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#1
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Speaking of mixture, remember the XC tow we did from Westcliffe to Salida?
Smoke over the Rockies... ;-) |
#2
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How could I forget?
Neither the Blanik nor the Pawnee had a radio so we both had hand helds. It was cold so we were bundled up with the radios inside our clothes and we had pre-briefed that you would move from high to low tow and back if you wanted to talk to me. We had crossed Music Pass, the Sand Dunes, and the San Louis Valley and were just heading into the mountains beyond when you gave me the signal. When I got out my radio and called you, you told me I was trailing black smoke. I immediately started looking for places to land, all of which were behind by now. Then I noticed that I'd neglected to lean the mixture as we continued climbing to about 12,500' MSL. Mixture is not one the things done often when all your power flying is from the surface to about 2K and back down. Thanks for the reminder. On 12/24/2014 9:46 PM, wrote: Speaking of mixture, remember the XC tow we did from Westcliffe to Salida? Smoke over the Rockies... ;-) -- Dan Marotta |
#3
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Roger on the leaning. Surprised you do not normally lean on tow. In summer temps here I start leaning at 200-500 AGL, even for a 2K tow.
I can watch the RPM come up when I lean. DA is already at 5500 or higher on the ground. |
#4
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Hi Bill,
We run DA in the 8,500+ range in the summer at Moriarty; the field elevation at Silver West (C08) is 8,290' MSL so I expect DA was considerably much higher. Back when the EGT and manifold pressure gauges worked, I would lean on tow but, with a constant speed prop it's better not to mess with it since cylinder head temperature is too slow to respond. Where are you flying? On 12/25/2014 2:20 PM, Bill T wrote: Roger on the leaning. Surprised you do not normally lean on tow. In summer temps here I start leaning at 200-500 AGL, even for a 2K tow. I can watch the RPM come up when I lean. DA is already at 5500 or higher on the ground. -- Dan Marotta |
#5
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On Friday, December 26, 2014 9:59:26 AM UTC-7, Dan Marotta wrote:
Hi Bill, We run DA in the 8,500+ range in the summer at Moriarty; the field elevation at Silver West (C08) is 8,290' MSL so I expect DA was considerably much higher.* Back when the EGT and manifold pressure gauges worked, I would lean on tow but, with a constant speed prop it's better not to mess with it since cylinder head temperature is too slow to respond. Where are you flying? On 12/25/2014 2:20 PM, Bill T wrote: Roger on the leaning. Surprised you do not normally lean on tow. In summer temps here I start leaning at 200-500 AGL, even for a 2K tow. I can watch the RPM come up when I lean. DA is already at 5500 or higher on the ground. -- Dan Marotta I once sat next to a Lycoming engineer on an airline flight. His advice for leaning an engine with CS prop at high DA was to ignore the gauges and lean slowly until you feel a light stumble then enrich just enough so that it smooths out. Gauges, he said, can lead a pilot to do stupid things with a mixture control. He said there was no chance whatsoever of harming an engine by leaning above 5,000' DA. His main point is if an engine is running strong and smooth, it's happy and lean engines are happier than rich ones. It worked for me over many thousands of hours. I could cover the engine analyzer and lean "by ear/feel" then look at the analyzer to find it was showing that the engine was perfectly leaned. If you really do over-lean an engine at high DA, it will just quit as you found out. Still another tip from the Lycoming guy was to lean for taxi using the technique above so the plugs stay clean. Finally, the Lyc guy made an interesting economic argument. (using current costs) If an O-540 averages 15 GPH and AVGAS costs an average of $5/gal then a 2000 hr TBO run will have burned $150,000 worth of gas. An O-540 overhaul is about $35,000 so it's easy to see one might burn more dollars in gas by running rich than what, if anything, could be saved at overhaul. |
#6
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The C-182RG I fly is not fuel injected and no good engine temp gauge. So that's what I do for cruise, lean until it stumbles then one rotation rich. Vernier mixture control. Learned that when I first learned to fly in C-150s. Same technique still works.
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#7
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On Friday, December 26, 2014 4:00:53 PM UTC-7, Bill T wrote:
The C-182RG I fly is not fuel injected and no good engine temp gauge. So that's what I do for cruise, lean until it stumbles then one rotation rich. Vernier mixture control. Learned that when I first learned to fly in C-150s. Same technique still works. Adjusting to the break point between rough and smooth gives best power mixture. To get best economy mixture, lean until the engine shakes so bad you can't stand it - then enrich the mixture slowly until you can just barely stand it. Best economy will always be slightly rough. |
#8
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All good stuff but I gotta do as the owner wants. He'd rather spend
money for gas than "burn the engine up". I've tried to convince him otherwise but, to keep the peace, I fly it like he wants it. BTW, we get 100 degree days here at 6,200' though not as often as you do. On 12/26/2014 4:00 PM, Bill T wrote: The C-182RG I fly is not fuel injected and no good engine temp gauge. So that's what I do for cruise, lean until it stumbles then one rotation rich. Vernier mixture control. Learned that when I first learned to fly in C-150s. Same technique still works. -- Dan Marotta |
#9
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Bill D wrote:
On Friday, December 26, 2014 9:59:26 AM UTC-7, Dan Marotta wrote: Hi Bill, We run DA in the 8,500+ range in the summer at Moriarty; the field elevation at Silver West (C08) is 8,290' MSL so I expect DA was considerably much higher. Back when the EGT and manifold pressure gauges worked, I would lean on tow but, with a constant speed prop it's better not to mess with it since cylinder head temperature is too slow to respond. Where are you flying? On 12/25/2014 2:20 PM, Bill T wrote: Roger on the leaning. Surprised you do not normally lean on tow. In summer temps here I start leaning at 200-500 AGL, even for a 2K tow. I can watch the RPM come up when I lean. DA is already at 5500 or higher on the ground. -- Dan Marotta I once sat next to a Lycoming engineer on an airline flight. His advice for leaning an engine with CS prop at high DA was to ignore the gauges and lean slowly until you feel a light stumble then enrich just enough so that it smooths out. Gauges, he said, can lead a pilot to do stupid things with a mixture control. He said there was no chance whatsoever of harming an engine by leaning above 5,000' DA. His main point is if an engine is running strong and smooth, it's happy and lean engines are happier than rich ones. It worked for me over many thousands of hours. I could cover the engine analyzer and lean "by ear/feel" then look at the analyzer to find it was showing that the engine was perfectly leaned. If you really do over-lean an engine at high DA, it will just quit as you found out. Still another tip from the Lycoming guy was to lean for taxi using the technique above so the plugs stay clean. Finally, the Lyc guy made an interesting economic argument. (using current costs) If an O-540 averages 15 GPH and AVGAS costs an average of $5/gal then a 2000 hr TBO run will have burned $150,000 worth of gas. An O-540 overhaul is about $35,000 so it's easy to see one might burn more dollars in gas by running rich than what, if anything, could be saved at overhaul. When we first got a JPI for our power flying club's 182, I leaned it using the fancy gauges and then by the method mentioned above. It ended up pretty much at the same settings both times. YMMV Pete |
#10
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Jean, NV. 2,833MSL, 100F jacks the DA.
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