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PostPosted: Mon Aug 21, 2017 6:51 pm 
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Been flying the beaver for over 1000 hours now and think I'm starting to learn the bird. I know she'll teach you something new just about every week. Just wondering what some of the old timers think in regards to engine operation with different power settings, leaning etc. I've seen the beaver flown with gradual power reduction to final trying to keep temperatures in check, and I've seen going from an abrupt cruise power to idle once on the intended lakes shoreline. Thoughts on what this will do to cylinders? Shock cooling risk? Cracked cylinders? Also wondering what your opinions are on leaning for .1 or .2 hops all flown below 2500 ASL. Any thoughts opinions and info welcomed.

DPB



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PostPosted: Mon Aug 21, 2017 7:10 pm 
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Leaning at low altitudes on short trips is at the discretion of the pilot.

Abrupt throttle movement, especially on power reduction on any radial engine is harmful to the engine because radial engines have counter weights and also it induces reverse loading on the bearings.

The larger the radial engine the more sensitive to throttle movements they are.

Personally I would not employ a throttle jockey on any airplane.

But that is just my opinion. :(


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PostPosted: Mon Aug 21, 2017 7:19 pm 
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This is kind of what i was thinking. Was just an observation of another aviator. Also cat driver. What sort of power settings did you use. I've heard of 28/18 in cruise and 29/19 .


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PostPosted: Tue Aug 22, 2017 5:19 am 
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Many years since I was behind a junior. As Cat points out, abrupt throttle movements are a strict no no. Power settings we used were 28/1800 and 30/2000 for climb I have had americans sit beside me and as why power setting were so low. They used 30/2000 for cruise (that was in a bch18). A very old time bush pilot once said to me just about the time I was starting to shave "it's not how much power you use but how you apply it" -- good words if you stop and think about it. There was a pilot who used 42 inches on every T/O and pulled back to 36 on step. It was a survey beaver and engine went its time. We never went there.

My pet peeve(I live on a lake beside a float base) are the throttle jammers, makes me cringe every time I hear the prop trying to keep up with throttle application. The junior was likely the 2nd best radial ever built and very reliable (R2800 #1) Maintain temps and manage the power well and it will serve very for a long time

Leaning seems to be a relatively modern issue. I can never remember ever leaning an engine until I started flying a DC3 - thinking was that on floats the aircraft was way slower than on wheels and rich was for better cooling and short trips you never really got temps stabilized enough to consider leaning. In the summer the whoredyne was always on the red line or in excess of 205C and approaching 232C, especially with an external load. That was then, circa 1970 -- so yes time marches on and times change. Maybe we were wrong, maybe not :mrgreen:



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PostPosted: Tue Aug 22, 2017 1:14 pm 
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I've got a couple thousand hours now behind and beside R985's and a slew of other piston engines...doesn't make me an expert however.. Just an observer.

I know exactly who you were flying with that was whacking the power to idle once they were at a lake shoreline. I remember the justification he gave me for it too and I still refused to do it. Needless to say, he goes through a lot of cylinders. But, when you're paying the bills, do whatever you want.

I'm sure you're aware that Radials and most piston engines like smooth applications and reductions in power. No big temps spikes or drops. Never drive the thing with the prop(more of a concern with the 1340)... Don't make the prop governor try and play catch up. Make sure you're in the green and warmed up properly before a takeoff (this was a big one, watched a couple rookies pop oil coolers and seals). These simple things will keep cylinders AND the person footing the overhaul bill happy. The quasi SOP we used on the coast was full rated takeoff, and as you broke water come back to 33/2200. Climb out after obstacles at 30/2000 and cruise at 28/1800, although occasionally a 'hot' cruise power of 29/19 in a couple of the machines that needed the extra :wink: I haven't spun a 985 in anger in just about a year now though...

Ohh and edited to add, we never leaned. Legs were too short to make a difference and on 87 it didn't much care for it.



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