Glider accident while filming commercial in 2011. NTSB Report updated

Excessive initial ecceleration can cause problems with certain types. I
have experienced it with 2 types.
PW5 with stick fully forward at the start of the launch. Hard acceleration
caused the glider to rotate from the nose wheel to the tail wheel and
rocket into the air. I only managed to regain control at about 50ft.
The other one is the K8. Light glider, high wing. Similar problem.

If slow acceleration is a safety problem what about the ground run and take
off with aerotow using belly hooks, and autotows?

On Saturday, June 29, 2013 8:22:46 AM UTC-6, Nigel Pocock wrote:
Excessive initial ecceleration can cause problems with certain types. I

have experienced it with 2 types.

PW5 with stick fully forward at the start of the launch. Hard acceleration

caused the glider to rotate from the nose wheel to the tail wheel and

rocket into the air. I only managed to regain control at about 50ft.

The other one is the K8. Light glider, high wing. Similar problem.



If slow acceleration is a safety problem what about the ground run and take

off with aerotow using belly hooks, and autotows?

K8's and PW-5's, as with all "nose dragger's, are supposed to rotate back onto their tail wheels. What do you mean exactly by "regained control"? You're still with us so, presumably, it worked. With those gliders you should have started the ground roll with the stick full forward.

Aero tow with a CG hook isn't safe as discussed elsewhere on this forum. However a tug can't generate the forces a winch can so a wing drop induced ground loop likely won't be as severe.

"Aero tow with a CG hook isn't safe"

bull****!

There is a lot of that around.

GC hook is a little more work on aerotow but not intrinsically unsafe.
Possibility of kiting is greater, and the glider is easier to get out of
position laterally. Conversely, the glider is easier to get where you
want it laterally...

Many aerotows later on a CG hook on a Std Cirrus.

On 2013/06/30 12:16 AM, Andy wrote:
"Aero tow with a CG hook isn't safe"

bull****!


--
Bruce Greeff
T59D #1771

If Bill D could be bothered to read my posting before spouting a reply he
wouls see that I had started the launch with full forward stick in both
cases.
Hard acceration with these gliders can cause the tail to hit the ground
hard - not safe. To avoid this the tail of the K8s are usually held down
for the launch. Too hard acceration can cause the glider to shoot into the
air and immediately into a 45 degree climb despite the stick position. If
the rope breaks at this point you have too little height to recover. Hence
the winch driver will give slower initial acceleration with these types.
By regained control I mean the elevator having any effect. Until then you
are just a passenger.
I was always taught with ground launch to keep it straight and level until
the glider lifts off in a shallow climb. When a safe speed had been reached
to rotate steadily into a full climb. At any point in this process you can
still recover and land safely using the correct procedures - as taught be
both the german and british systems.


At 14:42 29 June 2013, Bill D wrote:
On Saturday, June 29, 2013 8:22:46 AM UTC-6, Nigel Pocock wrote:
Excessive initial ecceleration can cause problems with certain types. I
=20
have experienced it with 2 types.=20
=20
PW5 with stick fully forward at the start of the launch. Hard
acceleratio=
n
=20
caused the glider to rotate from the nose wheel to the tail wheel and
=20
rocket into the air. I only managed to regain control at about 50ft.
=20
The other one is the K8. Light glider, high wing. Similar problem.
=20
=20
=20
If slow acceleration is a safety problem what about the ground run and
ta=
ke
=20
off with aerotow using belly hooks, and autotows?

K8's and PW-5's, as with all "nose dragger's, are supposed to rotate back
o=
nto their tail wheels. What do you mean exactly by "regained control"?
Yo=
u're still with us so, presumably, it worked. With those gliders you
shoul=
d have started the ground roll with the stick full forward.

Aero tow with a CG hook isn't safe as discussed elsewhere on this forum.
H=
owever a tug can't generate the forces a winch can so a wing drop induced
g=
round loop likely won't be as severe.

Nigel, I read your post and it's mostly an "old wives tale".

Yes, gliders lower their tails which can be an issue on hard surfaces so someone holds them down as seen in the PW-5 video. On turf, it's a non-issue.. However, it has nothing to do with acceleration causing premature uncommanded rotation. The tailwheel on the ground prevents it. Glider's don't "shoot into the air" or do anything else inappropriate under 1G acceleration. It's been thoroughly flight tested.

On Monday, July 1, 2013 8:58:00 AM UTC-6, Nigel Pocock wrote:
If Bill D could be bothered to read my posting before spouting a reply he

wouls see that I had started the launch with full forward stick in both

cases.

Hard acceration with these gliders can cause the tail to hit the ground

hard - not safe. To avoid this the tail of the K8s are usually held down

for the launch. Too hard acceration can cause the glider to shoot into the

air and immediately into a 45 degree climb despite the stick position. If

the rope breaks at this point you have too little height to recover. Hence

the winch driver will give slower initial acceleration with these types.

By regained control I mean the elevator having any effect. Until then you

are just a passenger.

I was always taught with ground launch to keep it straight and level until

the glider lifts off in a shallow climb. When a safe speed had been reached

to rotate steadily into a full climb. At any point in this process you can

still recover and land safely using the correct procedures - as taught be

both the german and british systems.





At 14:42 29 June 2013, Bill D wrote:

On Saturday, June 29, 2013 8:22:46 AM UTC-6, Nigel Pocock wrote:

Excessive initial ecceleration can cause problems with certain types. I

=20

have experienced it with 2 types.=20

=20

PW5 with stick fully forward at the start of the launch. Hard

acceleratio=

n

=20

caused the glider to rotate from the nose wheel to the tail wheel and

=20

rocket into the air. I only managed to regain control at about 50ft.

=20

The other one is the K8. Light glider, high wing. Similar problem.

=20

=20

=20

If slow acceleration is a safety problem what about the ground run and

ta=

ke

=20

off with aerotow using belly hooks, and autotows?



K8's and PW-5's, as with all "nose dragger's, are supposed to rotate back

o=

nto their tail wheels. What do you mean exactly by "regained control"?

Yo=

u're still with us so, presumably, it worked. With those gliders you

shoul=

d have started the ground roll with the stick full forward.



Aero tow with a CG hook isn't safe as discussed elsewhere on this forum.

H=

owever a tug can't generate the forces a winch can so a wing drop induced

g=

round loop likely won't be as severe.

Leaving aside the tail hitting the ground aspect, a glider doesn't
necessarily stop accelarating just because it has left the ground
- in fact it is sometimes quite noticeable to me (in a Discus
2cT) that the accelaration is increasing after lift off - especially
with a powerful winch that is capable of acheiving a safe cable
speed of 60+ knots (depending on the type being launched).

Long ago, even with a low powered old winch and far less than
1g acceleration, I remember routinely having to keep the stick
forward in a K8 to prevent over-rotation.

I put my trust in the BGA advice on winch launching which is
based on many decades of experience by dozens of clubs,
thousands of individual pilots and instructors, and with
numerous winch and glider types.

John Galloway


At 15:44 01 July 2013, Bill D wrote:
Nigel, I read your post and it's mostly an "old wives tale".

Yes, gliders lower their tails which can be an issue on hard
surfaces so
so=
meone holds them down as seen in the PW-5 video. On turf,
it's a
non-issue=
.. However, it has nothing to do with acceleration causing
premature
uncomma=
nded rotation. The tailwheel on the ground prevents it.
Glider's don't
"s=
hoot into the air" or do anything else inappropriate under 1G
acceleration.=
It's been thoroughly flight tested.

On Monday, July 1, 2013 8:58:00 AM UTC-6, Nigel Pocock
wrote:
If Bill D could be bothered to read my posting before
spouting a reply he
=20
wouls see that I had started the launch with full forward
stick in both
=20
cases.
=20
Hard acceration with these gliders can cause the tail to hit
the ground
=20
hard - not safe. To avoid this the tail of the K8s are usually
held down
=20
for the launch. Too hard acceration can cause the glider to
shoot into
th=
e
=20
air and immediately into a 45 degree climb despite the stick
position. If
=20
the rope breaks at this point you have too little height to
recover.
Henc=
e
=20
the winch driver will give slower initial acceleration with
these types.
=20
By regained control I mean the elevator having any effect.
Until then you
=20
are just a passenger.
=20
I was always taught with ground launch to keep it straight
and level
unti=
l
=20
the glider lifts off in a shallow climb. When a safe speed
had been
reach=
ed
=20
to rotate steadily into a full climb. At any point in this
process you
ca=
n
=20
still recover and land safely using the correct procedures -
as taught be
=20
both the german and british systems.
=20
=20
=20
=20
=20
At 14:42 29 June 2013, Bill D wrote:
=20
On Saturday, June 29, 2013 8:22:46 AM UTC-6, Nigel
Pocock wrote:
=20
Excessive initial ecceleration can cause problems with
certain types.
=
I
=20
=3D20
=20
have experienced it with 2 types.=3D20
=20
=3D20
=20
PW5 with stick fully forward at the start of the launch.
Hard
=20
acceleratio=3D
=20
n
=20
=3D20
=20
caused the glider to rotate from the nose wheel to the
tail wheel and
=20
=3D20
=20
rocket into the air. I only managed to regain control at
about 50ft.
=20
=3D20
=20
The other one is the K8. Light glider, high wing. Similar
problem.
=20
=3D20
=20
=3D20
=20
=3D20
=20
If slow acceleration is a safety problem what about the
ground run and
=20
ta=3D
=20
ke
=20
=3D20
=20
off with aerotow using belly hooks, and autotows?
=20

=20
K8's and PW-5's, as with all "nose dragger's, are
supposed to rotate
bac=
k
=20
o=3D
=20
nto their tail wheels. What do you mean exactly by
"regained control"?=
=20
=20
Yo=3D
=20
u're still with us so, presumably, it worked. With those
gliders you
=20
shoul=3D
=20
d have started the ground roll with the stick full forward.
=20

=20
Aero tow with a CG hook isn't safe as discussed elsewhere
on this
forum.=
=20
=20
H=3D
=20
owever a tug can't generate the forces a winch can so a
wing drop
induce=
d
=20
g=3D
=20
round loop likely won't be as severe.
=20

On Monday, July 1, 2013 10:47:30 AM UTC-6, John Galloway wrote:
Leaving aside the tail hitting the ground aspect, a glider doesn't

necessarily stop accelarating just because it has left the ground

- in fact it is sometimes quite noticeable to me (in a Discus

2cT) that the accelaration is increasing after lift off - especially

with a powerful winch that is capable of acheiving a safe cable

speed of 60+ knots (depending on the type being launched).



Long ago, even with a low powered old winch and far less than

1g acceleration, I remember routinely having to keep the stick

forward in a K8 to prevent over-rotation.



I put my trust in the BGA advice on winch launching which is

based on many decades of experience by dozens of clubs,

thousands of individual pilots and instructors, and with

numerous winch and glider types.



John Galloway


John, your post is too confused to answer. Keep in mind what is considered "normal" in the UK has not resulted in an enviable safety record. Instead of constantly retelling anecdotal stories to each other, maybe you should study the actual physics and what's done in other countries.

On Monday, July 1, 2013 1:56:30 PM UTC-5, Bill D wrote:
On Monday, July 1, 2013 10:47:30 AM UTC-6, John Galloway wrote:

Leaving aside the tail hitting the ground aspect, a glider doesn't



necessarily stop accelarating just because it has left the ground



- in fact it is sometimes quite noticeable to me (in a Discus



2cT) that the accelaration is increasing after lift off - especially



with a powerful winch that is capable of acheiving a safe cable



speed of 60+ knots (depending on the type being launched).







Long ago, even with a low powered old winch and far less than



1g acceleration, I remember routinely having to keep the stick



forward in a K8 to prevent over-rotation.







I put my trust in the BGA advice on winch launching which is



based on many decades of experience by dozens of clubs,



thousands of individual pilots and instructors, and with



numerous winch and glider types.







John Galloway





John, your post is too confused to answer. Keep in mind what is considered "normal" in the UK has not resulted in an enviable safety record. Instead of constantly retelling anecdotal stories to each other, maybe you should study the actual physics and what's done in other countries.

__________________________________________________ _________________________

I didn't find Johns post confusing nor do I recall him constantly telling anecdotal stories.

On Mon, 01 Jul 2013 08:44:50 -0700, Bill D wrote:

Nigel, I read your post and it's mostly an "old wives tale".

Yes, gliders lower their tails which can be an issue on hard surfaces so
someone holds them down as seen in the PW-5 video. On turf, it's a
non-issue.

Er, no!

Most British clubs also hold the tail down if we're launching a DG-50x
regardless of what the surface is. The tail really crashes down with
them, almost regardless of how strong the initial acceleration is.

I haven't winched a PW-5, not a Ka-8 so have no direct experience there.

However its also worth knowing that some types have a tendency to snap
rotate as they leave the ground on a winch launch unless you start the
run with almost full forward stick. I've seen more Ka-8s start like this
than not.

I also know from direct experience that full forward trim and a little
forward pressure beyond that is needed when winching an H.201 Libelle: do
that and you get a smooth lift-off at the ground attitude.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |