Setting the prop for crosscountry

Performance graphs are in chapter 5 of the Operator's Manual.

At the top of this forum page, hover your mouse over "SUPPORT / BULLETINS" and click on "ENGINE MANUALS".  On the next page, click on "4-Stroke Engines", then on "912 Series Engines".

Not sure how I can use that information or how it can answer my question ?  Not a tech genius .

Just set your prop pitch  for STATIC (tied down to something immovable) 5200RPM as per Rotax recommendation. 

This will give you good TO/Climb performances and okay cruise, without stressing your engine. Fuel consumption/hr is likely to be low.

At this setting WOT will climb to over Max (okay for 5 mins). 

Once established in climb, control WOT rpm with attitude.

Straight & level, I throttle back to between 5200-5500 rpm

Hi Fred,

A prop pitch set for 5400 WOT in level flight at your average altitude will use more fuel and have less cruise speed. Anything under 5500 rpm at WOT is over pitched and the lower that rpm is the more stress you put on the engine.  I did a huge multi prop research project years ago with four identical planes. 

Over pitching WILL cost you climb, speed, fuel and higher engine temps.

5600 - 5750 rpm WOT at your AVERAGE ALTITUDE is your BEST BALANCED pitch setting for a ground adjustable prop. It would be different if you had an in flight adjustable prop. If you want a better climb prop vs cruise then go on up to 5700 - 5800 rpm.

With a pitch set to that 5600 - 5760 range then a good cruise rpm is around 5200 - 5300. Above that fuel economy suffers for very little speed increase.

This research project took four identical planes, 14 props and months of side by side take offs and flights.

Hi Roger,

Your comments above have me starting to think about what might be happening with my Sonex/Rotax 912ULS/Airmaster CS - I have been struggling to control oil temperatures, rising to 112C and if concentration wavers 120C. Coolant (head temp) is in the low 90C's 

The Airmaster is provisional factory set to achieve 5450 rpm WOT in Cruise Mode - this pretty much falls within your comments "A prop pitch set for 5400 WOT in level flight at your average altitude will use more fuel and have less cruise speed. " and "Over pitching WILL cost ....., speed, fuel and higher engine temps."

The Airmaster soft stop settings can be adjusted to suit the aircraft and of course it can be switched to Manual Mode so the pilot can make in flight adjustments, relative to MAP.

Finally the QUESTION - would you suggest adjusting my Airmaster soft pitch stops  to a higher WOT RPM (" 5600 - 5760 range")??