Andrew (et al),
Can I suggest you check your build manual against the latest updates
available online? I've got a feeling that the depth of that counterbore has
been significantly reduced - but only after I did mine :-(
Regards,
Jeremy
Jeremy Davey
Europa Monowheel 537M G-EZZA
Europa Club Vice-Chairman, Webmaster, PFA NC Representative
PFA EC Member
"If you can keep your head when all about you are losing theirs, then it is
possible you haven't grasped the severity of the situation."
Tail done
Standard XS wings with mods underway
CM installed in fuse (with airbrakes fittings)
1250 build hours to date
Intended fit:
Rotax 914 turbo, Airmaster CS fully-feathering prop
Lots of lights, buttons, switches, gizmos, and alarms
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Andrew Sarangan
Subject: RE: Europa-List: counterboring spar
Thanks for that input. I understand your reasoning, but it would be a
better solution to countersink only as necessary and use a longer bolt.
The spar is only about 1" thick, and I don't like the idea of boring
60% of it away with a 3/4" drill. In fact a diameter of 11/16" to a
depth of 1/4" will comfortably fit the AN4 bolt head and the EURO
washer. So I ordered different lengths of AN4 bolts and will try them
out. They are only 50 cents each. I don't know why the manual wants us
to drill a deeper hole instead of giving us a longer bolt.
--- Kingsley Hurst <hurstkr@growzone.com.au> wrote:
> <hurstkr@growzone.com.au>
>
> > Wouldn't this cause the spar to become
> weaker, which is probably the most critical structure of the
> airplane?
>
> Andrew,
>
> The counter boring is done in the timber in the middle of the spar.
> When a beam is under load, the centreline takes no load. In the case
> of
> the spar under normal +ive G loading, the top of the spar is in
> compression and the bottom is in tension. The middle is neutral.
> The
> timber is only a spacer to hold the top and bottom spar rovings
> apart.
>
> Suggest you just use the bolt called out in the manual and
> countersink
> the hole until the other end of the bolt is just long enough to hold
> the
> parts it has to hold. If it is too long, it will conflict with the
> other bolt in the aluminium bracket when the wings are rigged.
>
> Regards
> Kingsley
> Mono Classic 281 in Oz.
>
>
>
>
>
>
>
>
>
=====
Andrew Sarangan
http://www.geocities.com/asarangan
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