Grob G102 Setup

I recently acquired a Grob G-102 and am still struggling with getting
that second wing installed during rigging.

I'd like to hear from any G-102 owners out there that are willing to
share their tips and tricks on setup, especially concerning getting
that wing lined up and installed.

BDS

Our club has a G102 that is a problem to rig unless the following points are
observed--

1. The vertical stabilized must be absolutely vertical and held that
way--usually by a person but a jig could be made. The person doing this must
be made aware of the importance of this task, as their attention will wander
otherwise.
2. The 4 wing pins must be very well greased--if not, they cannot push the
spring "fingers" inside the fuselage fitting aside and the friction will
prevent the insertion of the wing. This is the usual source of difficulty in
our experience.
3. The "olive" bearings that the pins on the end of the spar must be lined
up before inserting the wing and watched to be kept that way. The rear one
(left wing) is hard to see-often impossible, but keep trying. The right wing
goes in first so you can see the one you are chasing. Pay attention to
dihedral.

Good luck

--
Hartley Falbaum

"BDS" wrote in message
...
I recently acquired a Grob G-102 and am still struggling with getting
that second wing installed during rigging.

I'd like to hear from any G-102 owners out there that are willing to
share their tips and tricks on setup, especially concerning getting
that wing lined up and installed.

BDS

Interesting point about the vertical stabilizer - we have found that when
the wing is being particularly stubborn (almost all the time), having
someone grab the vertical stabilizer and "wiggle" it back and forth will
usually allow the wing to gradually slip into place. I don't like having to
do that though because it seems a little rough - I would like to find a
method that doesn't require this, but that may not be possible.

We have been greasing all of the pins and fittings but it sounds like a
little extra on those 4 fuselage pins wouldn't hurt.

Thanks for the input.

BDS

"HL Falbaum" wrote in message
...
Our club has a G102 that is a problem to rig unless the following points
are
observed--

1. The vertical stabilized must be absolutely vertical and held that
way--usually by a person but a jig could be made. The person doing this
must
be made aware of the importance of this task, as their attention will
wander
otherwise.
2. The 4 wing pins must be very well greased--if not, they cannot push the
spring "fingers" inside the fuselage fitting aside and the friction will
prevent the insertion of the wing. This is the usual source of difficulty
in
our experience.
3. The "olive" bearings that the pins on the end of the spar must be lined
up before inserting the wing and watched to be kept that way. The rear one
(left wing) is hard to see-often impossible, but keep trying. The right
wing
goes in first so you can see the one you are chasing. Pay attention to
dihedral.

Good luck

--
Hartley Falbaum

I am one of the self-proclaimed Grob 102 assembly experts at our club.



In addition to all the points that Hartley made, here are my
suggestions:



1. First you must consider the task. You basically need to align 4
different interrelated pins and receptacles at the same time. As you
know from a lot of experience, that can be much easier said than done.
However, done in the proper sequence, it can actually be a rather simple
process.



2. You need 4 well-directed people to do it quickly. (You can get by
with 3 if you have the proper tail jig to keep the fuselage from
rotating.) The four are distributed as follows: Person A at the
leading edge of the wing root, Person B at the trailing edge of the wing
root, Person C on the wingtip, and Person D on the tail. The person
directing the assembly, Person A, should be at the leading edge of the
wing root because that is the only person that can observe the entire
operation.



3. The right wing should be put on first. This should give you a chance
to observe the task a little closer. As you will see, each wing has a
swiveling drag pin at the front and rear of the wing root, an "olive"
style receptacle to receive the spar pin from the opposite wing, and a
spar pin protruding out from the end of the spar. Prepare the wings by
making sure that the "olive" is straight and ready for a pin to be
inserted into it.



4. The drag pins _must_ be well lubricated _and_ and the wing root
manipulated so that they are perfectly perpendicular to the receptacles
on each side of the fuselage before attempting to slide the wing into
place. Persons A and B (the ones on the wing root) are the ones who
must accomplish this - usually by cooperatively raising and lowering the
wing root. Practice a couple of times by taking it out and putting it
back in to get the sense of what you are doing.



5. Once the right wing is in place, I usually activate both of the right
side retainer mechanisms to keep that wing from being pushed out when we
start installing the left wing.



6. Place a wind stand under the right wing tip.



7. Observe the right wing spar and spar pin as it protrudes out of the
left wing spar receptacle on the left side of the fuselage. Rotate the
fuselage so that the spar is approximately centered vertically. Person
D accomplishes that task by rotating the fuselage.



8. Prepare to install the left wing by getting another wing stand near
the left wing tip to relieve Person C in case you have difficulty and
need to take a break.



9. Rotate the left wing and begin placing it into position but stopping
approximately 4 inches out (before any of the pins touch their
receptacles.



10. Persons A and B will position the wing root so that only the tips of
the fore and aft drag pins are in the fuselage receptacles. Lift and
maneuver the wing root so that the drag pins are exactly perpendicular
to the receptacles. Hold the wing steady in this position. Do NOT
attempt to install it yet.



11. Person A should observe the position of the right wing spar pin as
it is approaching the left wing "olive" receptacle. If the pin is high
or low then Person D should rotate the fuselage to correct it. Clockwise
to lower the pin, counter-clockwise to raise it. Of course Persons A
and B should readjust the root to make sure that the drag pins are still
perpendicular. Redo this step until it appears that, if you could slide
the wing in at that moment, the 3 left side pins would engage without
further manipulation.



12. Person A should now look inside the fuselage and observe the left
wing spar pin and its relation to the "olive" receptacle in the right
wing. Person C (the left wing tip person) is the one that can adjust
this. Person A gives Person C the appropriate corrections (up, down,
fore, aft) to get this pin aligned.



13. Begin slowly pushing the wing into place. The right spar pin should
begin to enter the left wing olive first. If it is not aligning
properly then redo the appropriate steps above to get it all aligned.



14. Now shift attention to the left spar pin as it enters the right wing
"olive". Give Person C appropriate directions to keep it aligned.



15. With the pins aligned this way, they should slip right together. A
little nudging, especially by Persons A and B is usually all that is
needed for the whole thing to slip together easily.



16. Engage all 4 of the retaining mechanisms. Be sure all of the
retainers are properly tightened. I like to have a person on each wing,
flexing them up and down and fore and aft to be able to get all the play
out of the mechanisms.



While this all sounds complicated, after you understand the task
properly, and get the appropriate people in place, it can be done in a
very few minutes. Remember, it doesn't require a lot of force. just
getting it properly aligned before you slowly slip it into place.



Good luck,



Larry













"BDS" wrote in message
:

Interesting point about the vertical stabilizer - we have found that when
the wing is being particularly stubborn (almost all the time), having
someone grab the vertical stabilizer and "wiggle" it back and forth will
usually allow the wing to gradually slip into place. I don't like having to
do that though because it seems a little rough - I would like to find a
method that doesn't require this, but that may not be possible.

We have been greasing all of the pins and fittings but it sounds like a
little extra on those 4 fuselage pins wouldn't hurt.

Thanks for the input.

BDS

"HL Falbaum" wrote in message
...
Our club has a G102 that is a problem to rig unless the following points
are
observed--

1. The vertical stabilized must be absolutely vertical and held that
way--usually by a person but a jig could be made. The person doing this
must
be made aware of the importance of this task, as their attention will
wander
otherwise.
2. The 4 wing pins must be very well greased--if not, they cannot push the
spring "fingers" inside the fuselage fitting aside and the friction will
prevent the insertion of the wing. This is the usual source of difficulty
in
our experience.
3. The "olive" bearings that the pins on the end of the spar must be lined
up before inserting the wing and watched to be kept that way. The rear one
(left wing) is hard to see-often impossible, but keep trying. The right
wing
goes in first so you can see the one you are chasing. Pay attention to
dihedral.

Good luck

--
Hartley Falbaum

As stated by HL, item one is an absolute! At Grob in Bluffton they have a
fuselage dolly that holds
it firmly in place to keep the fuselage from rotating after the right wing
is in place.

I assemble mine (upon rare occasion anymore since I keep it assembled in a
hangar now) by myself
with a wing holder but the most important little item turned out to be a
jack under the right wing with
very thick padding on top, under the wing about 1-2 feet from the fuselage
placed under the spar.
This keeps the fuselage from rotating when the weight of the left wing root
starts to load the fuselage
on its way in. A wing support at the tip doesn't really do the job because
of the wing flex and lets the
fuselage move sideways slightly.

Gale Winnett
Grob 102 III

Assuming your Grob 102 rigs the same as the Astir CS I used to fly
(maybe it's the same model), I always rigged best with just two people.
Really very simple:

Before starting - Grease all pins, including pins on spar ends, and
*check collars are unlocked* - it's amazing how often one has been
locked accidentally, and if so you'll never rig it.

1. Slide in starboard wing, lock the collars and trestle tip.

2. Check that the end of the spar is centred vertically in the space
wher the port wing spar will go. If not, adjust by rotating fuselage
(usually best, as the leverage of raising and lowering the tip often
rotates the fueslage so the spar end is still not centred). If the
fuselage slips in the belly dolly, a third person could hold the tail in
the correct position.

3. Insert port wing until the pins on the fuselage just start to engage
(you might need to reach over and lift the trailing edge slightly), then
trestle tip to take the weight, but keep wingtip holder at tip.
Trestling is not essential here, but why lose a friend?

4. Look at starboard wing root to see where the pin on the port wing
root has to engage with a bush/olive (i.e. hole). Ask wing tip holder to
raise/lower (trestle shouldn't have been too high to permit this)/move
forward/move back until this is lined up. *If the pin/hole are not
aligned the wing will never go on*. *Do not allow some well-meaning
idiot who has never rigged a glider of this type to wiggle the wingtip*.

5. Check the fuselage/port wing root pins are still engaged - if so,
reach over the wing, lift the trailing edge a little, lift the leading
edge a little and slide it in to place. Lock off collars.

If this takes more than 5 minutes you are doing it wrong. The two key
points are (a) making sure the starboard wing spar end is central
vertically and (b) aligning the port spar end pin with the hole in the
starboard wing.




wrote:
As stated by HL, item one is an absolute! At Grob in Bluffton they have a
fuselage dolly that holds
it firmly in place to keep the fuselage from rotating after the right wing
is in place.

I assemble mine (upon rare occasion anymore since I keep it assembled in a
hangar now) by myself
with a wing holder but the most important little item turned out to be a
jack under the right wing with
very thick padding on top, under the wing about 1-2 feet from the fuselage
placed under the spar.
This keeps the fuselage from rotating when the weight of the left wing root
starts to load the fuselage
on its way in. A wing support at the tip doesn't really do the job because
of the wing flex and lets the
fuselage move sideways slightly.

Gale Winnett
Grob 102 III

"Chris Reed" wrote in message
...

If this takes more than 5 minutes you are doing it wrong. The two key
points are (a) making sure the starboard wing spar end is central
vertically and (b) aligning the port spar end pin with the hole in the
starboard wing.

Well, I'm definitely doing it wrong - I'd say we'd be lucky to get the wings
on in less than 30-45 minutes and without losing a good 2-3 lbs of body
weight due to perspiration!

One time before de-rigging and at the suggestion of another club member I
marked the proper spar location for the right wing on the bulkhead just
behind it. Now I know when I put the right wing in that it is in the proper
place, or at least very close.

We do check all the pins and their mating bushings before trying to get them
to mate. The frustrating thing is that they all look just fine but the wing
will still refuse to go in. I have tried (due to frustration) to wiggle the
wing fore and aft and up and down but that never helps at all.

Based on the experience with wiggling the vert stab and many of the comments
here it sounds like my main problem is some twist in the fuselage during the
assembly process. I will pay closer attention to this next time and see if
things go more smoothly.

BDS

If everythig is alined and it won't go in, the front and rear drag pins need
more grease! The swivelling pins with the groove on them have a very short
and steep taper, and the spring fingers inside the receptacle on the fuse
are strong. A good viscous grease like wheel bearing grease works better
than white lithium. My new favorite (Thanks Larry "01") is Radio Shack
lubricating gel. I have not tried STP or Motor Honey but they might work
even better. They are liquid and harder to handle though. The part about
centering the right spar in the left spar box opening is critical.

Perfect practice makes perfect performance--
Best of luck

HL Falbaum
--

"BDS" wrote in message
...
"Chris Reed" wrote in message
...

We do check all the pins and their mating bushings before trying to get
them
to mate. The frustrating thing is that they all look just fine but the
wing
will still refuse to go in. I have tried (due to frustration) to wiggle
the
wing fore and aft and up and down but that never helps at all

BDS

Well, I own a 102 Std III and have never had any real trouble with it,
but I think that the the most critical points are 1) having the right
spar position marked on the bulkhead and 2) having a 1-man rig. The
1-man rig allows the weight of the wing to be supported at the center
of the wing, so that there is no vertical load being supported at the
inboard end. Those loads are being supported by the pin fittings that
you are trying to get to slide togethor. They will slide better if
they are not under load.

Todd Smith
Grob 102
3S

"BDS" wrote:

The frustrating thing is that they all look just fine but the wing
will still refuse to go in. I have tried (due to frustration) to wiggle
wing fore and aft and up and down but that never helps at all

Install the right wing, use a support a little inboard of the middle of the
right wing (near the wings CG). When you install the left wing stand at the
leading edge, and have a helper at the trailing edge. Support the wings
weight while you slide it in (use your right hand ). If everything is
aligned but it still doesn´t move, tilt the fuselage on its dolly very
slightly (like a rocking motion) with your left hand to make it go together.
A VERY slight, hardly noticeable back and forth motion on the left wingtip
can help, too.

Once you and your helpers have some training, it isn´t harder to assemble
than any other glider.

Michael