Constant speed prop question

jd21476

jd21476

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jd21476
Let’s say you were flying at 4000’ and wanted to climb to 5000’. Your flying 21 MP and 2200 rpm. What would you do with your power?

Leave it and climb?

Increase just your RPM?

Increase both MP and RPM?

or something else
 
How fast do you want to climb? And how does that relate to the reasons you selected the power settings you did?
 
It depends. If I have a passenger who isn’t really comfortable in small planes yet, increase RPM and add power gradually to climb at about 700 FPM. If it’s just me or my wife is in the back seat, balls to the wall and pitch for Vy. We’ll be there in 20 seconds.
 
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jd21476 said:
Let’s say you were flying at 4000’ and wanted to climb to 5000’. Your flying 21 MP and 2200 rpm. What would you do with your power?

Leave it and climb?

Increase just your RPM?

Increase both MP and RPM?

or something else
Click to expand...
How fast do you want get up there? Do you want to maintain your airspeed? 4000 to 5000 sounds like your IFR. There are rate and speed parameters you’re supposed to comply with. What airplane are you flying?
 
1000’ isn’t much, check your Climb checklist. Usually 25”/2500rpm but you won’t product 25” of power at altitude anyway.
 
I would push MP pressure up first, then RPM (well, actually mixture first, but you know what I mean). I usually cruise at 65% power and will go to 75% to climb. Usually I'm running WOT and bring rpm down to reduce power to 65. My power chart goes down to 2100, which will do the trick at all but the lowest altitudes. Because I'm already WOT, rpm is the only way to bring the power up.

For a 1000' climb though, if I'm already at cruise speed, I'll often just raise the nose a little and not touch the engine. Doesn't take long to gain that much.
 
jd21476 said:
Let’s say you were flying at 4000’ and wanted to climb to 5000’. Your flying 21 MP and 2200 rpm. What would you do with your power?

Leave it and climb?

Increase just your RPM?

Increase both MP and RPM?

or something else
Click to expand...

Typically, once I settle in cruise, I don't touch the rpm until on final approach.
 
Jim K said:
I would push MP pressure up first, then RPM (well, actually mixture first, but you know what I mean). I usually cruise at 65% power and will go to 75% to climb. Usually I'm running WOT and bring rpm down to reduce power to 65. My power chart goes down to 2100, which will do the trick at all but the lowest altitudes. Because I'm already WOT, rpm is the only way to bring the power up.

For a 1000' climb though, if I'm already at cruise speed, I'll often just raise the nose a little and not touch the engine. Doesn't take long to gain that much.
Click to expand...
When you do that in your plane, leave the engine/prop alone and just pull the stick back, how much of a change in airspeed do you get? And about what rate of Climb?
 
luvflyin said:
When you do that in your plane, leave the engine/prop alone and just pull the stick back, how much of a change in airspeed do you get? And about what rate of Climb?
Click to expand...
Depends how hard you pull ;)

TBH I don't really know; I just haven't paid much attention to the numbers. Cruising at 150 knots, pitch up maybe 5 degrees or so, speed bleeds of to 110-120ish, Climb rate will hit 1000fpm initially, then slow down as speed bleeds off, settling at maybe 500? Doesn't take long to gain 1000'.

Pretty rare to climb just 1k though. Usually it's going to be 2k to the next cruising altitude. For that I'd do the same WRT pitch, and also give her a little gas and bump the power to 75%, which in most circumstances will entail increasing rpm as the throttle is already fully open.
 
sarangan said:
Typically, once I settle in cruise, I don't touch the rpm until on final approach.
Click to expand...

This, except I never cruise at such a low altitude…6500 is my minimum :(usually higher) because I always cruise at WOT and it’s usually smoother at a higher altitude.
 
With my 252 (turbo) if the climb is more than 1000 feet, I go full rich, full RPM, full throttle, in that order. I want to CLIMB.

But that is my initial climb to altitude also.

NA, I would be at WOT if sufficient altitude, so would go richer, then increase RPM some to full
 
jd21476 said:
Let’s say you were flying at 4000’ and wanted to climb to 5000’. Your flying 21 MP and 2200 rpm. What would you do with your power?

Leave it and climb?

Increase just your RPM?

Increase both MP and RPM?
Click to expand...

What kind of airplane am I flying? That matters.

But, I also have the urge to answer questions with questions today. "I have a question about flying a fixed-pitch prop airplane. Let's say I want to climb from 4,000 to 5,000. I'm flying at 2200 RPM. What should I do with my power?"

You have a choice to increase power and climb at a better rate with a quicker acceleration back to cruise speed, or leave power as-is and take the hit in airspeed and wait forever to get back up to cruise speed. Or, something in between, though I'm not sure what the point of that would be.

In my Mooney, I'm probably going to enrichen mixture to a climb setting (I have a gauge for that!), then prop to climb RPM, then throttle to wide open if it's not already there. Level out at 5,000, accelerate back to cruise speed, set cruise power and mixture.

That said, for less than a thousand foot climb I probably wouldn't bother.

Jim K said:
I would push MP pressure up first, then RPM (well, actually mixture first, but you know what I mean).
Click to expand...

MP first?? o_O:nono:
 
Rgbeard said:
On my plane, 25"/2300 RPM is an acceptable 65% combination.
and 30"/2300RPM is an acceptable 75% combination.

For me to change from 65 to 75%, I can leave the prop alone, and just push MP.

Tell me where this is wrong, please.
Click to expand...

It isn't necessarily wrong, provided your RPM is high enough for the MP you push to. In your case, it looks to be OK.

It's also not the greatest habit to be in if you ever use lower RPM than is acceptable for your max MP, or if you fly multiple different aircraft types, etc...
 
flyingcheesehead said:
In my Mooney, I'm probably going to enrichen mixture to a climb setting (I have a gauge for that!), then prop to climb RPM, then throttle to wide open if it's not already there. Level out at 5,000, accelerate back to cruise speed, set cruise power and mixture.
Click to expand...
This is my generic answer.

But realistically I'm flying in a configuration where I'm already 75% power, so I would just climb and make sure MP or fuel flow does't depart the 75% setting (or MCP).
 
Only 1000’ i’m just pulling the yoke a little and retrimming or adding 3-500 fpm on the VS if the autopilot is flying. If i need to climb a significant amount or quickly it’s cowl flaps open mixture rich rpm 2500 mp 25” or WOT which is where it usually it at altitude anyway.
 
You have a Comanche with an O-540?
Two blade or 3 blade?

With the O540 and 3 blade in the Comanche, I know I can run below a line from with 1800RPM and 23" to 2300 RPM and over 30" and be safe. I also have a full engine monitor and know that I can start leaning as low as 2000MSL in the climb on a 90 degree day without getting my cylinders too hot. So what do I do with the scenario you provided? Touch nothing except the throttle, and increase the power. After reaching the new altitude, I set the power and mixture as desired.

In a different plane/engine/prop combo or if taking the commercial written, the answer may be different.
 
So basically all of you answered my question for the most part. I usually dont touch any power settings and just pitch for maybe 5 degrees nose up but I was flying with an instructor for an initial IFR lesson and he made a comment that I failed to increase RPM for the climb.
 
jd21476 said:
Let’s say you were flying at 4000’ and wanted to climb to 5000’. Your flying 21 MP and 2200 rpm. What would you do with your power?

Leave it and climb?

Increase just your RPM?

Increase both MP and RPM?

or something else
Click to expand...

*You are / you’re

Set climb rate to 500 FPM, bump up MP as needed to maintain desired setting as altitude increases.
 
Too many variables.

In my 310Q, I pull the props back to 2450 when I climb through 700' on take off and I don't touch the props again until I shut the aircraft down. MP goes back to 24" for the cruise climb at 130kts. Climbs above my cruise altitude are done with MP if needed depending on altitude and MP available otherwise I trade airspeed for altitude.
 
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