Takeoff RPM

sailvi767 · #1 02-22-2011, 06:09 PM

In a effort to be a good neighbor I have been normally using 2500 RPM on takeoff to keep the noise levels down. It has been suggested that this can be hard on the engine. Should I use 2700 or will the engine be fine with full throttle 2500 RPM takeoffs? Engine is a IO360 with 10 to 1 pistons if it matters. Takeoff performance is not a issue.

George

Brantel · #2 02-22-2011, 06:18 PM

Why would it be hard on the engine? FP users only get 2200-2300 till the speed comes up...

scard · #3 02-22-2011, 07:01 PM

Not detrimental...
We do fly out of an airport surrounded by neighborhoods. Our OP is, everything available until around 500', then 2500 rpm for the noise. (from 500', we've decided we'll probably survive, the airplane might not.) Just trying to be good neighbors. We were actually at the post office the other day getting a passport for a RV Bahamas trip to come, and the very professional postal worker with the "State Department Certification" processing our paperwork, lives right under the approach path for our airport... Good neighbor efforts, with sufficient safety, is important.
I'm not saying that we should have to modify aircraft operations for the noise comfort of neighbors that moved in long after the airport existed. However, it is clear that the airport is in danger if you don't. No matter where you live, unless you're in Idaho or Montana... are those really states with people in them?

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jrs14855 · #4 02-22-2011, 07:59 PM

Several examples in the Lyc book. Skyhawk engine is derated IO 360 rated at 2400 r/m. Commanche 250-parallel valve 540- turns 2575. Near identical engine turning 2700 r/m produces 260 hp

hydroguy2 · #5 02-22-2011, 08:06 PM

Quote:

Originally Posted by scard

.........unless you're in Idaho or Montana... are those really states with people in them?

.

Hey, I'm right here.

Kyle Boatright · #6 02-22-2011, 09:02 PM

Quote:

Originally Posted by Brantel

Why would it be hard on the engine? FP users only get 2200-2300 till the speed comes up...

With a 10:1 compression ratio, I'd run it at 2700 RPM on takeoff to avoid extra high cylinder pressures. Since RV's run <relatively> short props, the noise difference shouldn't be a big deal. It isn't a C-185 or something with a long prop which puts the tips in the transonic region at full RPM.

Flybuddy2 · #7 02-23-2011, 05:08 AM

I'd be curious to see the level of difference in sound, how detectable is it to someone on the ground?. Is it better to use max power to get away from the sound sensitive area faster vs a longer climbout at a few decibel reduction?

sailvi767 · #8 02-23-2011, 05:38 AM

That is a good question. The perceived sound level in the aircraft is less however I am wearing a noise canceling headset and the frequency change could mimic less noise. I have been told however in general a slower prop equals less noise.

George

sailvi767 · #9 02-23-2011, 06:29 AM

One other quick question. I am only seeing about 16.2 GPH on fuel flow during TO. Home field is 800 MSL. Should the Fuel flow be set a bit higher to protect the engine on TO or is this ok on a 360?

George

elippse · #10 02-23-2011, 08:35 AM

Use of power on takeoff is something like whether or not to use an intersection takeoff. The more air you put between you and the ground on takeoff the safer it will be. I elect to climb at best angle rather than best rate. If you are really concerned about noise, get a high efficiency prop that doesn't make any noise!