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Sim Flight Training: PPL: Landing Addendum (Read 542 times)
Dec 21st, 2007 at 6:32pm

Brett_Henderson   Offline
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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".  

The other general advice I always give is: if you are not one of those "FS9 is a grt game woot- I wnt 2 lnd a 747 in ths game how I play it land OK wot key 2 press plz?" sim pilots but instead someone who wants to learn how to fly in the sim, do NOT begin your lessons with a jet airliner or some high-performance type. The default C172 is OK, but if you like that you will love the (free) RealAir 172; it's much more realistic (I say this as a RL pilot with about 200 hours in C172s). The basics apply to every plane, but if you start with something fast and complicated, you will not get the basics down without some real struggle.  


Approach speed is the magic number while landing. 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.

I'll leave the 1-2-3s, step-by-step of landing as homework. Pretty much when to reduce power... when to deploy flaps.. when to turn final.. etc.... Because it differs. A turn to final from a standard base-leg, is different than a straight-in final, and different than a final during an instrument approach. The one thing they all share, is the importance of "stabilizing"... Having the plane at Vref and descending at a rate which will have you at the target, Rotty mentioned.

Any adjustments made will depend on the length of the final approach... wind...  and any situation that would have you altering the "steepness" (i.e. a very long, straight in final vs. a very short approach over an obstacle).

The practice configuration should be:  70kias / 20 degrees of flaps / 500fpm descent.  If you can get the plane into a 500fpm descent at 70kias and hold it there for a 1000 foot descent(within reason).. you're only an a flare/stall away from a beautiful landing.

This technique will serve you well as you move on to bigger/faster airplanes... Because they are NOT as forgiving when you try to "fly them into the ground". If you can get a 172 stabilized, you're going to REALLY appreciate getting a 737 stabilized (once you're ready)..   Wink
 
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Reply #1 - Dec 22nd, 2007 at 2:28am

beaky   Offline
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Brett_Henderson wrote on Dec 21st, 2007 at 6:32pm:
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.
 

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Reply #2 - Dec 22nd, 2007 at 9:19am

Brett_Henderson   Offline
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Quote:
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...  The amount of  "wing morphing" at your disposal... and the amount of thrust at hand makes it.. well...  it makes it more than a person needs to know, until they're flying stabilized approaches, effortlessly and flawlessly, in the trainer  Smiley

To all the aspiring pilots (sim or otherwise)... Instinctive flap use and proper power applications cannot be learned in big, fast airplanes. That's like trying to read a physics text book, before understanding, " See Spot run".

See Dick land. Land Dick, La...  ooops  *sigh*
 
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