David-aviator
Well Known Member
No question, these airplanes are most efficient above 8000'. But 8000'+ isn't always practical so I gathered some numbers today at 2500', the intent to show how to fly and burn less fuel.
(Local 100LL is $5.25 today.)
It was not a great day to do this as it was bumpy but the data is in the ball park. Engine at about 40 LOP. Numbers are still air.
7 GPH = 130 KTAS = 149.6 MPH = 21.40 MPG
6 GPH = 124 KTAS = 142.7 MPH = 23.80 MPG
5 GPH = 117 KTAS = 134.6 MPH = 26.90 MPG
4 GPH = 100 KTAS = 115.0 MPH = 28.70 MPG
So, if one has time to burn (as opposed to fuel) the reward for flying at 100 vrs. 130 is almost 25%. It does feel a bit strange limping along at 4 GPH, but thats the beauty of the engine, it doesn't care and the airplane flies just fine at 100 knots. It's a simulated LSA flight with a lot of HP in reserve.
I'd like to cut fuel costs more yet by getting away from 100LL and going with 93 mogas - but the fly in the ointment is ethanol. The St. Louis area has dirty air so no fuel sold locally is ethanol free. Go west about 80 miles and it is available.
An alternative is to find a Lycoming mechanical fuel pump with upgraded seals and baffles to withstand alcohol. They are available. Greg Poe, the late air show performer flew on 100% ethanol. I am following that lead, his engine came from Ly-Con in California. If I can get such a pump at a reasonable cost, it would pay for itself quickly in lower fuel costs. (NOTE: Greg Poe died of a heart attack, not from using ethanol)
(Local 100LL is $5.25 today.)
It was not a great day to do this as it was bumpy but the data is in the ball park. Engine at about 40 LOP. Numbers are still air.
7 GPH = 130 KTAS = 149.6 MPH = 21.40 MPG
6 GPH = 124 KTAS = 142.7 MPH = 23.80 MPG
5 GPH = 117 KTAS = 134.6 MPH = 26.90 MPG
4 GPH = 100 KTAS = 115.0 MPH = 28.70 MPG
So, if one has time to burn (as opposed to fuel) the reward for flying at 100 vrs. 130 is almost 25%. It does feel a bit strange limping along at 4 GPH, but thats the beauty of the engine, it doesn't care and the airplane flies just fine at 100 knots. It's a simulated LSA flight with a lot of HP in reserve.
I'd like to cut fuel costs more yet by getting away from 100LL and going with 93 mogas - but the fly in the ointment is ethanol. The St. Louis area has dirty air so no fuel sold locally is ethanol free. Go west about 80 miles and it is available.
An alternative is to find a Lycoming mechanical fuel pump with upgraded seals and baffles to withstand alcohol. They are available. Greg Poe, the late air show performer flew on 100% ethanol. I am following that lead, his engine came from Ly-Con in California. If I can get such a pump at a reasonable cost, it would pay for itself quickly in lower fuel costs. (NOTE: Greg Poe died of a heart attack, not from using ethanol)
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