LOP GUY POURS ON THE COAL SURPRIED BY RESULT

[MyNameIsNobody]

So, flew up north with my wife and two dogs Thursday. No weather in forecast, and then when launching saw Weather painted over Twin Cities.   Looked like we were OK, at 7500 feet, but we're only doing about 130 knots.  The usual cloud build up around lacrosse caused me to drop down to 5500. I generally run about 9.5 to 10 gallons an hour. This is  lean of peak. The weather was closing in so I decided to increase fuel flow. Ran 2500 RPM but increased  fuel flow to 12 1/2 gallons per hour. Speed jumped up to 150 knots.  The fuel flow/G3 was showing I was still lean of peak. Just, but still lean of peak. It surprised me.  I never fly at fuel flow  that  High. Drop down to 3500 and reduce fuel flow to 11 1/2 still lean of peak indicated?    Happy ending as we fueled, tied down,  and got back to the cottages  as the weather closed In and winds  really picked up.  Nice to know the old girl can get up and go when needed for an extra gallon an hour. 

Edited September 29, 2017 by MyNameIsNobody

[Ned Gravel]

Scott:

Isn't the red box from 50 LOP to 50 ROP at or below 7500' when you are pulling more than 70% power?

 

[ArtVandelay]

5 minutes ago, Ned Gravel said:

Scott:

Isn't the red box from 50 LOP to 50 ROP at or below 7500' when you are pulling more than 70% power?

 

50 LOP?  Pretty sure its not nearly that much, maybe 15?

[ArtVandelay]

you were not LOP at 5500', 2500 rpm and 12.2 gal...LOP should have been more like 10.2....at least according to J POH.

[MyNameIsNobody]

 I hear yeah   Totally agree. My lean find was still indicating LOP on the G3 at that fuel flow. Weird. It changes color on ROP.  I changed to the HP screen and it gave about 75% if ROP and was below 70 if LOP....Do not ever do this. Beating a storm. Cylinder temps were 300ish. No regrets, but agree I was ROP at that setting. No clue what was going on there. Maybe was not showing color?

[MyNameIsNobody]

1 hour ago, Ned Gravel said:

Scott:

Isn't the red box from 50 LOP to 50 ROP at or below 7500' when you are pulling more than 70% power?

 

No. Red box is 50 ROP to 100 ROP, right?  LOP is not red box. 

[MIm20c]

6 minutes ago, MyNameIsNobody said:

No. Red box is 50 ROP to 100 ROP, right?  LOP is not red box. 

It changes with % power. But 20-50 LOP to 50 ROP is what I’ve heard for 65-75 % power. 

So ideally 50 LOP or jump to 100 ROP for high power settings. 

[MyNameIsNobody]

1 minute ago, MIm20c said:

It changes with % power. But 20-50 LOP to 50 ROP is what I’ve heard for 65-75 % power. 

I do not agree with this. Even at peak not in red box, unless all I have previously red is not accurate. Not a ROP guy so not sure where box is on ROP side. I would love a reference on Peak to LOP being red box. Post it here. All ears and eyes on that.

[MIm20c]

4 minutes ago, MyNameIsNobody said:

I do not agree with this. Even at peak not in red box, unless all I have previously red is not accurate. Not a ROP guy so not sure where box is on ROP side. I would love a reference on Peak to LOP being red box. Post it here. All ears and eyes on that.

I found this LINK helpful, but I’m normally wrong about things 

[MyNameIsNobody]

I just pulled a MB article on red fin. If below 75% power LOP no problem with red box LOP (my normal is 70% or below). At 85% power could be in fin/box LOP. Maybe I was there on that fuel flow at 5500?  Dunno?  Cylinder temps were happy. Beating storm and gaining 20 knots was worth it on this occasion....?  Me thinks yes.

[MyNameIsNobody]

14 minutes ago, MIm20c said:

I found this LINK helpful, but I’m normally wrong about things 

 Funny, that is the same article I just read. Check out figure 5 or page 5. That's where I got my above comments. My manual on my Plane from Mooney shows those fuel flow's at 5000 feet. No Redbox back in those days…

[MyNameIsNobody]

 I  guess  my biggest surprise was gaining 20 knots  by increasing fuel flow 2.5 gallons  

[Emmet]

As long as you are LOP increasing the fuel flow increases power and that increases TAS. No surprise 

I doubt that you have still been LOP at 12.2 - don't trust the E3 especially when you only increased FF and haven't 

redone the leaning procedure.

 

Edited September 30, 2017 by Emmet

[Guest]

9 hours ago, MyNameIsNobody said:

 I  guess  my biggest surprise was gaining 20 knots  by increasing fuel flow 2.5 gallons  

With all planes it takes fuel to go fast.  Mooneys are known for being efficient by starving the engine of fuel.

Clarence

[jetdriven]

I see a lot of people flying too lean of peak. I've found in the IO360 anyway that there isn't any economic reason to lean past ~30ish LOP. Sometimes its best economy is in the 15 LOP range. 

[Bob - S50]

12 hours ago, MyNameIsNobody said:

 I  guess  my biggest surprise was gaining 20 knots  by increasing fuel flow 2.5 gallons  

I doubt the increase in groundspeed was all due to the higher fuel flow.  I suspect most of that came from change in winds.

[KSMooniac]

You cannot be LOP in an IO-360 at 12+ GPH. Simply can't happen.

Sent from my LG-US996 using Tapatalk

[MyNameIsNobody]

5 hours ago, Bob - S50 said:

I doubt the increase in groundspeed was all due to the higher fuel flow.  I suspect most of that came from change in winds.

Nope. Literally gained 20 knots in a minute

[AH-1 Cobra Pilot]

8 hours ago, M20Doc said:

 Mooneys are known for being efficient by starving the engine of fuel.

No, Mooneys are efficient because they have so much less drag than other aircraft.  The very similar airframes all do well with very different sized engines and beat most other aircraft with the same engines.

What everyone needs to understand is that an engine, any engine, is at its highest power when the fuel-air mixture is at the stoichiometric ratio.  This means that the fuel and oxygen in the air both burn completely with no residual of either in the exhaust.  That should be your 'Peak', and LOP will be less fuel, leaving no fuel, but some oxygen, left over in the exhaust.  The worry is that Peak is too hot for long-term engine life.  Could your instruments indicate that Peak is not overheating your engine?  Sure.  Do you want to bet an overhaul on it?...  That is the important question.

The stoichiometric ratio will vary by the fuel you use.  It can even vary slightly between loads of 100LL, but you will probably not notice the difference...maybe from summer blends to winter blends.  Regardless, you correct for it via the mixture knob, and unless you mark it, you will never know any difference.

[ArtVandelay]

4 minutes ago, Ah-1 Cobra Pilot said:

What everyone needs to understand is that an engine, any engine, is at its highest power when the fuel-air mixture is at the stoichiometric ratio.  This means that the fuel and oxygen in the air both burn completely with no residual of either in the exhaust.  That should be your 'Peak', and LOP will be less fuel, leaving no fuel, but some oxygen, left over in the exhaust.  The worry is that Peak is too hot for long-term engine life.  Could your instruments indicate that Peak is not overheating your engine?  Sure.  Do you want to bet an overhaul on it?...  That is the important question.

 

Not quite, actually best power is about 50 ROP, the reason I think is that all the avgas molecules can't react with all the air molecules, so in order to use up all the air you have to have a little excess of fuel.

[M016576]

8 hours ago, jetdriven said:

I see a lot of people flying too lean of peak. I've found in the IO360 anyway that there isn't any economic reason to lean past ~30ish LOP. Sometimes its best economy is in the 15 LOP range. 

I found this to be true as well with my J.

[Bartman]

I've been running LOP for 9 years and at the altitude I fly in my J there has never been a time that I have been more than about 15 LOP, except for GAMI testing and LOP mag testing.  She is still smooth at 50 LOP but its not very efficient and the speed drops off quickly that deep LOP.  The higher I go the less LOP and above about 10,000 in my experience it best to just run as close to peak as possible.  That was before I discovered an intake gasket last week, but had seen effects over last 3 flights.  I am anxious to see how she runs on Monday.

What I have noticed is that if I do not go rich enough and let EGT stabilize, then you can get misleading results and look like you are LOP when you are reallly ROP.

[Bartman]

I have done GPS testing both 3 and 4 direction in smooth air on more than one occasion and confirmed that with just me and 30 gallons of fuel at 8,500ft I will loose an honest 7 Knots from 100 ROP going to 10-15 LOP.  

[Tommy]

On 9/30/2017 at 8:40 AM, MyNameIsNobody said:

So, flew up north with my wife and two dogs Thursday. No weather in forecast, and then when launching saw Weather painted over Twin Cities.   Looked like we were OK, at 7500 feet, but we're only doing about 130 knots.  The usual cloud build up around lacrosse caused me to drop down to 5500. I generally run about 9.5 to 10 gallons an hour. This is  lean of peak. The weather was closing in so I decided to increase fuel flow. Ran 2500 RPM but increased  fuel flow to 12 1/2 gallons per hour. Speed jumped up to 150 knots.  The fuel flow/G3 was showing I was still lean of peak. Just, but still lean of peak. It surprised me.  I never fly at fuel flow  that  High. Drop down to 3500 and reduce fuel flow to 11 1/2 still lean of peak indicated?    Happy ending as we fueled, tied down,  and got back to the cottages  as the weather closed In and winds  really picked up.  Nice to know the old girl can get up and go when needed for an extra gallon an hour. 

You did change the power setting so your peak may have changed - in this case, peak EGT is now lower after increasing RPM. If you didn't re-do the lean find, the G3 might still think you were still operating LOP when you were actually operating at peak or ROP. FF does not lie, EGT can. (Yes. I do find that EGT goes down when I increase the RPM) 

[MyNameIsNobody]

12 hours ago, Tommy said:

You did change the power setting so your peak may have changed - in this case, peak EGT is now lower after increasing RPM. If you didn't re-do the lean find, the G3 might still think you were still operating LOP when you were actually operating at peak or ROP. FF does not lie, EGT can. (Yes. I do find that EGT goes down when I increase the RPM) 

Only increased fuel flow Tommy.  No change in RPM.