I have a 76x76 Catto fixed pitch prop, and am still exploring speed. I have seen 160 mph but don't have the wheel pants on at present.
Bill,
Could you remind us of which prop and the dimensions you have that allows 7000 rpm? I am assuming you have the RD-1C drive? (2.85?) What is your airspeed at 7000?
Bill B
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Schertz
Sent: Sunday, May 16, 2010 7:44 PM
To: Rotary motors in aircraft
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