Mooney 231 Slow Climbout

[natdm]

I've got a Mooney 231 with wastegate/intercooler and am struggling with climb-out. On take-off, I've got MP at 36" (indicated, not adjusted for power settings), full rich, prop forward, trim in the middle, and flaps set for take-off. FF indicates about 22.5-22.9. I've been told that's low, but my mechanic has repeatedly stated it's not low and I might need to be going higher than 36" with power corrections.

I'm in AZ, and the heat is around 85-100f when I fly, depending on time of day. On rotate, it takes a significant amount of time to reach a good climb-out at vy. I'll maintain vy, but be damn near in ground-effect until the end of a 3000ft runway MAYBE maintaining a 200fpm climb. Eventually, the plane tends to shoot up pretty quickly, around 800-1000fpm. 

Load is not the issue. With full tanks and two adults around 180lb, plenty of load left. 

Is this just a characteristic of the plane? If I up the MP to higher than 36-37", it tends to do a little better, but I'm always terrified of running it too rough.

 

[Tom 4536]

29 minutes ago, natdm said:

I've got a Mooney 231 with wastegate/intercooler and am struggling with climb-out. On take-off, I've got MP at 36" (indicated, not adjusted for power settings), full rich, prop forward, trim in the middle, and flaps set for take-off. FF indicates about 22.5-22.9. I've been told that's low, but my mechanic has repeatedly stated it's not low and I might need to be going higher than 36" with power corrections.

I'm in AZ, and the heat is around 85-100f when I fly, depending on time of day. On rotate, it takes a significant amount of time to reach a good climb-out at vy. I'll maintain vy, but be damn near in ground-effect until the end of a 3000ft runway MAYBE maintaining a 200fpm climb. Eventually, the plane tends to shoot up pretty quickly, around 800-1000fpm. 

Load is not the issue. With full tanks and two adults around 180lb, plenty of load left. 

Is this just a characteristic of the plane? If I up the MP to higher than 36-37", it tends to do a little better, but I'm always terrified of running it too rough.

 

Frank at Chandler Aviation, (MSC in Chandler, AZ), set my FF to 25.5GPH at 36MP, 2700RPM. My 231 has the intercooler & Merlyn. At OAT of 80-100F, my climb rate is about 800-1100FPM. This FF keeps the temps down while climbing.

My FF’s had been messed up by another shop during an annual and Frank was the only person who could get the FF correct so the engine ran properly.

[natdm]

Funny, Frank is the one that adjusts mine and won't put it higher. 

 

Edit for clarity: He's shown me that with the power settings provided by the POH, it might not need to be higher. Funny that he adjusted yours though. Mine used to overheat but now it doesn't overheat on those summer days, so it might be fine as far as FF is concerned.

Edited September 20, 2022 by natdm

[natdm]

@Tom 4536 any specs on that take-off? How soon do you achieve that climb rate? Mine takes a good long time, and then suddenly picks up pretty fast. Maybe I should pay you for a flight some time so I can see the difference, sounds like we have the same setup.

[M20F]

https://twincessna.org/wp-content/uploads/2022/03/SID97-3G.pdf
 
Fuel flow seems low to me.  

[natdm]

@M20F @Tom 4536 - Called Chandler AV and Frank had the cowling off, going to add another gallon/hour, after we talked. 

 

When you guys say 36"MP, is that after the adjustment for the turboplus? I'm told I should be reading the turboplus adjustment for 40", and calculating for OAT/differential. 36" isn't the "real readline", since it's dynamic. When you guys say 36", is that indicated, or is that adjusted?

 

Also, the low fuel flow doesn't have anything to do with my climb-out issue, right?

[M20F]

15 minutes ago, natdm said:

@M20F @Tom 4536 - Called Chandler AV and Frank had the cowling off, going to add another gallon/hour, after we talked. 

Also, the low fuel flow doesn't have anything to do with my climb-out issue, right?

Frank should be following the document I linked, which covers how to correctly set fuel flow.  

Fuel makes planes go.  That is why LOP is slower then ROP at same power settings.   
 

[Tom 4536]

23 minutes ago, natdm said:

@Tom 4536 any specs on that take-off? How soon do you achieve that climb rate? Mine takes a good long time, and then suddenly picks up pretty fast. Maybe I should pay you for a flight some time so I can see the difference, sounds like we have the same setup.

I looked at some data logged on an early morning when OAT was 20C, MP was 36, 2700RPM, FF was 25.4. At 100ft AGL, VS was 403fpm. At 200ft AGL, VS was 840fpm. At 500ft AGL, VS was 1110fpm.  This was with 72 gal fuel, take off weight was 2723lb.

I have a recent flight at 95F, but I have not downloaded the data yet. If you need that data, I can try to download it later this week. 

Also, at my last annual in May, Frank adjusted the FF up from 24.5 to 25.5. He felt it was necessary. It runs cooler on climb.

[A64Pilot]

From what I’m hearing is the airplanes initial climb rate is slow, then he gets a decent climb rate.

‘First question I have is, is the indicated airspeed constant, or is it higher when it starts climbing well?

IF MP and FF and RPM are the same when it’s not climbing well and when it is climbing well, it’s not an engine power issue, cause same MP, FF and RPM will produce the same HP.

[Tom 4536]

30 minutes ago, natdm said:

@M20F @Tom 4536 - Called Chandler AV and Frank had the cowling off, going to add another gallon/hour, after we talked. 

 

When you guys say 36"MP, is that after the adjustment for the turboplus? I'm told I should be reading the turboplus adjustment for 40", and calculating for OAT/differential. 36" isn't the "real readline", since it's dynamic. When you guys say 36", is that indicated, or is that adjusted?

 

Also, the low fuel flow doesn't have anything to do with my climb-out issue, right?

That is what I read on the MP gauge.

[natdm]

53 minutes ago, A64Pilot said:

From what I’m hearing is the airplanes initial climb rate is slow, then he gets a decent climb rate.

‘First question I have is, is the indicated airspeed constant, or is it higher when it starts climbing well?

IF MP and FF and RPM are the same when it’s not climbing well and when it is climbing well, it’s not an engine power issue, cause same MP, FF and RPM will produce the same HP.

I'll see what I can do to maybe film it on the next trip, but from what I can tell, speed does not stay consistent. I stay at vy for a little while, and the climb rate is 200fpm, then it shoots way up, with the same vy (or even faster!). 

[Will.iam]

If your 231 doesn’t have an intercooler then 40” for takeoff. I have a 252 that has a factory inter cooler and my redline is 36” mp so if you have a intercooler then 36” should be your limit. The encore which is the same engine with intercooler but they turn up the boost to 39” and that gets 220 hp in that engine. But key is to have enough ff to keep your cylinders from rising above 400 degrees cht. I have my ff set at 24.7 at takeoff. Used to be 23 and it was too hot for the engine. 100 degrees makes my plane climb like a dog too. If this is your first year of ownership wait to see what you get when it’s closer to 60 degrees on takeoff then you will know how much that heat is effecting you. It can be significant as it effectively raises your density altitude to much higher than actual. 

[natdm]

Thanks @Will.iam. It's intercooler'd, so 36" is what I aim for. It's my first year but if my friends M20C climbs a hell of a lot faster than mine, in the same weather, I get confused. I get that it's lighter, but also less power.

[A64Pilot]

1 hour ago, natdm said:

I'll see what I can do to maybe film it on the next trip, but from what I can tell, speed does not stay consistent. I stay at vy for a little while, and the climb rate is 200fpm, then it shoots way up, with the same vy (or even faster!). 

Right, what’s going on then is at the beginning your behind the power curve, the infamous region of reversed command, once you speed up the aircraft performs better.

I’d say let her stay on the ground a little longer and or stay down lower and accelerate before you begin your climb.

This is written by an Ag guy for Ag pilots, but it still applies.

https://agairupdate.com/2021/10/02/the-region-of-reversed-command/

[A64Pilot]

Guys your getting all wrapped up about MP, maybe his MP and power is low, but that doesn’t explain how at the same power setting he’s climbing at 200 FPM but then a little later without increasing power / MP he’s now climbing at 1,000 FPM.

[Will.iam]

2 hours ago, natdm said:

Thanks @Will.iam. It's intercooler'd, so 36" is what I aim for. It's my first year but if my friends M20C climbs a hell of a lot faster than mine, in the same weather, I get confused. I get that it's lighter, but also less power.

I have 201 pilots that climb faster than i do and they are always  commenting on that. I don’t catch up until about 8000ft and then every 1000 higher i get faster while they get slower. Your speed is in the altitude as our power to weight ratio is lower than non turbos. 

[A64Pilot]

Yes, but he’s saying his climb rate more than doubles in 200’, from 400FPM to over 1100FPM. During that short time his MP, RPM and fuel flow is constant, or I’m misreading his post.

[Fly Boomer]

1 hour ago, A64Pilot said:

Yes, but he’s saying his climb rate more than doubles in 200’, from 400FPM to over 1100FPM. During that short time his MP, RPM and fuel flow is constant, or I’m misreading his post.

I think you have it.  Sounds like he’s pulling it off too soon and/or not allowing it to accelerate in ground effect.

[Hank]

3 hours ago, A64Pilot said:

Yes, but he’s saying his climb rate more than doubles in 200’, from 400FPM to over 1100FPM. During that short time his MP, RPM and fuel flow is constant, or I’m misreading his post.

It's all about airspeed . . . . How fast when he lifts off? How fast at 400 fpm, how fast at 1100 fpm? My own climb rate increases significantly from rotation through Vx for obstacles [uphill portion of the runway] to Vy, and by 300' agl I'm climbing good. But up until then, ROC is increasing as my speed increases.

[A64Pilot]

All I’m saying is if he’s climbing at 1100 FPM by the time he gets through 400 AGL it doesn’t sound like an engine problem to me.

[Parker_Woodruff]

Are you registering this supposed 200'/min climb rate through the VSI?  There is a lag in that instrument.  How high above the ground are you at the end of that 3000' runway?

[Hank]

1 minute ago, Parker_Woodruff said:

Are you registering this supposed 200'/min climb rate through the VSI?  There is a lag in that instrument.  How high above the ground are you at the end of that 3000' runway?

Just one more thing to love about my IVSI!    No idea what the OP is using. But yes, I use the IVSI to see what my actual climb rate is. How else do you tell?

[larryb]

My Encore really does not like to climb until I get to 90kt.  So between liftoff and 90 I'll be climbing very slowly while accelerating to 90. It also takes me close to 3000 feet for takeoff and acceleration. My previous J model, significantly lighter, had a better initial climb. 

 

Looking at your TIT should tell you if your FF is adequate on takeoff. I use 1375 as a target. 

[1980Mooney]

On 9/20/2022 at 12:07 PM, natdm said:

@M20F @Tom 4536 - Called Chandler AV and Frank had the cowling off, going to add another gallon/hour, after we talked. 

When you guys say 36"MP, is that after the adjustment for the turboplus? I'm told I should be reading the turboplus adjustment for 40", and calculating for OAT/differential. 36" isn't the "real readline", since it's dynamic. When you guys say 36", is that indicated, or is that adjusted?

Also, the low fuel flow doesn't have anything to do with my climb-out issue, right?

I don't fly a turbo but just looking at your flight history on long flights above 10,000 ft your plane seems slow for a K with waste gate and intercooler.  And is there a typo in your N number in your profile? - are you N226C? 

Do you fly LOP?  Are you sure your engine is making full power?

[Bolter]

On 9/20/2022 at 10:29 AM, M20F said:

Fuel makes planes go.  That is why LOP is slower then ROP at same power settings.   
 

What do you mean by "power settings"?  Actual power, or you just mean same manifold and RPM settings, with a different mixture (ROP or LOP)?  For the same MP and RPM, a LOP mixture is less power than the ROP mixture, so it is not the same POWER.