In instrumentation of any kind the saying “don’t chase the needle” is good advice. What makes you think that the instruments are precise? What makes you imagine that the fuel flow meter is precise? When heavy, hot, and high with a fixed pitch prop you will lean to highest RPM. Calculate that fuel burn at the next fill up- total gallons for the trip and gallons per hour. Experiment over time with lean of peak RPM. You may be surprised to find that peak RPM gallons per trip is similar to lean of peak RPM gallons per trip. The airspeed and time enroute change, yet gallons per trip are similar. So- when heavy, hot, and high- “Don’t Chase the Instrument” Yes, lean to engine stumble and back off a bit for powered descents. Milk that altitude! And trust your most precise instrument- your pocket calculator! Happy Flying! (1500 hour pilot that flies C172 over Wyoming mountains in the summer at 12,000 feet at max gross)
Great demo Dan, well done, nicely explained. Leaning is not generally a well understood procedure in the UK, with our near sea level airfields and low-ish cruising altitudes. Not to mention that age-old debate still vehemently espoused by some, the Lean vs. Rich of peak argument. I’m with you though, and as Mike Busch says when done correctly leaning to lean of peak is not only much more economical (good news at today’s fuel prices) but significantly better for our engines. The downside as your video beautifully portrayed is the loss of 5-10kt TAS, on average. I can live with that, especially if my engine is going to thank me in the long run. All the fuel is burned when operating lean of peak verses rich of peak, where some of the fuel disappears out of the exhaust valves. The payoff is a much cleaner burn with far fewer carbon deposits left behind in the cylinders and on the valves. An added bonus is minimal chance of carbon monoxide leaks, as there virtually isn’t any CO left over from the combustion process when lean of peak. Worth stressing too that leaning on the ground, even at sea level, can be beneficial after the engine is started and before take off. For anyone who remembers old cars with manual chokes, we wouldn’t run around with the choke out after start - running our Lycomings and Continentals is pretty similar. These engines are old tech with pretty basic fuelling, which is why we’re given a mixture control to help them burn fuel and breathe air correctly. With the exception of start up, take off and go around, there’s not many times full rich does us any favours. Love your content thanks, keep it up. 👍 PS. great OAT gauge sticking mod in your left wing root 😅.
Very interesting Dan. I did a very rough calculation based on 100km journey and the fuel saving is significant but the time penalty was only marginal, a few minutes at worst.
Hi Allan. Yes, after three hours at Lean of Peak I save enough fuel to do another hour compared to running at Rich of Peak. Fantastic fuel and money saver, and should make the engine last longer too.
Great video! In Cessna 172/P model EGT is not included as a standard equipment so manufacturer provides a guidance how to lean a mixture in respect to the RPM (if no EGT is installed) Nevertheless with my personal experience I’ve noticed that technique “leaning till it’s killing, then a bit of giving” works out even better then RPM does.
That is a great book written by Mike Busch,I also speak to him from time to time. I would like to give you some more info on running LOP. Mike says NEVER use a lean assist on any engine monitor to go LOP. It takes no more than 3 seconds to be LOP from full rich and not to use EGT as a leaning reference as it is not an absolute temperature. Look up his leaning video on CZcams called” Savvy Aviation, The Red Box”. Nice video keep up the good work.
@@user-nx6qr1mt6f lean the engine until you hear roughness then go back in rich just enough for the roughness to go away and you are LOP. Or lean until,you feel loss of power and you are LOP.
@@user-nx6qr1mt6f not according to the author of the book you said every pilot should read. Watch the video and you will hear how Mike says just the opposite.
Thank you so much for the explanation
In instrumentation of any kind the saying “don’t chase the needle” is good advice.
What makes you think that the instruments are precise?
What makes you imagine that the fuel flow meter is precise?
When heavy, hot, and high with a fixed pitch prop you will lean to highest RPM. Calculate that fuel burn at the next fill up- total gallons for the trip and gallons per hour.
Experiment over time with lean of peak RPM.
You may be surprised to find that peak RPM gallons per trip is similar to lean of peak RPM gallons per trip.
The airspeed and time enroute change, yet gallons per trip are similar.
So- when heavy, hot, and high- “Don’t Chase the Instrument”
Yes, lean to engine stumble and back off a bit for powered descents. Milk that altitude!
And trust your most precise instrument- your pocket calculator!
Happy Flying! (1500 hour pilot that flies C172 over Wyoming mountains in the summer at 12,000 feet at max gross)
Thanks
Nicely explained! Thank you!
Glad it was helpful! Please subscribe if you can. Thanks, regards, Dan.
One of the best video on leaning. Thank you
Glad you think so!
NIce video Dan. I'll try those techniques on my O-470 next time I fly.
Thanks Cliff. Love to hear the minimum fuel flow you can get at lean of peak.
Great demo Dan, well done, nicely explained.
Leaning is not generally a well understood procedure in the UK, with our near sea level airfields and low-ish cruising altitudes. Not to mention that age-old debate still vehemently espoused by some, the Lean vs. Rich of peak argument. I’m with you though, and as Mike Busch says when done correctly leaning to lean of peak is not only much more economical (good news at today’s fuel prices) but significantly better for our engines. The downside as your video beautifully portrayed is the loss of 5-10kt TAS, on average. I can live with that, especially if my engine is going to thank me in the long run.
All the fuel is burned when operating lean of peak verses rich of peak, where some of the fuel disappears out of the exhaust valves. The payoff is a much cleaner burn with far fewer carbon deposits left behind in the cylinders and on the valves. An added bonus is minimal chance of carbon monoxide leaks, as there virtually isn’t any CO left over from the combustion process when lean of peak.
Worth stressing too that leaning on the ground, even at sea level, can be beneficial after the engine is started and before take off. For anyone who remembers old cars with manual chokes, we wouldn’t run around with the choke out after start - running our Lycomings and Continentals is pretty similar. These engines are old tech with pretty basic fuelling, which is why we’re given a mixture control to help them burn fuel and breathe air correctly. With the exception of start up, take off and go around, there’s not many times full rich does us any favours.
Love your content thanks, keep it up. 👍
PS. great OAT gauge sticking mod in your left wing root 😅.
Thanks Rupert. Great comments, tips and advice.
Very interesting Dan. I did a very rough calculation based on 100km journey and the fuel saving is significant but the time penalty was only marginal, a few minutes at worst.
Hi Allan. Yes, after three hours at Lean of Peak I save enough fuel to do another hour compared to running at Rich of Peak. Fantastic fuel and money saver, and should make the engine last longer too.
Great video!
In Cessna 172/P model EGT is not included as a standard equipment so manufacturer provides a guidance how to lean a mixture in respect to the RPM (if no EGT is installed) Nevertheless with my personal experience I’ve noticed that technique “leaning till it’s killing, then a bit of giving” works out even better then RPM does.
Hi Mikhail, you are right. The leaning until rough and adding a little fuel back until smooth is a great technique.
That is a great book written by Mike Busch,I also speak to him from time to time. I would like to give you some more info on running LOP. Mike says NEVER use a lean assist on any engine monitor to go LOP. It takes no more than 3 seconds to be LOP from full rich and not to use EGT as a leaning reference as it is not an absolute temperature. Look up his leaning video on CZcams called” Savvy Aviation, The Red Box”. Nice video keep up the good work.
If you don’t use EGT as a reference in discovering LOP, how are you supposed to find LOP?
A&P/IA
@@user-nx6qr1mt6f lean the engine until you hear roughness then go back in rich just enough for the roughness to go away and you are LOP. Or lean until,you feel loss of power and you are LOP.
czcams.com/video/msYJxkHg0Co/video.html
Proper and safe LOP involves EGT readings
@@user-nx6qr1mt6f not according to the author of the book you said every pilot should read. Watch the video and you will hear how Mike says just the opposite.
Dan: out of interest, why did you sell your RV7?
Hi Sheldon. I needed four seats! Still love the RV7's and I do miss the fun I had in mine. Love tail draggers.