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exM20K

Full Power Climb

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I didn't want to clog up the Springfield, OH off-field landing thread with this, and I think it's an important topic.

I climb at full power in the Acclaim, and as an APS attendee and reader of the engine manual, I'm convinced that there is no additional engine wear or increased likelihood of catastrophic failure from climbing at full power.  Higher detonation margins and better cooling at full power are undeniably "good" for the engine.

What there is: increased safety.  This incident has been widely written about, and it's a testament to the pilot's airmanship and the importance of climbing at a rate > engine out sink rate.  The prop departed a Malibu on climbout from Aspen.  It doesn't get much worse than that except for maybe being IMC instead of visual.  This pilot was able to maintain control at best glide and return to Aspen.  Amazing.

My Acclaim is just now getting the 310HP STC, and even with only a puny 280HP, this plane will climb, at typical weights, at 1200-1400 FPM.  Class B restrictions notwithstanding, I can well out-climb my glide, meaning passing a safe altitude for the impossible turn happens very quickly.  To me, this is a really important safety of flight feature and well worth a couple AMU's to bump the power and climb rate.

 

-dan

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+1 for the APS class. The best 1 AMU I've spent as an owner.

+1 for altitude as the most important safety commodity. I still don't understand pilots who climb slow with the gear hanging out waiting to use up all the useful runway. Once I'm off the ground I want all the altitude I can get as quickly as I can get it.

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+1 for the APS class. The best 1 AMU I've spent as an owner.
+1 for altitude as the most important safety commodity. I still don't understand pilots who climb slow with the gear hanging out waiting to use up all the useful runway. Once I'm off the ground I want all the altitude I can get as quickly as I can get it.

I totally agree, but some pilots get carried away thinking they need to climb at Vx or Vy when it should be more like your normal Vy+10 to 20 for both safety and engine cooling. Then if you do have a loss of power you actually have a few seconds before stall if you don't recognize it fast enough and push the nose over. Deakin does a good job of explaining this with lots of analysis and show how you can trade off the excess speed to maintain alt as you slow to Vg. https://www.avweb.com/news/features/Climb-Faster-221694-1.html


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I believe if you have even adequate cooling and clean oil distributed throughout the engine it will be able to withstand higher power with minimal engine problems.  

Having said that with the testing I’ve done so far on my C reducing the power to 25 squared drops my cht’s from 390-400 to 365-375.  In the future I’ll be trying 26/2500 to see how the temperatures hold up. I’m climbing at 130 mph and 500-750 fpm.

@exM20K make sure the mechanic bumps your FF. Might need another gal or two to keep things cool on the climb at 2700 although the acclaim has good size air intakes. 

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41 minutes ago, MIm20c said:

I believe if you have even adequate cooling and clean oil distributed throughout the engine it will be able to withstand higher power with minimal engine problems.  

Having said that with the testing I’ve done so far on my C reducing the power to 25 squared drops my cht’s from 390-400 to 365-375.  In the future I’ll be trying 26/2500 to see how the temperatures hold up. I’m climbing at 130 mph and 500-750 fpm.

@exM20K make sure the mechanic bumps your FF. Might need another gal or two to keep things cool on the climb at 2700 although the acclaim has good size air intakes. 

For sure. That's part of the STC. Sadly, there's no free lunch available: more HP=more fuel.

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55 minutes ago, MIm20c said:

make sure the mechanic bumps your FF. Might need another gal or two to keep things cool on the climb at 2700 although the acclaim has good size air intakes. 

Huh!? Gallon or 2? Its actually over 5 more, from a high number of 30.7 GPH to 36.0 GPH, but I'd target it for 37 GPH.

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9 minutes ago, kortopates said:

Huh!? Gallon or 2? Its actually over 5 more, from a high number of 30.7 GPH to 36.0 GPH, but I'd target it for 37 GPH.

I was implying a gallon or two above the stc’d amount which made a massive difference for a plane I was a safety pilot for. 

However, as I really appreciate and trust your guidance, have you found increasing the fuel flow in o-360’s to help with climbout cht’s?  Or is it too hard to get an evenly dispersed fuel mixture?

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I was implying a gallon or two above the stc’d amount which made a massive difference for a plane I was a safety pilot for. 
However, as I really appreciate and trust your guidance, have you found increasing the fuel flow in o-360’s to help with climbout cht’s?  Or is it too hard to get an evenly dispersed fuel mixture?

I was teasing you about the gallon or two :)
But to answer your question - that would be nice but the carburetor is not adjustable short of putting an unapproved different jet in.
Usually the bigger problem is just terrible mixture distribution.


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-dan,

to add to your discussion...

adding the 310hp comes with great benefits...

The STC seems to possibly have a small limitation.  The fuel flow they recommend is probably 27.2 gph...

You May want to do some research to see what others are using.  I have read from 1-3 gph more.... the added Fuel helps keep the CHTs in better control during the wild power generation stage....

Best regards,

-a-

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6 hours ago, carusoam said:

-dan,

to add to your discussion...

adding the 310hp comes with great benefits...

The STC seems to possibly have a small limitation.  The fuel flow they recommend is probably 27.2 gph...

You May want to do some research to see what others are using.  I have read from 1-3 gph more.... the added Fuel helps keep the CHTs in better control during the wild power generation stage....

Best regards,

-a-

Ovation or Acclaim?

Clarence

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37 minutes ago, M20Doc said:

Ovation or Acclaim?

Clarence

I think from what @kortopates said in a previous post 29gph is the sweet spot for the 310 ovation and 37gph for the 310 acclaim.  It’s interesting to me that the same hp engine with TN and a lot larger air intake would need that much extra fuel. I’d imagine the 15-25k is where the extra fuel is needed?

@exM20K Do you find the engine temps currently stay the same from 500-20k?  I’ve noticed a fair amount of acclaim’s for sale with top overhauls in the 500-800 hr range. Fuel flow set too low?

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I have the 310 upgrade and Don Maxwell set it at 30.7 or so.  He said it was set too low previously, maybe not to the STC but as someone mentioned the STC might be flawed.

Right now I have cool CHT's in climbout, number escapes me, but way lower than redline.  I also climb at high airspeed as well, 120-130 KIAS.  Since the adjustment I have never had CHT running hot, previously on a hot summer day it would get a lot closer to the redline.

I am content with the higher fuel flow number if it keeps things cool.     

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I am the same as Paul and Paul.  Full power climb, although once l get a couple of thousand feet I generally settle in to a 500 fpm climb to altitude, still full power full rich though.  I fly out of Class B airspace and even when IFR it is not normal to get more than 3 or 4,000 until out from under the B.  

There was a great article in AOPA magazine a few years ago about the impossible turn.  Their recommendation was not to use Vx or Vy, but to use a speed around best glide until you have reached the altitude at which you could successfully make the turn.  Best glide in my aircraft is 81-85 depending on gross weight, I use 85 as my climb speed.  Works good.  Vx is not particularly good because if you have an engine out you are too close to stall.  Vy takes too long to get to "turn altitude."  Thankfully, I have not had a chance to make the turn.  The article recommends going out, getting some altitude, and practicing the turn so you know how much altitude you need.  Get in a climb out attitude, pull the power, wait three seconds (because it takes a human pilot that long to figure out what is happening and react), make the turn and see how much altitude you lose.  Remember it is a steep 270.  Find a waypoint to use as your virtual runway and see how much altitude it would take to get back to that point.  I use 1000 feet, I could probably make 900.

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12 hours ago, MIm20c said:

@exM20KHaving said that with the testing I’ve done so far on my C reducing the power to 25 squared drops my cht’s from 390-400 to 365-375.  In the future I’ll be trying 26/2500 to see how the temperatures hold up. I’m climbing at 130 mph and 500-750 fpm.

Unless your POH says you cannot operate continuously at 2700 RPM, if you are wanting to cool the CHT's but increase your climb power, I think you would be better served by increasing the RPM rather than the MP.  Increasing the RPM will move the peak pressure further past TDC which should reduce CHT's.  That is, rather than trying 26/2500, I'd try 25/2600 or 25/2700.

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3 hours ago, MIm20c said:

I think from what @kortopates said in a previous post 29gph is the sweet spot for the 310 ovation and 37gph for the 310 acclaim.  It’s interesting to me that the same hp engine with TN and a lot larger air intake would need that much extra fuel. I’d imagine the 15-25k is where the extra fuel is needed?

@exM20K Do you find the engine temps currently stay the same from 500-20k?  I’ve noticed a fair amount of acclaim’s for sale with top overhauls in the 500-800 hr range. Fuel flow set too low?

280HP runs 30.5GPH in the TSIO550 / M20TN.

I haven't flown with the 310HP yet, and I don't have the POH supplement with me, but I believe it's set up for 33 or 34 -36 GPH at full power.  

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3 minutes ago, exM20K said:

280HP runs 30.5GPH in the TSIO550 / M20TN.

I haven't flown with the 310HP yet, and I don't have the POH supplement with me, but I believe it's set up for 33 or 34 -36 GPH at full power.  

I would not leave the shop until the 37 mentioned above is set. The difference between 27.2 and 29.2 for the NA version is 375 vs 400+. 

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3 hours ago, MIm20c said:

....for the 310 acclaim.  It’s interesting to me that the same hp engine with TN...

Mainly because there is nothing turbo normalized about the Acclaim, despite how Mooney marketed it as such. That is the biggest misunderstood myth about the Acclaim, what Mooney did was take the TSIO-550-G and de-rate down from 310HP to 280HP because they didn't need the full 310HP to claim the fastest single piston and management at the time thought 310HP was too much for the Mooney tail without beefing it up. Then to remove some of the stigma of a hot burning turbo, rather than call it for what it was, the marketing folks miss-represented it as turbo normalized because they felt that would help sell a cooler running engine after the Bravo's reputation for running hot and justified it by saying the maximum continuous MAP was only a little over sea level pressure. But the engine is a full fire breathing turbocharged TSIO-550-G  complete with dual turbochargers and intercoolers using turbo 7.5:1 pistons. In contrast a TN engine begins with a non turbocharged engine with 8.5:1 pistons and then the turbocharging system is added on with redline MAP limited to sea level. 

All the STC did was return it to it full 310HP setup, but since this wasn't originally done by Mooney, they needed to get an STC approval. I guess you could add they proved the tail really wasn't too small too. Mooney later bought the STC but as the airframe manufacturer they don't need an STC. They probably just didn't want someone else profiting off of their design and short sighted HP limitation given the popularity of the mod. 

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3 hours ago, Mark89114 said:

I have the 310 upgrade and Don Maxwell set it at 30.7 or so.  He said it was set too low previously, maybe not to the STC but as someone mentioned the STC might be flawed.

Right now I have cool CHT's in climbout, number escapes me, but way lower than redline.  I also climb at high airspeed as well, 120-130 KIAS.  Since the adjustment I have never had CHT running hot, previously on a hot summer day it would get a lot closer to the redline.

I am content with the higher fuel flow number if it keeps things cool.     

Now that is interesting. My AP-IA all but refuses to set it for more than 26.5gph, claiming that is what the STC and TCM give as the target number. Maybe I should look for a nearby shop willing to make that adjustment.

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22 minutes ago, Robert C. said:

Now that is interesting. My AP-IA all but refuses to set it for more than 26.5gph, claiming that is what the STC and TCM give as the target number. Maybe I should look for a nearby shop willing to make that adjustment.

Your guy is limiting it to the middle of TCM's range of 25.6 - 27.3 and isn't even willing to set it to their high number of 27.3 GPH. I can understood why some A&P's are reluctant to set it above, and its true that if some one gets carried away adding too much fuel its reducing its max HP output. But especially with these high HP engines the need to keep it cool in climb easily trumps a couple horsepower. You'll find those that really know engines will target a max FF from 0.5 to 1.5 GPH over TCM's high number for the engine with some going beyond that. For example, when RAM does their overhaul for the TSIO-520-N & -NB's for the 340's and 314's they raise the FF from Continentals high number of 31.7 GPH to 36.0 GPH! 

Edited by kortopates
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1 hour ago, MIm20c said:

I would not leave the shop until the 37 mentioned above is set. The difference between 27.2 and 29.2 for the NA version is 375 vs 400+. 

ok - but these are not the same engine.  Attached is a screen shot of the the operator manual.  210# is 36GPH, and that is the high limit

TSIO550G_FF.png

TSIO550G_FF_Limits.png

Edited by exM20K

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11 hours ago, M20Doc said:

Ovation or Acclaim?

Clarence

You got me on that one, Doc...

I was referencing the FF for the 310hp M20R... The STC kinda doesn't set the fuel flow where some people would prefer it...

I brought it up, because I expect the 310hp M20TN to have a similar challenge...

Unfortunately, I didn't realize how much the CR of the TN'd engine really alters the FF...

Is that really 310hp At 2700 rpm using a different CR?

I think the secret cat out of the bag is how much hp is really being produced by either engine...

Best regards,

-a-

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43 minutes ago, carusoam said:

Is that really 310hp At 2700 rpm using a different CR?

I think the secret cat out of the bag is how much hp is really being produced by either engine...

I do believe it’s making 310 but from the statement above it is probably TC’ing at that point. I’m curious what MP the 310hp acclaim is obtaining on full power climb out. 

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1 hour ago, MIm20c said:

I do believe it’s making 310 but from the statement above it is probably TC’ing at that point. I’m curious what MP the 310hp acclaim is obtaining on full power climb out. 

It's in the chart I copied: 34"

 

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By definition(?) 29.92” MP....  no more, or it becomes TC'd and not TN'd...  semantics... (inline with what Paul was saying)

I would need a digital presentation of my MP to know what it actually is...  with resistance to flow, the MP is less than 29.92” on a standard day at SL...

From the STC for the R&S...  Fuel flow @ max power...  150 /160 lbs/hr...   26.666 gph (160 x 6 lbs/gal.)

I don't have a fancy graph like the one posted by @exM20K.... just that one sentence...

Full power climb is WOT and 2700 rpm.... (they don't mention the keep an eye on the CHT part)

I really enjoy MS.  Why else would somebody pull out the STC to read and discuss it...?

Best regards,

-a-

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9 hours ago, MIm20c said:

I would not leave the shop until the 37 mentioned above is set. The difference between 27.2 and 29.2 for the NA version is 375 vs 400+. 

Similar for the Missile.  But at 300 HP not 310 we need 28-28.5 GOH at sea level for proper cylinder temps.

 

-Seth

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