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RV-9A GPH at altitude

Leland

Leland

Well Known Member
I thought the following data might be of interest to RV9A pilots.

This data was taken on my recent trip to Vetterman?s Black Hills Flyin. (This was by far the best flyin that I?ve been to.)

The fuel-burn rate for the 2.9 hour flight from Livermore, California to Wells, Nevada averaged 6.2 gallons/hour (GPH), including the full-throttle climb to 13,500?, cruise and decent. The burn rate at 13,500?, with the mixture leaned to the edge of roughness, was 6.0 GPH while cruising at 146 knots TAS. (The density altitude was 14,900?.) The cruise burn-rate was measured over a 20 minute period since the instantaneous EIS reading fluctuates. The full-rich, full-throttle TAS at this altitude was 150 knots (2460 RPM and 18.4" M.P.).

The second leg of the flight from Wells to Kemmerer Wyoming at 11,400? showed a TAS of 156 knots at 2540 RPM and 20.1" M.P, for full-throttle and full-rich conditions (burn rate was estimated at 6.9 GPH).

The maximum TAS of this plane near sea level is 162 knots. Its airspeed indicator is accurate to 1-2 knots.

Leland

Faired and painted RV9A
550 hours since new on a carbureted O320D1A
One P-Mag and one conventional magneto
Catto fixed pitch 3-blade propeller
 
Good info Leland.

It was a pleasure getting to meet you at the Badlands. That was a fun fly in.
 
Mine is real close

Good info mine is set up pretty close to your 9a except it has light speed and one mag and a mt fixed pitch prop. I am achieving pretty close to the same speeds and fuel burns on my trips at that altitude
Tim
 
Best Power?

It would be interesting to know what it would do at best power mixture as compared to full rich, especially at altitude.

Leland said:
I thought the following data might be of interest to RV9A pilots.

This data was taken on my recent trip to Vetterman?s Black Hills Flyin. (This was by far the best flyin that I?ve been to.)

The fuel-burn rate for the 2.9 hour flight from Livermore, California to Wells, Nevada averaged 6.2 gallons/hour (GPH), including the full-throttle climb to 13,500?, cruise and decent. The burn rate at 13,500?, with the mixture leaned to the edge of roughness, was 6.0 GPH while cruising at 146 knots TAS. (The density altitude was 14,900?.) The cruise burn-rate was measured over a 20 minute period since the instantaneous EIS reading fluctuates. The full-rich, full-throttle TAS at this altitude was 150 knots (2460 RPM and 18.4" M.P.).

The second leg of the flight from Wells to Kemmerer Wyoming at 11,400? showed a TAS of 156 knots at 2540 RPM and 20.1" M.P, for full-throttle and full-rich conditions (burn rate was estimated at 6.9 GPH).

The maximum TAS of this plane near sea level is 162 knots. Its airspeed indicator is accurate to 1-2 knots.

Leland

Faired and painted RV9A
550 hours since new on a carbureted O320D1A
One P-Mag and one conventional magneto
Catto fixed pitch 3-blade propeller
Click to expand...
 
Great observation Leland. These are real numbers. I just returned from a long x-country trip (600 nm) and still have fuel left for more then two hours.
 
Please define: leaned to the edge of roughness,

Please define: "...leaned to the edge of roughness..."

Is that 50? ROP , PEAK , 50 LOP, what? :confused:

Thanks...
 
ALMARTON said:
Please define: "...leaned to the edge of roughness..."

Is that 50º ROP , PEAK , 50 LOP, what? :confused:

Thanks...
Click to expand...

Since I have a fixed pitch propeller and a carburetor, I lean while watching the RPM and listening to the engine. I lean until the engine sounds a bit rough and then richen a 1/4 turn. I have not found watching the EGT(s) while leaning to be helpful.
Leland
 
Last edited:
Leland said:
Since I have a constant speed propeller and a carburetor, I lean while watching the RPM and listening to the engine. I lean until the engine sounds a bit rough and then richen a 1/4 turn. I have not found watching the EGT(s) while leaning to be helpful.
Leland
Click to expand...
While it may be true that watching your EGT(s) climb during the initial process of leaning may not tell you much, watching them when you get around the peak EGT (which should happen just before your engine starts getting rough) may be of use to pay attention to. This is the time when you could end up having something go awry.
 
Interesting. I've operated a few carb'd engines with CS props in my day and EGT was always the primary instrument when leaning. Though I'm no mechanic or guru, I have always been under the impression that if you get into roughness before you find peak EGT, then something is wrong.
 
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