Procedure for best rate of climb

[ellisr]

Hi there, I have a couple of questions which I hope you all could offer advice on. I received mixed advice from a flight instructor and wanted to verify this.

POH calls for T/O flaps and X KIAS (varies by weight) for best rate of climb then flaps up and Y KIAS for cruise climb.

So am I correct to assume that the best rate of climb is with flaps at T/O? Seems logical per the POH but I was recommend by someone to raise flaps asap after take off for better performance, that advice seems counter intuitive versus the POH.
What would be a best practice altitude to go from best rate of climb to cruise climb after take off?
POH also recommends 2400RPM and Max Pwr. I was told by an instructor that you should never have more power than RPM as it will damage the engine. So is that a fallacy?

Thanks, Russ

[trepine]

Best climb is mixture leaned to max power, power full, prop full, flaps to t/o.

But usually you'll have mix rich and I have to pull power and prop back about 500 agl and raise flaps to get my airspeed up to cool the engine and keep CHT under 400. That is usually what limits me in staying in the best climb configuration.

[Antoine]

+ 1 here.
Just to clarify: it is OK to use 2700 RPM.
There is an addendum to the POH in this regard.
I climb at 2700 RPM best power until 500 AGL and then retract flaps and climb at 90 KTAS 2500 RPM best power.
Using flaps adds drag. I only do that as long as necessary for safety reasons.

My point of view is that your instructor is propagating obsolete beliefs. There are other limitations to be kept in mind but not this one.

[Rich]

The T/O flaps is there to shorten takeoff roll, not help climb rate. I typically retract as soon as I get around 70 knots and a couple of hundred feet. For max climb rate you need max power, which means max RPM and proper leaning.

That said, you don't often need max climb rate for long, so pulling back to 2500-2600 and using a somewhat higher speed (like 90 knots) is helpful for engine cooling, once you've gained a bit of altitude.

[Chris]

I was told by an instructor that you should never have more power than RPM as it will damage the engine. So is that a fallacy?

Yes, that is a common fallacy. I operate pretty much identically to what Antoine has described, though I usually wait until 600' AGL before retracting flaps. I used to retract them sooner, but I find it gives me better safety margins when operating near max gross weight at high density altitude if I leave them in longer.

[Rich]

I was told by an instructor that you should never have more power than RPM as it will damage the engine. So is that a fallacy?

Thanks, Russ

Sigh... Many "old codgers' tales" still persist

[PapaSierra]

Antoine: Do you lean at all as some mentioned while climbing out? I've been keeping full rich until done with cruise climb, then leaning. For T/O climb I pull throttle back to 2400 and manifold to 21 when I've achieved 1000' AGL in pattern work (usually just after turning to crosswind), but always leave full rich for touch n goes.

As a student I've been mostly having it on full rich as I practice various maneuvers - slow speed, power on & off stalls, etc.

Thoughts? The subject question has been on my mind recently too!

[trepine]

What altitude is your airport. I lean for best power on run-up and after mag check add in about another 1 of mixture. If on climb my CHT approaches 400 I add in a little more mixture.

Also if you have an engine monitor when you do your run up, I find it more useful on the mag check to watch all cylinders egt rise on one fall on both then rise again on the other single mag. This pretty much gaurentees both induction systems are fully functioning to all cylinders.

[PapaSierra]

Hi Gilman,

I am in Florida and about 40' MSL. So during run up (2,000 RPM) when I'm doing Mag checks, I should also be leaning at that time and RPM. I have G1000 so I can watch temps, but I haven't learned enough yet about exactly what to do to achieve max power. I've been trying to read and study as much as possible but am both a new plane owner and a SEL student pilot. What procedure to you do to lean for max power? (Is that the same as "Peak"?)

[trepine]

At near sea level full mixture should be fine for takeoff, but it is best to do your mag check leaned, and then make sure to put it back to full mixture after your run up.

To lean on run up slowly decrease the mixture while watching the RPM value. You will see as you lean the RPM will go up some, usually about 50-100 RPM, and then as you lean more it will start to fall again. After it starts to fall add in a notch or two to bring RPM back to max. Then after you cycle your prop, do your mag check. All 4 egt on your g1000 must rise. If 3 egt rise and one falls it means you have a problem on that cylinder, most likely a fouled plug.

Then when you put the mag back to both you will see all 4 egt drop.

Repeat for the other mag, same as before all 4 egt must rise.

One of the huge benefits of this is if you ever fail a mag check you know which cylinder and which mag system to look at which can get you back in the air 30 min later.