Fatal crash Arizona

....now redo your calculations while flying through 8 knots of sink.

Mike

On Wednesday, May 7, 2014 6:28:41 AM UTC-7, Mike the Strike wrote:
...now redo your calculations while flying through 8 knots of sink.



Mike

...and calculate the height loss while making a 180-degree turn. Taking the 12.8 seconds just mentioned at 800 feet per minute gives you a height loss of 170 feet from the airmass movement alone, plus whatever you add for the glider itself. Safety margins in severe sink disappear frighteningly quickly.

Mike

On Wednesday, May 7, 2014 9:35:46 AM UTC-4, Mike the Strike wrote:
On Wednesday, May 7, 2014 6:28:41 AM UTC-7, Mike the Strike wrote:

...now redo your calculations while flying through 8 knots of sink.







Mike



..and calculate the height loss while making a 180-degree turn. Taking the 12.8 seconds just mentioned at 800 feet per minute gives you a height loss of 170 feet from the airmass movement alone, plus whatever you add for the glider itself. Safety margins in severe sink disappear frighteningly quickly.



Mike

Now throw in wind shear and tailwind component when failure to anticipate leads to turning in the wrong direction.
Double AARRGGHH!!
UH

Can you really get 8kts of sink at 200ft? Where is the air going, into the ground?

Boggs

On Wednesday, May 7, 2014 7:20:33 AM UTC-6, Vaughn wrote:
On 5/7/2014 2:55 AM, 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.

I agree with you. I'm shaking my head every time I read this thread.



In a modern glass glider (such as the DG1000's I instruct in) with a

40 knot stall speed and being towed at 70 knots you should be able to

execute a safe 180� turn with*zero* loss of height.



The comparison isn't quite as simple as just looking at L/D. Turn

radius also has a lot to do with your chances of making it back to the

field, and turn radius is proportional to the SQUARE of airspeed.



Compare your example (40 knot stall) with a (horrors) 2-33. The highest

stall listed for a 2-33 is around 30 knots. If you do the math, you

will find that your DG1000 has nearly double the turn radius of the

slower glider.



Vaughn

You're exaggerating the stall speed differences. Regardless of what the 2-33 "manual" says, no 2-33 ever got as slow as 30 knots. 35 knots is a practical minimum speed. The flight test stall speed for a DG 1000 is 37 knots..

However, no one should consider a turn back at stall speed. Virtually all gliders will be at 50 - 55 knots so the turn radius will be essentially the same.

8 knots sink? That's a straw man argument. While extreme air movement is always possible, most PT3 incidents are in relatively benign conditions. In extreme conditions a turn back is probably moot anyway.

The point is when conditions allow, a pilot should know how to turn back safely.

On 5/6/2014 10:41 PM, Robert M wrote:
Why is anyone aero towing with a tow hook that will back release?

Excellent question. In the U.S., looking back in time (e.g. the Schweizer
fleet), historical inertia? In any event, I've never owned a glider that did
NOT have a back-releasable, non-CG hook on it, and except for my club's
G-103s, never piloted one either.

Bob W.

On Wednesday, May 7, 2014 10:34:48 AM UTC-5, Bill D wrote:

The point is when conditions allow, a pilot should know how to turn back safely.

Precisely. It's called airmanship - knowing how to handle your plane in any conceivable situation.

If you aren't practicing something new and unusual (or at least thinking about it) on every flight, you are limiting your growth as a pilot.

My one real PTT happened at Turf Soaring (Pleasant Valley Airport) many years ago, giving a ride in old 66W - a beat up old 2-32. Tow rope was hooked up incorrectly (muddy) and released just past the end of the runway (taking off to the East) at what i guess was around 150 - 200 ft, no more. No good options other than turning back or landing in the desert; so I turned back...and had enough energy to roll back up to the surprised line boy who had just launched me. Turned the glider around, hooked up again, and the customer got his full ride the second time.

BUT--conditions were calm with light winds and no lift; and the tow was fast - and it was pretty easy to whip that big old beast around in a steep turn and bring it back to land, as I had a lot of time in 2-32s at the time. Never felt that I was too low during the turn, but didn't even try getting real slow (if you have time in 2-32s you will appreciate why!).

Yes, it can be done. But you have to know your plane WELL, and have the right conditions, and fully understand the consequences of pooching it!

Get out there and practice!

Kirk
66

Can you really get 8kts of sink at 200ft? Where is the air going, into the
ground?


Having experienced two in-pattern microbursts, I'd say, "Yes, indeed!" to Q1.

As to Q2, as soon as I finish interviewing the bugs on my leading edges and
car windshield, I'll post the interview on YouTube. :-)

Bob W.

P.S. Putting my More Seriously Hat, elsewhere in this thread someone else
pointed out the relative uselessness of L/D in patterns when "real sink" was
an issue. Thoughtful pilots will agree. Maybe this is more of a "routine
issue" in (say) the western U.S. than elsewhere in the country, but I have my
doubts when it comes to (e.g.) wavish pattern conditions (e.g. Cumberland, MD;
Petersburg, WV).

At 17:01 07 May 2014, kirk.stant wrote:
On Wednesday, May 7, 2014 10:34:48 AM UTC-5, Bill D wrote:
=20
The point is when conditions allow, a pilot should know how to turn
back
=
safely.

Precisely. It's called airmanship - knowing how to handle your plane in
an=
y conceivable situation.

If you aren't practicing something new and unusual (or at least thinking
ab=
out it) on every flight, you are limiting your growth as a pilot.

My one real PTT happened at Turf Soaring (Pleasant Valley Airport) many
yea=
rs ago, giving a ride in old 66W - a beat up old 2-32. Tow rope was
hooked=
up incorrectly (muddy) and released just past the end of the runway
(takin=
g off to the East) at what i guess was around 150 - 200 ft, no more. No
go=
od options other than turning back or landing in the desert; so I turned
ba=
ck...and had enough energy to roll back up to the surprised line boy who
ha=
d just launched me. Turned the glider around, hooked up again, and the
cus=
tomer got his full ride the second time.

BUT--conditions were calm with light winds and no lift; and the tow was
fas=
t - and it was pretty easy to whip that big old beast around in a steep
tur=
n and bring it back to land, as I had a lot of time in 2-32s at the time.
N=
ever felt that I was too low during the turn, but didn't even try getting
r=
eal slow (if you have time in 2-32s you will appreciate why!).

Yes, it can be done. But you have to know your plane WELL, and have the
ri=
ght conditions, and fully understand the consequences of pooching it!

Get out there and practice!

Kirk
66

and that dear reader illustrates the problem nicely. Emergency procedures
do not have to be formulated for experienced thinking pilots. I would like
to think that I could get away with doing what Kirk has done. Emergency
procedures have to be formulated for the lowest common denominator, would a
low launches pilot be able to achieve success? Would a relatively
experience pilot who is flying minimum launches per year cope with it? That
is what formulating procedures is all about, having something that everyone
can achieve, not just the top 10%.

On Wednesday, May 7, 2014 12:40:09 PM UTC-6, Don Johnstone wrote:
At 17:01 07 May 2014, kirk.stant wrote:

On Wednesday, May 7, 2014 10:34:48 AM UTC-5, Bill D wrote:

=20

The point is when conditions allow, a pilot should know how to turn

back

=

safely.



Precisely. It's called airmanship - knowing how to handle your plane in

an=

y conceivable situation.



If you aren't practicing something new and unusual (or at least thinking

ab=

out it) on every flight, you are limiting your growth as a pilot.



My one real PTT happened at Turf Soaring (Pleasant Valley Airport) many

yea=

rs ago, giving a ride in old 66W - a beat up old 2-32. Tow rope was

hooked=

up incorrectly (muddy) and released just past the end of the runway

(takin=

g off to the East) at what i guess was around 150 - 200 ft, no more. No

go=

od options other than turning back or landing in the desert; so I turned

ba=

ck...and had enough energy to roll back up to the surprised line boy who

ha=

d just launched me. Turned the glider around, hooked up again, and the

cus=

tomer got his full ride the second time.



BUT--conditions were calm with light winds and no lift; and the tow was

fas=

t - and it was pretty easy to whip that big old beast around in a steep

tur=

n and bring it back to land, as I had a lot of time in 2-32s at the time..

N=

ever felt that I was too low during the turn, but didn't even try getting

r=

eal slow (if you have time in 2-32s you will appreciate why!).



Yes, it can be done. But you have to know your plane WELL, and have the

ri=

ght conditions, and fully understand the consequences of pooching it!



Get out there and practice!



Kirk

66



and that dear reader illustrates the problem nicely. Emergency procedures

do not have to be formulated for experienced thinking pilots. I would like

to think that I could get away with doing what Kirk has done. Emergency

procedures have to be formulated for the lowest common denominator, would a

low launches pilot be able to achieve success? Would a relatively

experience pilot who is flying minimum launches per year cope with it? That

is what formulating procedures is all about, having something that everyone

can achieve, not just the top 10%.

So, if the dumbest, least competent guy on the airfield might not be able to pull it off the UK solution is to eliminate the requirement for everybody? Talk about dumbing down.

I'm absolutely sure I can pull off at turn back and I'm certain my students can as well. I'll probably have to when I take a check ride in a couple of weeks in a 2-32. If so, the examiner will give me no warning whatsoever when he pulls the release at 200' AGL on departure. No sweat - even though there's no off field options.

I've had it happen for real many times including a couple of "What's this gizmo do?" on ride flights. I've watched post solo students pull it off when a rope broke. If we had not trained for this skill, we wouldn't be here. It's a lifesaver.