Checked out prices and engineering details of polycore.
2.6MPa compressive strength and 0.5MPa sheer seems pretty good value
when 2/3 the price of Kiri strip and about 1/3 the weight.Even after
the extra glass and possibly resin needed, this is cheaper and
lighter and should be easier for fairing and finishing. The heavier
scrim with the pp film should reduce the compression of the scrim and
reduce print through at <10% difference in price. Possibly save that
in resin. The 2.5MPa compression is well above the 0.1 of an
atmosphere so no troubles with distortion if using resin infusion.
The hard part seems to be for Mark having to modify plans to suit the
process.
--- In harryproa@..., "Rob Denney" <proa@i...> wrote:
>
>
>
> If using polyprop honeycomb, the vertical strip as used by
> Farrierlooks pretty good,
>
> Yes, but glassing the bottom and topsides in one side full length
on a table, then bending it to shape and glassing the inside will be
quicker, easier and lighter. The top section will require some cuts,
so that may be easier in a mould or frames.
>
> possibly even vacuuming into a female mould
> if iit can handle vacuum.(though I don't find fairing concave
> surfaces for female moulds easy).
>
> Use a piece of conduit and glue the sandpaper to it. Still not
as easy as a male mould, but not too difficult. Keep the conduit
aligned fore and aft, but move it at 45 degrees. Remember, it only
has to be fair, not smooth.
>
> It wouldn't necessarily have to be
> a full atmosphere. It may be there is a happy medium that the
barrier
> can handle.
>
> Good point. Experimentation will show this pretty quickly.
>
> Is there much distortion of the honeycomb under vacuum?
> Should not be, although the scrim between the cells will probably
depress. I suspect print through will be a problem as well.
>
>
> On quantities:For a Harry it would probably need at least 50
sheets
> so that wouldn't be a problem. Though in the short term I am
> considering playing with some to make a dinghy and a fold up
kayak
> but double handling and freight up to Darwin would probably
negate
> joining in on a bulk buy
>
> Fair enough, but when you place the small order try to negotiate
a rebate for these sheets, when you place the big order
>
> As the ww hull is so lightly loaded would you need more than
double
> bias and a few stringers for any more than the centre of the lw
> hull.
>
> No.
> regards,
>
> Rob
>
>
>
>
>
>
> --- In harryproa@..., "Rob Denney" <proa@i...>
wrote:
> >
> >
> > I have been told a few times by learned authorities that
schooner
> rigs
> > don't point well :-)
> >
> > Yesterday it was a Foundation 36 (well equipped quick keel
boat
> which they use for the Match Racing championships here). About 5
> knots of breeze, we tacked behind him and climbed up and past.
Then
> the breeze kicked in, and the new beam mounted rudder broke. Not
> enough reinforcing onto the drum. Easy enough to fix and before
it
> happened, we proved that beam mounted rudders do work. (13 knots
in
> 10 knots breeze). Makes the boats even easier to build, although
> because of the small amount of bury on the rudder shaft, the
loads
> are very high.
> >
> > I'm liking that polyprop honeycomb more and more. Certainly for
any
> > simple curves. I am not sure how much more expensive it is and
have
> > asked for pricing for comparisons but it has to win when you
> consider
> > effort, weight and resiliance. There is the extra glass needed,
> > triaxial rather than double diagonal, and pssibly extra resin-
> though
> > the choice of facing there shouldn't be too much difference.
> >
> > The polyprop does not soak up resin, as there is a barrier
between
> the scrim and the honeycomb. Not sure it would withstand vacuum,
> though. The price of kiri has gone through the roof, so polyprop
> looks pretty good. A discount kicks in at 50 sheets, so maybe we
> could combine a few orders and get it cheaper?
> >
> > The bow section of the boats is not highly loaded. You could
use
> double bias, with a strip of uni top and bottom and on each side
back
> to the beams, then triax between the beams.
> >
> >
> > regards,
> >
> > rob
> >
> >
> >
> >
> >
> >
> >
> > ----------------------------------------------------------------
----
> ------------
> >
> > Yahoo! Groups Links
> >
> > a.. To visit your group on the web, go to:
> > http://au.groups.yahoo.com/group/harryproa/
> >
> > b.. To unsubscribe from this group, send an email to:
> > harryproa-unsubscribe@...
> >
> > c.. Your use of Yahoo! Groups is subject to the Yahoo!
Terms of
> Service.
>
>
>
>
>
> --------------------------------------------------------------------
----------
>
> Yahoo! Groups Links
>
> a.. To visit your group on the web, go to:
> http://au.groups.yahoo.com/group/harryproa/
>
> b.. To unsubscribe from this group, send an email to:
> harryproa-unsubscribe@...
>
> c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of
Service.