On 4/18/2019 9:13 AM, Tango Eight wrote:
On Thursday, April 18, 2019 at 10:47:26 AM UTC-4, Tim Taylor wrote:
Please don't teach the dive to lose altitude technique. The problem is
total energy, simply the kinetic plus potential energy. Most pilots are
trained with judgment on altitude (potential energy) but have poor
judgment how speed (kinetic energy) will impact touch down point and
speed. Our brains are much better at doing estimates with constant
speed. Yes, it is a neat trick to dive at the ground but has a higher
probably for error than simpler techniques. See the article in soaring
about the pilot that flew off the end of the runway. If you are really
high, 500 to 1000 feet agl, the glider polar works both ways around the
best l/d, rather than speeding up it is better to slow down and use full
spoilers and a slip. I have modeled both techniques and the achieved l/d
over the ground is just as low with the slower technique and there is no
speed to scrub once you are back in correct height band for the approach.
If you are really high, slow down to near stall speed, use full spoilers
and slip. As you get lower (about 400 feet agl) accelerate to normal
approach speed for the conditions.

Even better is to teach students to be flexible and not get fixated on
completing a traditional pattern, S-turns or a 360 if a pilot is really
too high are better options.

No 360s please. That has disaster written all over it.

Kai Gertsen introduced me to the "reversed base leg" approach years ago.
This works great, it's easy to fly, easy to teach and the technique is the
same in any glider. You extend the (too high) base leg past the runway
centerline some appropriate distance, make a 180 (turn towards the runway),
make a second base leg from the other side of the runway.

I've experimented with S-turns (after reading George Moffatt). They work
well. I was able to turn a much too high approach into a spot landing
twice in two tries. Glider folk on the ground won't enjoy this, they'll
think something is wrong.

Apologies for 'going further off into the weeds' here - at least relative to
the OP's explicit original question - but this is the sort of discussion I: 1)
find personally interesting, because 2) it touches upon 'stuff' that every
'serious' gliderpilot likely also finds interesting. I'm defining 'serious' in
this context as every Joe Glider Pilot interested in preservation of
self/glider for another fun flight tomorrow, regardless of whether it's to
sit-on-the-flagpole or go XC or whatever...

If JGP has somehow botched a pattern to the point he's 'uncomfortably high' on
final - and haven't we all done so for various reasons, ranging from
intentional practice, to unexpected serious/sustained lift on base or final,
to 'something(s) else' - he'll be faced with 'What to do about it to safely
salvage the situation?'

FWIW, I'm not a believer in 'specific rules of thumb that are always 100%
correct/applicable,' but am more a 'fundamentalist thinker.' In high-final
terms, I fall into the category that believes salvation is most likely safely
accomplishable for Joe Average Glider Pilot (me!) by avoiding - as far as
'reasonably possible' - edging into Joe Test Pilot territory. I put 360's on
final into the JTP category, for example...*somewhat* akin to 'practicing
departure-from-controlled-flight in the pattern,' in the sense that the
potential 'good return' isn't worth the unavoidably-accepted 'in-flight risk.'
("Hey! Lemme practice turning my back on the field at the last minute; it
seems like a good idea just because it flashed into my mind as 'salvation.'
Woohoo!")

At my specific home field (Boulder, CO), doing so would also guarantee either
crossing (twice!) through a parallel power-plane-runway's final approach, or
(again, twice) 'somewhat below' the glider pattern's final/base legs. Not so
wise in my book, regardless of the 'wisdom' (Not!) of turning one's back on
one's intended touchdown area.

Those times I (intentionally, mostly, but rarely, unintentionally) found
myself 'WAY too high on shortish final approach' at Boulder I opted either for
landing long (once convinced it was safely possible) or,(seriously considered,
but never actually required) S-turning along final to lengthen the final's
flightpath length. The latter was always Option 2, in a preferred sense, for
the reasons Tango Eight alludes to. (It's bad enough to alarm myself; no need
to go out of my way to alarm other pilots who may be sharing nearby airspace!
Ground-pounders? Worry about 'em later...)

I rejected the 'dive-n-drag' approach (commonly used 'for fun' at one time by
the gliding FBO's ride pilots in their 2-32s 'just because hey could') cuz I
never ended up 'ridiculously high' in a spoilered ship, only in (my own)
large-deflection-landing-flapped ships, and if there's a *second* situation
such ships don't handle particularly gracefully (the first being low, slow,
and short), it's being in ground-effect with excess speed and full flaps.
(Kids, can you spell: F - L - O - A - T ???)

WRT off-field approaches, both the S-turning option and the 'extended/reversed
base leg seem 'eminently-safely-usable' to me, without 'messing about with'
(for the first time, likely, for many) the suddenly-increasing-kinetic-energy
playground associated with a diving-final-approach. (Best to avoid JTP-land,
again...)

YMMV, of course.

Bob W.

P.S. I believe it's GOOD (for JGP) to seriously consider, and 'safely practice
this sort of stuff' by way of self-education and preparation for their own,
personal 'Reality Show!'

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