Leonard_Smith_nz
Active Member
All,
Went up over the weekend to do some high speed runs at 8000 feet with aircraft at MAUW. Ground temperatures 15 degrees C (62F) and QNH 1008. Did 4 runs on N, E, S, W with full throttle and mixture full rich.
For all runs noted figures in the order of: MP 22.2, engine RPM 2630, fuel flow 57 liters/hour and IAS 144 knots. Once back on terra firma I entered the GPS ground speed data into Doug Gray's spreadsheet to calculate TAS and came up with 164 knots (188 mph).
My aircraft is fitted with all fairings and spats. It has an empty weight of 1081 lbs and has flown pretty straight from day one. While these figures are a little below Vans numbers I'm happy with my aircraft's performance.
A few points that I wondering about:
1. If this test scenario sees my TMX O-360 producing 75% power how agressively can I lean the motor (if at all). I recall a Lycoming directive to not lean at 75% or above.
2. As various experts on this list have noted, the fuel flow is indicative of the power produced. 57 liters/hours is EXTREMELY high for 75% power. I see these sort of numbers when I run her flat out at 1500ft...and there I get nearly 170 knots TAS
Just wondering out loud...and learning as I go. Any observations appreciated.
Went up over the weekend to do some high speed runs at 8000 feet with aircraft at MAUW. Ground temperatures 15 degrees C (62F) and QNH 1008. Did 4 runs on N, E, S, W with full throttle and mixture full rich.
For all runs noted figures in the order of: MP 22.2, engine RPM 2630, fuel flow 57 liters/hour and IAS 144 knots. Once back on terra firma I entered the GPS ground speed data into Doug Gray's spreadsheet to calculate TAS and came up with 164 knots (188 mph).
My aircraft is fitted with all fairings and spats. It has an empty weight of 1081 lbs and has flown pretty straight from day one. While these figures are a little below Vans numbers I'm happy with my aircraft's performance.
A few points that I wondering about:
1. If this test scenario sees my TMX O-360 producing 75% power how agressively can I lean the motor (if at all). I recall a Lycoming directive to not lean at 75% or above.
2. As various experts on this list have noted, the fuel flow is indicative of the power produced. 57 liters/hours is EXTREMELY high for 75% power. I see these sort of numbers when I run her flat out at 1500ft...and there I get nearly 170 knots TAS
Just wondering out loud...and learning as I go. Any observations appreciated.
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