Torsional Loads
Beech18Bob
I recall, late 60's, seeing Airspeed Ambassadors doing engine runs on their twin Centaurus radials. The torsional oscillations of the triple finned rear fuse was quite alarming - at least 12" displacement. What it did to airframe life let alone PAX nerves can only be imagined. But, the tail never fell off so it must have been strong enough.