Grob G102 Setup

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