Anyone know of a manual or book on the proper use of a constant speed prop on an 8KCAB?(150 lycoming). I've been told everthing from the "don't go over square on penality of death rule" to run it full throttle all the time and just use the prop control for rpm control. Thanks. Ben 1N2
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constant speed prop
- Thread starter hubblugg
- Start date
Hey Ben,
I have a Decathlon with a 150 and C/S prop. I was told from three different instructors I flew aerobatics with to let it run. They never have a problem getting an engine to TBO and many go beyond. Their Decathlons are flown 5+ hours a day, every day. Another instructor I flew with had me pulling back the prop to square after climb-out and anytime in cruise. He claimed it was to save the engine. Could it be the engines that run every day make it to TBO by the fact of frequent use?
I'll see what I can find in my manuals and pass it on.
Rich
I have a Decathlon with a 150 and C/S prop. I was told from three different instructors I flew aerobatics with to let it run. They never have a problem getting an engine to TBO and many go beyond. Their Decathlons are flown 5+ hours a day, every day. Another instructor I flew with had me pulling back the prop to square after climb-out and anytime in cruise. He claimed it was to save the engine. Could it be the engines that run every day make it to TBO by the fact of frequent use?
I'll see what I can find in my manuals and pass it on.
Rich
Ben-
Simple but complex question, the old mantra about not running "over square" is completely false, all engine manufacturers publish official power setting charts with over square settings.
What you don't want to do is use high manifold pressure and low RPM's, the aeronautical equivalent of starting out in fourth gear, struggling up a high in a gear that's one or two cogs too high. You don't want to takeoff, go-around, or climb with the prop in high pitch/low RPM. Advance the RPM's then advance the throttle, reduce the throttle then the RPM's.
In this care we're discussing a simple, non-turbocharged, engine, takeoff with the prop forward (high RPM) and full throttle, after the climb is established reduce RPM if required to get the prop at the redline. If the prop is at or below the redline don't touch the prop/RPM control until you level off. Climbing with reduced RPM's will only prolong the climb, decrease the cooling airflow, the increased time spent at high power, high heat production, will not be a positive thing for your engine. After level off set the RPM's at the lowest level for smooth operation and use the MP required to get the correct % of power, find the MP/RPM values in the aircraft or engine manual.
Tom-
Simple but complex question, the old mantra about not running "over square" is completely false, all engine manufacturers publish official power setting charts with over square settings.
What you don't want to do is use high manifold pressure and low RPM's, the aeronautical equivalent of starting out in fourth gear, struggling up a high in a gear that's one or two cogs too high. You don't want to takeoff, go-around, or climb with the prop in high pitch/low RPM. Advance the RPM's then advance the throttle, reduce the throttle then the RPM's.
In this care we're discussing a simple, non-turbocharged, engine, takeoff with the prop forward (high RPM) and full throttle, after the climb is established reduce RPM if required to get the prop at the redline. If the prop is at or below the redline don't touch the prop/RPM control until you level off. Climbing with reduced RPM's will only prolong the climb, decrease the cooling airflow, the increased time spent at high power, high heat production, will not be a positive thing for your engine. After level off set the RPM's at the lowest level for smooth operation and use the MP required to get the correct % of power, find the MP/RPM values in the aircraft or engine manual.
Tom-