Who brings the power back on climb?

[231flyer]

Takeoff at full rich, full RPM, and 42".  Reduce to 2500 RPM and 35" after 500' and flaps retracted.  Fuel flow is set at 14 gph and temps are comfortably in the green.

[jetdriven]

Testwest posted a graph that showed a 25-25 climb in an M20J almost halves the climb rate and you have to climb at a 5 knot slower speed to get it.  So, at any given time, you are somewhat more than half as high as you would be if you had climbed at full throttle and 2700 RPM.  Altitude = options, but also, altitude is a pretty good noise buffer.  

The Lycoming 320 and 360 engines in the Mooneys have NO time limit. 2500 RPM is only 8% less RPM than 2700, and what do you get in return?  Can anyone document a failure or a reduced overhaul interval based on running the enigne at 2700 RPM?    2700 RPM is also listed as a normal cruise RPM.  

[John Pleisse]

Every examiner and CFI I have flown with taught rpm reduction to be good noise neighbors and to lessen the stress on your engine. Certainly not novel...not exciting.....easily contradicted by modern aviation wrtiers, but time proven common sense.

Fussing with knobs at lower altitudes should be more of a concern.

[danb35]

Skyking, I'd be willing to be that your POH only recommends (as mine does) reducing to 25"/2500 for climb.  Under FAA rules (I assume Canadian rules are the same, but I'm not familiar with them), the only mandatory parts of your POH are in the Limitations section, so this recommendation may be disregarded at your option.  I choose to disregard it for the simple reason that I don't see any good reason for it.

Sounds like I fly my F the same way Ross does his--WOT from takeoff to descent (and sometimes even in descent until close to the field), full RPM until level at cruise, lean to target EGT ~ 1250 degrees in climb, though I don't open the ram air until a bit higher.  Once level in cruise, lean to ~9 gph.  Oh, and gear up as soon as I'm off the ground--the Johnson bar is a lot harder to operate if I let the speed build up.  Seems to make the most sense to me to use max available power for climb, as long as no limitation prohibits it (and none does in any NA engine that I know of, certainly not the 180-200 HP Lycomings used in Mooneys).

[201er]

Quote: Bnicolette

Mike, where in the POH does it mention reducing power.  I saw somebody else posted that also and I can't find it in the '81 or '83 POH's?  Is it something that maybe they took out for later models or is it located in some other section than the Normal Procedures?  Or it could be that pulling power back is kind of like using Marvel Mystey Oil.  Nobody can really explain it, it's just something they've been taught or doing forever.

[Ron McBride]

I pull the prop back to 2500 rpm on take off. I have been doing this for 40 years. I think that it is probably a little easier on the engine.

Pulling the pro back on some brand B and C aircraft is a huge noise reduction. This is good for our airport neighbors.

Fly safe and friendly.

Ron

[bd32322]

I sometimes reduce RPM to 2600 for noise reasons at low altitude - especially at night and then firewall forward everything if its a long climb. Speed and cowl flaps are set according to cooling margins shown on the JPI

[Shadrach]

Quote: N9154V

I pull the prop back to 2500 rpm on take off. I have been doing this for 40 years. I think that it is probably a little easier on the engine.

Pulling the pro back on some brand B and C aircraft is a huge noise reduction. This is good for our airport neighbors.

Fly safe and friendly.

Ron

[RJBrown]

With 1825 TT on the engine it uses less oil at 2500 than full forward.

[Shadrach]

I also climb at 2500 RPM (WOTRAO), but relatively speaking, the extra oil burn is a very small addition to annual operating cost. I'm betting ~1% or less...

[jetdriven]

Do any of you bring back the power for climb in a 172 or some other small training airplane?  Why or why not? 

[John Pleisse]

Quote: jetdriven

Do any of you bring back the power for climb in a 172 or some other small training airplane?  Why or why not? 

[201er]

Quote: jetdriven

Do any of you bring back the power for climb in a 172 or some other small training airplane?  Why or why not? 

[jetdriven]

So whats the difference.  A 172 SP has a 2700 RPM limit and an IO-360 engine.  Abuse is abuse.

[Immelman]

I will bring the power back if there is a good reason. A good reason would be to comply with an engine manufacturer's limit or recommendation. But if Lycomnig says I can run my IO-360 at 2700/full throttle continuously for the climb, I am not going to let the POH (which also says I should lean to 50dF ROP...) tell me I need to make a power reduction. Within 5-7 minutes after takeoff I'll be through 5000' anyway where it becomes a moot point, as manifold pressure is limited by atmosphere.

[jetdriven]

That same POH also says full rich before changing power settings, or full rich until over 3,000'.  In Houston thats a density altitude of over 6,000 feet.  Our M20J has a ~330 CHT and an EGT of ~1285 on takeoff at 59 degrees, sea level, and 29.92 altimeter setting.  The engine doesnt know what altitude its at, so why wait until a 6000' dendsity altitude to grab the red knob of death?

[John Pleisse]

Quote: jetdriven

So whats the difference.  A 172 SP has a 2700 RPM limit and an IO-360 engine.  Abuse is abuse.

[201er]

But if you are adjusting the prop strictly for noise reasons then you should either:

A) Leave it full and climb like hell and be well over the noise sensitive area before you reach it

or

Reduce prop, continue till high or far enough, then put it back in and continue climb

 

What am I missing?

[jetdriven]

Can anyone classify a Mooney as a loud airplane?  Is an 80 dBa M20J louder at 2700 RPM and 1800' than a 2500 RPM M20J at 1000'?   Just how important is this noise abatement stuff?  I know a 185 with its 2850 RPM and many larger engined airplanes are rather loud, but a Mooney?  

[John Pleisse]

More challenge of convention with hair-splitting symantics. 100 rpm.

We have a 185 on the field with a full P-Ponk conversion. It is the loudest thing I have ever heard.

[Parker_Woodruff]

The only way I'd bring the power back is via mixture for a Lean of Peak climb at about 13 GPH

[SkyPilot]

My 1967 M20F owner's manual states on page 24: After gear-up, reduce propellor rpm to 2550 to 2600 rpm. On page 25 it states: Recommended power setting for climb is 2600 rpm and 26 inches manifold pressure.

I've only put 24 hours on the bird so I'm still getting used to it. Climb does seem less impressive than advertised however.

I've got an IO-360-1A1. I've been dropping rpm to 2600 and manifold to 25 inches, but after reading this thread, I'm going to try "firewalled" a few times and just make sure my prop doesn't go over 2700. Hopefully the so far great old engine doesn't blow!

[DaV8or]

I do WOT, max RPM and target egt. Ram air around 5k, although these days, I'm not using my ram air at all until the factory feels like making induction boots again and decides to sell me one. My theory is that air going through the filter is easier on the boot. Anyhow, I was just going to say, ever since I put the digital engine monitor in with it's digital tach, I can tell that the prop only ever goes to actual red line at the power up just after brake release. It's really just momentary and then it stays just under red line for the rest of the flight. With the old mechanical tach, you really couldn't tell. The needle would just wobble around near the red line and I can understand not wanting to keep it there long for lack of accurate information.

[Dale]

In my 262 M20K the POH says for a normal climb use 32" MP and 2500 RPM.  For best rate of climb, and best angle of climb, my POH says 36" MP and 2700 RPM.  Same numbers for a go around.  I generally climb out at 36" MP and 2690 until 1000 feet and then I go to normal climb at 32" MP and lower the RPM from 2700 as per the POH, although i like to keep the RPM higher than the book, so the turbo doesn't have to work as hard.  Engine temps all very good on climb out.

[Shadrach]

Quote: SkyPilot

My 1967 M20F owner's manual states on page 24: After gear-up, reduce propellor rpm to 2550 to 2600 rpm. On page 25 it states: Recommended power setting for climb is 2600 rpm and 26 inches manifold pressure.

I've only put 24 hours on the bird so I'm still getting used to it. Climb does seem less impressive than advertised however.

I've got an IO-360-1A1. I've been dropping rpm to 2600 and manifold to 25 inches, but after reading this thread, I'm going to try "firewalled" a few times and just make sure my prop doesn't go over 2700. Hopefully the so far great old engine doesn't blow!