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Bob,
Attached is a graph of the performance of a Mazda mechanical pump at
different rpm. Several things about the performance can be deduced. The
measurements were taken by pumping water from a barrel through the engine
and back to the barrel. Flow was measured by the time required to fill a 5
gallon bucket, and pressure drop was measured into and out of the engine
water pump.
First, at zero flow, the pump is generating its maximum pressure. At zero
pressure, the pump is generating its maximum flow. Since the measurements
are made at the inlet and outlet of the pump, the pressure drop of the
engine core is included. If you look at the three rpm curves, at 2448 rpm,
the pump can generate just under 5psi head, and a no head flow of ~20gpm.
this means that the pressure drop through the core is 5 psi at 20 gpm.
At 3730 rpm you get 8.5 psi and 33 gpm, at 5594 you get 19psi and 44 gpm.
I also measured the pressure drop across GM evap cores as a function of
flow. Data is plotted on the curve.
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
From: "Bob White" <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, November 06, 2004 9:39 PM
Subject: [FlyRotary] Re: EWP Info
> On Sat, 6 Nov 2004 20:52:55 -0600
> "Russell Duffy" <13brv3@bellsouth.net> wrote:
>
> > Hi Bob, somehow these numbers do not pass the "smell test". There is
> > no way you can pump 20 GPM with the back pressure in the system on 5
> > Amps alone. Larry's observations below make sense. A little air blower
> > motor moving air uses 5 Amps. Bulent
> >
> >
> > Hi Bulent,
> >
> > You're starting to sound like a disbeliever. We're not going to have
> > to banish you to the other list are we :-)
> >
> > Rusty (I believe)
> >
>
> Now now! Let's not have any banishing around here. :)
>
> I don't know what the numbers mean but I will let you know how it works
> out. Todd reported his pump measured 4.3 amps at 9.3 gpm (if I
> understood his last post). Mezarie may be reporting the "no load"
> pumping capacity, or Summit may have the current wrong. I should have
> the pumps sometime next week.
>
> Any idea what a ball park figure for the pressure drop across the engine
> and an evap core would be? I could simulate it on the bench.
>
> Bob White
>
>
> --
> http://www.bob-white.com
> N93BD - Rotary Powered BD-4 (soon)
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
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