I have installed an F-33 on an Ison AirBike (single seat ultralight, tractor configuration) and measured 125 lbs of static thrust - 5850 RPM, 1125 degrees F EGT, 400 degrees F CHT with a 2 blade, B model 56 " powerfin.  The prop has about 9.5 degrees of pitch (about 0.115 inches of pitch measured from the trailing edge using the powerfin pitch window in the hub).

Outside air temperature was about 80 degrees, 800 feet elevation.

I was expecting more than this, but have not seen anything in print  as a guide.  My old Rotax 447 gave me 220 lbs of thrust.

Anybody have any numbers you think I should be getting?

What about you Rotax 277 owners?

Many thanks!

Ernie Luce, San Antonio, Texas

Hi Ernie,

While I don't place much stock in the value of static thrust figures, I think you're right to expect more out of the F33 than what you're getting.  I've been collecting snippets of info on this engine for a while & have seen  a number of independent reports in the area of 150 lbs static.  Best guess is that would equate to ~120 lbs at 40 mph or so, whereas your current setup is probably (SWAG) ~100 lbs at that speed.  The difference in climb performance would likely be quite considerable.

All of those user reports that I've seen stated the use of the 3-blade, E model (narrower blades) Powerfin, generally about 48" diameter.  Earthstar is using this setup after trying other engines & props.  They speak highly of it.  The backpack parachute crowd is also quite keen on it.   I think you'll also find that 3 blades serve to greatly reduce the vibration inherent in using a single cylinder engine.  

You might also talk to Matt at RecPower & find out what he's seen customers use.

Daniel

Thanks - I've posted on the the hirthflyers group as well and also got a suggestion to consider narower blades.  I have a message into Matt and am awaiting his reply.  Thanks for your input!

Ernie