Carbon Cub V Speeds

[turbopilot]

A while ago we had a email exchange about one of the "salesman said" quotes comparing Carbon Cub speeds by model. Since then I have been trying to pull together the different V speeds by model.

I have seen different Vo speeds for the SS. CubCrafter website says max gross weight Vo speeds for the SS, FX and XCub are 97mph, 106mph and 99mph. I never routinely fly an airplane above the Vo. I know some people do it routinely. The SS and FX Vo differ because of the maximum gross weight. Most SS's fly at or near maximum gross weight in cruise while I would guess most FX's fly well below maximum gross weight. Since Vo is based on aircraft flying weight it would appear max Vo for the SS and FX are about the same given the same weight. The big surprise is the XCub given the published high cruise speeds with a Vo of 99mph. This is very low.

In any event CubCrafter salesman puffing about speed differences really gets put in perspective if you are the kind of pilot who operates at or below Vo in any of the models. My SS will cruise at 60% power (108 hp) at around 106 mph at sea level. That is 9 mph into the yellow arc for the SS at 1320 lbs. It would appear both the SS and FX are essentially restricted to a power setting of 50% power or below at sea level. If you load up an FX to 2,000lbs it appears you can go 106 mph or 60% power. I don't have an FX pilot manual these numbers were pulled from the CubCrafters web site.

 

[Tsquared]

for the FX3. All in mph

vne 170
vfe 84

power off stall, max weight 2000lbs
Vso 50.
vs1 48.
at full flaps the flaps disrupt airflow to the horizontal stab and elevators. the result is the aircraft will lose elevator authority and mush into a stall at a slightly higher speed than with out flaps

not published but mine, with power on (1500+rpm) and full flaps the stall speed is 38.

 

[turbopilot]

for the FX3. All in mph

vne 170
vfe 84

power off stall, max weight 2000lbs
Vso 50.
vs1 48.
at full flaps the flaps disrupt airflow to the horizontal stab and elevators. the result is the aircraft will lose elevator authority and mush into a stall at a slightly higher speed than with out flaps

not published but mine, with power on (1500+rpm) and full flaps the stall speed is 38.

Thanks I will update the table. The FX Vo seems low for 2,000lbs but that is a CubCrafter number. But then again the XCub is even lower at 2,300 lbs. Don't understand. Wonder what is driving those numbers?