----- Original Message -----

From: Robert

To: harryproa@...

Sent: Sunday, June 06, 2004 9:23 PM

Subject: [harryproa] Re omega and foam/carbon beams

Tony,
Idiosyncrsies of our medium of communication.
That's the upper case omega- as used in electronics to denote
resistance. The lowercase looks like a rounded w and is used to
symbolise how fast something is spinning. I checked out the Kendricks
design and he describes the design of the beam in a bit more detail.
They loook very nice designs and for some reason seem 'friendly'
The beams seems to make sense to me considering the loads it is
designed for but I haven't had the time or energy lately to do the
maths and he reckons they are easy to make

Mark
About the foam/carbon rod beams. Is it all the same density foam or
is it higher density on the outside and lower density inside. I am
not sure of the maths but I would have envisaged as optimum something
like a log decay fuction of density as you go to the centre.
I was considering using the high quality extruded polystyrene as a
roof  to provide upside down bouyancy. 2mm plywood on the top side
and carbon underneath skinning it. I'm not sure of the suitability in
terms of price, stiffness and toughness of carbon for the topside.
Hope to see you in a few weeks but have to see how I recover from a
post viral neurological problem.






--- In harryproa@..., "Tony Richardson"
<atrichardson@b...> wrote:
> I'm not sure if upper or lower case but I tried to paste it as a
symbol into the email and by the looks of it it didn't work.
> The symbol looks like a 0 with the bottom chopped out and two
horizontal lines attached at the bottom.
> sortof _0_ but with the lines attached.
> Pioneer electronics use it as a symbol as well.
> Rgs
> Tony
>   ----- Original Message -----
>   From: Robert
>   To: harryproa@...
>   Sent: Friday, June 04, 2004 12:28 PM
>   Subject: [harryproa] Re: Beams to windward hull
>
>
>   Sorry Tony,
>   Is that an upper case omega or lower case? Can you give a more
>   detailed description?
>
>   Robert
>   -- In harryproa@..., "Tony Richardson"
>   <atrichardson@b...> wrote:
>   > Has anyone tried an omega shape Ω or variants of that shape
for
>   beams ?
>   > I remember the small Kendrick tri (scarab) having something
similar
>   > Rgs
>   > Tony
>   >   ----- Original Message -----
>   >   From: Robert
>   >   To: harryproa@...
>   >   Sent: Friday, June 04, 2004 11:21 AM
>   >   Subject: [harryproa] Re: Beams to windward hull
>   >
>   >
>   >   Horses for courses. It is hard to beat bamboo for ability to
take
>   >   loads and torque from all directions but if the bamboo was
>   >   constrained with the load more in one direction I would
imagine
>   it
>   >   would end up more oval.
>   >   If there is no problem with torque go for an I beam. My idea
for
>   a
>   >   folding beam is based on an I beam, allowing easier load
transfer
>   >   when partly folded, with judicious addition of fairing to
provide
>   >   resistance to torque and fore and aft bending moment. It is
>   tempting
>   >   to just buy some of those composite beams used in the
building
>   >   industry as a start
>   >   For simplicity in building and reasonably close to optimum I
>   would
>   >   go for a ring framed wooden box section reinforced on the
corners
>   >   with carbon tow. This way the web can also act as a flange.
>   >   Fibreglass in the same circumstances would be less useful as
it
>   >   stretches too much and the timber goes past its limit long
before
>   the
>   >   fibreglass takes up the strain. There may have to be some
cloth
>   >   reinforcement around the beam to prevent the carbon tow from
>   >   delaminating from the timber.
>   >
>   >   I have been closely observing the Harry construction and I am
>   most
>   >   impressed with the engineering. It seems to be based on years
of
>   sea
>   >   time and knowing what breaks, and mathematical and material
>   analysis
>   >   on how to best achieve the strength required with building
>   techniques
>   >   within the ability and cost of the low volume builder. I
>   certainly
>   >   wouldn't stray from the specs. This is what you're paying the
>   money
>   >   for.
>   >
>   >
>   >   --- In harryproa@..., "Tony Richardson"
>   >   <atrichardson@b...> wrote:
>   >   >
>   >   >   ----- Original Message -----
>   >   >   You wrote
>   >   >      - You have to make a box section, nothing else is
remotely
>   >   >   comparable.
>   >   >    
>   >   >   I dissagree
>   >   >   I'm no engineer but I do have a tri with round beams
>   >   >   Rob and I built them in a female mould mostly of uni's
>   >   >   It flies two hulls and has no seastays/wires etc
>   >   >   They have a degree of flex in them though
>   >   >   The beams weigh 5kg each bare.
>   >   >   The boat is only 16ft but it is 15ft wide
>   >   >   Rgs
>   >   >   Tony
>   >
>   >
>   >
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