On the ground, cooling stabilizes at 180-190F deg and
oil is usually 10 degrees below the cooling with an OAT of 65-70F deg.
When running with higher OAT (75-85F deg) after about
0.5 hours of moderate taxi runs (up to 4300RPM) the cooling temps reach 212Fdeg
with the oil about 200F deg.
Can something be done to get lower operating
temperatures without redesigning the system?
Would switching to pure water help and if so by how
much?
Would removing the thermostat help and if so by how
much?
How much change should I expect if I were to do both?
You guys down south should have a good idea of how
best to enhance cooling.
What are your suggestions?
Jim Maher(Dyke Delta)
Jim;
Going to pure water will decrease the
delta T from rad in to rad out. Removing the thermostat will increase the
flow rate which will also decrease the delta T across the rad. The net
effect is increased average heat rejection temperature at a given power level,
and therefore, increased heat rejection. However, without knowing your current
flow rate and temp drop through the rad, there is no way to tell how much
improvement you’d get.
But from what you describe, I’d
say don’t do anything at this point. Wait til your plane flies and
see how it cools on climbout and cruise. Your ground cooling seems
adequate to get you airborne. If you have a long wait on the ground; turn
your engine off, until you have to move again.
If you want to know the effect of pure
water or thermostat removal on your system, you’ll have to make the
change and see the results.
FWIW,
Al (Scheduled for first flight this
weekend; forecast temps upper 90’s. Yikes!)