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Rich wrote:The rubber straps are relatively inexpensive. Order several at a time.

Hi Rich -

FWIW, when Glenn Lawler worked on my "new" plane he fabricated a strap from DA42 cooling hose material. This is still going strong after ~1000 hrs.

Chris

ouff you scare me a little, my bad, i have a 7497

The same exhaust system that is now standard on all Diamond DA40-XL/XLS series, is available to all MT propeller equipped DA40's and is now compatible with the new Hartzell 2-blade aluminum prop (7497) or composite propeller installed under STC SA02476CH-D. 2004-2008 DA40s with the 7495s propeller must change propellers in order to install the PFS exhaust. Power Flow is an authorized distributor for this propeller and can include a current price quote from Hartzell with the quote for your new Tuned Exhaust.

I believe the prop model number needs to be HC-C2YR-1BFP/F7497. My DA40 has the incompatible Hartzell prop.

I just upgraded to the Power Flow exhaust with a new Hartzell Prop. I can definitely tell the difference especially in climb.

What is the typical rpm power setting for cruise? I see a lot of people recommend 2450rpm but can find a real answer. Any suggestions?

Thanks for your help

Hi David. Welcome.

A lot of DAN members report good results with 2450 RPM and up. Some advocate WOT and 2700 as soon as your altitude permits. There have also been discussions noting that the PF tuning is centered on 2350 but also noting that the power curve is pretty flat (broad). I often fly at altitudes above 10,000 MSL. When I do, I fly at WOT at 2350 RPM.

I fly WOT and 2500 RPM, solely because that is where my engine is smoothest. This magic number seems to vary for each plane.

I choose different RPMs depending on the situation at hand. It really depends on the phase of the moon, the current sunspot cycle and whether or not I at eggs before the flight.

Thank you guys! It seems really pretty complex and different from each plane. I will try to test it out and see where the sweet-spot for my plane is.

David,

Two small points:

The particularities of each prop balance will dictate an exact RPM or two at which the the engine will not be quite as smooth. If this RPM works for you otherwise, just change the RPM by 5-10; there is no need for a dramatic change. This works in reverse for finding the smoothest RPM settings as well.

I'm not sure how significant this is but I avoid flying at a single RPM over time. For a given RPM setting, I vary it +/- 20 RPM over time. In theory, this might eliminate uneven wear patterns caused by a persistent vibration pattern.

@rwtucker

I am fairly new to flying and did not even consider the possibility of uneven wear pattern but its a very good point! I'll be varying the rpm from now on on cruise.