the LOP climb. The last sacred cow.

[jetdriven]

A few times I have accomplished a LOP climb in the M20J, and at this time I am unsure if it actually saves anything. In a  54.7 gallon M20J every gallon counts. Climb performance at 11 GPH is akin to pulling back the power to "good old 25 square", and although fuel flow is lower, the time to climb is longer too.  Changing altitude in cruise almost seems better, bring RPM to 2700, richen to 10-11 GPH or what is about 20 LOP, and climb.  Dont even have to open the cowl flaps for a 1,000' step climb.

 

Has anyone else gathered any data?  Is it worth doing?

[201er]

LOP Climb scares me cause there is far less margin for error. Although it pains me to watch 19+ gph go out the exhaust, it's only for a few minutes and doesn't really cost as much as it looks. Also it's far too much work/focus too early in the game. It's one thing to play with mixture controls up at altitude, but to be doing that coming just out of the airport is too much. Even furthermore, in a NA the climb is only going to take 5-10 minutes so the savings would be brief but the workload severe. On the other hand leaning LOP for a 2 hour long cruise has a massive effort vs savings ratio.

[M016576]

Quote: jetdriven

A few times I have accomplished a LOP climb in the M20J, and at this time I am unsure if it actually saves anything. In a  54.7 gallon M20J every gallon counts. Climb performance at 11 GPH is akin to pulling back the power to "good old 25 square", and although fuel flow is lower, the time to climb is longer too.  Changing altitude in cruise almost seems better, bring RPM to 2700, richen to 10-11 GPH or what is about 20 LOP, and climb.  Dont even have to open the cowl flaps for a 1,000' step climb.

 

Has anyone else gathered any data?  Is it worth doing?

[jetdriven]

My descent profile is about the same, Job. 170 KIAS, 700 FPM, WOT, 2300-2500 RPM, top of descent fuel flow ~8 GPH lean to that, and perhaps enrichen very slightly below 3000'.  2 miles out, MP to 18", bring mixture to peak or slightly ROP. 

[Shadrach]

I've done it a few times, once from brake release. My bird climbs quite well using the target EGT method. My anecdotal take is that it's only worth wile in a turbo. For N/A you're really not spending that much time in climb when ROP and you'd spend significantly more LOP so why bother.  The exception is altitude changes; If I'm in cruise at 5500 and want to go up to 7500, I'll leave at cruise power LOP or peak unless I need max rate.  It takes little time to climb 2000ft in almost any Mooney when you start at cruise speed.

[Becca]

Quote: jetdriven

A few times I have accomplished a LOP climb in the M20J, and at this time I am unsure if it actually saves anything. In a  54.7 gallon M20J every gallon counts. Climb performance at 11 GPH is akin to pulling back the power to "good old 25 square", and although fuel flow is lower, the time to climb is longer too.  Changing altitude in cruise almost seems better, bring RPM to 2700, richen to 10-11 GPH or what is about 20 LOP, and climb.  Dont even have to open the cowl flaps for a 1,000' step climb.

 

Has anyone else gathered any data?  Is it worth doing?

[bd32322]

Quote: jetdriven

My descent profile is about the same, Job. 170 KIAS, 700 FPM, WOT, 2300-2500 RPM, top of descent fuel flow ~8 GPH lean to that, and perhaps enrichen very slightly below 3000'.  2 miles out, MP to 18", bring mixture to peak or slightly ROP.