Truth is somewhere in between polar positions
For the purpose of safety my group designed a concept for de clutching a conventional anti torque tail rotor on the ground. Of course unlike the X-2 concept we needed to re engage the tail rotor prior to take off.
There was never a concern on bearing fretting when de clutched. We didn’t brake to halt rotation, we used max pitch to dissipate inertia. Therefore there was always go to be creep from clutch drag and external forces. This was actually a concern to some, but we didn’t want the added weight and complexity of a brake.
Our tail gearbox was splash lube. Getting to an acceptable operating temperature came quickly after less than a couple minutes. Less than the time to complete preflight. On the X-2 they can engage after take off and wait a bit if required before increasing pitch.
We never got beyond the test bench stage. No technology issues. Just cost and weight impacts were unacceptable.
Last edited by CTR; 13th Dec 2019 at 17:01.