Flaps and V-Tails of Death

"Robert Ehrlich" wrote...
Flaps only ships are very rare in France and kowledge about their handling
is probably even more rare. I wonder how one can handle in such a ship
what
is described in our flight Bible, the "blue book" (Manuel du pilote Vol a
Voile,
i.e. glider pilot's manual) as the 3 most common mistakes when landing:
1) flare to high; 2) flare with excessive back stick action; 3) bounce.
In this 3 cases the glider comes a few feet above the ground at a speed
just marginally above stall speed and quickly decaying due to the drag of
open airbrakes. The immediate action to avoid that the glider falls on
the ground like a stone in the following seconds is to retract the
air-brakes,
so that the drag stops killing your speed and you regain some lift, then
try to land better ahead. But what can you do with no air-brakes?

Speed control is important in gracefully landing flaps-only gliders
(spoilers-only too, of course). What I've found - and often seen - is that
gliders' large-deflection flaps essentially 'quit working' as drag producing
devices if landed 'too fast.' True even for HP-16's. Come in too fast and
you _will_ float a long ways in flapped gliders...unless you slowly ease off
on the flaps, in which case the ship will gently settle...sort of the
flaps-only equivalent of easing on more spoilers if running out of field.
Certainly not a Big Deal if understood beforehand.

BTW, the most common mistake I've seen in flapped ships IS landing too
fast...probably fallout from: 1) (U.S. centric) training in Schweizer 2-33's
in which being too fast doesn't generally lead to landing alarm/excitement;
and 2) (worldwide?) training in reasonably benign (in the touchdown sense)
spoilers-only, nose-dragging trainers lacking a springy nosewheel. G-103's
in the U.S. often tell the tale of what bad can happen when trying to force
one of them on the ground at too fast a speed (PIO/fuselage damage/etc.).

Regarding your specific questions, in the event someone DOES manage to flare
too high (whether from doing a good flare but too high, or from
over-aggressive aft-stick motion/'ballooning', or simply bounces the
touchdown) in a flaps-only ship, the only proper recourse is to wait. If
you're savvy enough and have time, you can re-establish the proper pitch
angle for touchdown _then_ wait...but wait. Don't churn the stick and don't
adjust the flap position. The bad news is drag IS high and ground-effect
DOES hugely lessen as speed decays. The good news is there is usually a LOT
of downwash, even on a truly botched flare with full flaps, and it's not the
easiest thing to do to drop a flapped ship in from 3 feet. Certainly no
more difficult IMHO than doing so in a spoilers-only ship. Dropping in
either configuration is possible, of course.

IMHO, about the only situation I can envision where a flaps-only ship IS
worse than a spoilers-only one is that of getting low and slow on the
approach. Is there a spoilers-only driver alive who doesn't take some
comfort in the thought s/he can slam the spoilers shut in that situation and
not distinctly improve things in the near-term future? Get yourself in that
situation in a flaps-only ship and you're essentially out of options. The
GOOD news is that you're much more likely to get low and slow in a ship
having weak landing aids...generally not a problem in gliders having _only_
large deflection flaps as landing aids.

Regards,
Bob W.


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.538 / Virus Database: 333 - Release Date: 11/10/2003