Looking4Lower
New Member
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The old radial engines had a supercharger on the back of the engine and equal length intake pipes that did a good job of mixing the fuel/air and delivering it evenly to the cylinders, making LOP easy and safe.
Yes, but this still is not recommended procedure for all radial engines. And even then it is generally accepted that LOP operations will result in having to overhaul sooner. Which isn't a big deal for an airline, but when I operated round motors it was generally regarded as a not real good idea.
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When I flew freight in the Convair (R-2800 radial engines that make 2400 horsepower at takeoff), LOP for cruise was standard, as it has been for many decades. Same thing at other companies who operate similar equipment. We had a torque gauge (or BMEP in some planes) that we could use to watch the power output on an engine...we would lean to peak torque, then continue leaning down a fixed amount. Interestingly, some big radial airplanes (like the ones I flew) don't even have an EGT gauge - once the power curves are known, a fixed torque drop is used to lean. For takeoff and climb, full "auto rich" is always used, but the pressure carburetor is fairly complex and it does some compensating that a small updraft carb doesn't do.
In small planes without an engine monitor, I cruise with a fairly rich mixture to cruise cuz it's impossible to tell where all the cylinders are individually operating as far as EGT/CHT. When I have had an engine monitor, it's sometimes surprising to see how different they all are ("flying in loose formation" as Deakin would say).
Deakin sells a book by Pratt and Whitney called "The Aircraft Engine and its Operation" (it's no longer published, so you can buy a copy from him or you can find one on ebay if you look long enough). Even though it seems to be written with heavy radials in mind, the basic info and the diagrams are OUTSTANDING. Also, John Deakin's articles on props, mixture and throttle operation are OUTSTANDING too, regardless of what you think about LOP or Gamijectors. For me, they clarified many mysteries and myths about engine operation.
BTW, I went thru John Deakin's CAF C-131 ground school class, and I can tell you that he's a class act!
The old radial engines had a supercharger on the back of the engine and equal length intake pipes that did a good job of mixing the fuel/air and delivering it evenly to the cylinders, making LOP easy and safe.
Yes, but this still is not recommended procedure for all radial engines. And even then it is generally accepted that LOP operations will result in having to overhaul sooner. Which isn't a big deal for an airline, but when I operated round motors it was generally regarded as a not real good idea.
[/ QUOTE ]
When I flew freight in the Convair (R-2800 radial engines that make 2400 horsepower at takeoff), LOP for cruise was standard, as it has been for many decades. Same thing at other companies who operate similar equipment. We had a torque gauge (or BMEP in some planes) that we could use to watch the power output on an engine...we would lean to peak torque, then continue leaning down a fixed amount. Interestingly, some big radial airplanes (like the ones I flew) don't even have an EGT gauge - once the power curves are known, a fixed torque drop is used to lean. For takeoff and climb, full "auto rich" is always used, but the pressure carburetor is fairly complex and it does some compensating that a small updraft carb doesn't do.
In small planes without an engine monitor, I cruise with a fairly rich mixture to cruise cuz it's impossible to tell where all the cylinders are individually operating as far as EGT/CHT. When I have had an engine monitor, it's sometimes surprising to see how different they all are ("flying in loose formation" as Deakin would say).
Deakin sells a book by Pratt and Whitney called "The Aircraft Engine and its Operation" (it's no longer published, so you can buy a copy from him or you can find one on ebay if you look long enough). Even though it seems to be written with heavy radials in mind, the basic info and the diagrams are OUTSTANDING. Also, John Deakin's articles on props, mixture and throttle operation are OUTSTANDING too, regardless of what you think about LOP or Gamijectors. For me, they clarified many mysteries and myths about engine operation.
BTW, I went thru John Deakin's CAF C-131 ground school class, and I can tell you that he's a class act!
