Bill;
I’d say the temp
measurements are bit off; and it doesn’t take much. If the DT was 15o,
those numbers would change by a factor of 3.
Al
-----Original
Message-----
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Schertz
Sent: Sunday, May 16, 2010 3:55
PM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: alternative water pump
One added fact, the plane with me
and full fuel is ~1958#, getting 1100 fpm at 100 mph.
Bill Schertz
KIS Cruiser
#4045
N343BS
Phase I testing
Sent: Sunday,
May 16, 2010 6:43 PM
Subject:
[FlyRotary] Re: alternative water pump
A very good question. Let me
describe the setup and areas of uncertainty.
2. Temp into the coolers is measured
with a CHT thermocouple clamped to the 1-3/8" tube that comes from the water
pump, just before it is split to go to the two evaporator
cores.
3. Temp out of the coolers is
measured with another CHT thermocouple clamped to the 1-38" return line to the
water pump, just after the flows have rejoined. There is also a VDO type
temperature sensor at that point in the loop, and it reads very close to the CHT
thermocouple.
4. The pressure reading is done on
the coolant_in (water pump out) line, I have a 10 psi cap on the reservoir,
which is connected to the low pressure side of the water pump. The engine when
cold shows no pressure, it comes alive when the engine starts, and pressure
varies with engine RPM, and the base pressure rises to ~10 psi as the fluid
warms (based on pressure reading after engine shutdown while engine still
hot).
5. I have not yet fully calibrated
the fuel consumption totalizer on the EM-2, or the gallon/hour reading, but at
6000 engine RPM I am seeing between 8-9 gph, and at wide open throttle (7000)
~12 if I remember correctly. Didn't look at fuel flow during climb, as I was
busy with other things.
6. The plane as currently configured
is with myself and full fuel, gets ~1100 fpm at 110 mph on take off to 3000 feet
(still nailing down these numbers)
I don't believe I am getting 100-143
gpm from the system, the delta is obtained by subtracting two relatively large
numbers, I think the delta has to be greater also, but am not sure where the
inaccuracy is. When I have nothing else to do, I could dunk the probes in
boiling water as a calibration test.
Bill Schertz
KIS Cruiser
#4045
N343BS
Phase I testing
Sent: Sunday,
May 16, 2010 10:07 AM
Subject:
[FlyRotary] Re: alternative water pump
On the water. The flow is high
enough that very little temperature drop through the radiators is required to
remove the heat from the engine. Q = (mass flow)*(heat-capacity)*(delta-T). If
you increase the mass flow, you decrease the deltaT. I get about a 5*F
delta T on the radiators, on the other hand, the air coming out of the rads is
about 100F higher than the air going in.
Bill,
Further to my query
yesterday; putting some numbers on the 5o DT gives me
this:
With 35 gpm, engine
power is 55 hp with pure water; 40 hp with 50/50 water/EG.
160 hp would require
103 gpm with pure water, 143 with 50/50 water/EG.
What am I
missing?
Al