Constant Speed Propeller

Hi Bill,

I will reread the Airmaster manual (its not with me at the moment) however,my understanding, is that the prop is supplied with factory set max/min pitch stops, specifically for the Rotax 912 ULS.

I take your point, with regard to not seeing 5450 rpm/ WOT in Cruise - Before deciding to make any adjustments, I will try going to Manual mode and increasing (Fining) the prop to 5450 rpm - I am sure there will be a small oil temperature drop, however I doubt it will acheive  my target (below 100C in Cruise).

Do not confuse the non-adjustable factory Hard-Stops with the 3 User adjustable Soft-Stops. (Coarse/Fine/Feather).
If you can not get to 5750 on the ground in Manual mode you are probably hitting the Soft-Stop.
If Manual Mode can't reach it, Automaic will not either.

You stated earlier,  "I have only ever seen 5350 rpm"
Have you confirmed personally that the automatic limits are set at 5750 and 5450?
Or do you just believe this is where they are set?

'Have you confirmed personally that the automatic limits are set at 5750 and 5450?
Or do you just believe this is where they are set?'

You are way too "On The Ball" Bill - I confess, with much shame, that I believe.

Some updates;

Had a fly this afternoon - 3000ft, OAT 11C, QNH 1021,  WOT, RPM in cruise (Manual mode) 5450, MAP 27.6, Oil temp down to 104C (an improvement but still above 100C).

Measured my oil cooler - it is Rotax  "Large" - could go to "Extra Large" - what think you?

I'm confused by some of those figures. I have an Airmaster (with WarpDrive blades) on 912S in a Europa. Factory preset rpm is 5700 t/o, 5400 climb, 5000 cruise. I find these are pretty accurate on my MGL digital readout, controls within +/-50 generally. (Readings of Rotax analog tacho can be way out.)

Yes you need to adjust the m/switches to suit the installation esp wrt coarse limit for safety - make sure you can still climb away.

Europa has a bit of a reputation for marginal cooling. Oil cooler is behind radiator in a duct and projects lower but there is some overlap. For UK winter conditions I have the projecting bit blanked.

T/o power climb is always my hottest condition and I'm sure would overheat in less than 5 mins. WOT at 5400 and 80kts climbing will also reach max temps but take longer.

Cruise at 5000/25" gives me about 110kts and oil and cht both drop back to around 80deg C.

I don't normally go above 26" at 5000, I will up the rpm if I want more power because it just feels/sounds smoother, but on the Rotax curves there is no restriction on MAP at 5000 if you have the right octane. The traditional rule of thumb of not over square is to guard against pre-ignition isn't it?

Hi Mike,

Cant be certain of my  TO Mode rpm (WOT) - I switch to Climb Mode (WOT) as soon as hit about 90 knots/500ft - rpm usually around 5300.

I will do a static ground WOT to check for TO Mode Max RPM.

I am slowly coming to the realisation that I must adjust the "switches" - I think the factory settings in Cruise Mode is too course (3500 rpm (WOT))

Burning 98 RON

I have calibrated the Dynon Engine RPM, against a laser/phot tacho -  now spot on

I have been doing speed tests, to check accuracy of Dynon read out - we seem to be consistently running at 133-135 Kn indicated (TAS 145-147 Kn) 3000ft. which comes out to be very close, compared with the timed/distance. 

We (NSW Australia) are heading into winter, so I will not accept a temperature that is just within Rotax normal parameters - must get cruise temps below 100C. Its okay, on a hot day,  to go to 120C on climb out but not in cruise.

From past Rotax 912 ULS experience, I prefer to keep my engine at or above 5200 rpm, when under load.