Are 'Single 180 Turn From Downwind to Final' and 'Stall-spin on Turnfrom Base to Final' mutually exclusive?

We [British] divide the downwind to base turn into two approximately 45 degrees turns, to insert a 'diagonal leg'.

I'm going to give this a try. I don't like the "wait until the touchdown point is 45 degrees behind you before turning base" part of the square pattern training...I can't see the touchdown point then. This BGA method seems like better training for XC outlandings than a square pattern

Le mardi 2 août 2016 18:58:43 UTC+2, a écritÂ*:

I said it before but I'll say it again:

The majority of gliders are more stall and spin resistant at medium to steeper banks than at shallower bank angles. (This is aerodynamically different than most airplanes).

And I ask you again: Would you please elaborate on this?

I've flown about 40 gliders, and voluntarily spun most of them. To my experience, your statement is nonsense.

On 8/2/2016 10:58 AM, wrote:
All you expert pilots are I'm sure fully capable of flying in such a manner
as to back up your arguments and I'm sure that you are very safe due to
your refined skills. But, is your particular point really relevant to the
overall safest best practice that the sport as a whole should be teaching
and modeling? Are you always in peak form at the end of an epic XC? Are
all of your friends in soaring as reliably skilled as you?

I said it before but I'll say it again:

The majority of gliders are more stall and spin resistant at medium to
steeper banks than at shallower bank angles. (This is aerodynamically
different than most airplanes). A continuous 30 degree bank from downwind
to final exposes a pilot to a longer period of stall/spin-at-low-altitude
risk than two brief periods of stall/spin resistant steeper banked turns.
(Or 3 turns in the clipped base pattern).

Since this thread is a "natural" for topical drift, here's additional "best
pattern practices" food for thought...

While playing in this millennium's NTSB glider-fatality database this past
winter, the question floating into mental view - when considering the (very
many) landing-pattern-related departures from controlled flight fatalities -
was, "Why did Joe Deceased Pilot NOT fly "a normal pattern?"

The (closely related?) question, "Why didn't Joe Deceased Pilot fly the BEST
PRACTICES pattern?" never occurred to me, since it seemed so obvious that loss
of aerodynamic control almost exclusively occurred during "grossly
non-standard" ("drunken sailor?") patterns as distinct from "seriously botched
standard patterns." Some might think the questions a distinction without a
difference, but not to my mind.

IOW, those U.S. glider pilots killing themselves in landing patterns generally
do so from patterns not REMOTELY appearing to be an implementation of a "best
practices" pattern. Makes a person think, it does...

Bob W.

At higher G loading as in steep turns many if not most gliders run out of elevator authority making them difficult if not nearly impossible to stall. Airplanes on the other hand have the propeller wash influencing elevator authority.

Le mardi 2 août 2016 22:07:26 UTC+2, a écritÂ*:
At higher G loading as in steep turns many if not most gliders run out of elevator authority making them difficult if not nearly impossible to stall.. Airplanes on the other hand have the propeller wash influencing elevator authority.

If your talking bank angles beyond 60 degrees, maybe. Anything below - absolutely not. That is, if you respect max mass in the seat.
Actually, if you stall a 25+ m ship at 60 deg bank, spin entry is much more violent than at 30 deg bank, and stopping the spin takes significantly more time. I've done that, and I won't do it again.

So, relating to patterns where you probably don't do more than 45 degree banks, your statement is senseless.

I haven't flown any 25 m gliders. I've flown about 35 types, a lot of trainers... The vast majority of them are much easier to stall and spin from shallow bank angles then from medium and steep bank angles. If I am alone in this perception that's news to me.

On Tuesday, August 2, 2016 at 3:03:43 PM UTC-7, wrote:
I haven't flown any 25 m gliders. I've flown about 35 types, a lot of trainers... The vast majority of them are much easier to stall and spin from shallow bank angles then from medium and steep bank angles. If I am alone in this perception that's news to me.


Seems to me that if you are in danger of spinning from a shallow turn in the landing pattern, you are going much too slow. If you are going that slow, won't a sudden steep turn put you below the stall speed? And won't that cause you to fall rather quickly from the sky?

Not commenting on whether this is true or not but only to inform of at least one place where glider pilots are taught that steeper turns are less likely to result in a stall. From Glider Basics - From First Flight to Solo, by Tom Knauff:

"It is very important for you to understand it is extremely difficult, if not impossible, to stall a glider in turns of 30 degrees angle of bank or more." You can find the entire discussion on page 79 of his book, as well as in multiple other locations in the text.

Robert

On Tuesday, August 2, 2016 at 3:22:20 PM UTC-5, Tango Whisky wrote:
Le mardi 2 août 2016 22:07:26 UTC+2, a écritÂ*:
At higher G loading as in steep turns many if not most gliders run out of elevator authority making them difficult if not nearly impossible to stall. Airplanes on the other hand have the propeller wash influencing elevator authority.

If your talking bank angles beyond 60 degrees, maybe. Anything below - absolutely not. That is, if you respect max mass in the seat.
Actually, if you stall a 25+ m ship at 60 deg bank, spin entry is much more violent than at 30 deg bank, and stopping the spin takes significantly more time. I've done that, and I won't do it again.

So, relating to patterns where you probably don't do more than 45 degree banks, your statement is senseless.

Can we agree that stalling is directly related to angle of attack and secondarily related to airspeed?

Le mercredi 3 août 2016 01:43:20 UTC+2, a écritÂ*:
Can we agree that stalling is directly related to angle of attack and secondarily related to airspeed?

Absolutely.
At moderate bank angles, say below 60 degree, all gliders I've flown so far do have enough elevator authority to stall them. As the g-loads increase with banking angle, the momentum created by one wing stalled and the other sill flying increases, so departure into spin will be more violent.

Now, if you moce the center of gravity forward, the you will limit the elevator authority needed to stall the glider. Seats are typically limited to 242 pounds due to the maximum allowable stress on the harness attachment points and exceedig this, you often can't stall the glider even with wings levelled. In trainers, this is more pronounced as part of the backseat load counts towards the effective load in the front seat (in a Duo, it's about one third). So, having two stately mammiferes on board will drastically increase spin resistance, and decrease the maximum bank angle where you can still stall the glider.

But the typical single seater glass ship flown within the CoG range defined by the manufacturer has no increased spin resistance whatsoever at bank angles used during pattern.