Grob SB's

On Friday, January 18, 2019 at 4:14:55 PM UTC-5, Martin Gregorie wrote:
On Fri, 18 Jan 2019 12:20:33 -0800, Papa3 wrote:

On Friday, January 18, 2019 at 6:02:45 AM UTC-5, Martin Gregorie wrote:


How much, if anything is there in common between the fixed u/c mounting
structure in a Twin Astir and an Acro II?

Just a thought inspired by the apparent ease with which the early
Libelle 201s could be converted from fixed to retractable u/c.



Completely different animals. A number of owners have investigated
this, and it's not a simple issue at all. The structure is completely
different as well as the mechanicals of the wheel, mounts, etc.

Fair enough. I've flown both Twin Astir and Acro IIs, so it seemed
possible that replacing the folding undercarriage with a fixed one on the
same attachment points would have been an easy job, and cheapish too,
since it could reuse tested structure in an, apparently, very similar
airframe.

I should have looked at Martin Simon's book "Sailplanes 1965-200" before
opening my trap: it describes a complex lay-flat retract system which
almost certainly could not have been easily replaced with fixed gear.
(Takes foot back out of mouth).


--
Martin | martin at
Gregorie | gregorie dot org

Actually, LTB-Lindner has very nice, dimensioned, 3 view drawings on the website. You can see for example that the width of the fuselage is slightly different, the depth is different, etc.

Very impressed by the support from LTB Lindner by the way; they have been responsive and very helpful.

On Fri, 18 Jan 2019 14:05:21 -0800, Papa3 wrote:

Actually, LTB-Lindner has very nice, dimensioned, 3 view drawings on the
website. You can see for example that the width of the fuselage is
slightly different, the depth is different, etc.

Yes, Martin Symons describes that too, but you can't see it because the
only 3-view drawing is for the G.103 Twin II.

FWIW my first XC experience was in the club's G.103 in a regionals, with
Mike Young flying. He won the day and I learned a lot from that ride.


--
Martin | martin at
Gregorie | gregorie dot org

At 20:20 18 January 2019, Papa3 wrote:
On Friday, January 18, 2019 at 6:02:45 AM UTC-5, Martin Gregorie
wrote:


How much, if anything is there in common between the fixed u/c
mounting
structure in a Twin Astir and an Acro II?

Just a thought inspired by the apparent ease with which the
early Libelle

201s could be converted from fixed to retractable u/c.



Completely different animals. A number of owners have
investigated this,
and it's not a simple issue at all. The structure is completely
different
as well as the mechanicals of the wheel, mounts, etc.

Several operators I know of have pinned the gear in the down and
locked
position. We'd all love to reshape the rear seatpan, but it's
integral
to the structure and would require an engineered solution.

We have 2 Twin Astir 1 Trainers with factory sprung fixed gear with
a disc brake. The rear seat stays the same. I think the wheel
location is a couple of inches forward of the one in the RG Twin 1's
because the tail is heavier to lift. I don't think that even if Lindner
has the spare Trainer gear parts, that they want to provide a retrofit
kit to convert a regular Twin into a Trainer.

RO

On Friday, January 18, 2019 at 6:15:16 PM UTC-8, Michael Opitz wrote:
At 20:20 18 January 2019, Papa3 wrote:
On Friday, January 18, 2019 at 6:02:45 AM UTC-5, Martin Gregorie
wrote:


How much, if anything is there in common between the fixed u/c
mounting
structure in a Twin Astir and an Acro II?

Just a thought inspired by the apparent ease with which the
early Libelle

201s could be converted from fixed to retractable u/c.



Completely different animals. A number of owners have
investigated this,
and it's not a simple issue at all. The structure is completely
different
as well as the mechanicals of the wheel, mounts, etc.

Several operators I know of have pinned the gear in the down and
locked
position. We'd all love to reshape the rear seatpan, but it's
integral
to the structure and would require an engineered solution.

We have 2 Twin Astir 1 Trainers with factory sprung fixed gear with
a disc brake. The rear seat stays the same. I think the wheel
location is a couple of inches forward of the one in the RG Twin 1's
because the tail is heavier to lift. I don't think that even if Lindner
has the spare Trainer gear parts, that they want to provide a retrofit
kit to convert a regular Twin into a Trainer.

RO

There is a Twin Astir here that is modified so the gear does not retract. The gear handle only operates the gear warning. I may see the owner on Monday.
Jim

At 08:22 19 January 2019, JS wrote:
On Friday, January 18, 2019 at 6:15:16 PM UTC-8, Michael Opitz
wrote:
At 20:20 18 January 2019, Papa3 wrote:
On Friday, January 18, 2019 at 6:02:45 AM UTC-5, Martin
Gregorie
wrote:


How much, if anything is there in common between the fixed
u/c
mounting
structure in a Twin Astir and an Acro II?

Just a thought inspired by the apparent ease with which the
early Libelle

201s could be converted from fixed to retractable u/c.



Completely different animals. A number of owners have
investigated this,
and it's not a simple issue at all. The structure is completely
different
as well as the mechanicals of the wheel, mounts, etc.

Several operators I know of have pinned the gear in the down
and
locked
position. We'd all love to reshape the rear seatpan, but it's
integral
to the structure and would require an engineered solution.

We have 2 Twin Astir 1 Trainers with factory sprung fixed gear
with
a disc brake. The rear seat stays the same. I think the wheel
location is a couple of inches forward of the one in the RG Twin
1's
because the tail is heavier to lift. I don't think that even if
Lindner
has the spare Trainer gear parts, that they want to provide a
retrofit
kit to convert a regular Twin into a Trainer.

RO

There is a Twin Astir here that is modified so the gear does not
retract.
The gear handle only operates the gear warning. I may see the
owner on
Monday.
Jim


I know there are regular retractable gear Twin 1's that have been
modified so the gear can't retract, but for USA purposes, those
modifications are not approved within the TCDS, so can one make
a mod like that with just a 337 form and still keep a USA Standard
Airworthiness? Lindner has no interest in approving such a mod. If
there are broken or bent parts in the mechanism, they will sell you
the replacement parts so that it can be brought back to original
specs.

RO