Flaps/No flaps...practical difference??

On Friday, August 16, 2019 at 6:07:44 PM UTC-4, BobW wrote:
Captain Obvious here (maybe)...

There's a world of difference between 'mere' camber-changing flaps (with or
without a 'landing' position) and large-deflection landing-flaps in terms of
steepest-glide-angle at approach-speed, and reduced (compared to unflapped
ships of equal span) stall speed, everything else being equal (which of course
it ain't). The devil's in the details.

Yeah, likely the main benefit of stalling-speed-reduction occurs somewhere
around (say) 30-ish degrees of flap deflection, beyond which the remaining
aerodynamic effect is pretty much additional drag, and yeah, manufacturers of
'flapped ships (w/o large deflection capability)' almost certainly optimize
such designs (and their landing spoilers) so that the *primary* purpose of the
flaps is to maximize soaring-performance-range for some design-targeted span
(and not maximize short-field capability), and hence == when considering
*these* sorts of flapped designs == there's arguably little
landing-capability difference between flapped and unflapped ships.

But to suppose that's true for *all* flapped designs (i.e. those w.
large-deflection landing flaps, e.g. some early versions of ASW 20s, pre-D
versions of PIK-20s, and a few, semi-rare (even in the U.S.; likely even more
rare in EASA-land) U.S. designs (Nugget, SGS 1-35, Zuni, many older HPs,
etc.)), is incorrect. Depending on the ship, *seriously* incorrect.

Most U.S. pilots w. 1-26 experience would likely agree no other glider would
be their first choice for landing in a small/approach-obstructed field. I
would, too, but for the HP-14 I flew for several hundred hours, more or less
immediately after my 1-26 time. The Zuni in which I have most of my
flapped-ship time, not so much, though its actual touchdown speed is (thanks
to its flaps) lower than all other 15-meter span glass ships with which I have
observational experience since ~1980.

Reiterating...the devil is in the details in the case of 'flaps.' All flaps
aren't the same - not by a long stretch. I chose large-deflection
landing-flapped ships for all my single-seaters, post-1-26, exactly for this
reason...and continue to believe they're something of a 'lost religious war'
in soaring-land.

I've got an RHJ-8 looking for a home, flaps not quite as effective as HP-14
but quite frightening to passengers unused to such a treat of a landing...

On 8/16/2019 6:59 PM, Dave Nadler wrote:
On Friday, August 16, 2019 at 6:07:44 PM UTC-4, BobW wrote:
Captain Obvious here (maybe)...

There's a world of difference between 'mere' camber-changing flaps (with
or without a 'landing' position) and large-deflection landing-flaps in
terms of steepest-glide-angle at approach-speed, and reduced (compared to
unflapped ships of equal span) stall speed, everything else being equal
(which of course it ain't). The devil's in the details.

Snip...


Most U.S. pilots w. 1-26 experience would likely agree no other glider
would be their first choice for landing in a small/approach-obstructed
field. I would, too, but for the HP-14 I flew for several hundred hours,
more or less immediately after my 1-26 time...

Reiterating...the devil is in the details in the case of 'flaps.' All
flaps aren't the same - not by a long stretch. I chose large-deflection
landing-flapped ships for all my single-seaters, post-1-26, exactly for
this reason...and continue to believe they're something of a 'lost
religious war' in soaring-land.

I've got an RHJ-8 looking for a home, flaps not quite as effective as
HP-14 but quite frightening to passengers unused to such a treat of a
landing...

Oh man..born 40 years too soon, I was! I lusted after this ship (and its two
siblings) ever since I learned of 'em. May yours find a(nother) good home!

Bob W.

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