Full power or not

[rocketman1988]

WOT...let it run!

Not really the same but I had a C-421 with Continental GTSIO-520's.

Ran it hard all the time after speaking with one of the original engine designers...

Those "troublesome" engine ran 800 hours BEYOND TBO with NO issues...

[leok]

There are several reasons.

One, is KPTK airspace ends at 3500' and we are under KDTW class B at 6000' so I generally don't climb out very high. (2500' to 3000' as I leave the area.

Two, I prefer to pull back the power once I hit 1000' AGL to reduce fuel flow. When local I am usually more interested in duration aloft rather than speed. Depending on what I plan on doing, go somewhere or just cruise around I set 70% or less power, pull the RPM back to 2450 or less and lean out to around 1400 EGT and >400 degrees CHT (so far never an issue). 70% is around 23 inches. I typically will adjust the RPM a little for best speed at whatever manifold I settle on. 2450 seems to be a happy average.

Three, pulling back the power and RPM reduces the noise somewhat which is a neighborly thing to do.

Four, I love the acceleration and climb of full power on take off, but just don't get the same rush once at altitude. That is unless for some reason I want the higher cruise speed/climb rate and don't care about the incremental cost.

[rongawer]

Originally Posted by rocketman1988

WOT...let it run!

Not really the same but I had a C-421 with Continental GTSIO-520's.

Ran it hard all the time after speaking with one of the original engine designers...

Those "troublesome" engine ran 800 hours BEYOND TBO with NO issues...

Completely agree. Run them hard, often, and they'll continue to do that.

Leok, throttling back for slow flight, or local cruise/sight seeing/joy of flying flight is understandable, but that would be the only time I'd agree.

If you're taking off to go somewhere, running at WOT to altitude, with proper mixture management, will generally be an incremental reduction in cost. Not only is the throttle volumetric flow more efficient, the higher MP pressure will result in a higher cylinder pressure leading to a more efficient combustion. It also reduces the time to climb and getting to cruise power/speed faster. It's a higher fuel burn in the climb, but with less time in the climb, you'll be at cruising altitude with a lower cost per mile sooner, reducing block-block costs - and time. You can pull back the RPM if you want, but leave the throttle full open.

Not directly a take-off power setting, but another consideration is your Carson Speed, which is the most efficient speed for the airframe based on 32% increase over best L/D speed, generally best glide which for the -10, ~ 85KIAS, making the Carson Speed about 112KIAS, which is why 110-120KIAS climb speed is fairly efficient.

Noise is a non-linear squared function, so if you're concerned about noise at lower altitudes, then getting up high and away from the ground faster makes more sense to reduce your noise the fastest, in addition to changing headings away from population as soon as practicable. Once at cruise: WOT, RPM to suit desired power/speed, and the adjust mixture appropriately. If that's still too fast for your taste, pull back the RPM and readjust mixture, but leave WOT.

If you want to reduce RPM, ok, but just realize the higher the RPM, the higher the horsepower, and most folks fly airplanes to go places, generally fast (a function of "total performance") - and more horsepower will produce more speed. Whatever you do there, just leave your throttle full open and you may find not only better performance, but overall efficiency too.