Which is the right RPM

[Bob - S50]

2 hours ago, NicoN said:

And indeed, the difference with a lowRPM/HighMAP vs HighRPM/lowMAP was having lower CHT (about 15°) and nearly no speed penalty with the lowRPM variant.

The engine felt a little quieter,. Of course, I do not expect good climb rates with this setting. And also, i should try the same in much higher altitudes

"Nearly no speed penalty" implies you lost a little speed with the lower RPM/higher MP.  That means you were comparing apples with oranges.  Unless the speed was the same then the engine was not producing the same amount of power.  Less power means lower CHT.  You could do the same thing by leaving the RPM where it was and pull the throttle back to reduce MP to get to the same reduced speed.  If you did that, the CHT would also be lower, maybe even lower than what you saw.

[Marcopolo]

21 hours ago, gsxrpilot said:

FL260 is the highest altitude I've been to, but I was still at 100% power when reaching FL260. 

Holy Crap, with my manually controlled waste gate (360-GB), I am only able to keep 100% power to just above 16k, I can maintain >SL MAP to just over FL230.  Your turbo can keep 36" of MAP all the way to FL260?

[NicoN]

Wooow!

What is the max. Altitde for a M20K?

My personal record is only FL140

Do you need to pay special attention to the engine at that altitude? Of course oxygen is needed

[gsxrpilot]

30 minutes ago, Marcopolo said:

Holy Crap, with my manually controlled waste gate (360-GB), I am only able to keep 100% power to just above 16k, I can maintain >SL MAP to just over FL230.  Your turbo can keep 36" of MAP all the way to FL260?

Yep. 36", 2700 RPM, 26gph all the way up.

[gsxrpilot]

3 minutes ago, NicoN said:

Wooow!

What is the max. Altitde for a M20K?

My personal record is only FL140

Do you need to pay special attention to the engine at that altitude? Of course oxygen is needed

FL280. I pay very close attention to lots of things up there. The handling feels a bit different. It feels just a touch "mushy" to me. O2 is critical. I have a whole regimen that I follow with several backup options for O2. The thin air doesn't carry away heat very well, so even though the OAT will be -20 or so, I have to keep the cowl flaps 1/4 to 1/2 open to keep the CHT's under 380.

The benefits are speed - 206 knots TAS running 14 gph ROP or 195 knots TAS at 9.5 gph LOP.  This leads to some unbelievable range. Safety from the glide range. In the event of an engine out, anything within 50 miles is within glide range. Of course the flip side of that is that it takes a long time to get down even in an emergency descent. 

It's also quiet, the think air doesn't carry sound very well. And you've got the airspace to yourself. The heavy iron is 10,000 ft above you and 90% of GA is 10,000 ft or more, below you.

It's not for everyone, but I enjoy flying high, far, and fast in my little Mooney.

[rbridges]

11 minutes ago, gsxrpilot said:

The benefits are speed - 206 knots TAS running 14 gph ROP or 195 knots TAS at 9.5 gph LOP.  

That's crazy!

[Marcopolo]

26 minutes ago, gsxrpilot said:

It's not for everyone, but I enjoy flying high, far, and fast in my little Mooney.

 

By far the best photo of you that's been posted to date. 

[rbridges]

13 minutes ago, Marcopolo said:

 

By far the best photo of you that's been posted to date. 

I didn't know that was Paul.  I thought it was Bane looking for Batman.

 

[Hank]

49 minutes ago, gsxrpilot said:

 

I bet my friends at www.zenni.com could make some sunglasses that will fit over your Darth Vader mask . . . . I like their product, and love their prices!

[Bob - S50]

1 hour ago, gsxrpilot said:

FL280. I pay very close attention to lots of things up there. The handling feels a bit different. It feels just a touch "mushy" to me. O2 is critical. I have a whole regimen that I follow with several backup options for O2. The thin air doesn't carry away heat very well, so even though the OAT will be -20 or so, I have to keep the cowl flaps 1/4 to 1/2 open to keep the CHT's under 380.

The benefits are speed - 206 knots TAS running 14 gph ROP or 195 knots TAS at 9.5 gph LOP.  This leads to some unbelievable range. Safety from the glide range. In the event of an engine out, anything within 50 miles is within glide range. Of course the flip side of that is that it takes a long time to get down even in an emergency descent. 

It's also quiet, the think air doesn't carry sound very well. And you've got the airspace to yourself. The heavy iron is 10,000 ft above you and 90% of GA is 10,000 ft or more, below you.

It's not for everyone, but I enjoy flying high, far, and fast in my little Mooney.

Just be careful up there.  In the Air Force we were not supposed to fly above FL250 in an unpressurized aircraft.  Doing so put us at greater risk of developing the bends (or other less common decompression ailments).  Yes, like the bends against which scuba divers have to be careful.

[gsxrpilot]

14 minutes ago, Bob - S50 said:

Just be careful up there.  In the Air Force we were not supposed to fly above FL250 in an unpressurized aircraft.  Doing so put us at greater risk of developing the bends (or other less common decompression ailments).  Yes, like the bends against which scuba divers have to be careful.

Yes, always careful. And as I've said, it's not for everyone. For me it's enjoyable, safe, and comfortable.

[Danb]

Paul it looks like your CO2 meter is just above your right ear looks like a great place, how do you have it attached

[gsxrpilot]

26 minutes ago, Danb said:

Paul it looks like your CO2 meter is just above your right ear looks like a great place, how do you have it attached

It's a GoPro mount. In this case I used the box top that every GoPro is attached to in its box when you buy it. I pulled two screws that were holding on the headliner and ran them through the mount and back into their holes. The clip on the SensorCon slides into a GoPro mount like it was made for it. 

[PaulM]

 

2 minutes ago, gsxrpilot said:

Paul it looks like your CO2 meter is just above your right ear

I'm trying to find a 3d printed form of the telex microphone (100TRA), or an old just microphone  so that I can mount the CO (Carbon Monoxide) sensor on the left of the pilot. 

 

[McMooney]

i see a k in my future, sigh

[Fly Boomer]

11 hours ago, McMooney said:

i see a k in my future, sigh

To get the numbers that Paul gets, you probably need a 252 or Encore.  The ceiling for the 231 is much lower, cowl flaps are different -- quite a few differences.

[Pinecone]

On 2/9/2019 at 1:13 PM, Bob - S50 said:

I think the best RPM depends on your:

1.  Magneto timing.  A engine that is timed at 25 BTDC probably needs to run at a higher RPM than one that is timed at 20 BTDC.

2.  Propeller length.  Longer propellers need to run at lower RPM to get maximum efficiency.

3.  MP.  Higher MP requires higher RPM.  For example, you wouldn't want to run your engine at 30" and 2000 RPM.  That would exceed engine design limits.  For a normally aspirated engine, while it is OK to run a little over square (maybe a couple inches) you don't want to be too much over square.

4.  TAS.  Higher true airspeed requires a higher RPM to obtain maximum prop efficiency.  As noted, higher RPM causes higher friction loss, but it offset somewhat by higher prop efficiency.

I'm a bit surprised by your findings.  I've found that when my -A3B6D engine CHT is high, I can usually drop it by 5 or 10 degrees by increasing the RPM by 100.

1) Agree

2) Agree

3)  There are no magic numbers WRT relationship of MP and RPM.  My POH lists a power setting of 2200 RPM and 34.8 inches MP.  

4)  That depends on the design of the prop.

Lower RPM is also more fuel efficient as the time from combustion to exhaust valve opening is longer.  

[Pinecone]

6 hours ago, Fly Boomer said:

To get the numbers that Paul gets, you probably need a 252 or Encore.  The ceiling for the 231 is much lower, cowl flaps are different -- quite a few differences.

252 ONLY.  Encore is limited to FL240.

As I heard it, the marketing people wanted to call the plane the 252, and it took flying at FL280 to get 252 MPH TAS, so that became max altitude.

[Marc_B]

17 hours ago, McMooney said:

i see a k in my future

I think Paul has probably convinced...er educated many pilots of the virtues and excellence of the 252/Encore!  I know he was a huge push for me and the Mooney I got lucky to find!

[Fly Boomer]

2 hours ago, Pinecone said:

As I heard it, the marketing people wanted to call the plane the 252, and it took flying at FL280 to get 252 MPH TAS, so that became max altitude.

That's what Bob Kromer said at a MooneyMax a few years ago.  Also said he would never go that high again in a non-pressurized single.

[McMooney]

> 1000 nm and  teens to low twenties is what excites me, i'm probably thinking a 231 eventually.  currently i fly > 8k just to avoid other traffic,  so nice to be able to just sit back and relax

[Hank]

1 hour ago, McMooney said:

currently i fly > 8k just to avoid other traffic,  so nice to be able to just sit back and relax

Me, too. I travel at 7500--10,000 msl. Turbo is not needed, I just climb slowly in the summer when loaded heavy.