Grob Twin Astir

The Twin Astir Trainer (fixed gear version) came with a standard
hydraulic disc brake from the factory. The ones which people
are
retrofitting are the more numerous retractable gear versions.
There
was a problem with that disc being too thin and deforming, but
TOST put out a retrofit kit to fix that issue last year.

I view the extra stopping power of the disc brake as another tool
in
my toolbox of flight controls. I don't use all of its capabilities
unde

normal conditions, but if a situation occurs where I need that
power,
want to be able to access it NOW. For example, if I have a
low altitude rope break and am forced into a situation where
there is
not much room to stop, I (personally) would rather get on the
brake
hard (even if it means scraping the nose) in order to avoid being
forced to make an intentional ground loop (and breaking the tail
boom +) to avoid a looming obstacle.

I flew professionally for 42 years, and it always grated on me
when
someone took a useful tool out of my toolbox "for my own good".

Whether one is a pilot, cabinet maker, electrician or whatever,
one
has tools to ply one's trade. Some of those tools will have the
capability to kill or maim. It is the responsibility of the
OPERATOR to
use those provided tools with skill, accuracy and judgement.
Don't
blame the tool, when the problem is in reality an inept
operator....

RO

I would agree with you IF gliders, especially 2 seat gliders were
alway
flown by pilots experience as you and I. Truth is they are not, they
ar
frequently flown by very inexperienced and sometimes inept
pilots, that i
the nature of gliding. The wheel brake on a glider is not a missio
critical item, unlike a powered aircraft the brakes are not tested
befor
taxiing, in most cases we only find they do not work on landing
which i
why I never rely on them. I accept a good brake may be best in th
situation you describe but that occurs rarely. The risk of damage
by a nos
over is much greater and more common. One of those cases
where the cure i
worse than the disease. I do accept that the Twin Astir is very tail
heav
and almost impossible to nose down with the OEM brake, not so
with a mor
efficient disc brake.

The Twin Astir was the Duo Discus of its day. Training was done in
K-7's and K-13's, and the inept pilots were not allowed to fly the
"sacred cow" higher performance Twin Astirs. The Twins were
used for the more experienced pilots enjoyment, and to teach XC.
This is evident in how the two Twin Astirs which our club operates
were kept in absolute pristine condition for 30+ years.

The Twin II was designed for training, but had a low max gross
weight, and a lower payload than the Twin Astir. Fast forward a few
decades, and most of the Twin II's have been crashed and repaired
to the point that the seat load is no longer very usable
(except in England where you have a higher gross weight
agreement with Grob). So now, due to prices and seat loads being
what they are, people are starting to try and use the Twin Astir for
primary training. There are trade-offs because this glider wasn't
designed with this purpose in mind. Ground handling is one trade-
off, and the wheel brake is another.

To your point of a low altitude rope break being rare, well we had a
towplane engine failure at about 50' three years ago. The glider
wound up in the bushes off the end of the runway with significant
damage. These scenarios do happen. The more likely scenario in
the Northeast USA is that the inept pilot gets low too far away from
home, and then has to land off airport in one of our small hilly
fields. In that case, I would still want the inept pilot to have a
strong wheel brake to stand the glider on its nose if he/she has to.
The philosophy here is that even though the field may look good,
one stops the glider right away for fear of ripping the gear off due
to falling into an unseen gopher hole, etc. Most fields here are short
enough that there is usually no question about the need to get it
stopped immediately anyway. If they are going to be allowed to fly
a Twin Astir, the inept people need to be taught not to yank on the
dive brake handle (during a normal landing) as though they have a
death wish...

Obviously, you people can operate your gliders as you see fit. I had
thought of using the automotive technology argument, but someone
else already brought that up. We have chosen to upgrade our
equipment to the newer technology, (that most new gliders come
equipped with) and are happily operating our Twins with it. If you
want to take a useful tool out of your pilot's toolbox, that is your
decision. I will keep that useful tool in mine though...

RO

On Thursday, 29 September 2016 15:00:07 UTC+2, Don Johnstone wrote:
I would agree with you IF gliders, especially 2 seat gliders were always
flown by pilots experience as you and I. Truth is they are not, they are
frequently flown by very inexperienced and sometimes inept pilots, that is
the nature of gliding. The wheel brake on a glider is not a mission
critical item, unlike a powered aircraft the brakes are not tested before
taxiing, in most cases we only find they do not work on landing which is
why I never rely on them.

If a student is inept then he/she should not be sent solo.
I had less than 10 flights to my name and I could already feel when I was over braking and skidding on a grass runway in the clubs G103 without an instructor needing to correct me.

Do you propose that we send students into the air with only half the tools in the bag and then plead ignorance when they decapitate themselves going through a fence during an off field landing because they couldn't stop in time and messed up an attempted ground loop?

I consider brakes mission critical and test them on every pre-flight.
No brakes or inefficient brakes means the glider is grounded.

Sheesh ... just now someone is going to propose that a half functioning elevator is safer for students because it will help reduce PIO's.

....Actually, the Grob already has the half functioning elevator, but that is to prevent spins not stop PIO!
I'm sorry!😉 I agree with your post but had to take the bait.

On Fri, 30 Sep 2016 02:30:40 -0700, dtarmichael wrote:

...Actually, the Grob already has the half functioning elevator, but
that is to prevent spins not stop PIO!

IME the elevator is reasonably functional on a G103 Twin 2 Acro but it
could certainly use a better rudder.

However it will spin: I did my annual spin checks one year in our one.


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

At 05:40 30 September 2016, Surge wrote:
On Thursday, 29 September 2016 15:00:07 UTC+2, Don
Johnstone wrote:
I would agree with you IF gliders, especially 2 seat gliders were
always
flown by pilots experience as you and I. Truth is they are not,
they are
frequently flown by very inexperienced and sometimes inept
pilots, that
i=
s
the nature of gliding. The wheel brake on a glider is not a
mission
critical item, unlike a powered aircraft the brakes are not tested
before
taxiing, in most cases we only find they do not work on landing
which is
why I never rely on them.

If a student is inept then he/she should not be sent solo.
I had less than 10 flights to my name and I could already feel
when I was
o=
ver braking and skidding on a grass runway in the clubs G103
without an
ins=
tructor needing to correct me.

Do you propose that we send students into the air with only half
the tools
=
in the bag and then plead ignorance when they decapitate
themselves going
t=
hrough a fence during an off field landing because they couldn't
stop in
ti=
me and messed up an attempted ground loop?

I consider brakes mission critical and test them on every pre-
flight.
No brakes or inefficient brakes means the glider is grounded.

Sheesh ... just now someone is going to propose that a half
functioning
ele=
vator is safer for students because it will help reduce PIO's.

I have just spent a week flying in the backseat of nothing but a
Twin Astir, with a cable and drum brake. I found that the well
maintained drum brake is more than efficient enough to stop the
glider and is well able to rub the nose on the ground if over used.
So I repeat my question, why would anyone want to "improve" the
brake by including a hydraulic system when proper maintenance
will provide a perfectly effective brake and one which is far less
likely to cause problems?

On Friday, October 7, 2016 at 5:00:07 PM UTC-7, Don Johnstone wrote:
So I repeat my question, why would anyone want to "improve" the
brake by including a hydraulic system when proper maintenance
will provide a perfectly effective brake and one which is far less
likely to cause problems?

Perhaps because some people have a different idea of maintenance?
Jim

"According to this FADEC dump, you ran the engines up to 106% on this takeoff out of Jackson Hole. Care to explain why you went to 106%?"

"Because they wouldn't go to 110%."

On Monday, October 10, 2016 at 12:11:16 PM UTC-5, Bob Kuykendall wrote:
"According to this FADEC dump, you ran the engines up to 106% on this takeoff out of Jackson Hole. Care to explain why you went to 106%?"

"Because they wouldn't go to 110%."

No, Bob. If it is a FADEC, you are not in control of the limits. :-)