[Loch-ruadh] Trebuchet project

[Adam Harrison]

Some comments from someone with experience here...
> [ Picked text/plain from multipart/alternative ]
> If you're casting your own weights  - You could make
> them where you do away
> with the bucket by placing them directly onto an
> axle - think stringing
> washers onto a bar.

Exactly how the fixed counterweight trebuchet
works-hence the name "fixed counterweight".  :-)

The problem with this arrangement goes back to the
discussion on wheels.  To maximize the efficiency of
the engine, the counterweight needs to drop in a
straight line for as long as possible.  This is
accomplished in two ways-by having the counterweight
hand and therefore change position relative to the arm
pivot point without changing position relative to the
ground, OR by having the entire trebuchet move forward
and backward thereby accomplishing the same thing.

  Might work better because think
> of the reinforcement for
> the bottom of the bucket and the sides to withstand
> the weight.

True, but now you have to worry about getting wheels
and axles to support the entire weight of the machine
as well.  and you've minimized your support of the
frame into 4 small areas.

  The axle
> will have to withstand it anyway.

true.

  You maximize the
> volume of material by
> doing away with the bucket.

You maximize the volume of the counterweight, but
perhaps not the entire engine.

 Its not period

Yes it is-watch the NOVA episode again-the first treb
they build is _exactly_ what you're describing.

 but
> unless you have period
> weights, period windlass, pulleys, etc - what does
> it matter?

We are attempting to create an engine as period as
possible while making mundane sacrifices for
transportablity and safety.  Also we want our
trebuchet to be the best looking on the field.  The
same went for the ballista, and that's why it isn't
made out of 2x4's and doesn't use bungee cord for it's
power source.

> How do you plan to transport 800 to ton of weight?

Well, we're shooting for a CW of 350-450lbs, but the
question remains- How do we transport it?  That's one
of the questions the LR-Treb-Project at yahoogroups.com
group was set up to answer.

> And load it?

That is another question the
LR-Treb-Project at yahoogroups.com group was set up to
answer.  Did you read the first message I posted,
listing the things we needed to hammer out before and
during construction?

  And how ARE
> you going to buy all that lead?

The Canton is funding the trebuchet to a certain
extent.  Also Wilhelm has suggested wheel weights from
tire shops.  they will give away used ones for free
and he has a way to re-form them into pieces suitable
for our use.

  And WHERE?

Scuba shops, Metal scrapyards, anywhere we can get a
good deal on it.


  Home
> Depot or Loewes or Walmart,
> right now, has sand.  For under $5 everyone could
> donate one bag and leave it
> at the sight if we had to - sand, last time I
> looked, wasn't toxic.

That's a good idea in theory, but think about how much
volume that sand will take up...  The counterweight
would be HUGE, and once again the issue of
transportation comes up.  I don't know about you, but
I don't want to HAVE to re-fund the trebuchet every
event we take it to an event.

  And
> casting lead is very easy, but dangerous.

True...  that's definately a consideration.  that's
why I was originally suggesting SCUBA weights.
they're already in a nice cubic shape, they have slots
for a scuba belt--i.e. easy to transport and load the
weight, the drawback is they're about 2.50 per lb...

>
> Just my inexperienced two cents - I've not had to
> move trebuchets to sights
> or ballistas, so I don't know how difficult it might
> become.  Maybe your
> truck is up to the weight?

Not sure whose truck you were referring to.  My truck
has a payload capacity near 1650lbs, plus a towing
capacity of 3500lbs...  --more than enough, the
problem is, size.  my truck isn't a full size truck,
so it will probably run out of space before carrying
capacity.

Can we take this over to the
LR-Treb-Project at yahoogroups.com list please?  There
are A_LOT of people on this list that aren't concerned
with this...

-Bjorn




>
> Asa
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