LOP climbs?

[dans2992]

So out here in Phoenix, a late afternoon departure means trying to climb while the OAT is about 113-115.

By reducing MP, and slowing the climb quite a bit, I am able to keep CHTs in check. However, the oil temp is hot (ie 230-235).

Would climbing LOP result in better temps? I realize it would slow the climb, but I'm already slowing it quite a bit anyhow to keep temps in check.

 

[Geico266]

Try "stair step" climbing. Climb until oil hits 220 then level off 10-15 mins for cooling, repeat.

235f on oil is acceptable considering the OATs. Guard your CHTs like a hawk.

 

[dans2992]

I will give that a try. Oil temp seems to take a LONG time to come down, even level, especially down low.

With the terrain profiles around here, leveling for 10-15 mins would mean circling....

 

[TheGolfPilot]

Im not a mechanic, but from personal experience, when it is a hot day I climb with the mixture rich and leaning in the climb is only done when I can do so and keep my temps under 400. Sure it reduces my power output a bit and burns a little extra fuel, but I feel that keeping the temps under 400 is important.

 

[James331]

I've never worked for a company that did much, if any, LOP ops.

I'm ok with LOP for some stuff, but for a climb, heck no.

 

[Ted]

The issue with LOP climbs in the summer is you'll need to be really lean to keep the temps low enough, by which point you have no climb rate. Unless you have insanely excellent cooling, you likely won't see a benefit.

I would honestly not worry about that oil temperature a bit on your airplane/engine, especially if it's only for climb.

 

[coloradobluesky]

Top off with oil. For the initial climb, having more cool oil slows down the heating.

Does enrichening actually result in lower oil temps? If so, its a trade I would make. Save the LOP heroics for cruise. Once Im in cruise, I just lean as much as I can, until it runs rough once Im high enough not to be more than 65% power.

If I get high temps in climb, I just go faster, slower climb rate. Additional speed aids cooling.

REally all thos LOP instructions are for turbocharged engines. Now those ARE different!

 

[kgruber]

I'd climb full throttle/2550 RPM (Cessna 185) and start leaning at 3000 DA to maintain EGT at that point. (And, this was long before APS stole my procedure and called it their own)

Climbing at partial throttle is just slow death for an airplane engine.

 

[dans2992]

The issue with LOP climbs in the summer is you'll need to be really lean to keep the temps low enough, by which point you have no climb rate. Unless you have insanely excellent cooling, you likely won't see a benefit.



I would honestly not worry about that oil temperature a bit on your airplane/engine, especially if it's only for climb.

Ok, but to hold that oil temp, I throttled back to 20" MP, 2400 RPM, increased airspeed and was getting 200 fpm.

I just thought there might be a better way.... These OATs are just crazy hot. ATIS was 46 degrees C...

 

[Henning]

So out here in Phoenix, a late afternoon departure means trying to climb while the OAT is about 113-115.

By reducing MP, and slowing the climb quite a bit, I am able to keep CHTs in check. However, the oil temp is hot (ie 230-235).

Would climbing LOP result in better temps? I realize it would slow the climb, but I'm already slowing it quite a bit anyhow to keep temps in check.

I always climb LOP, my temps, CHT and oil, always look good.

 

[dans2992]

I always climb LOP, my temps, CHT and oil, always look good.

Are you flying a turbo? I'm flying NA.

Using the GPH x 14.9 = HP formula for LOP ops, 11.3 GPH is 65% power LOP.

I'm thinking of climbing WOT, max RPM, and doing the "big mixture pull" down to 11gph. As long as I am LOP, and the temps stay fine, the engine is not running rough, does that seem OK? I think it's reasonable to just keep it at 11gph all the way up....

 

[Henning]

Are you flying a turbo? I'm flying NA.

Using the GPH x 14.9 = HP formula for LOP ops, 11.3 GPH is 65% power LOP.

I'm thinking of climbing WOT, max RPM, and doing the "big mixture pull" down to 11gph. As long as I am LOP, and the temps stay fine, the engine is not running rough, does that seem OK? I think it's reasonable to just keep it at 11gph all the way up....

I do with both. For NA I remain WOT and Max RPM for the climb and lean back about 5°LOP around 200' and leave it there for the climb, at the top of the climb I'll pull back the mixture until the engine falls off the pipe and then richen it up to the power surge and leave it there. From there I pull back RPM to make my desired cruise speed. It has to be a really hot day to see CHTs above 340° and my oil always stays in the middle of the green arc.

I gauge my % power LOP by my airspeed.

 

[dans2992]

5 degrees LOP at that altitude/power setting is still in the infamous "red box" isn't it?

 

[Henning]

5 degrees LOP at that altitude/power setting is still in the infamous "red box" isn't it?

Depends on RPM, that's why I stay high RPM. You don't have to worry about charts when you have CHT on every jug. If CHT stays below 370° you're not in trouble. 340-350 and you are about as efficient as it gets making climb power and plenty safe from destructive forces in the combustion chamber.

 

[kgruber]

Thanks, but I'll stay well ROP in climb on a hot day. I don't want to waste away down at low altitude with low power trying to get to a comfortable cruise temperature.


Put the power to it and get the hell out of hell.

 

[Henning]

Thanks, but I'll stay well ROP in climb on a hot day. I don't want to waste away down at low altitude with low power trying to get to a comfortable cruise temperature.


Put the power to it and get the hell out of hell.

I'm not at low power, I'm just not wasting fuel and loading up my valves, rings, and combustion chamber with carbon. I might pick up a small bit of ROC going ROP from 5° LOP, but nothing significant when it comes to time taken to get to cooler air. If you reduce your RPM any from redline, I'm making more power than you.

 

[kgruber]

If you reduce your RPM any from redline, I'm making more power than you.

No. You are not. 2850 is limited to 5 minutes. I rarely use it even for takeoff because of the noise and it's not needed when cold.

I'll have at least 30HP over your LOP at 2700.

And, my engines are always spotless. Don't give me that LOP mantra, I was GAMI customer #19, and know when and how to use it. Climbing out of the hot soup is NOT one of those times.

 

[dans2992]

So, it does not yield lower CHT/oil temp than full rich then...?

 

[kgruber]

So, it does not yield lower CHT/oil temp than full rich then...?

Yes, but only because LOP is making less HP.

It is Okay to use the HP you want/need for the conditions. You don't have to go everywhere LOP, just use it to your advantage.

Remember, flat engines were run for decades ROP, without problems.

Hell, even John Deakin had to replace all Bonanza cylinders at 600 or 800 hrs.....I forget. He doesn't mention that very often.

 

[Let'sgoflying!]

what grade of oil is available to your engine, which are you using
-I wonder ifn't it might affect temps

 

[Ted]

Ok, but to hold that oil temp, I throttled back to 20" MP, 2400 RPM, increased airspeed and was getting 200 fpm.

I just thought there might be a better way.... These OATs are just crazy hot. ATIS was 46 degrees C...

At that power setting you're just not very efficient, hence poor performance and high OAT. I'd just keep it below redline and use a full rich/climb power setting with a cruise climb airspeed. Temps will be high, that's fine.

 

[dans2992]

At that power setting you're just not very efficient, hence poor performance and high OAT. I'd just keep it below redline and use a full rich/climb power setting with a cruise climb airspeed. Temps will be high, that's fine.

That's what I did on the flight today, and I was able to maintain 400 fpm or so while keeping CHTs < 400 and oil temp below 235....

 

[James331]

Thanks, but I'll stay well ROP in climb on a hot day. I don't want to waste away down at low altitude with low power trying to get to a comfortable cruise temperature.


Put the power to it and get the hell out of hell.

That.