Hi,
On several occasions, I experienced that the coolant temperature has reached close to the max of 120 degrees C when on the ground.
I did some tests to find out what causes this and what can be done to mitigate high coolant temperatures on the ground.
I wanted to share my results and ask if any of you guys had similar issues and possible solutions?
My setup:
Bristell NG5 with Rotax 912 iS
Propeller: DUC 3-bladed Swirlblack in-flight adjustable
Coolant: Prestone premixed 50/50
Coolant radiator, roughly 32x16 cm mounted low behind the propeller
TLDR; RPM of 2500 and facing aircraft into the wind makes a big difference on coolant temperature while on the ground.
Day 1 test conditions:
OAT: 13 degrees C
Wind: 7 kts, aircraft faced into the wind.
I did 5 test runs with different settings, in between the test runs I let the engine cool back down. The test runs are 11 minutes each and I started the timer once the coolant temperature had reached 80 degrees C
1st test: 2000 RPM, Lane A & B on, prop 100% (fully fine propeller pitch)
2nd test: 2000 RPM, Lane A only (to force the engine out of ECO mode, which gives lower EGT, however, oil temp is N/A), prop 100%
3rd test 2000 RPM, Lane A & B on, prop 70% (prop slightly course, similar to a fixed pitch prop)
4th test 1650 RPM, Lane A & B on, prop 100%
5th test 2500 RPM, Lane A & B on, prop 100% (Gave lowest coolant temperature but the highest oil temp)
Coolant temp: https://imgur.com/a/wdhla9D
Oil temp: https://imgur.com/a/rcmBkZD
Day 2 test conditions:
OAT: 7 degrees C
Wind 11kts
I did 2 test runs, one with the aircraft facing directly into the wind and the other facing opposite the wind. 2000 RPM, prop fully fine, and both Lane A & B on. 11 minutes test runs, the timer started when coolant reached 80 degrees C
1st test: Facing directly into the wind
2nd test: Facing opposite the wind. (At the end of test run the coolant temp was 22 degrees C higher than the previous test)
Coolant temp: https://imgur.com/a/vs0s3oH
Oil temp: https://imgur.com/a/jTPkjRR
