Roll and pitch combined upsets require special attention.
The loads to speeds graphs appearing in the aircraft flight envelope charts are for a single input deflection.
Engineers consider each axis separately in designing for the air loads accompanying a full control at any flight speed up to Maneuverin Speed (Va) in aircrafts flight envelopes.
Inputs on more than one axis simultaneously need to be taken into account separately.
Two factors need to be kept in mind during a banking pull:
The pull to counter the centrifugal forces and the increased apparent weight of the bank , are two forces adding to each other.
If the ball is kept in the middle, loads will be symmetrical both the wings and fuselage will feel the same acceleration levels.
The next factor to consider is when rudder is simultaneously applied to the pull wether in a bank or not this increases the load on the rudder’s side wing.
Inputs in more than one axis, like inside rudder while pulling then unloading (Aerobatics pilots know this maneuver as a "Flick" or "Snap Roll) will load inside wing approx 30% more than the G meter will display on fuselage panel G meter.
"Design loads" are another story they are structural "G" margins accounted for in certification as safety buffers expressed in percentage:
In "Normal" category, G loads are factored at 3,8G's + 50% margin; Structural failure should not occur before 3,8G's + 50% = (5,7 G)
In "Aerobatic" category positive G loads are min 6 G's + 100% = (12 G)
Last edited by markkal; 8th December 2024 at 18:06.