Dear All,
I will confess that I have only looked at a few of the postings about the spar
pins, but what I have seen indicates that the main question is about why there
is only one Pip pin type spar pin and why this one should be on the port side.
The reason is due to the layout of the spars.
During static load test, it was discovered that, at high loading, the tip end of
the starboard wing's spar began to slide aft off of the port pin. The further
it moved the greater the bending force it applied to the pin, making it yet
easier for the spar to slide off it. On the first test, the spar came off the
pin (at around the equivalent of about 7.5 'g' I should add) allowing the wing
to rotate and the spar tang to slice its way through the fuselage bottom.
It was clear that we needed to prevent the spar end to slide aft when under
load.
Initial thoughts went to bolts and nuts, but this would make rigging and
derigging
slow and labourious (we fitted this arrangement to the first XS, so we know
---From first hand). The pip pin was tested and proved to work well. The loads
on the pips meant that a hardened steel washer was required to prevent them
damaging the spar bush, hence its inclusion. However, due to the high cost of
the pip pins and as it was only needed to secure the end of the starboard spar
(the spars overlap each other such that the port spar is sandwiched between
the seat back bulkhead and therefore has no possibility of moving) it was
decided
to stay with the tried and tested high strength bolt with its welded in Allen
key.
I hope that I have not missed the real thread of the discussion, but perhaps the
above will answer some questions anyway.
Best Regards
Andy Draper
Technical Director
e-mail andy@europa-aircraft.com
>>> "Fergus Kyle" <VE3LVO@rac.ca> 10/02/04 03:27:33 >>>
----- Original Message -----
From: <DuaneFamly@aol.com>
Subject: Re: Europa-List: Wing spar pins
|
| Ferg,
|
| Seems to me by the response that a PIP pin in the starboard side would be
bad
| as long as it inserted and removed easily. Any problem with the strength
of
| the PIP pin? It could also be backed by washers as on the port side.
Wouldn't
| hurt?
|
|
| Mike Duane A207
| Redding, California
| XS Conventional Gear
| CM & rudder pedals with cables installed. Working on tailwheel and baggage
| bay. Trial fit of top and both wings. The wings fit! Conventional gear
soon.
Mike,
Well, I don't know. I kept the bolt version starboard side,
'cause the manual said to. No, I don't think there is any problem with the
pip-pin's strength since it's used portside, but the extra cost of the
'ears' isn't utilised, so why use it. Peter Zutrauen had it right when he
mentioned the need for it portside, but I don't see how it can be needed on
the starboard. My only caution there was the need to pen it in with the
original fixture since the dimensions MIGHT keep the ears in and allow the
starboard pip-pin to vibe out. If you use the retainer specified in the
manual, what is the advantage of the pin-pin? How would you apply the
washers, since no dimension is given (might be same as port) and pin is in
the cup...........?
Just mulling...........
Cheers, Ferg
|