Our spanner wielders tell me that,
from an engineering viewpoint:
- pulling/pushing on a fixed pitch prop is acceptable providing it's done only at the root
- pulling/pushing on a C/S prop is NOT acceptable because it kna^&ers the bearings. Apparently the centripetal force when the prop is spinning tends to make the bearings much more "solid" and they can then accept the thrust loadings (and the nasty things that aeros do to them), this is not the case when stationary
- it is acceptable to lift the nose by pushing down on the rear fuselage, providing it is done over a frame
- it is NOT acceptable to push down on the tailplane
Your Spanners May Vary
HFD