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

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?

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.

At 23:43 02 August 2016, wrote:
Can we agree that stalling is directly related to angle of attack and
secondarily related to airspeed?

Yes it is. The trigger for a departure is often the application of the
controls to change the attitude of the glider. Given one of the first
lessons we learn is the effectiveness of the controls in relation to
airspeed, the slower we are the more control needed.
In a constant banked turn the control movements tend to be much
reduced, the application of aileron in particular, with the consequent
changing of angle of attack at the tips of each wing, is much less.
The control required to increase or reduce bank in a turn is far less
that that required to go from level flight to banked turn. So is this a
factor? Certainly it should be that the increase in angle of attack at the

tip of the "upgoing" wing should be much less.
Like everything else in flying, if you do it right there is no problem.
When it is going wrong the application of control to put it right is quite

frequently our undoing.
To complete a 180 deg final turn requires one turn entry and one exit.
A "square circuit" requires two. In theory 50% less opportunity for
screwing it up.

Why is it always the guys who are wound to tight, the ones that accuse others of being wound too tight? (Generally doing so with the excessive use of capitals).

:O

"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."

Exactly. Or, if you are going much too slow you are in danger from spinning from a shallow turn in the landing pattern.

If you are going much too slow you are in less danger from spinning from a medium/steeper turn in the landing pattern because at low speed most gliders run out of up elevator authority before reaching critical angle of attack.

Just repeating this nonsense doesn't make it become true...

How do you teach your students to fly the approach in a glider?

On Wednesday, August 3, 2016 at 12:12:40 PM UTC-4, wrote:
How do you teach your students to fly the approach in a glider?

To have more than one tool in the toolbox.

best,
Evan

True (for me....).

"Train for the worst, plan for the best".

I do a sorta standard 3 sided pattern, allowing for adjustments.
I will also allow students to get low on the "wrong side of the pattern" to see what they do.
At the end of tha day, are they OK, is the aircraft flyable?
If yes to both, that's a start, discuss from there.

Some here know where I've landed before, not happy on my end other than worst was a broken gear door hinge or grass stains......
I can teach from my "less than wonderful choices" in the past.
Do the "standard pattern" (at least in the US) most of the time so others can "guess" what you're doing.
Adjust as needed.
Be prepared for stupid stuff "weather, other pilots, ground peeps, etc......".