mongo
Registered User
I tested the Catto and Sterna ground adjustable props, here is what I found.
I have an Ex2 Carbon Cub with a Lycon built O-360, it dynoed at 229hp @2700rpm, it has 11:1 pistons, ported cylinders, dual E mags, a modified cam and what ever else they do.
I set each prop using a digital protractor 20" out from the center line. I did not use the Catto shim system since it would never get the two blades closer than 0.8 degrees.
I performed several static pull tests, initial climb and sustained climb tests and a 4 direction cruise test using the average ground speed.
Sterna 88"
Catto 86"
The Catto accelerates harder which makes sense based on the pull tests, it also reaches the maximum rate of climb at rotation faster. The Catto was always 300rpm greater than static RPM in the climb, while the Sterna only gained about 75 to 100rpm from static. This was nice for acceleration (with the Catto) but not great for turbulence, where the RPM changes more requiring a lower cruise RPM so you stay in a reasonable range. This trait seemed to improve some with increased pitch.
Conclusions:
The Catto is superior in STOL operations, but it is always 4-5mph slower than the Sterna in cruise.
The Sterna is my 7 iron, it is great for everyday use, it goes fast and still climbs very well but does not put a grin on my face at takeoff like the Catto.
The fastest I could get the Catto in cruise was with a ridiculously low static rpm of 2200, where I would cruise at 112mph. When I set the Sterna for cruise I could get 119mph with 2250 static rpm. The Sterna always out climbed the Catto when they were set for the same cruise speed.
The Catto has a nicer spinner assembly but the shim system for blade pitch is hopeless, it is much faster and more accurate to just use a protractor and remove the shim system. The Sterna weighs 2lbs less than the Catto when comparing complete assembly's.
The Catto is as loud as a 185 when the rpm is above 2600, which has a cool factor…..


I have an Ex2 Carbon Cub with a Lycon built O-360, it dynoed at 229hp @2700rpm, it has 11:1 pistons, ported cylinders, dual E mags, a modified cam and what ever else they do.
I set each prop using a digital protractor 20" out from the center line. I did not use the Catto shim system since it would never get the two blades closer than 0.8 degrees.
I performed several static pull tests, initial climb and sustained climb tests and a 4 direction cruise test using the average ground speed.
Sterna 88"
- Set to 13.8 degrees, 2420 static rpm
- 108.5mph @ 2500rpm cruise
- 7.3Gph
- 104mph @ 2420
- 6.4Gph
- Pull Test
- 704lbs @ 2420rpm
- Sustained climb at 50mph from 2000-3000'
- 1400fpm
- 108.5mph @ 2500rpm cruise
- Increasing static RPM did not improve static thrust, I tested 2500 and 2600rpm.
- Each increase of pitch by 1 degree was +7mph in speed and about -1000rpm static
Catto 86"
- Set to 14.5 degrees, 2320 static rpm
- 104mph @ 2500rpm cruise
- 6.0Gph
- Pull Test
- 735lbs @ 2320rpm
- Sustained climb at 50mph from 2000-3000'
- 1600fpm
- 104mph @ 2500rpm cruise
- Set to 13.5 degrees, 2430 static rpm
- 98mph @ 2500rpm cruise
- 5.7Gph
- Pull Test
- 775lbs @ 2430rpm
- Sustained climb at 50mph from 2000-3000'
- 1800fpm
- 98mph @ 2500rpm cruise
- Set to 12.0 degrees, 2570 static rpm
- 89mph @ 2500rpm cruise
- 5.5Gph
- Pull Test
- 801lbs @ 2570rpm (WOW)
- Sustained climb at 50mph from 2000-3000' (crazy high angle of attack)
- 1900fpm
- 89mph @ 2500rpm cruise
The Catto accelerates harder which makes sense based on the pull tests, it also reaches the maximum rate of climb at rotation faster. The Catto was always 300rpm greater than static RPM in the climb, while the Sterna only gained about 75 to 100rpm from static. This was nice for acceleration (with the Catto) but not great for turbulence, where the RPM changes more requiring a lower cruise RPM so you stay in a reasonable range. This trait seemed to improve some with increased pitch.
Conclusions:
The Catto is superior in STOL operations, but it is always 4-5mph slower than the Sterna in cruise.
The Sterna is my 7 iron, it is great for everyday use, it goes fast and still climbs very well but does not put a grin on my face at takeoff like the Catto.
The fastest I could get the Catto in cruise was with a ridiculously low static rpm of 2200, where I would cruise at 112mph. When I set the Sterna for cruise I could get 119mph with 2250 static rpm. The Sterna always out climbed the Catto when they were set for the same cruise speed.
The Catto has a nicer spinner assembly but the shim system for blade pitch is hopeless, it is much faster and more accurate to just use a protractor and remove the shim system. The Sterna weighs 2lbs less than the Catto when comparing complete assembly's.
The Catto is as loud as a 185 when the rpm is above 2600, which has a cool factor…..


