe altitude)

The expanded soft field procedure:

Soft or rough field takeoffs are performed with 10° flaps by lifting the airplane off the ground as soon as practical in a slightly tail low attitude. If no obstacles are ahead, the airplane should be leveled off immediately to accelerate to a higher climb speed. When departing a soft field with an aft C.G. loading, the elevator trim control should be adjusted towards the nose down direction to give comfortable control wheel forces during the initial climb.

There's actually a surprising amount of other useful information in that POH. Cessna have definitely put a lot of work into making it useful. The C172N POH is not as clear and it doesn't recommend using flaps at all, and it has slightly different target airspeeds.

[Pilot DAR]

at around 40 knots which is below a safe flying speed.

Well, because you have included the word "safe" in that statement, I'm going to agree with you in this context. However, it is certainly possible to have a 172 in sustained flight during takeoff at a slower speed, and fly it away. The challenge is that you can get into very high angles of attack doing it, and you are getting closer to the stall (which is just settling back in this condition), or banging the tail on the ground, which never good. Stop watching the ASI, look out the windshield, and feel what the airplane is telling you, the airspeed is only one part of the whole thing.

The stall warning is just that - a warning. If you are not planning to stall, then don't pull back any more. But, if you're in controlled flight, not settling, and accelerating, you do not need to lower the nose either. Acceleration takes time (or you'd have been pinned into your seat!). So give it time, safely controlling it, and it will fix itself. The super fast correction you're applying 'cause your instructor told you to is a form of over controlling. Yes, a pilot can cause a less good condition of flight instantaneously by control inputs which are poorly timed relative to what the aircraft is going to be doing in a few seconds, and tens of second hence. Patience......

If you are in the air at 40 knots, and returning to earth is inevitable, would you not much rather do so in a flared attitude? Keep the nose where you had it, a little "tail low" (to use Cessna's term). A 172 is amazingly shock absorbent in that attitude. If you contact three point, or worse, nosewheel first, the nose strut, firewall, and perhaps propeller, and engine damage is going be costly.

Yes, practice, but unfortunately you cannot practice uneven runway techniques on a smooth paved runway. You can practice just holding the aircraft attitude and getting airborne at a lower than normal speed, and that's excellent, but anything you do on a smooth runway, which seems to induce an "uneven" surface will get very bad fast. If you're going to practice "tail low" takeoffs in a 172, do so with as forward a C of G as you can accomplish. In a lightly loaded 172M or later, I would expect to be happily in ground effect, accelerating, with maybe just a brief peep of the stall horn, at 40 knots.

[achimha]

Here's the C172N manual (1978):

NORMAL TAKEOFF
1. Wing Flaps -- UP.
2. Carburetor Heat -- COLD.
3. Throttle -- FULL OPEN.
4. Elevator Control -- LIFT NOSE WHEEL (at 55 KIAS).
5. Climb Speed -- 70-80 KIAS.

SHORT FIELD TAKEOFF
1. Wing Flaps -- UP.
2. Carburetor Heat -- COLD.
3. Brakes -- APPLY.
4. Throttle -- FULL OPEN.
5. Mixture -- RICH (above 3000 feet, LEAN to obtain maximum RPM).
6. Brakes -- RELEASE
7. Elevator Control -- SLIGHTLY TAIL LOW.
8. Climb Speed -- 59 KIAS (until all obstacles are cleared).

[cockney steve]

First , let me say, I'm NOT a pilot.! (models don't count )

If anyone has any doubts, wait till your lawn needs cutting, then try sprinting across it, whilst pushing a wheelbarrow..repeat , early morning with dewy grass......then try again after it's been cut.

now we've established that there's a LOT of drag from an undercarriage, why all the paranoia about floating a few inches above the surface,in Ground-effect?

the aircraft won't SLAM back down,unless you force it, but it WILL accelerate a damned sight quicker than it does when it's dragging wheels along a ground-surface (paved or otherwise)

[The500man]

What's interesting about the N, is that it says with 10° of flap (for rough field), subtract 5 KIAS from the flaps up takeoff speed. Which if you go and look at section 5 is 50-52 KIAS depending on weight. So 45-47 KIAS.

That sounds about right to me. Accelerating from about 45-50 in an N seemed to take forever to me on grass when I last flew one (as I wrote earlier).