Grob Twin Astir

[K m]

Group,
My club is looking to convert a Twin Astir brake system to a Hydraulic Disk from a Mechanical Drum. Our serial number does not fall within the serial number range of the Kit that is offered by Lindner. We have the Lindner kit and will be going with a 337. My question is does anyone know of a 337 on an Astir brake mod? Also, I have been trying to find info on any different versions of the Astir and can't find much. Is there any reference online that points to different models or versions? Ive read that water ballast was an option and some models came with a disk brake from the factory (These have a different wheel carrier structure). Does anyone know if gross weights remained the same on the Astir through the production run? This info may hel when submitting paperwork to the FAA.
Thanks!

[K m]

On Thursday, January 28, 2016 at 8:56:01 PM UTC-7, K m wrote:
> Group,
> My club is looking to convert a Twin Astir brake system to a Hydraulic Disk from a Mechanical Drum. Our serial number does not fall within the serial number range of the Kit that is offered by Lindner. We have the Lindner kit and will be going with a 337. My question is does anyone know of a 337 on an Astir brake mod? Also, I have been trying to find info on any different versions of the Astir and can't find much. Is there any reference online that points to different models or versions? Ive read that water ballast was an option and some models came with a disk brake from the factory (These have a different wheel carrier structure). Does anyone know if gross weights remained the same on the Astir through the production run? This info may hel when submitting paperwork to the FAA.
> Thanks!

It was brought to my attention in a PM that my first post may have been too vague for a legitimate answer. Utah Soaring Association (USA)is retrofitting a disk brake onto a G103 Twin Astir. It was also pointed out to me that there were 7 different variants of the Astir (?!). The USA club owns two Twin II's (One an Acro) and two Astir's. I know of some factory options for the Astir (Including a trainer version) but never anything close to 7 variants. Is there reference for this somewhere?
Our Astirs have the welded steel tube wheel carriers which rotate sideways under the rear seat when they retract.
Thanks for any info.

[Ventus_a]

On Thursday, January 28, 2016 at 8:56:01 PM UTC-7, K m wrote:
Group,
My club is looking to convert a Twin Astir brake system to a Hydraulic Disk from a Mechanical Drum. Our serial number does not fall within the serial number range of the Kit that is offered by Lindner. We have the Lindner kit and will be going with a 337. My question is does anyone know of a 337 on an Astir brake mod? Also, I have been trying to find info on any different versions of the Astir and can't find much. Is there any reference online that points to different models or versions? Ive read that water ballast was an option and some models came with a disk brake from the factory (These have a different wheel carrier structure). Does anyone know if gross weights remained the same on the Astir through the production run? This info may hel when submitting paperwork to the FAA.
Thanks!

It was brought to my attention in a PM that my first post may have been too vague for a legitimate answer. Utah Soaring Association (USA)is retrofitting a disk brake onto a G103 Twin Astir. It was also pointed out to me that there were 7 different variants of the Astir (?!). The USA club owns two Twin II's (One an Acro) and two Astir's. I know of some factory options for the Astir (Including a trainer version) but never anything close to 7 variants. Is there reference for this somewhere?
Our Astirs have the welded steel tube wheel carriers which rotate sideways under the rear seat when they retract.
Thanks for any info.

Try this link to EASA TCDS for Grob sailplanes

https://easa.europa.eu/documents/type-certificates/aircraft-cs-25-cs-22-cs-23-cs-vla-cs-lsa/easaa250

:-) Colin

[Frank Whiteley]

On Saturday, January 30, 2016 at 2:49:27 PM UTC-7, K m wrote:
> On Thursday, January 28, 2016 at 8:56:01 PM UTC-7, K m wrote:
> > Group,
> > My club is looking to convert a Twin Astir brake system to a Hydraulic Disk from a Mechanical Drum. Our serial number does not fall within the serial number range of the Kit that is offered by Lindner. We have the Lindner kit and will be going with a 337. My question is does anyone know of a 337 on an Astir brake mod? Also, I have been trying to find info on any different versions of the Astir and can't find much. Is there any reference online that points to different models or versions? Ive read that water ballast was an option and some models came with a disk brake from the factory (These have a different wheel carrier structure). Does anyone know if gross weights remained the same on the Astir through the production run? This info may hel when submitting paperwork to the FAA.
> > Thanks!
>
> It was brought to my attention in a PM that my first post may have been too vague for a legitimate answer. Utah Soaring Association (USA)is retrofitting a disk brake onto a G103 Twin Astir. It was also pointed out to me that there were 7 different variants of the Astir (?!). The USA club owns two Twin II's (One an Acro) and two Astir's. I know of some factory options for the Astir (Including a trainer version) but never anything close to 7 variants. Is there reference for this somewhere?
> Our Astirs have the welded steel tube wheel carriers which rotate sideways under the rear seat when they retract.
> Thanks for any info.

Had a phone chat with the original poster this morning. USA owns two Twin Astir 1's with the retract. The serial numbers are 5 apart, 3285 and 3290. The G-103 production underwent some serial production changes. For example, some have a single retract handle in the front seat, others in both seats. It's not clear what changes may have been options or serial production changes. ltb-Lindner.com hopefully has serial production data and would know whether the G-103 in question was produced with a drum or disc brake. The service bulletin allows retro-fitting of a disc brake on serial numbers 3000-3139, except for the T models (fixed gear). Presumably, higher serial numbers weren't included because they were built with disc brakes installed. At least one of the above has a disc brake. If that's the case, then it would seem the disc brake installation could be made as restorative without a 337. Maybe someone qualified could chime in about that. There were some further improvements made to the original disc brake system, which would be an approved installation.

Frank Whiteley-

[Michael Opitz]

At 18:24 31 January 2016, Frank Whiteley wrote:
>On Saturday, January 30, 2016 at 2:49:27 PM UTC-7, K m wrote:
>> On Thursday, January 28, 2016 at 8:56:01 PM UTC-7, K m
wrote:
>> > Group,
>> > My club is looking to convert a Twin Astir brake system to a
Hydraulic
>=
>Disk from a Mechanical Drum. Our serial number does not fall
within the
>ser=
>ial number range of the Kit that is offered by Lindner. We have the
>Lindner=
> kit and will be going with a 337. My question is does anyone
know of a
>337=
> on an Astir brake mod? Also, I have been trying to find info on
any
>differ=
>ent versions of the Astir and can't find much. Is there any
reference
>onlin=
>e that points to different models or versions? Ive read that water
ballast
>=
>was an option and some models came with a disk brake from the
factory
>(Thes=
>e have a different wheel carrier structure). Does anyone know if
gross
>weig=
>hts remained the same on the Astir through the production run?
This info
>ma=
>y hel when submitting paperwork to the FAA.
>> > Thanks!
>>=20
>> It was brought to my attention in a PM that my first post may
have been
>t=
>oo vague for a legitimate answer. Utah Soaring Association (USA)is
>retrofit=
>ting a disk brake onto a G103 Twin Astir. It was also pointed out
to me
>tha=
>t there were 7 different variants of the Astir (?!). The USA club
owns two
>=
>Twin II's (One an Acro) and two Astir's. I know of some factory
options
>for=
> the Astir (Including a trainer version) but never anything close to
7
>vari=
>ants. Is there reference for this somewhere?
>> Our Astirs have the welded steel tube wheel carriers which
rotate
>sideway=
>s under the rear seat when they retract.=20
>> Thanks for any info.
>
>Had a phone chat with the original poster this morning. USA owns
two Twin
>A=
>stir 1's with the retract. The serial numbers are 5 apart, 3285
and 3290.
>=
> The G-103 production underwent some serial production
changes. For
>exampl=
>e, some have a single retract handle in the front seat, others in
both
>seat=
>s. It's not clear what changes may have been options or serial
production
>=
>changes. ltb-Lindner.com hopefully has serial production data
and would
>kn=
>ow whether the G-103 in question was produced with a drum or
disc brake.
>T=
>he service bulletin allows retro-fitting of a disc brake on serial
numbers
>=
>3000-3139, except for the T models (fixed gear). Presumably,
higher
>serial=
> numbers weren't included because they were built with disc
brakes
>installe=
>d. At least one of the above has a disc brake. If that's the case,
then it
>=
>would seem the disc brake installation could be made as
restorative
>without=
> a 337. Maybe someone qualified could chime in about that. There
were
>some=
> further improvements made to the original disc brake system,
which would
>b=
>e an approved installation.
>
>Frank Whiteley-
>
The Nutmeg Soaring Association of Freehold, NY has 3 Twin 1's,
and has sold another one, for a total of 4 which we have owned.
We retrofitted one with a disc brake IAW TM 315-50 last spring.
That one still has the old cast aluminum parts in the gear cage.
After a few months of operation with the new disc brake, a side load
managed to bend the disc plate, and render it inoperable. Our
mechanics deemed the part to be either substandard or under-
designed and filed a complaint with TOST through Wings and
Wheels. It took a few months, but TOST responded by replacing
the bent disc with a new stronger one, and also said they would
replace other older defective discs in the field. We have
corresponded with at least one other Twin 1 club operator in
Germany who told us that they previously had a disc brake, had
problems with it, and went back to the drum brake to avoid the
previously noted problems. So, it seems entirely possible that the
Utah late serial number Twin 1 was originally produced with a disc
brake, but later changed to the drum brake configuration due to an
under-designed disc brake plate. If you get a new disc brake from
TOST, it should now come standard with the thicker reinforced
plate. Ours has been fine since we installed the beefed up plate.

Mike Opitz

[Michael Opitz]

>>
>The Nutmeg Soaring Association of Freehold, NY has 3 Twin 1's,
>and has sold another one, for a total of 4 which we have owned.
>We retrofitted one with a disc brake IAW TM 315-50 last spring.
>That one still has the old cast aluminum parts in the gear cage.
>After a few months of operation with the new disc brake, a side
load
>managed to bend the disc plate, and render it inoperable. Our
>mechanics deemed the part to be either substandard or under-
>designed and filed a complaint with TOST through Wings and
>Wheels. It took a few months, but TOST responded by replacing
>the bent disc with a new stronger one, and also said they would
>replace other older defective discs in the field. We have
>corresponded with at least one other Twin 1 club operator in
>Germany who told us that they previously had a disc brake, had
>problems with it, and went back to the drum brake to avoid the
>previously noted problems. So, it seems entirely possible that the
>Utah late serial number Twin 1 was originally produced with a
disc
>brake, but later changed to the drum brake configuration due to
an
>under-designed disc brake plate. If you get a new disc brake
from
>TOST, it should now come standard with the thicker reinforced
>plate. Ours has been fine since we installed the beefed up plate.
>
>Mike Opitz
>
On thinking this issue through a little further, we have come to the
conclusion that it would be pretty easy to tell if the Twin had a
previous disc brake installation. The disc brake uses a hydraulic
reservoir located underneath the rear seat pan. If there was a
previous disc brake in the glider, the reservoir, or at least evidence
of the FRP mounts will be there to see. If one finds this evidence,
then a disc brake installation would be a restoration to the OEM
condition, and not need a 337 form. Also, if the logbook history is
complete, there would be an annotation of a change from the
original disc to a drum brake configuration. Hope this helps..

Mike Opitz

[Michael Opitz]

>>
>The Nutmeg Soaring Association of Freehold, NY has 3 Twin 1's,
>and has sold another one, for a total of 4 which we have owned.
>We retrofitted one with a disc brake IAW TM 315-50 last spring.
>That one still has the old cast aluminum parts in the gear cage.
>After a few months of operation with the new disc brake, a side
load
>managed to bend the disc plate, and render it inoperable. Our
>mechanics deemed the part to be either substandard or under-
>designed and filed a complaint with TOST through Wings and
>Wheels. It took a few months, but TOST responded by replacing
>the bent disc with a new stronger one, and also said they would
>replace other older defective discs in the field. We have
>corresponded with at least one other Twin 1 club operator in
>Germany who told us that they previously had a disc brake, had
>problems with it, and went back to the drum brake to avoid the
>previously noted problems. So, it seems entirely possible that the
>Utah late serial number Twin 1 was originally produced with a
disc
>brake, but later changed to the drum brake configuration due to
an
>under-designed disc brake plate. If you get a new disc brake
from
>TOST, it should now come standard with the thicker reinforced
>plate. Ours has been fine since we installed the beefed up plate.
>
>Mike Opitz
>
On thinking this issue through a little further, we have come to the
conclusion that it would be pretty easy to tell if the Twin had a
previous disc brake installation. The disc brake uses a hydraulic
reservoir located underneath the rear seat pan. If there was a
previous disc brake in the glider, the reservoir, or at least evidence
of the FRP mounts will be there to see. If one finds this evidence,
then a disc brake installation would be a restoration to the OEM
condition, and not need a 337 form. Also, if the logbook history is
complete, there would be an annotation of a change from the
original disc to a drum brake configuration. Hope this helps..

Mike Opitz

[CindyB[_2_]]

On Thursday, January 28, 2016 at 7:56:01 PM UTC-8, K m wrote:
> Group,
> My club is looking to convert a Twin Astir brake system to a Hydraulic Disk from a Mechanical Drum. Our serial number does not fall within the serial number range of the Kit that is offered by Lindner. We have the Lindner kit and will be going with a 337. My question is does anyone know of a 337 on an Astir brake mod?


We did a conversion on a Twin Astir at Cal City, ~1996. It was a side folding gear.... I think. The glider had earlier been owned by Bob Harris, and he used it for wave learning before taking the single Grob to the record climb. The Astir was operated by Douglas Soaring Club, when it had the conversion. We used a Cleveland wheel and disc. With a standard (4 or 6-ply) main wheel and heavy payload, anything other than a greaser landing resulted in too much sidewall flexion, which broke out the disc, and amazingly didn't grab on the calipers and create havoc.
The solution was to use a ten-ply sidewall tire, for very little flexion and higher psi in the tire. This then made for kangaroo results, if you plopped on with any vertical energy. The glider was sold to an operator in SE Colorado, and he was warned very directly about it's landing handling.

N173SS was then totalled within about six months time, by a commercial pilot who failed to latch the canopy, ballooned, released and crashed adjacent to the runway, NTSB Identification: DEN99LA028.

I don't know if you can get the FAA file on N173SS for a glider that is deregistered. We had a local DAR create the data for the 337 that was issued. I just thought you should know some of the drawbacks we experienced in the process. The drum brake was always a poor decelerator, but the disc offered a whole different potential for problems (nose overs and belly rubs, PIOs, wrong fluid installation, etc.).
No difference in payload other than the reduction by the added gear weight. Every pound counts in the older multi-repaired airframes. Good luck with yours and hope this info helps.

Cindy B

[K m]

On Friday, February 12, 2016 at 12:06:32 PM UTC-7, CindyB wrote:
> On Thursday, January 28, 2016 at 7:56:01 PM UTC-8, K m wrote:
> > Group,
> > My club is looking to convert a Twin Astir brake system to a Hydraulic Disk from a Mechanical Drum. Our serial number does not fall within the serial number range of the Kit that is offered by Lindner. We have the Lindner kit and will be going with a 337. My question is does anyone know of a 337 on an Astir brake mod?
>
>
> We did a conversion on a Twin Astir at Cal City, ~1996. It was a side folding gear.... I think. The glider had earlier been owned by Bob Harris, and he used it for wave learning before taking the single Grob to the record climb. The Astir was operated by Douglas Soaring Club, when it had the conversion. We used a Cleveland wheel and disc. With a standard (4 or 6-ply) main wheel and heavy payload, anything other than a greaser landing resulted in too much sidewall flexion, which broke out the disc, and amazingly didn't grab on the calipers and create havoc.
> The solution was to use a ten-ply sidewall tire, for very little flexion and higher psi in the tire. This then made for kangaroo results, if you plopped on with any vertical energy. The glider was sold to an operator in SE Colorado, and he was warned very directly about it's landing handling.
>
> N173SS was then totalled within about six months time, by a commercial pilot who failed to latch the canopy, ballooned, released and crashed adjacent to the runway, NTSB Identification: DEN99LA028.
>
> I don't know if you can get the FAA file on N173SS for a glider that is deregistered. We had a local DAR create the data for the 337 that was issued. I just thought you should know some of the drawbacks we experienced in the process. The drum brake was always a poor decelerator, but the disc offered a whole different potential for problems (nose overs and belly rubs, PIOs, wrong fluid installation, etc.).
> No difference in payload other than the reduction by the added gear weight. Every pound counts in the older multi-repaired airframes. Good luck with yours and hope this info helps.
>
> Cindy B

Thanks! Working through the 337 process as we speak. We have a Tost brake assembly and we have strengthened the gear structure at the attach point.

[[email protected]]

Have you tried rebuilding the drum brake? My club used to have a Twin Astir retractable and the drum - tiny though it looked - always did a fair job of stopping the ship. It was strong enough to make rubbing the underside of the nose on the runway a concern.

[[email protected]]

On Thursday, January 28, 2016 at 10:56:01 PM UTC-5, K m wrote:
> Group,
> My club is looking to convert a Twin Astir brake system to a Hydraulic Disk from a Mechanical Drum. Our serial number does not fall within the serial number range of the Kit that is offered by Lindner. We have the Lindner kit and will be going with a 337. My question is does anyone know of a 337 on an Astir brake mod? Also, I have been trying to find info on any different versions of the Astir and can't find much. Is there any reference online that points to different models or versions? Ive read that water ballast was an option and some models came with a disk brake from the factory (These have a different wheel carrier structure). Does anyone know if gross weights remained the same on the Astir through the production run? This info may hel when submitting paperwork to the FAA.
> Thanks!

My club (Franconia Soaring) is looking for a replacement rear canopy for our G103 Twin Astir (serial number 3069). Can anyone help, or point me in the right direction?
Thanks !

[Michael Opitz]

>My club (Franconia Soaring) is looking for a replacement rear canopy
for
>ou=
>r G103 Twin Astir (serial number 3069). Can anyone help, or point
me in
>the=
> right direction?
>Thanks !
>
Lindner has canopy blanks in stock, and can ship quickly. Our club
(Nutmeg Soaring in Freehold,NY) might be looking to replace both a
front and rear canopy on a Twin Astir over the coming winter.
Shipping the canopies nested/spooned together greatly reduces the
shipping price per canopy. You can email me directly if you want to
explore the options. mropitz1 at aol dot com
Mike Opitz

[[email protected]]

On Tuesday, September 27, 2016 at 9:15:04 PM UTC-4, Michael Opitz wrote:
> >My club (Franconia Soaring) is looking for a replacement rear canopy
> for
> >ou=
> >r G103 Twin Astir (serial number 3069). Can anyone help, or point
> me in
> >the=
> > right direction?
> >Thanks !
> >
> Lindner has canopy blanks in stock, and can ship quickly. Our club
> (Nutmeg Soaring in Freehold,NY) might be looking to replace both a
> front and rear canopy on a Twin Astir over the coming winter.
> Shipping the canopies nested/spooned together greatly reduces the
> shipping price per canopy. You can email me directly if you want to
> explore the options. mropitz1 at aol dot com
> Mike Opitz

Thanks Mike... I just wrote to you at aol
-Andy-

[Don Johnstone[_4_]]

At 06:46 19 February 2016, wrote:
>Have you tried rebuilding the drum brake? My club used to have a
Twin
>Astir=
> retractable and the drum - tiny though it looked - always did a fair
job
>o=
>f stopping the ship. It was strong enough to make rubbing the
underside of
>=
>the nose on the runway a concern.

Very true, the original Grob 103 Twin Astir had no nosewheel so a
super efficient brake is not a good idea, unless of course you want to
grind off the gel coat, or even worse the underlying structure under
the nose. The Grob103 Acro did have a nosewheel and therefore the
more efficient disc brake was not a problem.
I always wonder if people actually think through the implications of
making something "better". Perhaps there was a reason why the
original design did not have a super efficient brake.
Duct tape can't fix stupid, it can muffle the noise.

[John[_36_]]

It's ironic that the I received an email from the Utah Soaring Association indicating yesterday telling about one of our Grob Astir's had a hard landing a few weeks ago that ripped off the disk brake caliper. The damage inspection found this is not the first time this has happened as the caliper hangs down at the 6 o'clock position. The Utah board is looking at taking it back to the original drum brake design for better hard landing durability.

[Papa3[_2_]]

Robert Mudd in Moriarty was very helpful when we needed a canopy last year. There are a few different sub-versions, so it's important to make sure you know exactly which frame you have.

P3

[Michael Opitz]

At 09:59 28 September 2016, Don Johnstone wrote:
>At 06:46 19 February 2016, wrote:
>>Have you tried rebuilding the drum brake? My club used to have
a
>Twin
>>Astir=
>> retractable and the drum - tiny though it looked - always did a
fair
>job
>>o=
>>f stopping the ship. It was strong enough to make rubbing the
>underside of
>>=
>>the nose on the runway a concern.
>
>Very true, the original Grob 103 Twin Astir had no nosewheel so a
>super efficient brake is not a good idea, unless of course you want
to
>grind off the gel coat, or even worse the underlying structure
under
>the nose. The Grob103 Acro did have a nosewheel and therefore
the
>more efficient disc brake was not a problem.
>I always wonder if people actually think through the implications
of
>making something "better". Perhaps there was a reason why the
>original design did not have a super efficient brake.
>Duct tape can't fix stupid, it can muffle the noise.
>
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 under
normal conditions, but if a situation occurs where I need that power, I
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

[[email protected]]

Michael-

Hear Hear!

[Bruce Hoult]

On Thursday, September 29, 2016 at 3:15:10 PM UTC+13, Michael Opitz wrote:
> At 09:59 28 September 2016, Don Johnstone wrote:
> >At 06:46 19 February 2016, wrote:
> >>Have you tried rebuilding the drum brake? My club used to have
> a
> >Twin
> >>Astir=
> >> retractable and the drum - tiny though it looked - always did a
> fair
> >job
> >>o=
> >>f stopping the ship. It was strong enough to make rubbing the
> >underside of
> >>=
> >>the nose on the runway a concern.
> >
> >Very true, the original Grob 103 Twin Astir had no nosewheel so a
> >super efficient brake is not a good idea, unless of course you want
> to
> >grind off the gel coat, or even worse the underlying structure
> under
> >the nose. The Grob103 Acro did have a nosewheel and therefore
> the
> >more efficient disc brake was not a problem.
> >I always wonder if people actually think through the implications
> of
> >making something "better". Perhaps there was a reason why the
> >original design did not have a super efficient brake.
> >Duct tape can't fix stupid, it can muffle the noise.
> >
> 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 under
> normal conditions, but if a situation occurs where I need that power, I
> 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....

Y'know ... when I learned to fly, we were *taught* to use the nose of the Blanik on the ground for extra braking in an emergency. It's a long time ago, but I seem to recall it may even have been demonstrated.

[Don Johnstone[_4_]]

At 02:02 29 September 2016, Michael Opitz wrote:
>At 09:59 28 September 2016, Don Johnstone wrote:
>>At 06:46 19 February 2016, wrote:
>>>Have you tried rebuilding the drum brake? My club used to have
>a
>>Twin
>>>Astir=
>>> retractable and the drum - tiny though it looked - always did a
>fair
>>job
>>>o=
>>>f stopping the ship. It was strong enough to make rubbing the
>>underside of
>>>=
>>>the nose on the runway a concern.
>>
>>Very true, the original Grob 103 Twin Astir had no nosewheel so a
>>super efficient brake is not a good idea, unless of course you want
>to
>>grind off the gel coat, or even worse the underlying structure
>under
>>the nose. The Grob103 Acro did have a nosewheel and therefore
>the
>>more efficient disc brake was not a problem.
>>I always wonder if people actually think through the implications
>of
>>making something "better". Perhaps there was a reason why the
>>original design did not have a super efficient brake.
>>Duct tape can't fix stupid, it can muffle the noise.
>>
>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 under

>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 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. I accept a good brake may be best in the
situation you describe but that occurs rarely. The risk of damage by a nose
over is much greater and more common. One of those cases where the cure is
worse than the disease. I do accept that the Twin Astir is very tail heavy
and almost impossible to nose down with the OEM brake, not so with a more
efficient disc brake.

[Bob Whelan[_3_]]

On 9/29/2016 6:55 AM, Don Johnstone wrote:
> At 02:02 29 September 2016, Michael Opitz wrote:
>> At 09:59 28 September 2016, Don Johnstone wrote:
<Snip...>
>>> Very true, the original Grob 103 Twin Astir had no nosewheel so a super
>>> efficient brake is not a good idea, unless of course you want to
>>> grind off the gel coat, or even worse the underlying structure under
>>> the nose. The Grob103 Acro did have a nosewheel and therefore the
>>> more efficient disc brake was not a problem. I always wonder if people
>>> actually think through the implications of
>>> making something "better". Perhaps there was a reason why the original
>>> design did not have a super efficient brake. Duct tape can't fix
>>> stupid, it can muffle the noise.
>>>
<Snip...>
>> 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 under
>> 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 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. I accept a good brake may be best in the
> situation you describe but that occurs rarely. The risk of damage by a
> nose over is much greater and more common. One of those cases where the
> cure is worse than the disease. I do accept that the Twin Astir is very
> tail heavy and almost impossible to nose down with the OEM brake, not so
> with a more efficient disc brake.
>

Hmmm...Izziss (i.e. inexperience/incompetency/inattention/etc.) why anti-skid
brake technology on motor vehicles has become so popular? Would it not be
simpler/cheaper/better to have weaker brakes on motor vehicles? Ah, for the
good ol' days of drum brakes all around and no power assist. Thanks for
helping me belatedly realize weak, fading brakes on my first tow vehicle were
actually a safety *asset!* :)

In this particular "religious argument" I cast my vote for "overly powerful,"
easily modulatable, glider wheel brakes. My 2nd high-performance single seater
(purchased w. me having a whopping 200 hours stick time) actually had this
combination...and some 39 years later I still have difficulty imagining
anything better.

Bob W.

[Paul Agnew]

I learned the hard way that automobile antiskid brakes do not shorten braking distance. They only improve handling during heavy braking.

Paul A.
Jupiter, FL
Treasure Coast Soaring

[Dan Marotta]

.... And 4-wheel-drive simply gets you in deeper before you get stuck.

I think I'll slink off to my safe place now and hide so I don't feel
uncomfortable any more.

On 9/29/2016 11:33 AM, Paul Agnew wrote:
> I learned the hard way that automobile antiskid brakes do not shorten braking distance. They only improve handling during heavy braking.
>
> Paul A.
> Jupiter, FL
> Treasure Coast Soaring

--
Dan, 5J

[Michael Opitz]

>>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

[CindyB[_2_]]

On Wednesday, September 28, 2016 at 7:37:29 AM UTC-7, John wrote:
> It's ironic that the I received an email from the Utah Soaring Association indicating yesterday telling about one of our Grob Astir's had a hard landing a few weeks ago that ripped off the disk brake caliper. The damage inspection found this is not the first time this has happened as the caliper hangs down at the 6 o'clock position. The Utah board is looking at taking it back to the original drum brake design for better hard landing durability.


I guess someone didn't read my post from January -- recommending the ten ply tire... and smooooooth landings. Sorry for their troubles. Pilot training issues, usually. More training. I side with Mike O -- leave me all the tools. Then I can choose which to use, or what parts to sacrifice.

Cindy B

[Surge]

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.

[[email protected]]

....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.

[Martin Gregorie[_5_]]

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 |

[Michael Opitz]

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

Does it have the Z tape installed in front of the control surfaces as per
the Grob/Lindner optional service letter SL-12? If not, you might find
the effectiveness will be enhanced if you do install it. It works
wonders for the Twin Astir rudder... It is certainly easy and cheap
enough to try, and it is factory approved as well.....

RO

[Martin Gregorie[_5_]]

On Fri, 30 Sep 2016 13:26:10 +0000, Michael Opitz wrote:

>>IME the elevator is reasonably functional on a G103 Twin 2 Acro but it
>>could certainly use a better rudder.
>
> Does it have the Z tape installed in front of the control surfaces as
> per the Grob/Lindner optional service letter SL-12? If not, you might
> find the effectiveness will be enhanced if you do install it. It works
> wonders for the Twin Astir rudder... It is certainly easy and cheap
> enough to try, and it is factory approved as well.....
>
I don't recall seeing any zigzag strip in front of the rudder hinge. I'll
look next time I'm at the club and mention this where it may do some good
if it is not turbulated.

Thanks for the tip.


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

[Michael Opitz]

At 23:25 30 September 2016, Martin Gregorie wrote:
>On Fri, 30 Sep 2016 13:26:10 +0000, Michael Opitz wrote:
>
>>>IME the elevator is reasonably functional on a G103 Twin 2
Acro but it
>>>could certainly use a better rudder.
>>
>> Does it have the Z tape installed in front of the control surfaces
as
>> per the Grob/Lindner optional service letter SL-12? If not, you
might
>> find the effectiveness will be enhanced if you do install it. It
works
>> wonders for the Twin Astir rudder... It is certainly easy and
cheap
>> enough to try, and it is factory approved as well.....
>>
>I don't recall seeing any zigzag strip in front of the rudder hinge.
I'll
>look next time I'm at the club and mention this where it may do
some good
>if it is not turbulated.
>
>Thanks for the tip.
>
>
>--
>martin@ | Martin Gregorie
>gregorie. | Essex, UK
>org |


Martin,

You are welcome. If your Acro doesn't already have the Z tape
installed, I would be interested to hear your opinion as to if
the efficacy of the rudder is noticeably improved (or not) after the
installation. If the fin airfoil profiles of the Twin Astir and the Acro
are close, I suspect that you will notice a favorable improvement.

Good luck...

RO

[Don Johnstone[_4_]]

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?

[Bob Kuykendall]

"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%."

[Steve Leonard[_2_]]

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. :-)

[Martin Gregorie[_5_]]

On Sat, 01 Oct 2016 00:40:43 +0000, Michael Opitz wrote:

> You are welcome. If your Acro doesn't already have the Z tape
> installed, I would be interested to hear your opinion as to if the
> efficacy of the rudder is noticeably improved (or not) after the
> installation. If the fin airfoil profiles of the Twin Astir and the
> Acro are close, I suspect that you will notice a favorable improvement.
>
I finally checked our Acro II last Sunday: as I thought there's no fin
turbulation on it, so I've passed your reference to the Lindner TN to the
relevent club committee member.

It turns out that our Acro now has a fairly low cockpit weight capacity.
On Sunday we were using it for trial flights but we had to temporarily
take one of our ASK-21s off scheduled training duties to fly a reasonably
heavy trial flighter. Some of our members would like to use it for mutual
XC flying since its a better XC glider than an ASK-21 and has a decent
SDI flight computer fitted. That said, our ASK-21s do routinely go XC on
good days with students who are close to soloing - an 80km o/r to HusBos
is favourite with our paid instructors.


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

[JS]

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

[Michael Opitz]

At 22:46 10 October 2016, Martin Gregorie wrote:
>On Sat, 01 Oct 2016 00:40:43 +0000, Michael Opitz wrote:
>
>> You are welcome. If your Acro doesn't already have the Z tape
>> installed, I would be interested to hear your opinion as to if the
>> efficacy of the rudder is noticeably improved (or not) after the
>> installation. If the fin airfoil profiles of the Twin Astir and the
>> Acro are close, I suspect that you will notice a favorable
improvement.
>>
>I finally checked our Acro II last Sunday: as I thought there's no
fin
>turbulation on it, so I've passed your reference to the Lindner TN
to the
>relevent club committee member.
>
>It turns out that our Acro now has a fairly low cockpit weight
capacity.
>On Sunday we were using it for trial flights but we had to
temporarily
>take one of our ASK-21s off scheduled training duties to fly a
reasonably
>heavy trial flighter. Some of our members would like to use it for
mutual
>XC flying since its a better XC glider than an ASK-21 and has a
decent
>SDI flight computer fitted. That said, our ASK-21s do routinely go
XC on
>good days with students who are close to soloing - an 80km o/r to
HusBos
>is favourite with our paid instructors.
>
>
>--
>martin@ | Martin Gregorie
>gregorie. | Essex, UK
>org |


Martin,

Low seat load was the reason we sold our Acro several years ago.
If you have a lot of 2 seaters, you can schedule around it, but the
issue becomes a pain if you only have one or two 2-seaters to work
with.

If you can put up with the ground handling issues of a tail dragger,
and a little bit stiffer flight controls, you may find (as we have) that
the original Twin Astir gives a lot for the money invested. A lot of
them had been used as advanced XC trainers, and not for basic
training, so therefore minimal damage history.. This equates to a
retention of the already very high factory seat load of 242 Lbs/seat
plus another 22 Lbs in the baggage compartment. Some even have
water ballast. For XC training, the Twin 1 has a markedly slower
stall speed (with very effective trim) than the Twin II for better
thermalling performance. Best L/D is also ~4 points better than the
Twin II, so it is also noticeably better on the glides as well. For XC
training, I would take the Twin Astir over an Acro any day....IMHO

You can crash a Twin Astir, then add 40 Lbs of repair material and
still have a higher seat load than a NDH (No Damage History)
Twin II (let alone an Acro which will be 30-40 Lbs less than a
regular Twin II). Of course, these numbers are for the rest of the
world which doesn't have the RAF and BGA Twin II increased gross
weight agreements with Grob.....

RO

[Frank Whiteley]

On Monday, October 10, 2016 at 9:00:20 PM UTC-6, Michael Opitz wrote:
> At 22:46 10 October 2016, Martin Gregorie wrote:
> >On Sat, 01 Oct 2016 00:40:43 +0000, Michael Opitz wrote:
> >
> >> You are welcome. If your Acro doesn't already have the Z tape
> >> installed, I would be interested to hear your opinion as to if the
> >> efficacy of the rudder is noticeably improved (or not) after the
> >> installation. If the fin airfoil profiles of the Twin Astir and the
> >> Acro are close, I suspect that you will notice a favorable
> improvement.
> >>
> >I finally checked our Acro II last Sunday: as I thought there's no
> fin
> >turbulation on it, so I've passed your reference to the Lindner TN
> to the
> >relevent club committee member.
> >
> >It turns out that our Acro now has a fairly low cockpit weight
> capacity.
> >On Sunday we were using it for trial flights but we had to
> temporarily
> >take one of our ASK-21s off scheduled training duties to fly a
> reasonably
> >heavy trial flighter. Some of our members would like to use it for
> mutual
> >XC flying since its a better XC glider than an ASK-21 and has a
> decent
> >SDI flight computer fitted. That said, our ASK-21s do routinely go
> XC on
> >good days with students who are close to soloing - an 80km o/r to
> HusBos
> >is favourite with our paid instructors.
> >
> >
> >--
> >martin@ | Martin Gregorie
> >gregorie. | Essex, UK
> >org |
>
>
> Martin,
>
> Low seat load was the reason we sold our Acro several years ago.
> If you have a lot of 2 seaters, you can schedule around it, but the
> issue becomes a pain if you only have one or two 2-seaters to work
> with.
>
> If you can put up with the ground handling issues of a tail dragger,
> and a little bit stiffer flight controls, you may find (as we have) that
> the original Twin Astir gives a lot for the money invested. A lot of
> them had been used as advanced XC trainers, and not for basic
> training, so therefore minimal damage history.. This equates to a
> retention of the already very high factory seat load of 242 Lbs/seat
> plus another 22 Lbs in the baggage compartment. Some even have
> water ballast. For XC training, the Twin 1 has a markedly slower
> stall speed (with very effective trim) than the Twin II for better
> thermalling performance. Best L/D is also ~4 points better than the
> Twin II, so it is also noticeably better on the glides as well. For XC
> training, I would take the Twin Astir over an Acro any day....IMHO
>
> You can crash a Twin Astir, then add 40 Lbs of repair material and
> still have a higher seat load than a NDH (No Damage History)
> Twin II (let alone an Acro which will be 30-40 Lbs less than a
> regular Twin II). Of course, these numbers are for the rest of the
> world which doesn't have the RAF and BGA Twin II increased gross
> weight agreements with Grob.....
>
> RO

Competent repairs add little weight. A former BGA senior inspector who had a repair station flew a DG-300 through some wires and smashed it to pieces.. When rebuilt, it weighed within 10oz of new. That same inspector removed 37 lbs of filler from my previously repaired Kestrel 19 while re-contouring the fuselage between the wheel and tail boom. Takes a craftsman I guess..

The Twin Astir and T version winch launch very nicely and are quite cross country capable. If someone designed a nice filet for the wing root, it would probably go 10% better.

I'd heard there might be an effort to increase the Twin II payload, but nothing recently.

Frank Whiteley

[David Salmon[_3_]]

At 06:00 11 October 2016, Frank Whiteley wrote:
>On Monday, October 10, 2016 at 9:00:20 PM UTC-6, Michael Opitz wrote:
>> At 22:46 10 October 2016, Martin Gregorie wrote:
>> >On Sat, 01 Oct 2016 00:40:43 +0000, Michael Opitz wrote:
>> >
>> >> You are welcome. If your Acro doesn't already have the Z tape
>> >> installed, I would be interested to hear your opinion as to if the
>> >> efficacy of the rudder is noticeably improved (or not) after the
>> >> installation. If the fin airfoil profiles of the Twin Astir and the
>> >> Acro are close, I suspect that you will notice a favorable=20
>> improvement.
>> >>
>> >I finally checked our Acro II last Sunday: as I thought there's no=20
>> fin=20
>> >turbulation on it, so I've passed your reference to the Lindner TN=20
>> to the=20
>> >relevent club committee member.=20
>> >
>> >It turns out that our Acro now has a fairly low cockpit weight=20
>> capacity.=20
>> >On Sunday we were using it for trial flights but we had to=20
>> temporarily=20
>> >take one of our ASK-21s off scheduled training duties to fly a=20
>> reasonably=20
>> >heavy trial flighter. Some of our members would like to use it for=20
>> mutual=20
>> >XC flying since its a better XC glider than an ASK-21 and has a=20
>> decent=20
>> >SDI flight computer fitted. That said, our ASK-21s do routinely go=20
>> XC on=20
>> >good days with students who are close to soloing - an 80km o/r to=20
>> HusBos=20
>> >is favourite with our paid instructors.
>> >
>> >
>> >--=20
>> >martin@ | Martin Gregorie
>> >gregorie. | Essex, UK
>> >org |
>>=20
>>=20
>> Martin,
>>=20
>> Low seat load was the reason we sold our Acro several years ago.
>> If you have a lot of 2 seaters, you can schedule around it, but the=20
>> issue becomes a pain if you only have one or two 2-seaters to work=20
>> with.
>>=20
>> If you can put up with the ground handling issues of a tail dragger,
>> and a little bit stiffer flight controls, you may find (as we have)
that=
>=20
>> the original Twin Astir gives a lot for the money invested. A lot
of=20
>> them had been used as advanced XC trainers, and not for basic=20
>> training, so therefore minimal damage history.. This equates to a=20
>> retention of the already very high factory seat load of 242 Lbs/seat
>> plus another 22 Lbs in the baggage compartment. Some even have=20
>> water ballast. For XC training, the Twin 1 has a markedly slower=20
>> stall speed (with very effective trim) than the Twin II for better=20
>> thermalling performance. Best L/D is also ~4 points better than the=20
>> Twin II, so it is also noticeably better on the glides as well. For
XC=20
>> training, I would take the Twin Astir over an Acro any day....IMHO
>>=20
>> You can crash a Twin Astir, then add 40 Lbs of repair material and=20
>> still have a higher seat load than a NDH (No Damage History)
>> Twin II (let alone an Acro which will be 30-40 Lbs less than a=20
>> regular Twin II). Of course, these numbers are for the rest of the=20
>> world which doesn't have the RAF and BGA Twin II increased gross=20
>> weight agreements with Grob.....
>>=20
>> RO
>
>Competent repairs add little weight. A former BGA senior inspector who
>had=
> a repair station flew a DG-300 through some wires and smashed it to
>pieces=
>.. When rebuilt, it weighed within 10oz of new. That same inspector
>remove=
>d 37 lbs of filler from my previously repaired Kestrel 19 while
>re-contouri=
>ng the fuselage between the wheel and tail boom. Takes a craftsman I
>guess=
>..
>
>The Twin Astir and T version winch launch very nicely and are quite cross
>c=
>ountry capable. If someone designed a nice filet for the wing root, it
>wou=
>ld probably go 10% better.
>
>I'd heard there might be an effort to increase the Twin II payload, but
>not=
>hing recently.
>
>Frank Whiteley

20 years ago we had an Acro with a strange history. Apparently it had spun
in and the whole front end replaced with one from another that had caught
fire in the factory. I don't remember any weiight problems. It was a lovely
glider to fly, except, with the slightest rain on the wings it reverted to
the performance of a brick. Never managed to spin it, and a 1g stall
attempt would just result in mushing flight. I have ridge soared it with
the stick on the back stop. It was a very well engineered and made glider,
and we too used it for cross country training, and I well remember once
taking a visiting king for a flight in it.
It came with a small pair of canards, to enable it to enter a spin more
easily, but because it had a new nose, the fixing holes were not there, and
we didn't need it to spin anyway as we had Puchaczs. Not the easiest to
rig, but it lived in the hangar, so not a problem. A glider I remember
with a great deal of affection.
Re the Kestrel 19, when mine was being rigged, you could hear the loose
bits left in thhe wings, rattling around.
Dave

>

[Bruce Hoult]

On Tuesday, October 11, 2016 at 4:00:20 PM UTC+13, Michael Opitz wrote:
> At 22:46 10 October 2016, Martin Gregorie wrote:
> >On Sat, 01 Oct 2016 00:40:43 +0000, Michael Opitz wrote:
> >
> >> You are welcome. If your Acro doesn't already have the Z tape
> >> installed, I would be interested to hear your opinion as to if the
> >> efficacy of the rudder is noticeably improved (or not) after the
> >> installation. If the fin airfoil profiles of the Twin Astir and the
> >> Acro are close, I suspect that you will notice a favorable
> improvement.
> >>
> >I finally checked our Acro II last Sunday: as I thought there's no
> fin
> >turbulation on it, so I've passed your reference to the Lindner TN
> to the
> >relevent club committee member.
> >
> >It turns out that our Acro now has a fairly low cockpit weight
> capacity.
> >On Sunday we were using it for trial flights but we had to
> temporarily
> >take one of our ASK-21s off scheduled training duties to fly a
> reasonably
> >heavy trial flighter. Some of our members would like to use it for
> mutual
> >XC flying since its a better XC glider than an ASK-21 and has a
> decent
> >SDI flight computer fitted. That said, our ASK-21s do routinely go
> XC on
> >good days with students who are close to soloing - an 80km o/r to
> HusBos
> >is favourite with our paid instructors.
> >
> >
> >--
> >martin@ | Martin Gregorie
> >gregorie. | Essex, UK
> >org |
>
>
> Martin,
>
> Low seat load was the reason we sold our Acro several years ago.
> If you have a lot of 2 seaters, you can schedule around it, but the
> issue becomes a pain if you only have one or two 2-seaters to work
> with.
>
> If you can put up with the ground handling issues of a tail dragger,
> and a little bit stiffer flight controls, you may find (as we have) that
> the original Twin Astir gives a lot for the money invested. A lot of
> them had been used as advanced XC trainers, and not for basic
> training, so therefore minimal damage history.. This equates to a
> retention of the already very high factory seat load of 242 Lbs/seat
> plus another 22 Lbs in the baggage compartment. Some even have
> water ballast. For XC training, the Twin 1 has a markedly slower
> stall speed (with very effective trim) than the Twin II for better
> thermalling performance. Best L/D is also ~4 points better than the
> Twin II, so it is also noticeably better on the glides as well. For XC
> training, I would take the Twin Astir over an Acro any day....IMHO

All you say is correct.

The only problem is the diabolical rear seat shape cause by making room for the wheel to retract.

My club flew a pair of original 1978 Twin Astirs as the basic trainers for about a dozen years (mid 90s to late 00s). They were great in almost every way and a huge step up from the Blanik's we had before them. But the DG1000 18s we've replaced the Grobs result in sooo much less money going to the instructors' chiropractors.

[Michael Opitz]

>All you say is correct.
>
>The only problem is the diabolical rear seat shape cause by
making room
>for=
> the wheel to retract.
>
>My club flew a pair of original 1978 Twin Astirs as the basic
trainers for
>=
>about a dozen years (mid 90s to late 00s). They were great in
almost every
>=
>way and a huge step up from the Blanik's we had before them.
But the
>DG1000=
> 18s we've replaced the Grobs result in sooo much less money
going to the
>i=
>nstructors' chiropractors.
>

I wish our club could afford to buy and insure a couple of DG-
1000/18's, or Duo Discus, or even K-21's, but we don't have the
money at present. Maybe after some more years.. We own our own
airport where we have runway and hangar repair/replacement
issues to deal with also. Money has to very carefully allocated.
We were tenants for 47 years, being forced to move from one
airport to another at the whim of the owners, so having our own
permanent home now is a blessing, but it also has it's own issues.

When I instruct in the back seat of a Twin, I just use one of those
curved lumbar support cushions myself. One of our club members
has back issues, and has carved himself a foam cushion that suits
his needs for longer flights. I am 6'2" / 205 Lbs, and I am OK in
the back seat, even on flights of 3-4 hours duration. We are buying
a Trainer version with the fixed, sprung gear to use for primary
training. We are hoping that the sprung gear helps absorb the
shocks of some of the primary students "less than smooth"
landings.

To Frank's point about repair weight gains, I know... I worked for
Klaus H at S-H between college and going into the USAF a long, long
time ago. The fact (in the USA) is that virtually all Twin II's which
do come up for sale are "single seaters with a large baggage
compartment". Some have gained over 100(!!!) Lbs in repair
weight due to multiple accidents. Our answer has been to go to the
Twin I which has a much higher seat load to start with, and can
tolerate a repair weight gain much more readily...

RO

[[email protected]]

On Tuesday, October 11, 2016 at 9:00:07 AM UTC-4, Michael Opitz wrote:
> >All you say is correct.
> >
> >The only problem is the diabolical rear seat shape cause by
> making room
> >for=
> > the wheel to retract.
> >
> >My club flew a pair of original 1978 Twin Astirs as the basic
> trainers for
> >=
> >about a dozen years (mid 90s to late 00s). They were great in
> almost every
> >=
> >way and a huge step up from the Blanik's we had before them.
> But the
> >DG1000=
> > 18s we've replaced the Grobs result in sooo much less money
> going to the
> >i=
> >nstructors' chiropractors.
> >
>
> I wish our club could afford to buy and insure a couple of DG-
> 1000/18's, or Duo Discus, or even K-21's, but we don't have the
> money at present. Maybe after some more years.. We own our own
> airport where we have runway and hangar repair/replacement
> issues to deal with also. Money has to very carefully allocated.
> We were tenants for 47 years, being forced to move from one
> airport to another at the whim of the owners, so having our own
> permanent home now is a blessing, but it also has it's own issues.
>
> When I instruct in the back seat of a Twin, I just use one of those
> curved lumbar support cushions myself. One of our club members
> has back issues, and has carved himself a foam cushion that suits
> his needs for longer flights. I am 6'2" / 205 Lbs, and I am OK in
> the back seat, even on flights of 3-4 hours duration. We are buying
> a Trainer version with the fixed, sprung gear to use for primary
> training. We are hoping that the sprung gear helps absorb the
> shocks of some of the primary students "less than smooth"
> landings.
>
> To Frank's point about repair weight gains, I know... I worked for
> Klaus H at S-H between college and going into the USAF a long, long
> time ago. The fact (in the USA) is that virtually all Twin II's which
> do come up for sale are "single seaters with a large baggage
> compartment". Some have gained over 100(!!!) Lbs in repair
> weight due to multiple accidents. Our answer has been to go to the
> Twin I which has a much higher seat load to start with, and can
> tolerate a repair weight gain much more readily...
>
> RO

I suspect that much of what RO calls "repair weight" is actually lazy refinishing weight. I know of a couple Grobs that got a sanding to rough up the gelcoat, a bunch of filler to bury the cracks, then finish coats.
A properly done repair doesn't add much weight, the added weight is only that of the doubling plies or internal backing added before the scarf and laminating gets done.
UH

[Bruce Hoult]

On Wednesday, October 12, 2016 at 2:00:07 AM UTC+13, Michael Opitz wrote:
> > But the DG1000 18s we've replaced the Grobs result in sooo
> > much less money going to the instructors' chiropractors.
> >
>
> I wish our club could afford to buy and insure a couple of DG-
> 1000/18's, or Duo Discus, or even K-21's, but we don't have the
> money at present. Maybe after some more years.. We own our own
> airport where we have runway and hangar repair/replacement
> issues to deal with also. Money has to very carefully allocated.
> We were tenants for 47 years, being forced to move from one
> airport to another at the whim of the owners, so having our own
> permanent home now is a blessing, but it also has it's own issues.

Understand that. My club just moved six months ago from being renters on an airport for 50+ years to a single-purpose gliding site. That's meant some big upfront expenses for a new winch ($140k) and new hangar, adjusting the fleet a little (PW5 isn't very winch friendly, Pawnee won't get enough utilization to be worth keeping), and lesser ongoing expenses as we can afford them for putting in clubhouse, bunkhouse, caravan/tent park and facilities, water and electricity. Ongoing though, the expenses should be a lot lower than the airport land rental plus landing fees plus tower fees which together came to something like $40 a flight before spending a cent on the tow or glider. Plus, uncontrolled airspace to at least 9500 everywhere nearby instead of altitude restrictions of 2500, 3500, or 5500 ft everywhere within 15 km of the old field.