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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Sat, 31 Jul 2004 22:27:03 GMT
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Viewed:
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25070 times
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In lugnet.technic, Kevin L. Clague wrote:
> In lugnet.technic, Eric Sophie wrote:
> > Kevin, it looks like you are making strides to create a sound compressor. This
> > will be of great importance (of course) as this will be the heart of the beast.
> >
> > Once this stage of the project is conqured, a major hurdle will have been
> > obtained. Good work.
>
> Thanks Eric,
>
> I have a progress report, boss.... ;^)
Report.
> I have completed two compressors. The first is basically a two large pump
> compressor driven by two RC racer's motors (very powerful). This compressor is
> implemented with one large piston and two old-style pnuematics' "pneumatic
> distribution bricks". These bricks have a one way valve that makes the piston
> behave as a pump.
>
> The second compressor is composed of 12 small pumps, implemented as two radial
> compressors, each run by an RC racer motor.
That is so cool, we should leave the compressor exposed some how so it could be
seen.
*Ahem, carry on.
> The 12 small pumps to 2 large pump ratio is used to make an apples to apples
> comparison of these pumps. Six compressions of a small pump moves the same
> volume of air as one compression of a large pump.
Plus is that sweet radial design x2!
*Ahem, yes.
> Mr. Pneumatics, Dr. C. S. Soh, has always been quite vocal about the
> superiority of small pumps vs. large pumps. He did static pressure comparisons
> between a small pump and a large pump, each powered by a mini-motor. His test
> showed that the small pumps are superior.
Radially. (makes "OK" symbol with hands)
> For a long time, I've been a large pump fan, because it can move more air.
> And of the compressors I made, the large pump versions pushed much more air at
> operating pressure of the applications I was powering.
Right, hence the conumdrum.
> My two compressors were designed to do a fair comparison of capacity (the
> amount of air moved at operating pressures). I used my inchworm as the
> pneumatic application. It requires a lot of air and has high pressure
> requirements.
Plus its super cool!
*Ahem, yes, and?
> I've not done any serious measurement yet, but it is very clear to me that Dr.
> Soh *is* absolutely correct. When running the large pump using RC racer motors
> turning an 8T driving a 40T, and the small pump compressor at the same gear
> ratio, (and the same battery packs), the motors turn faster with the small pump
> compressor. I didn't use a tachometer to measure RPM, but the motors are quite
> loud, and whine at a frequency related to how fast the motor turns. The whining
> with small pumps was higher pitch than the large pumps.
>
> I changed the gear ratio to 24:40. The small pump compressor motors ran at a
> slower rate (understandable), but had no problem driving the inchworm. The
> large pump compressor could not run, because the motors did not have enough
> torque.
>
> This tells me that the small pump compressor clearly superior. It is my
> belief that the small pump compressor is smaller, because the maximum torque at
> any point in a rotation is only the torque needed to compress a small pump. The
> six small pumps are distributed across the 360 degrees of one turn. The torque
> needed to compress a large pump is much higher, and happens twice per rotation
> of the compressor.
>
> One thing to note is that I finally have a compressor that can run the
> inchworm faster than I can by pumping by hand.
>
> So, Dr. Soh, you were right all along. Feel free to say "I told you so!"
Wait, but you did go back to the z8-z40 gear ratio right?
The z24 - z40 config can work, but a direct mate of the gears is, well,
unorthodox, depending. It could be mated one brick level forward with a couple
of z16's for a 1:1 ration before tranfering load to the z24 - z40, indirectly.
I'm just curious.
If the motor can handle it, then that's fine too.
I gotta show you a couple of tricks at BF.
> Kevin
>
> P.S. The downside to this particular small pump design is that it is much larger
> than the large pump design. Now it is time to work on a non-radial design that
> is smaller. It will take more gears and therefore more loss, but will still be
> superior.
Ok, but man I like that radial design.
*Ahem, I mean. Carry on.
e
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Message is in Reply To:
 | | Re: SSClagorpion - Compressor
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| (...) Thanks Eric, I have a progress report, boss.... ;^) I have completed two compressors. The first is basically a two large pump compressor driven by two RC racer's motors (very powerful). This compressor is implemented with one large piston and (...) (20 years ago, 31-Jul-04, to lugnet.technic)
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