1. Full down elevator to reduce the downforce from the tailplane, and maybe generate some upforce. Helpful to add full nose down trim I guess.

To increase the effect of the 'down' elevator, you need 'up' trim. the trim tab would then be 'down', and adding to the 'down elevator' effect (and increasing the the load for the pilot!). 'Up' trim would decrease the 'down elevator' effect.

And in all the Cessnas I've flown, putting down flap results in a nose-up trim change. Surely not what is wanted in this situation?

SSD

Nose up??? Flap reduces AoA! Trim as required.

As SSD says, whoever mentioned flaps didn't quite have the right idea. They said (quite correctly) that it results in a "nose-down attitude", but this is only achieved after you've dialled in a lot of nose-down trim to counteract the rather substantial tendency to pitch UP.

If you doubt what SSD says, try doing a go-around in a Cessna from full flaps, but be ready to push forward really hard!

Not sure that's the same thing: If you do a go-around in such a situation you should have a reasonable amount of nose-up trim to maintain the right glidepath and speed. Adding more power to the equation, and hence speed, will of course bring the nose up and require considerable force to couter...with or without flaps. Nose trim down for the new speed is of course essential.

Why the mystery? It's simpler than that. From a trimmed condition, put down some flap in 150/172. The nose will rise (putting down flap gives a nose-up trim change!). You will need to counter this with forward stick, then forward trim to take away the stick force.

Isn't this basic stuff, or am I missing something?

SSD

To quote SD:
This is true for stable flight. What you say is true the instant you slap flap on. Not the same thing.

Depending on the amount of flap and the type of A/C, high or low wing, then the angle of the airflow as it strikes the stabiliser can also have a great effect on trim, which tends to push the nose up. Especially with the initial stages of flap.

HWD had it nailed though. The (primary) problem is not with control authority but with stability. Chances are you'll be flying tail first in an instant... and this will not depend on your airspeed. :/

Cheers,
Fred

Staying with the high wing situation,

the issue of instant and terminal uncontrollability did not seem to apply for our NZ hero, so how did he manage it, and why?

and the suggestion that he was lucky to hit the ground when his C180 had fortuitously decided to twitch upwards a bit is denied by his own (second hand) evidence (see above).

The "going around" trim change doesn't apply here because the trim change is required to counteract the thrust of the engine (which in our case, we do not have . . . ) at full power acting in concert with the centre of drag

SSD's assertion about needing to point the trim tab down is well made, and in this situation I'd be happy to lean on the control column for a bit, whatever the stick forces

Also, now we're without the engine, the CofG has obviously moved rearward, BUT also Upwards, and now resides just behind the trailing edge, perhaps in line with the wings & tailplane.

The point is, the man walked away - and did the flaps make the difference? how? why?

SD

Just to add a little to the discription of the Cessna incident, so well put by HectorusRex.

I believe if memory serves me correctly that the A/C had just become airbourne, no load and the prop blade was discarded at approx 150ft.

montys ex teaboy's recollection is as I understood the event to have occurred in my conversation with Goose very shortly after this incident.
I'm certain that he made no mention of using trim, as in the early C180's this was a very slow manual operation, and he would have had both hands full.
I seem to recall him mentioning using his knees to assist in getting full forward control column!
More than a little luck went his way.

Ah well, another good story scuppered by gratuitous facts.

Still, those 150 feet must have seemed horribly high.

SD

Eh :confused: