Wednesday, February 15, 2012

Post flight Analysis

SeeYou allows all sorts of post flight analysis.
In this case I reviewed my last land-out, this time in Mangakino.
Attached is the track log. The circles are me trying to get a climb as well as checking out the paddock well before it was required...1500ft above the final paddock. Admittantly I had a number of others lined up as well but when another glider landed in the final paddock it acted like a big magnet and dragged myself and one other into the ground.

Interesting.
It shows my final resting place was 800ft AMSL.
I was at 1280ft AMSL as I startd a turn on to base leg.
However I was also 500 meters away from the paddock...1760 ft.
If you use your old high School math it suggests the angle between me, the ground and my aiming point was 20 degrees. That's well less than the recommended 30 degrees.

A few interesting points come to mind...
The ground over which I was completing my downwind leg was much lower than where I eventually landed...which probably gave the impression of being higher above the aiming point than I thought.
Despite this we had to use plenty of airbrake on final...hmmm.

Also I have heard suggestions that your final should be about 30 seconds long (I have no idea why or where this comes from). In this case it was about half this at 18 seconds...hmmm.

What the picture doesn't show but SeeYou does is I landed directly into wind...that's a big tick.

However I (we...as 3 of us ended up in the same paddock) choose poorly as the paddock next door was flatter and had short grass...we landed in a paddock of quite long grass..which could have removed a gear door or two. The long grass was hiding a few large holes, all of which we missed but the outcome could have been different.


But does all this prove landing out is risky?? No, cos we had more accidents and damage (none serious thankfully) at the main launch point than we did in out-landings.


So lets have a look at another one. Landed out at the Spud Patch. Landed into to wind...albeit only a few knots.

A much skinner outcome. I knew the field as land-able. I knew another glider was just behind and above me looking at the same spot to land-out. My gadget said we'd make the strip with 600ft to spare (my safety margin built into both final glide calculators).
Long strip with short grass and options from either end...I eventually aero-towed out.

Shorter finals...only 12 seconds.
But the angle between me, the ground and the aiming point was 22 degrees...or thereabouts...same as last time.
Needed airbrake on finals and landed short to allow the other Discus to land long.




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