Transitioning

[Derek]

32 minutes ago, EricJ said:

yellow "avoid this range" band on the tach

Yeah, I did notice that too. I wasn't keeping a close eye on the tach during the approach and was just modulating the throttle as felt appropriate for the descent profile I needed. However, I did see the tach a few times and noticed being in that range. I seem to recall adjusting my throttle position when i realized i was in that range.

I also recall asking my CFI about if operating in that range on my approaches was bad. He said that the concern was for continuous operation and that a short stretch in the approach wouldn't be an issue.  However, I did feel the vibration, and to make a smoother ride I'd like to avoid it even if it is safe in small doses.

Thanks for the tip! It's something I will be keeping in mind as I try and improve my handling.

[HRM]

1 hour ago, Derek said:

Excuse my muttering and mumbling...

Let he who is without sin cast the first stone...

Great looking bird, enjoy!

[carusoam]

Great video.

Looks like you have done this before...

Add an external camera so we can judge your centerline acuity.  

thanks for sharing the video...

Best regards,

-a-

[bradp]

16 hours ago, EricJ said:

Lookin' good!   Enjoy the airplane!

My only suggestion would be to check the yellow arc on your tach, if you have one.   Depending on your engine/prop combination there's a range where torsional vibration in the crankshaft can shake the balance weights loose, which is bad, so there's usually a yellow "avoid this range" band on the tach.   I can't quite tell whether/where you have a yellow arc, but the camera was shaking right when you had the rpm in the usual range.

I noticed the exact same thing. Seemed from the vibration you were in the prohibitive region of tach and MP for most of the pattern.  You’ll pass through the vibration region no matter what but this should be brief and heading somewhere (ie on the way to idle) not hanging out in it.  It just takes adjustment of your “profile” to keep a little power in ie energy management.  
 

great vid! 

[midlifeflyer]

This is not exactly standard procedure but one option is to fly RPM rather than MP in he pattern. Remember that at lower MP settings, a full-forward prop will act like a fixed pitch prop and you can control RPM with the throttle. You do this every time you do a run-up. So, basically, you can fly that Mooney like a Cherokee or 172, setting and monitoring RPM.

Not a technique I teach unless I see someone in a transition having difficulty, but I know folks who use it as a standard for transition training, essentially "demystifying" the prop and making it familiar i the pattern.

Edited January 4, 2020 by midlifeflyer

[EricJ]

16 minutes ago, midlifeflyer said:

This is not exactly standard procedure but one option is to fly RPM rather than MP in he pattern. Remember that at lower MP settings, a full-forward prop will act like a fixed pitch prop and you can control RPM with the throttle. You do this every time you do a run-up. So, basically, you can fly that Mooney like a Cherokee or 172, setting and monitoring RPM.

Not a technique I teach unless I see someone in a transition having difficulty, but I know folks who use it as a standard for transition training, essentially "demystifying" the prop and making it familiar i the pattern.

This is what I do in the pattern.   It's pretty straightforward and makes it very easy to stay out of the yellow arc.

Since I typically cruise at full throttle, about the only time I pay much attention to MP is on final descent or instrument approaches.

[midlifeflyer]

2 minutes ago, EricJ said:

This is what I do in the pattern.   It's pretty straightforward and makes it very easy to stay out of the yellow arc.

That's why I mentioned it. It seems particularly applicable to airplanes with a "keep out" zone at low power settings.

[carusoam]

23 hours ago, Derek said:

 

I also recall asking my CFI about if operating in that range on my approaches was bad.
 

He said that the concern was for continuous operation and that a short stretch in the approach wouldn't be an issue. 

However, I did feel the vibration, and to make a smoother ride I'd like to avoid it even if it is safe in small doses.

 

This is completely acceptable way of looking at a small problem and delaying fixing it for a long time...

Its OK, because...  (My TT instructor said the same thing)

 

My last days of M20C ownership came with a broken engine mount...

Want to see some vibration? Fly around with only three small bolts holding the engine in place.

i followed the same instructions for a decade...

 

The method you use to fix this... is to transition through it as quickly as possible... as in a scale of seconds, not minutes...

Because you can...

Somewhere around here is the explanation of harmonic vibrations... how powerful they are and why we don’t usually feel them...

they come with other forms of vibration that are often mistaken for what we are trying to avoid... sometimes they are collocated so avoiding one avoids the other...

Not fear mongering... just adding the experience I used and it’s end result... they may not be related... just a single point of data...

But, the yellow arc on the tach was put there for a reason... they wouldn’t have done it if they didn’t have to...

Best regards,

-a-

 

[midlifeflyer]

1 hour ago, carusoam said:

This is completely acceptable way of looking at a small problem and delaying fixing it for a long time...

Its OK, because...  (My TT instructor said the same thing)

 

My last days of M20C ownership came with a broken engine mount...

Want to see some vibration? Fly around with only three small bolts holding the engine in place.

i followed the same instructions for a decade...

 

The method you use to fix this... is to transition through it as quickly as possible... as in a scale of seconds, not minutes...

Because you can...

Somewhere around here is the explanation of harmonic vibrations... how powerful they are and why we don’t usually feel them...

they come with other forms of vibration that are often mistaken for what we are trying to avoid... sometimes they are collocated so avoiding one avoids the other...

Not fear mongering... just adding the experience I used and it’s end result... they may not be related... just a single point of data...

But, the yellow arc on the tach was put there for a reason... they wouldn’t have done it if they didn’t have to...

Best regards,

-a-

 

Good point. I've flown in about a half dozen different J models and in most the vibration was barely noticeable. But in one of them, wow! You could really feel something was wrong.

[Derek]

2 hours ago, carusoam said:

the yellow arc on the tach was put there for a reason.

Absolutely right. I'll be working on my ops to make sure I avoid it 

[carusoam]

For a list of similar challenges...

review the limitations section of the POH...  (some birds are more of a challenge than others...)

This section details the markings on each instrument...

Often these limitations are under informative...

Others leave you with a false sense of security... like the redline on the CHT gauge...

Experience indicates that there are best locations to operate in... as opposed to regions to avoid...

in lieu of having tons of Mooney experience...  pick up as much as you can from the community called MS... 

Lots of this stuff is written down and searchable with some effort...

PP thoughts only not a CFI...

Best regards,

-a-

[bradp]

Flying a profiled pattern and approach to land works for most of us J owners to stay out of the yellow arc.  Result is the same as the principle that Mark is referring to on and off the governor, above. 
 

In a J something like enter Downwind above gear speed - for me that’s 150 MPH.  Gear down abeam touchdown point.  Slow to flaps speed (usually 15 in MP will do it).  Start descent.  Keep 12-15 MAP as required to turn base 100 MPH, full flaps, turn final at same, slow to 90 MPH for final, 80 MPH short final, Vref at HAT.    This slowing on short final keeps the vibration to a few seconds because when I’m descending on final the prop has enough inertia and my speed is high enough that it takes a bit to go from 2x00 RPM to 1900 RPM and then through the yellow arc.  
 

Am I windmilling the prop as to drive the engine with the prop from airspeed.  You bet.   But we all do that when landing and the I’ll effects are only theoretical in a direct drive engine. GTSIO 520 okay fine don’t let the prop drive the engine by all means.  But not our little lycoming engines.
 

An (the) alternative scenario is to hang on the prop on the back side of the power curve to maintain >15 MP.  That might keep you out of the yellow but IMO such an approach would be contrary to safety   

 

[Hank]

This thread was on my mind this afternoon. I was pulling throttle at 110mph and 900 fpm on the crosswind turn and still blowing through pattern altitude in ny little C. Downwind at 90mph, Takeoff Flaps, is 14-15" and right at 2000 RPM (red arc 2000-2250); dropping gear starts the descent. Landing with Takeoff Flaps, or slightly more if I was a little high or fast, once again had the trim right at my takeoff position (just above the mark). Worked like this four times today.