Sim Flight Training: PPL: Landing Addendum

[Brett_Henderson]

Reading another thread, I'm reminded that we never touched on the finer points in landing. I've made many references to the, "stabilized approach" without really getting into it. Flying a plane down to the runway, and then trying to force it to stop flying, is a common mistake in simming... because you can get away with it. The whole trick is to have the plane all but landed on final, and then just wait on the runway to come to you.. and then end the whole process with a mild stall, just above the ground.

I'm borrowing a quote from Rotty...


[quote]But in general, the key to landing any plane is to understand its slow-flight characteristics, and from there how to descend in that configuration while holding a heading.
You can study up on the speeds, etc or you can just experiment, at altitude, with some random altitude selected as "ground". Start 1000 feet above that, with the plane configured for landing, and try to maintain a speed a little above stalling speed with no more than a 500 fpm descent rate. Speed is critical here- you cannot expect to land well if you randomly dive at the runway. Things need to be stable as you begin to descend. Slow, but not too slow. Sinking, but not too much. You should be able to level off, then stall (on purpose), without going past your selected altitude. Once you manage that, try it from 1000 feet above the runway, and try to flare (pull back) so that you hear that stall horn just as the mains kiss the runway. You will find that if you have the plane set up for a stable airspeed and descent rate, it will be like magic.

Your visual target should be the place you want to flare (not touch down) on the runway: the numbers are fine, usually. Use aileron, elevator and rudder to keep that target where it is. That's "all there is to it".

[beaky]

It's no coincidence that approach speed (also known as Vref), is nearly equal to Vy (best rate of climb). It's the airspeed when the wing is most stable, happy and just being a wing. In fact.. the main reason Vy and Vref are not equal, is that Vref will normally be associated with flap deployment.

This is a good point, and in fact I never thought of it that way, although I should.
 I've tended to think in more immediate terms: Vref provides the right angle and descent rate at a convenient, safe slow speed that's still far enough above stall for good directional control...  but of course the reason for that is the wing's characteristics.
 If you see an airplane a with wildly different Vref (and other speeds) than the typical trainer, you can be sure the wing is quite different, even if the plane is similar in weight, etc.
And the typical difference between Vref and Vy being due to flaps should be thought of this way: flaps change the aspect of the wing... it "morphs" into a different airfoil.

[Brett_Henderson]

And the typical difference between Vref and Vy being due to flaps should be thought of this way: flaps change the aspect of the wing... it "morphs" into a different airfoil.

That' a good way to visualize it. Another way I look at it; is that flaps and thrust are like reciprocals.. especially as it applies to approaches. Whatever it is that added power will do during an approach; flaps will do the opposite.

Of course this does not apply equally to aircraft with delta-wings and canards, but it does in the whole stabilization theory.

One you're flying planes well outside of being considered "trainers"; you'll be dealing with more and greater, out of proportion, available flaps and thrust. If wing-loading is the denominator; the proportional difference between Vy and Vref is substantial. Like on a 737...