How do others deal with the restricted rpm zone on landing?

[201er]

17 minutes ago, Hank said:

You reduce throttle for cruise descents? All i3 do is push the yoke for 500 fpm and retrim . . . The caution zone on the tach never comes into play.

Inefficient 

[Hank]

1 hour ago, 201er said:

Inefficient 

Depends on your point of view. My O-360 doesn't do LOP very well.

Descending at cruise power lets the air & ground speeds climb to make up for the slow climb tk altitude after departure. My block fuel burn flying this way (ROP) is pretty consistent at 9 gph. Not bad for 145-148 KTAS at or above 8000 msl.

The other choice is to reduce pkwer and descend at cruise airspeed. I need to do that once, run the nhmbers and see what the fuel difference is.

One is shorter flight time at cruise fuel burn, the other is longer flight time at lower fuel burn. Is the fuel burn low enough to offset the longer time? I dunno. May have to play with my pencil and see what it takes, starting with calculating flight time at 145 mph versus 170 mph. If only I had fuel flow measurement capability, it would be so much easier . . . .

[jaylw314]

6 hours ago, Hank said:

You reduce throttle for cruise descents? All i3 do is push the yoke for 500 fpm and retrim . . . The caution zone on the tach never comes into play.

It only becomes an issue if it's bumpy or if I get slam dunked by ATC

[Skates97]

6 hours ago, Hank said:

You reduce throttle for cruise descents? All i3 do is push the yoke for 500 fpm and retrim . . . The caution zone on the tach never comes into play.

I do the same thing. I'm not concerned if it's more efficient to throttle back and burn a few less gallons. 

[Hank]

I was reading through my Owners Manual and was pleasantky surprised to find this topic addressed there. This is what Mooney has to say about the red arc on my tach:

I am officially not worried about RPM in the pattern. This topic is not addressed at all in the discussions about descents and landing. As I have always done, I will select a cruise RPM outside the red stripe, enter the pattern at 2300 (my red zone is 2000-2250), and ignore both MP and RPM needles way over on the other side of the panel while I'm making left turns, reducing power and landing.

[Skates97]

1 minute ago, Hank said:

I was reading through my Owners Manual and was pleasantky surprised to find this topic addressed there. This is what Mooney has to say about the red arc on my tach:

I am officially not worried about RPM in the pattern. This topic is not addressed at all in the discussions about descents and landing. As I have always done, I will select a cruise RPM outside the red stripe, enter the pattern at 2300 (my red zone is 2000-2250), and ignore both MP and RPM needles way over on the other side of the panel while I'm making left turns, reducing power and landing.

Hmmm... Where did I see this before? 

On 11/3/2017 at 8:40 AM, Skates97 said:

It appears that way. I have never experienced the vibration or rumble in my C/D that others have said they get in their J's. Regarding RPM, my POH says:

"In selecting a cruise rpm, it is recommended that the engine not be operated for cruise purposes within the range of 2150 to 2300 rpm."

The 1977 POH has similar language:

"In selecting a cruise RPM, the engine must not be continuously operated within the range of 2000 to 2250 RPM."

Both of them are talking about flight in cruise, not slowing down in the pattern and landing. Maybe I missed that somewhere in the times that I have read the POH? It seems to me that at least in regards to a C model that people have taken the word "continuous" out of context and are applying it to all phases of flight, including the few minutes prior to landing. From what I see it is clearly referring to flight in cruise.

 

[Hank]

When I read that, it reminded me of the endless discusions here, turning minutia into mountain ranges. So I screenshotted it . . . .

[jetdriven]

On 11/6/2017 at 9:56 PM, Skates97 said:

I do the same thing. I'm not concerned if it's more efficient to throttle back and burn a few less gallons. 

It’s less than one gallon and it saves several minutes on a flight. Add back your 4$ is saved airframe time it may be a cost neutral thing, and the speeds and time was free. We know this is true for the Vz climb profile. 

[cnoe]

I just stumbled upon this thread. My J has never exhibited any significant vibration in the landing phase and I give the prop speed zero thought. I’m much more concerned about dodging North Korean missiles on final than worrying about some transient rpm restriction.


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[jetdriven]

Especially  given since there are 10,000 airframes produced, several thousand still flying regularly and not one documented case of prop failure from fatigue from this RPM zone thing.  There’s an awful lot of this on this site. Just like the fuel  bladders that always leak but nobody can ever produce one. Damaged props from pulling out of the hangar.  Just like those Loss of elevator control in the slip leading to an accident. The trimmed up M20J  that’s impossible to control on a go around. Etc. 

Edited November 24, 2017 by jetdriven