Subject:
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Re: SSClagorpion - Compressor
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Newsgroups:
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lugnet.technic
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Date:
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Fri, 21 May 2004 23:21:29 GMT
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Viewed:
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19085 times
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In lugnet.technic, Steve Hassenplug wrote:
> In lugnet.technic, Kevin L. Clague wrote:
> > In lugnet.technic, Benton Jackson wrote:
> > > If there's more pressure being produced than
> > > the system needs at the moment, air goes in the tank, if there's less pressure,
> > > air comes out of the tank.
> >
> > I was assuming that the model would use whatever air pressure it was given,
> > unless the state machine was shut off. Given the volume of air that it will
> > take to make the circuit progress, an air tank won't hold enough air to help.
>
>
>
> Here's an important question. What will be the limiting factor in how fast this
> beast can move? Is it:
> A) Travel time for the pneumatic cylinders
> or
> B) Volume of air available?
>
> I'm under the impression it will be limited by the volume of air available.
>
> An important thing to note is that the number of pistons moving is not always
> the same, so the load on the compressor is not constant.
>
> A quick look at Kevin's diagram for quad-242 shows (if I read it correctly) ten
> states. The transitions between those states include two times where four
> pistons move, four times where two pistons move, and four times where one piston
> moves. I think. I'm pretty sure that doesn't include timing pistons.
>
> That means the system expands (or contracts) twenty pistons, in ten steps, or an
> average of two pistons, all the time.
>
> So, I THINK using air tanks, the compressor only has to provide enough air for
> two pistons for the quad 242 to move at full speed. But, without air tanks, the
> compressor has to suppily four pistons, at peek times.
>
> Of course SSClagorpion has twice the number of legs, but all the above logic
> should be correct.
>
> Is that right?
>
> I'd guess the test that was posted was using a system that had a constant draw
> (number of pistons moving is always the same), in which case, the air tanks
> would not help it move faster, because there is no time when the compressor is
> suppilying more air than the system will use.
>
> Steve
Steve,
A very interesting set of questions and logic. I don't know the answer, but
can add insights that are related.
As the available volume/pressure increases, the pistons expand and contract
faster. I don't know if there is a linear relationship. If we double the
pressure, does the thing expand/contract in half the time? I don't know. I can
easily set up a test though. If I use one pump, then two pumps, then three
pumps, I can measure the pressure (using my virgin pressure sensor), and the
rate of transitions of a dual piston engine. I doubt that it is linear across
the entire pressure/volume range. I also doubt though that there is some kind
of knee in the curve, where no matter how much you increase the pressure, the
piston rate never increases.
After I get my last brickink order with three more check valve bricks, I can
get us from one to 6 pumps.
Kevin
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Message has 2 Replies:
 | | Re: SSClagorpion - Compressor
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| (...) The limiting factor with the speed of the model is composed of two things: 1. The total volume of air between the valve that is switched and the cylinders that were previously supplied before the valve was switched. 2. The rate of supply of (...) (20 years ago, 22-May-04, to lugnet.technic)
| | | Re: SSClagorpion - Compressor
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| (...) I have another idea for an interesting test using air tanks. Set up a pneumatic engine and add an extra piston to ONE side. (so there are three total pistons, and two move at the same time) See show the speed compairs with vs without airtanks. (...) (20 years ago, 24-May-04, to lugnet.technic)
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Message is in Reply To:
| | Re: SSClagorpion - Compressor
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| (...) Here's an important question. What will be the limiting factor in how fast this beast can move? Is it: A) Travel time for the pneumatic cylinders or B) Volume of air available? I'm under the impression it will be limited by the volume of air (...) (20 years ago, 21-May-04, to lugnet.technic)
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