RPM restriction - is brief operation within it on final a problem?

[Shadrach]

1 hour ago, EricJ said:

One difference is whether the crank has the dynamic counterbalances or not.   J models do have them, so they're potentially more sensitive to conditions that disturb the counterweights.    Lycoming SB245D talks about it a bit, including why it is more problematic at low Manifold Pressure, and SI 2012L talks about it as well.   The yellow arc torsional vibrations are not created equal even across Lycoming four-cylinders for this reason.

I have a Hartzell Top Prop that deletes the restriction, presumably because it is a heavier propeller, but I still avoid the yellow arc except on final, where I'm kinda never looking at the tach.

I think the MTs eliminate it as well but it would not be because they’re heavier.

[EricJ]

7 minutes ago, Shadrach said:

I think the MTs eliminate it as well but it would not be because they’re heavier.

Changing the mass either direction would probably change the natural frequencies of the torsional vibration modes, so sufficent addition or subtraction of mass may attenuate the vibration.   The moment of inertia may matter as well, but I don't know how that compares between the Top Props and the more conventional models.

  

[N201MKTurbo]

4 hours ago, Hank said:

Somewhere in the DFW area would be "meeting in the middle," and about a full-tank range for me unless I flew at 20"/1950, which extends my range from my normal ~800 sm to 1000 sm plus 45 minute reserve, if I make the trip at sea level . . .

ElPaso for Gods sake, it takes me a whole tank to get to Dallas! Maybe Midland...

[Hank]

1 minute ago, N201MKTurbo said:

ElPaso for Gods sake, it takes me a whole tank to get to Dallas! Maybe Midland...

DFW area would be a full tank for me, too. But your tank is bigger, you can run LOP and your plane is faster, why is halfway a bad idea? For reference, I'm hangared at KALX.

Where in Texas is Midland? My Texas geography is pretty scant, drove across it once and drove to Dallas and Ft. Worth once each, none since the 80s.

[N201MKTurbo]

59 minutes ago, Hank said:

DFW area would be a full tank for me, too. But your tank is bigger, you can run LOP and your plane is faster, why is halfway a bad idea? For reference, I'm hangared at KALX.

Where in Texas is Midland? My Texas geography is pretty scant, drove across it once and drove to Dallas and Ft. Worth once each, none since the 80s.

The only thing worse than flying across Texas is driving, it gives you more time to contemplate your life.

[A64Pilot]

On 12/22/2021 at 7:48 PM, Shadrach said:

I think the MTs eliminate it as well but it would not be because they’re heavier.

I’m not saying this is why,but wood usually does a very good job of dampening vibrations.

[OR75]

On 12/22/2021 at 7:39 PM, N201MKTurbo said:

The only thing worse than flying across Texas is driving, it gives you more time to contemplate your life.

That was years ago … but flying from TX to CA gave the time to learn the ins and outs of the GNS 430 I had just installed