RPM Variations

Good weather so I have flown each day for the past 6 days. I note that engine RPM varies a bit more than I like. It can raise or lower a 100 rpm easily, and the only thing I can 'figure' is that small altitude or pitch changes that load the engine differently are the reason I see this RPM change.

Do you see the same thing on your RV-12?

Johnf , no variations in rpm. Aside from fact I am experiencing some variation presently (see prop hub post). My engine was performing well before hub change and I never noted any change in rpm unless I moved the throttle.
Dick Seiders

JohnF said:

Good weather so I have flown each day for the past 6 days. I note that engine RPM varies a bit more than I like. It can raise or lower a 100 rpm easily, and the only thing I can 'figure' is that small altitude or pitch changes that load the engine differently are the reason I see this RPM change.

Do you see the same thing on your RV-12?

Click to expand...

A pitch change will change airspeed and the engine rpm.

Pitch change

I flew Young Eagles Saturday and RPM/airspeed was all over the place at fixed throttle as the kids didn't hold attitude real well. Hoping to get a chance to fly solo this weeks and check things out that way. I even noticed small,changes a week ago encountering some fairly large thermals-- and comiong out of them.

Wayne 120241

John, Marty is obviously correct on pitch changes. I assumed you were talking of uncontrolled changes in level flight. Can you clarify?
Dick Seiders

Think John F means - -

At various altitudes he sees a minor RPM change. If I recall, John starts out at high Alt. I think it sounds very normal. The higher, the less RPM's.

John Bender

Level flight, manual stick control...just flying around...engine RPM moves up or down, say, 100 rpm or so with no throttle changes...

Tomorrow, weather permitting, I will use the autopilot and 'lock on' the altitude to see if the engine speed stabilizes. I really suspect my manual control is the reason I see these minor changes. The Dynon VSI shows vertical speed changes up or down while in cruise mode, and I'll see if the stabilization of the altitude also holds engine rpm relatively stable.

Yes, I am flying at typically 8500 to 9500 density altitude.

More when I look at this a bit more carefully. I don't think its anything that I should be too concerned about, its just the bottom of the barrel of odds and ends that come with a relatively new plane...part of the fun.

Wow ! 7th day in a row of great weather...calm wind, cavu visibilty 60+ and dead smooth air

Used auto pilot at density altitude 10,500-ft and rpm set at 5250...varied only up and down occasionlly 10-ft...went to manual control and saw the rpm vary as before, so I am convinced pilot input is the cause of engine speed variations as they coincide with Dynon D-180 indications of "up or down.

Anyway it was fun !