Thanks for your response to my questions.
To address your question about the difference that I am seeing in takeoff climb rpm I have attached an updated screen shot. I was attempting to show a comparison of four consecutive days. In particular, the last two days as they are the closest to each other in timing, most like each other and had the same tank of fuel.
Regarding propeller pitch on my ELSA RV-12, it was originally set to 71.4 degrees as required by Van’s Aircraft. Based on flight testing I have been flattening the pitch to increase the Vy takeoff rpm to be at least 5,200 rpm (i.e., per Rotax’s requirement). This is partly why I asked about the sensitivity of WOT takeoff rpm of the Rotax 912 ULS with a fixed prop to density altitude variation. As I am amazed how the local density altitude has increased almost 4,000 feet moving from the winter days to these currently very warm spring days.
To better understand the sensitivity of WOT takeoff rpm to density altitude changes I reduced some of my earlier flight test data to show this sensitivity and I have attached it. It appears that WOT takeoff rpm decreases approximately 15 rpm per 1,000 feet of density altitude increase. Is this typically what you see?
Regarding cold starts (i.e., choke open and throttle closed) I was surprised with the warming weather that engine seemed to start slower and more slowly advance to 2,000 rpm without advancing the throttle. I understand the gear box speed sensitivity and I will in the future more aggressively advance the throttle to increase the idle speed to 2,000 rpm.
Was your comment about wind speed affecting engine rpm focused on ground operation or in flight? Regarding ground operation I could understand how the wind pointing towards the airplane or away from the airplane could affect the idle rpm. Like how the engine rpm with the throttle closed is higher on final approach than when taxing or stationary. But, in flight I would think the effect on the propeller is driven by airspeed.
Regarding attending Rotax training, I clearly want to attend the Service and Maintenance training classes. Leading Edge Airfoils is the closest to me. Hopefully they will update their training schedule shortly. This would greatly simplify getting to and from these classes.
Thanks for your responses. This is helpful.
Brett
