G3X for X-Cub Vne is latched to KTAS

[charliefoxtrot00]

Hello, the Vne barber pole for the X-cub seems to be latched to KTAS instead of KIAS. It decreases with altitude (as KTAS increases, relative to KIAS), which should not be the case in this aircraft.

[charliefoxtrot00]

Here's a picture of the "barber pole," incorrectly showing a VNO of 102 kias and a VNE of just over 103kias, when the VNE of an XCub is 132kias. These indications should be fixed at those airspeeds and not change.

[mattnischan]

@charliefoxtrot00 - There may be some aircraft specific code required to make that work or possibly a change in the aircraft config itself. However, the G3X is a mod for every aircraft that has the G3X, and not just specific ones.

Does this wrong behavior with the overspeed indicator occur with all other G3X aircraft as well?

[charliefoxtrot00]

@mattnischan I flew in the JV-3 and the VNE barber pole/redline was consistently pegged to 165KIAS no matter the altitude, weather settings, or baro setting (Kollsman window).

However, the XCub does not display the same behavior. I dug a little further and collected empirical data from 20 different flight tests. In each, I set the aircraft at a known field elevation and activated the active pause. I then played with the variables of pressure msl (in weather settings) and the altimeter window.

The strongest correlation to VNE is the altitude indicated on the altimeter tape, regardless of actual altitude, temperature, or pressure altitude. One can adjust from the minimum Kollsman window range to the maximum, see the altitude change, along with the VNE, and know that the actual altitude has not changed a bit. This is highly unusual behavior.

Regardless, the XCub VNE should likely not change at all, regardless of altitude - indicated, pressure, density or otherwise. It should be tied to KIAS unless Cub Crafters does something really opposite the rest of their fleet.

My data are attached.

XCUB G3X Flight Tests.xlsx