Basic Training Gliders

There are two approved methods of adding rear ballast to the K21 to move the
C. of G. aft.

It is possible to fit a lead ballast block in the rear fuselage just aft of
the fin spar, this is not intended to be fitted or removed between flights,
and of course the machine must be re-weighed..

It is also possible to have a hole through the fin to take a bar to carry
external ballast in the form of up to 10 x 1kg lead weights, which is
intended to be adjusted or removed between flights as required. See
"optional extras" on the specification sheet at
http://www.as-segelflugzeuge.de/englisch/e_main.htm , "Your Sailplane", "ASK
21", at the bottom of the page "Download Info:", "Specification ASK 21
(english)".

Both schemes are described in the owners' handbook. See also the
Schleicher AD and Technical notes
http://www.as-segelflugzeuge.de/englisch/e_main.htm "TN/LTA", "ASK 21" in
particular TN-No 4 &4a, see also "further TN/AD see overview (PDF)".

Note also that in common with all German gliders (as far as I know) the
minimum front cockpit weight is always shown as 70 kg (154 lbs). However
if the glider is carefully weighed it may be found that the minimum front
cockpit load calculated by moments when flown solo is less than this. Of
course the minimum front cockpit load calculated by moments will always be
reduced when there is a rear seat pilot, by an amount which increases as the
rear cockpit load is increased.

The importance of all this is that the glider will not hold a stable spin
unless the C. of G. is close to the aft limit (the numbers are in the
handbook), but you will be in trouble if you fly it with the C. of G. aft of
the aft limit.

Don't even think of trying for a full spin, or flying with the C. of G. well
aft unless you have read the pilots' manual AMENDED BY TN 23. The TN
itself is on the Schleicher web-site but the page amendments are not.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Markus Gayda" wrote in message
...

For the ASK-21 is a "spin-weight" available which can be installed on the
rudder. Of course you have to weigh the pilots before deciding which
weights to add to the glider.

But then you have a very nice trainer with which you can also train spins.

CU
Markus

Derek Copeland wrote:

While a headrest may be an important
safety item in a car to protect you from whiplash in
a rear end shunt, I am still trying to work out in
what circumstances a glider might get rammed from behind?!!!!!!
Stupid F***ing Bureaucrats!

Perhaps the "Stupid F***ing Bureaucrat" saw the same video I saw at an
SSA convention: it showed the pilot dummy movement during a test crash
of a glider, with violent whiplash occurring. I then asked Gerhard
Waibel about the safety value of the headrest in Schleicher gliders, and
he told me it was very important. So, I retrieved the headrest for my
ASH 26 E from the basement and put it back in the glider!


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

At 20:42 04 December 2005, Eric Greenwell wrote:
Derek Copeland wrote:

While a headrest may be an important
safety item in a car to protect you from whiplash
in
a rear end shunt, I am still trying to work out in
what circumstances a glider might get rammed from
behind?!!!!!!
Stupid F***ing Bureaucrats!

Perhaps the 'Stupid F***ing Bureaucrat' saw the same
video I saw at an
SSA convention: it showed the pilot dummy movement
during a test crash
of a glider, with violent whiplash occurring. I then
asked Gerhard
Waibel about the safety value of the headrest in Schleicher
gliders, and
he told me it was very important. So, I retrieved the
headrest for my
ASH 26 E from the basement and put it back in the glider!

So what do you have to do to achieve the whiplash -
Tailslide backwards into the ground?

I did once injure my neck as a result of a student's
very heavy landing. Basically my head went forwards
and down and I got what is called an 'acute flexion
injury' which is the reverse of the usual whiplash
injury where the head initially goes backwards. I don't
believe that a headrest would have helped. I had to
wear a surgical collar for several weeks after this,
but luckily no permanent damage was done.

On the subject of making K21s spin, there is a privately
owned K21 at Lasham that spins and recovers very nicely
(unlike our club owned one), even with a slightly heavy
pilot like myself on board. This was rebuilt after
a crash several years ago, before which it had been
a perfectly normal K21 with the usual reluctance to
spin. I don't know whether the tail got heavier or
the angle of incidence of the tailplane was changed
during the repairs, to account for this change in spinning
characteristics. Perhaps Schleichers should take a
look at this particular glider and incorporate any
changes from the standard specification into their
production models?

Derek Copeland

At 21:48 04 December 2005, Derek Copeland wrote:
At 20:42 04 December 2005, Eric Greenwell wrote:
Derek Copeland wrote:

While a headrest may be an important
safety item in a car to protect you from whiplash
in
a rear end shunt, I am still trying to work out in
what circumstances a glider might get rammed from
behind?!!!!!!
Stupid F***ing Bureaucrats!

Perhaps the 'Stupid F***ing Bureaucrat' saw the same
video I saw at an
SSA convention: it showed the pilot dummy movement
during a test crash
of a glider, with violent whiplash occurring. I then
asked Gerhard
Waibel about the safety value of the headrest in Schleicher
gliders, and
he told me it was very important. So, I retrieved the
headrest for my
ASH 26 E from the basement and put it back in the glider!

So what do you have to do to achieve the whiplash -
Tailslide backwards into the ground?

I did once injure my neck as a result of a student's
very heavy landing. Basically my head went forwards
and down and I got what is called an 'acute flexion
injury' which is the reverse of the usual whiplash
injury where the head initially goes backwards. I don't
believe that a headrest would have helped. I had to
wear a surgical collar for several weeks after this,
but luckily no permanent damage was done.

On the subject of making K21s spin, there is a privately
owned K21 at Lasham that spins and recovers very nicely
(unlike our club owned one), even with a slightly heavy
pilot like myself on board. This was rebuilt after
a crash several years ago, before which it had been
a perfectly normal K21 with the usual reluctance to
spin. I don't know whether the tail got heavier or
the angle of incidence of the tailplane was changed
during the repairs, to account for this change in spinning
characteristics. Perhaps Schleichers should take a
look at this particular glider and incorporate any
changes from the standard specification into their
production models?

Derek Copeland


The answer to the whiplash question is very simple
and whiplash describes the action which causes the
injury. When a car, or glider decelerates very rapidly,
the head, which is unrestrained and has a fairly high
mass continues to move forward until it is stopped
at full body extension. It then whips back and if there
is nothing to stop it extends backwards, that is what
causes the injury. It is correct that a headrest prevents
injury in a rear shunt but that is not the primary
cause of 'whiplash' injuries. It is the whipping action
following a sudden deceleration.
I suppose if an impact in a glider is severe enough
to cause the whiplash then that injury may be the least
of your problems as you are much closer to the crash
in a glider that you are in a car.

Derek Copeland wrote:

The front
cockpit has a largish headrest that almost completely
blocks the forward view from the rear cockpit. In Europe,
because the DG1000 is certified by EASA, we are not
even allowed to remove it, as it is specified in the
type certificate! While a headrest may be an important
safety item in a car to protect you from whiplash in
a rear end shunt, I am still trying to work out in
what circumstances a glider might get rammed from behind?

Perhaps a ground loop?


Jack

At 23:18 04 December 2005, Jack wrote:
Derek Copeland wrote:

The front
cockpit has a largish headrest that almost completely
blocks the forward view from the rear cockpit. In
Europe,
because the DG1000 is certified by EASA, we are not
even allowed to remove it, as it is specified in the
type certificate! While a headrest may be an important
safety item in a car to protect you from whiplash
in
a rear end shunt, I am still trying to work out in
what circumstances a glider might get rammed from
behind?



Derek

Perhaps you should try to understand whiplash.

When the glider/car or whatever is carrying a body
is stopped suddenly the head goes forwards.

When restrained by the seatbelts the remainder of the
body cannot follow it. Hence in cars we now have airbags.
Unfortunately for the poor neck, the shoulders and
head eventually whip back (in reality a fraction of
a second).

The shear forces on the neck as it goes backwards from
the top of the seat are enormous hence in cars, the
head restraint is fitted. It is not a head rest.

Perhaps for gliders we should insist on airbags and
head restraints for both seats?

Having flown from the rear of many two seaters the
head gear and hairstyle of the front seat passenger
causes more problems than a well designed head retraint.


IMHO the worst thing the front seat passenger can wear
is a white hat or an have affro/permed hairstyle.

Dave

At 22:42 04 December 2005, Don Johnstone wrote:
The answer to the whiplash question is very simple
and whiplash describes the action which causes the
injury. When a car, or glider decelerates very rapidly,
the head, which is unrestrained and has a fairly high
mass continues to move forward until it is stopped
at full body extension. It then whips back and if there
is nothing to stop it extends backwards, that is what
causes the injury. It is correct that a headrest prevents
injury in a rear shunt but that is not the primary
cause of 'whiplash' injuries. It is the whipping action
following a sudden deceleration.
I suppose if an impact in a glider is severe enough
to cause the whiplash then that injury may be the least
of your problems as you are much closer to the crash
in a glider than you are in a car.
--------------------------------------
I actually did an instructional flight in the back
seat of a DG1000 today, and was reminded how poor the
forward visibility from the rear cockpit is. You have
to peer though a small semi-circular gap between the
canopy hoop, the front headrest and the student's head.
The forward view is far worse than in a K13 with its
one piece canopy, and not helped by the fact that you
sit fairly low down in the cockpit. I think that I
will make a point of only flying this type with well
switched on students who keep a good look out!

I suppose that it's a case of what is the greater risk.
Whiplash in the event of a crash or heavy landing,
or a head on mid-air collision with another aircraft
because you can't see ahead?

BTW I don't dislike the DG1000. It handles and performs
beautifully, it has good airbrakes (unlike the Duo
Discus), it is fully aerobatic in 18 metre mode (unlike
the Duo) and you can operate the undercarriage from
both cockpits (unlike the Duo).

BUT, I don't like the restricted view from the rear
cockpit, the difficult and heavy ground handling, getting
in and out of the thing, and the trigger type trimmer
mounted on the stick that doesn't seem to work. You
end up trimming with the trimmer tell-tale knob on
the side of the cockpit wall, so why bother with the
trigger in the first place?

Good try for the ideal trainer DG, but no cigar yet!


Derek Copeland

P.S. The r.a.s. black hole seems to re-appeared. this
is my third attempt at posting this!

"Derek Copeland" wrote in
message ...
At 22:42 04 December 2005, Don Johnstone wrote:
The answer to the whiplash question is very simple
and whiplash describes the action which causes the
injury. When a car, or glider decelerates very rapidly,
the head, which is unrestrained and has a fairly high
mass continues to move forward until it is stopped
at full body extension. It then whips back and if there
is nothing to stop it extends backwards, that is what
causes the injury. It is correct that a headrest prevents
injury in a rear shunt but that is not the primary
cause of 'whiplash' injuries. It is the whipping action
following a sudden deceleration.
I suppose if an impact in a glider is severe enough
to cause the whiplash then that injury may be the least
of your problems as you are much closer to the crash
in a glider than you are in a car.
--------------------------------------
I actually did an instructional flight in the back
seat of a DG1000 today, and was reminded how poor the
forward visibility from the rear cockpit is. You have
to peer though a small semi-circular gap between the
canopy hoop, the front headrest and the student's head.
The forward view is far worse than in a K13 with its
one piece canopy, and not helped by the fact that you
sit fairly low down in the cockpit. I think that I
will make a point of only flying this type with well
switched on students who keep a good look out!

I suppose that it's a case of what is the greater risk.
Whiplash in the event of a crash or heavy landing,
or a head on mid-air collision with another aircraft
because you can't see ahead?

BTW I don't dislike the DG1000. It handles and performs
beautifully, it has good airbrakes (unlike the Duo
Discus), it is fully aerobatic in 18 metre mode (unlike
the Duo) and you can operate the undercarriage from
both cockpits (unlike the Duo).

BUT, I don't like the restricted view from the rear
cockpit, the difficult and heavy ground handling, getting
in and out of the thing, and the trigger type trimmer
mounted on the stick that doesn't seem to work. You
end up trimming with the trimmer tell-tale knob on
the side of the cockpit wall, so why bother with the
trigger in the first place?

Good try for the ideal trainer DG, but no cigar yet!


Derek Copeland

P.S. The r.a.s. black hole seems to re-appeared. this
is my third attempt at posting this!


It does seem like the cockpits just keep getting worse. Maybe someone
should just try to improve the old Grob 103. Putting everything else aside,
the cockpit was nice.

Maybe the perfect trainer will be the Stemme S2 - if they ever build it.

Bill Daniels

Derek Copeland wrote in
:

BUT, I don't like the restricted view from the rear
cockpit, the difficult and heavy ground handling, getting
in and out of the thing, and the trigger type trimmer
mounted on the stick that doesn't seem to work. You
end up trimming with the trimmer tell-tale knob on
the side of the cockpit wall, so why bother with the
trigger in the first place?

Good try for the ideal trainer DG, but no cigar yet!


Derek Copeland


Yes, the DG trimmer control is cr@p, in all the DG's I have flown. Also
the very stiff aileron control in the 1000 -- takes both hands on the stick
to enter a thermal.

The front seat of the 1000 is quite comfortable, but the back seat is like
sitting on a toilet.

The Duo has a few minor faults, but the visibility is superb from both
cockpits and the handling is light and well balanced, nore like a single
seater.
-Bob Korves

Dave Martin wrote in
:

(snip)
Perhaps for gliders we should insist on airbags and
head restraints for both seats?

Having flown from the rear of many two seaters the
head gear and hairstyle of the front seat passenger
causes more problems than a well designed head retraint.


IMHO the worst thing the front seat passenger can wear
is a white hat or an have affro/permed hairstyle.

Dave

No glider air bags for me. Most of my landings would set them off!

When I fly our Duo I insist on the front seat person wearing a dark colored
hat. Otherwise all the rear seater sees in the canopy is reflections of
white hat.
-Bob Korves