Koolprop on jabiru

[avidflyer]

Any idea how accurate your ASI is? I did a bunch of math, figuring tip speeds, and then googled tip speed and found this info on the warp drive site.
http://www.warpdriveprops.com/propspd2.html
You might be at a better (more efficient) tip speed at the 3150 rpm. Also, if my memory is correct, you have aluminum connecting rods on the earliest engines, later ones are steel. Maybe the lower rpm is less stressful on the engine?? JImChuk

[Shane Alley]

I haven't checked my asi accuracy.
I was also wondering about increasing pitch a little and keeping the engine at a lower rpm for longevity. The old prop wouldn't let the engine rev past 2800 and it has been trouble free for 570 hrs.
I just hated the noise and vibration. I wanted a longer prop because I'm more interested in stol capabilities than speed. I will look into the tip speed efficiency info. Maybe I should limit rpm to 3000.

[Shane Alley]

Using that tip speed calculator you loaded shows my tip speed is Mach .818
It says maximum performance is .8 to .92
Seems that I'm good at 3150 max rpm.

[avidflyer]

Fourth paragraph says that best performance is at or below 700 fps or 475 mph. At 3150 rpm, your prop tip speed is 628 mph. I think our Jabirus are in need of a gearbox to be most efficient. Nobody wants the extra weight or complexity though. JImChuk

[Shane Alley]

Ok yes I went back and read that paragraph. I will need to do some more testing to see if I can get the same performance with more pitch to slow the rpm down some.

[avidflyer]

RPM = HP as well, so there is that consideration as well. What did the prop cost you? JImChuk

[Shane Alley]

It was 1050 shipped

[Danzer1]

Fourth paragraph says that best performance is at or below 700 fps or 475 mph. At 3150 rpm, your prop tip speed is 628 mph. I think our Jabirus are in need of a gearbox to be most efficient. Nobody wants the extra weight or complexity though. JImChuk

That also says at cruise - so if you're cruising at 3150 it's high. If you cruise at 2400 or so you're pretty close! I'm not a Jabiru guy so FWIW!

Greg