Do you lean as you climb ?

[0TreeLemur]

On 3/4/2024 at 2:38 PM, pagirard said:

Thanks everyone for your time and the great responses. I have now modified my climb procedure (full rich and full throttle on TO) and starting to lean for 1250degF EGT starting at 5000'. I also adjusted my climb speed to 105kts IAS have a much better CGH and climb performance.

 

Also learned a lot about the prop and prop governor limit !

Thanks a lot everyone.

Your target EGT might be different from 1250F depending on how far from the exhaust valve your EGT probes are and random errors.  The best way to identify your target max. power EGT is to observe the indicated EGT on takeoff from a field near sea level, mixture forward, in your airplane.   It might be 1300 or 1200.

[Shadrach]

1 hour ago, PT20J said:

Ross, that would be true if the power available were constant. However, it's not. Power available is thrust times TAS and so it is zero at zero airspeed and increases as airspeed increases until prop efficiency drops off. At low speeds, the variation in power available with airspeed is greatest and this affects Vy since ROC is the difference between power required (which varies as the square root of weight) and the power available.

Thanks,, that makes sense. However, does that not mean that the calculation is useful for calculating the initial Vy number by weight if you were so inclined. So if we use my initial calculation.

Book Vy at max gross of 2740lbs =99kts

Take off weight me with 4hrs of fuel = 2135lbs

2135/2740=.78

 √.78 = .88

.88*99kts = 87

Calculated Vy at 2135lbs = 87kts 

And then compare book Vy at some higher altitude, (The book simply decreases the initial Vy number by 1 mph per 1000ft). We see the:

Book Vy at 2740lbs @ 9000ft = 90kts

Calculated Vy a 2135lbs @ 9000ft = .88 * 90 = 80kts

or if we just subtract 1 mph per 1000 ft of altitude as the book does (9mph =7.82kts) we come up with

87kts -7.87kts =79kts

So the results of calculating by sqrt of weight and subtracting 1mph per 1000ft differ by a rounding error.

 

 

[PT20J]

I think the altitude has the bigger effect because it reduces the power available. But, I never really think too much about it. I'm in Deakin's camp on climb speeds. https://www.advancedpilot.com/articles.php?action=article&articleid=1842

When I'm up around 10,000 or higher I usually just split the difference between sea level gross weight Vx and Vy and find that close enough for a good climb speed.

[MikeOH]

Did a test flight from 1000 MSL to 11,500 MSL. OAT at take-off was 65F, I held 105 mph IAS for the entire climb and leaned for take-off EGT from 2000 on up.  Had 60 gallons at take-off, estimate 2350 total.  Pretty disappointing: 620 fpm.  With 2600 SMOH, maybe it's time to overhaul.

[Ragsf15e]

27 minutes ago, MikeOH said:

Did a test flight from 1000 MSL to 11,500 MSL. OAT at take-off was 65F, I held 105 mph IAS for the entire climb and leaned for take-off EGT from 2000 on up.  Had 60 gallons at take-off, estimate 2350 total.  Pretty disappointing: 620 fpm.  With 2600 SMOH, maybe it's time to overhaul.

You were heavier than us for sure.  You also had warmer temps.  Finally, you went higher than us which really drops your average.  Try again on one of those arctic California mornings when it’s 35 degrees.  Have 35 gallons on board.  Get the average up to 10k.

[Shadrach]

1 hour ago, MikeOH said:

Did a test flight from 1000 MSL to 11,500 MSL. OAT at take-off was 65F, I held 105 mph IAS for the entire climb and leaned for take-off EGT from 2000 on up.  Had 60 gallons at take-off, estimate 2350 total.  Pretty disappointing: 620 fpm.  With 2600 SMOH, maybe it's time to overhaul.

I would not assume TSMOH alone is the culprit.  I had to fabricate some cowl flap hinges or I would have been out collecting data this weekend.

[Hank]

10 hours ago, MikeOH said:

Did a test flight from 1000 MSL to 11,500 MSL. OAT at take-off was 65F, I held 105 mph IAS for the entire climb and leaned for take-off EGT from 2000 on up.  Had 60 gallons at take-off, estimate 2350 total.  Pretty disappointing: 620 fpm.  With 2600 SMOH, maybe it's time to overhaul.

My Owner's Manual says to reduce airspeed 1 mph per 1000 feet to 10K, 100 mph at sea level down to 90 mph at 10K; no information is provided any higher.  Keeping constant airspeed should reduce your climb rate.

Unless your F is really that different from my C . . . .

[Ragsf15e]

5 hours ago, Hank said:

My Owner's Manual says to reduce airspeed 1 mph per 1000 feet to 10K, 100 mph at sea level down to 90 mph at 10K; no information is provided any higher.  Keeping constant airspeed should reduce your climb rate.

Unless your F is really that different from my C . . . .

Our F poh has the same 1kt/1000’ decrease, but it starts at 110mph.  I used 100mph initial climb and achieved a better climb rate than 110mph.  Im thinking there’s lots of factors and they might have just made a best guess with rounding when they published the Vy.