Fatal crash Arizona

On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:

Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.

Perhaps I have a fundamental misunderstanding...
but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight. So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down. If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.

It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed.

I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

On Wednesday, May 7, 2014 1:20:44 PM UTC+12, Bill D wrote:
I can assure you that the higher a glider's performance, the safer it is. It's the old, low L/D gliders that can run out of altitude before getting lined up with the runway.

It's a mystery to me why some people think you can "get away with" so much more in old gliders than in those great big heavy clumsy glass ones.

Somewhere in this thread I saw a statement that you could safely turn back from 150 ft in an old glider (which I agree with), but you're a dead man if you try it below 300 ft in glass.

The differences that govern such a thing just aren't that big!

Let's look at some numbers for weight and wing area of typical training gliders (from Wikipedia):

ASK13: 290 kg, 17.5 m^2
Blanik L13: 292 kg, 19.15 m^2

PW6: 360 kg, 15.3 m^2
ASK21: 360 kg, 17.95 m^2
Puchacz: 368 kg, 18.16 m^2
Janus: 365 kg, 17.3 m^2

G103: 390 kg, 17.9 m^2
Duo Discus: 410 kg, 16.4 m^2
DG1000: 415 kg, 17.5 m^2

There's not a lot of difference in the wing areas, with individual variations bigger than the generational differences.

Yes, the glass ones weigh a bit more. How much more?

Someone flying solo in an ASK21 is at about the same all up weight as someone in a ASK13 with a smaller than average instructor in the back seat.

Someone flying solo in a DG1000 is at about the same all up weight as someone in a ASK13 with a largish instructor in the back seat.

We expect students to be able to cope with the flying characteristic differences between having an instructor and not having one -- and to cope with that difference on their first time flying alone!

On Thursday, May 8, 2014 7:43:42 PM UTC-6, son_of_flubber wrote:
On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:



Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.



Perhaps I have a fundamental misunderstanding...

but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight.
---------------
I think you are confusing pitch attitude with angle of attack. In unaccelerated flight, for a given weight and airspeed, the AOA will always be the same whether you are being towed or not.
------------
So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down.
------------
Yes it will slow down if the pitch attitude isn't reduced. However, lowering the nose to establish a normal glide at pattern speed will actually see an increase in AOA due to the lower speed - you're just changing the flight path from a climb to a glide at a slower speed.
--------------
If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.
--------------
What you are saying is if the pilot attempts a turn while continuing the nose-up climb after a rope break, the glider will slow down. Of course it will but in most cases this is desirable since the tow speed was well above pattern speed. Just don't continue the slowdown below pattern speed. The AOA is more closely related to airspeed than pitch attitude.



It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed. I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

Yes, this technique is correct but the glider is just transitioning from being towed to a normal glide. The AOA will actually increase as the glider slows down.

Discussions like this highlights why gliders should have an AOA indicator in addition to and ASI.

On Thursday, May 8, 2014 9:43:42 PM UTC-4, son_of_flubber wrote:
On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:



Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.



Perhaps I have a fundamental misunderstanding...

but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight. So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down. If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.



It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed.



I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

You have a few things wrong.
First- angle of attack is related to the geometry of the glider and airflow over it. On tow the attitude of the glider is slightly nose up relative to the ground compared to the attitude it would have at the same angle of attack in a gliding configuration.
Second- "Every time" implies that we handle all releases the same. In normal flight we will transition from tow attitude and speed to gliding attitude and the associated speed. If in lift, that likely means slowing to thermalling speed. If not in lift we would be going to the appropriate speed to fly.
Third- There is no reason to try to gain altitude in PTT as the amount of gain accomplished by going from tow speed to pattern/approach speed is likely to be quite small. The correct action is to lower the nose slightly to establish a gliding attitude and speed appropriate for the conditions. In many cases, tow speed is about right for the return to the runway.
Also note that "every time" we turn right on release because that is standard. There is a 50% chance that, due to wind velocity and direction(including shear that may be present), terrain considerations, and position, that the correct action is to turn left.
These considerations are why we MUST have an emergency response plan in mind on every launch. There is no time to figure it out- you must execute the plan you have in your head already.
And forget all the mumbo jumbo calculations espoused in this thread.
UH

This discussion clearly indicates one of the fundamental reasons gliding safety is far worse than it should be. Issues such as rope breaks (PT3) have been discussed over and over again, for many years, and this thread demonstrates the wide variation of knowledge of procedures of this and other common launching emergencies.

Also, one must wonder how many pilots flying gliders with the Tost tow hook have ever returned them to the factory for the required periodic overhaul.

Considering who the glider community is - intelligent, well educated, well to do individuals, you must wonder why most simply go out of their way to avoid the simple educational process which will allow safe flight.

Tom Knauff

At 14:42 09 May 2014, Tom wrote:
This discussion clearly indicates one of the fundamental reasons gliding
sa=
fety is far worse than it should be. Issues such as rope breaks (PT3)
have
=
been discussed over and over again, for many years, and this thread
demonst=
rates the wide variation of knowledge of procedures of this and other
commo=
n launching emergencies.

Also, one must wonder how many pilots flying gliders with the Tost tow
hook=
have ever returned them to the factory for the required periodic
overhaul.

Considering who the glider community is - intelligent, well educated,
well
=
to do individuals, you must wonder why most simply go out of their way to
a=
void the simple educational process which will allow safe flight.

Tom Knauff


Not for the first time, I find myself in complete agreement with you Tom.

Chris Rollings

At 16:33 09 May 2014, Chris Rollings wrote:
At 14:42 09 May 2014, Tom wrote:
This discussion clearly indicates one of the fundamental reasons gliding
sa=
fety is far worse than it should be. Issues such as rope breaks (PT3)
have
=
been discussed over and over again, for many years, and this thread
demonst=
rates the wide variation of knowledge of procedures of this and other
commo=
n launching emergencies.

Also, one must wonder how many pilots flying gliders with the Tost tow
hook=
have ever returned them to the factory for the required periodic
overhaul.

Considering who the glider community is - intelligent, well educated,
well
=
to do individuals, you must wonder why most simply go out of their way
to
a=
void the simple educational process which will allow safe flight.

Tom Knauff


Not for the first time, I find myself in complete agreement with you Tom.

Chris Rollings

Me too

At 02:06 09 May 2014, Bruce Hoult wrote:
On Wednesday, May 7, 2014 1:20:44 PM UTC+12, Bill D wrote:
I can assure you that the higher a glider's performance, the safer it
is.
It's the old, low L/D gliders that can run out of altitude before getting
lined up with the runway.

It's a mystery to me why some people think you can "get away with" so
much
more in old gliders than in those great big heavy clumsy glass ones.

Somewhere in this thread I saw a statement that you could safely turn
back
from 150 ft in an old glider (which I agree with), but you're a dead man
if
you try it below 300 ft in glass.

The differences that govern such a thing just aren't that big!

Let's look at some numbers for weight and wing area of typical training
gliders (from Wikipedia):

ASK13: 290 kg, 17.5 m^2
Blanik L13: 292 kg, 19.15 m^2

PW6: 360 kg, 15.3 m^2
ASK21: 360 kg, 17.95 m^2
Puchacz: 368 kg, 18.16 m^2
Janus: 365 kg, 17.3 m^2

G103: 390 kg, 17.9 m^2
Duo Discus: 410 kg, 16.4 m^2
DG1000: 415 kg, 17.5 m^2

There's not a lot of difference in the wing areas, with individual
variations bigger than the generational differences.

Yes, the glass ones weigh a bit more. How much more?

Someone flying solo in an ASK21 is at about the same all up weight as
someone in a ASK13 with a smaller than average instructor in the back
seat.

Someone flying solo in a DG1000 is at about the same all up weight as
someone in a ASK13 with a largish instructor in the back seat.

We expect students to be able to cope with the flying characteristic
differences between having an instructor and not having one -- and to
cope
with that difference on their first time flying alone!

I think you are missing the point. The difference between the perceived
attitude of a Discus flying at 45kts (too slow) or 55kts (much better) in a
turn is very small, easy to get wrong.
The perceived attitude difference in a T21 Sedburgh between 35kts (slow)
and 45kts(better) is quite large, easy to spot if you got it wrong. Bearing
in mind that a T21 would not stall until you got it back to 22-25kts made
low turns much more unexciting. The T21 and T31 are the gliders I was
referring to.
When it all turns to ratsh1t in a glass glider it happens that much more
quickly than it ever did in wood.

On Friday, May 9, 2014 4:59:59 PM UTC-7, Don Johnstone wrote:
At 16:33 09 May 2014, Chris Rollings wrote:

At 14:42 09 May 2014, Tom wrote:
must wonder why most simply go out of their way to
avoid the simple educational process which will allow safe flight.

Tom Knauff


Not for the first time, I find myself in complete agreement with you Tom.

Chris Rollings



Me too

Me three. That makes it unanimous. Both sides of the pond, and both coasts.
If we count Dean Carswell, that's both sides of the here and after.

Cindy B

At 00:13 10 May 2014, Don Johnstone wrote:
At 02:06 09 May 2014, Bruce Hoult wrote:
On Wednesday, May 7, 2014 1:20:44 PM UTC+12, Bill D wrote:
I can assure you that the higher a glider's performance, the safer it
is.
It's the old, low L/D gliders that can run out of altitude before
getting
lined up with the runway.

It's a mystery to me why some people think you can "get away with" so
much
more in old gliders than in those great big heavy clumsy glass ones.

Somewhere in this thread I saw a statement that you could safely turn
back
from 150 ft in an old glider (which I agree with), but you're a dead man
if
you try it below 300 ft in glass.

The differences that govern such a thing just aren't that big!

Let's look at some numbers for weight and wing area of typical training
gliders (from Wikipedia):

ASK13: 290 kg, 17.5 m^2
Blanik L13: 292 kg, 19.15 m^2

PW6: 360 kg, 15.3 m^2
ASK21: 360 kg, 17.95 m^2
Puchacz: 368 kg, 18.16 m^2
Janus: 365 kg, 17.3 m^2

G103: 390 kg, 17.9 m^2
Duo Discus: 410 kg, 16.4 m^2
DG1000: 415 kg, 17.5 m^2

There's not a lot of difference in the wing areas, with individual
variations bigger than the generational differences.

Yes, the glass ones weigh a bit more. How much more?

Someone flying solo in an ASK21 is at about the same all up weight as
someone in a ASK13 with a smaller than average instructor in the back
seat.

Someone flying solo in a DG1000 is at about the same all up weight as
someone in a ASK13 with a largish instructor in the back seat.

We expect students to be able to cope with the flying characteristic
differences between having an instructor and not having one -- and to
cope
with that difference on their first time flying alone!

I think you are missing the point. The difference between the perceived
attitude of a Discus flying at 45kts (too slow) or 55kts (much better) in
a
turn is very small, easy to get wrong.
The perceived attitude difference in a T21 Sedburgh between 35kts (slow)
and 45kts(better) is quite large, easy to spot if you got it wrong.
Bearing
in mind that a T21 would not stall until you got it back to 22-25kts made
low turns much more unexciting. The T21 and T31 are the gliders I was
referring to.
When it all turns to ratsh1t in a glass glider it happens that much more
quickly than it ever did in wood.



All completely correct but there is one even bigger problem, most pilots
when making a low level turn off a launch failure or to modify a
circuit/pattern that has got too low, tend to be looking for/at the place
they intend to land with little or no attention to spare for the ASI,
attitude or slip/skid indicator, that's why these events are so productive
of stall/spin accidents. Training needs to emphasise, GLANCE AT THE ASI
EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES. Attitude is un unreliable
indicator very near the ground, even the smallest undulations in the
terrain can give a false impression and just being low can make the
attitude look more nose down than it is.