Assembly Problems

I have always had problems in getting the first main wing pin started.
Recently I did some checking and found that not all main wing pins are
created equal. Some come with generous tapered ends and others come
with a very sharp slope or no taper at all. My Genesis 2, for example
has a 4:1 taper while most Schempp-Hirth equipment will be sporting a
generous 10:1 taper. I reasoned the 10:1 slope would make it much
easier to get that troublesome first pin started.

I slid one pin into the fork end of my spar as it sat in the trailer
and found it went completely through the spar and stuck out the back
by a good inch. Idea, why can't I grind a more generous tapered end
onto one of my main wing pins? I would grind only on the part that
extends out the backside of the spar. What could that hurt? I removed
the handle and chucked the pin into my drill press. Then I turned ot
on and held a hand grinder, also running, against the whirling pin in
the area where I wished to extend the taper. Followed that up with a
file, then some sand paper and finally emery cloth. It came out shinny
and bright and looked like the factory had done it right in the first
place.

Result, I am now able to get my newly tapered pin started with ease. I
carefully align the forked wing then secure the tip with a 4 legged
wing stand (step ladder with legs shortened to correct height) + a
bungee strap. The tonged wing is then inserted and the lateral
adjustment of my UDO tool is left floating. I insert a 12 inch stick
(broom handle) into the right pin holes and force the two wings
together by applying an inward force on the broom handle. Next I check
for height alignment of the other pin holes and adjust for perfect
alignment by pumping my foot operated fuselage jack (hydraulic). When
the holes are exactly right, I apply a bit of grease inside where the
two bushings meet and also a tad of grease on the tapered end of my
modified pin. While pulling inward on my broom handle, I shove my
properly tapered pin in. You know what? It works! The gentle tapered
pin self aligns the two bushings and in she goes.

Flew 3.5 hours on Thursday and the wings didn't fall off, so my
grinding on the main wing pin must have been all right.

:) JJ

Be sure to remove and secure the broom handle. Around this time of year,
they have been seen flying around - unmanned.

Colin K7FM


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I did something similar for my ASW 20 years ago, by adding a 1"
extension to one pin to make the tapered portion longer. It helped just
as JJ describes.

Nowadays, a good alternative is the eccentric cam tool available from
Cobra. You put the tool in a pin hole on one side, turn it 90 degrees to
draw the wings together and align them, place a wing pin in the other
hole, remove the tool and put in the second pin.

I use it occasionally on my ASH 26 E when I don't get the things quite
right the first time, as it's quicker and easier me than fiddling with
my particular set of dollies and wings. You can make your own easily if
you can machine things, as a friend did for me before the Cobra unit was
available.

JJ Sinclair wrote:
I have always had problems in getting the first main wing pin started.
Recently I did some checking and found that not all main wing pins are
created equal. Some come with generous tapered ends and others come
with a very sharp slope or no taper at all. My Genesis 2, for example
has a 4:1 taper while most Schempp-Hirth equipment will be sporting a
generous 10:1 taper. I reasoned the 10:1 slope would make it much
easier to get that troublesome first pin started.

snip

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Eric Greenwell
Washington State
USA

Thanks, JJ, for finally doing what some of us have been talking about
for years; i.e., grinding a longer taper on the main pins.

I've been a solo rigging advocate since the early '80s so I deal with
this every time I fly. The pins on my LS-3 had a nice long taper; if
the wings were anywhere close, I could usually pull them into
alignment with a main pin.

Not so for my ASW 24, the main pins of which have a very short taper
requiring the wings to be aligned much more closely before they can be
inserted to snug everything together. So I, too, occasionally need a
little help.

My "broomstick" is a little higher tech than JJ's, being made out of
Delrin or Nylon. But the function is the same.

The Libelle 301 and 201 did it right way back in the mid to late '60s:
an over-center "wrench" that used metal pins embedded in the top of
the wing spars to lever the wings together the last few centimeters.
Sometimes "progress" takes us in the wrong direction.

Chip Bearden
ASW 24 "JB"

Chip Bearden wrote:
The Libelle 301 and 201 did it right way back in the mid to late '60s:
an over-center "wrench" that used metal pins embedded in the top of
the wing spars to lever the wings together the last few centimeters.
Sometimes "progress" takes us in the wrong direction.

The lever was almost a necessity, due to the multiple pins on the ends
of the spars that had fit into the sockets on the wing. What made the
system work well wasn't so much the lever as the access: without a
turtle deck, you could see the pins' alignment and guide the person on
the wing tip.

It might take more careful alignment to get the pins into a Schleicher
glider, but at least pushing in the second wing doesn't push out the
first one. If you like using a tool, a Schliecher glider can have it's
wings pulled together just as quickly and easily as the Libelle with
Cobra's eccentric wing pin tool. It does take an extra moment to put in
two pins instead of one, but it's better than fighting multiple spar end
pins that you can't see.

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Eric Greenwell
Washington State
USA

Eric Greenwell wrote in message ...
Chip Bearden wrote:
The Libelle 301 and 201 did it right way back in the mid to late '60s:
an over-center "wrench" that used metal pins embedded in the top of
the wing spars to lever the wings together the last few centimeters.
Sometimes "progress" takes us in the wrong direction.

The lever was almost a necessity, due to the multiple pins on the ends
of the spars that had fit into the sockets on the wing. What made the
system work well wasn't so much the lever as the access: without a
turtle deck, you could see the pins' alignment and guide the person on
the wing tip.

It might take more careful alignment to get the pins into a Schleicher
glider, but at least pushing in the second wing doesn't push out the
first one. If you like using a tool, a Schliecher glider can have it's
wings pulled together just as quickly and easily as the Libelle with
Cobra's eccentric wing pin tool. It does take an extra moment to put in
two pins instead of one, but it's better than fighting multiple spar end
pins that you can't see.

Good point. Access to the Libelle pins was superb without the fuselage
structure over the wings that modern gliders have today. I agree that
the wrench was a near necessity with all the pins and sockets. For
those who haven't assembled one: each spar end--a forked double spar
on one wing and a single spar tongue on the other wing--has a pin that
fits into a socket in the opposite wing.

On the other hand, I recall assembling my father's Diamant HBV, the
15M version that used Libelle 301 wings with a more conventional
fuselage design (i.e., the area above the wing spars was enclosed).
Once we learned a few tricks, that became straightforward...so long as
we had the wrench.

I also recall that a few other early fiberglass gliders had similar
wrenches. Possibly even the later Diamants (16.5 and 18m versions)
which used a wing pin design a little more similar to today's types.

The Cobra eccentric wing pin tool sounds like an interesting
alternative to the over-center wrench.

Chip Bearden
ASW 24 "JB"

Chip Bearden wrote:

I also recall that a few other early fiberglass gliders had similar
wrenches. Possibly even the later Diamants (16.5 and 18m versions)
which used a wing pin design a little more similar to today's types.

The PIK 20 (at least the E model) had one. Same situation, I think: with
pins on the ends of the spar butts, it takes some levering to get every
thing to slide together that last 2-3 mm so the pin can be slid in.

The Cobra eccentric wing pin tool sounds like an interesting
alternative to the over-center wrench.

The pilots that have them say it is slick, making it easy for one person
to assemble without a lot of running back and forth. For Schleicher and
gliders with a similar wing pin system, it's actually better than a
lever, because it tends to align the holes instead of just drawing the
wings together.

My cheaper, home-made, but similar tool works almost as well, but the
Cobra tool is a better design out of better materials. I'd buy one if I
didn't already have mine, since I self-rig 95% of the time.


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Eric Greenwell
Washington State
USA

"Eric Greenwell" wrote in message
...
Chip Bearden wrote:

I also recall that a few other early fiberglass gliders had similar
wrenches. Possibly even the later Diamants (16.5 and 18m versions)
which used a wing pin design a little more similar to today's types.

The PIK 20 (at least the E model) had one. Same situation, I think: with
pins on the ends of the spar butts, it takes some levering to get every
thing to slide together that last 2-3 mm so the pin can be slid in.

The Cobra eccentric wing pin tool sounds like an interesting
alternative to the over-center wrench.

The pilots that have them say it is slick, making it easy for one person
to assemble without a lot of running back and forth. For Schleicher and
gliders with a similar wing pin system, it's actually better than a
lever, because it tends to align the holes instead of just drawing the
wings together.

My cheaper, home-made, but similar tool works almost as well, but the
Cobra tool is a better design out of better materials. I'd buy one if I
didn't already have mine, since I self-rig 95% of the time.


Thought one of the PIK-20 issues was fuselage expansion in warmer. That
above 70F it got very difficult.

Frank

F.L. Whiteley wrote:

The PIK 20 (at least the E model) had one. Same situation, I think: with
pins on the ends of the spar butts, it takes some levering to get every
thing to slide together that last 2-3 mm so the pin can be slid in.



Thought one of the PIK-20 issues was fuselage expansion in warmer. That
above 70F it got very difficult.

I don't know if it was common on PIKs, but can happen to almost any
glider. The most recent one I saw was on a Nimbus 4. The lever on the
PIK wasn't used to overcome the expansion issue, a manufacturing issue,
which usually is fixed by increasing the gap between the wing sockets
and the fuselage pins (or vice versa), as it was on the Nimbus 4.
Sometimes it's just a shim that needs to be removed; sometimes the pin
shoulder needs a few mils machined off of it.


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Eric Greenwell
Washington State
USA

The Cobra tool works like a charm.

It's just a wingpin-diameter cylinder with a ~1/3 wingpin-diameter
cylinder sticking off the end of it, offset to the
outer edge of the larger cylinder. You simply insert
it through the fork bushing with the offset to the
inside so it can engage the tounge bushing and twist
180 degrees. It uses a wide contact area and is made
from nylon, so the likelihood of scoring the bushings
in minimal. I would think it would be fairly easy
to make one for someone with access to a decent machine
shop, but Cobra charged me 85 Euros, so it depends
what your time's worth.

In the past I've seen people using steel pry-bar tools,
which scare the heck out of me.

9B

At 18:42 25 October 2004, Eric Greenwell wrote:
Chip Bearden wrote:

I also recall that a few other early fiberglass gliders
had similar
wrenches. Possibly even the later Diamants (16.5 and
18m versions)
which used a wing pin design a little more similar
to today's types.

The PIK 20 (at least the E model) had one. Same situation,
I think: with
pins on the ends of the spar butts, it takes some levering
to get every
thing to slide together that last 2-3 mm so the pin
can be slid in.

The Cobra eccentric wing pin tool sounds like an interesting
alternative to the over-center wrench.

The pilots that have them say it is slick, making it
easy for one person
to assemble without a lot of running back and forth.
For Schleicher and
gliders with a similar wing pin system, it's actually
better than a
lever, because it tends to align the holes instead
of just drawing the
wings together.

My cheaper, home-made, but similar tool works almost
as well, but the
Cobra tool is a better design out of better materials.
I'd buy one if I
didn't already have mine, since I self-rig 95% of the
time.


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Eric Greenwell
Washington State
USA