Mmmm ....
...
I've been doing some work on and off over the last few years on the aerodynamics and dynamics of slung loads, and one thing that no-one is really sure of is why some loads spin on a single strop (in forward flight) and others don't....
Are you serious ?
The answer is quite simple ... you don't know what is going to happen till you pick up the load ...
There are so many variables ... aerodynamics, GoG, type of rig, length of line, speed of flight etc etc
That is why you get the 'big bucks' to fly this kinda stuff ...
Find a good external load instructor and get him to explain it to you ...
It took a lot of time for me to learn how it was done (and a lot of that time was in New Guinea with a 330 J Puma flying 4500Lbs of drill pipe and some awkward pre-fab buildings) so I do know how to do it ... alas with some things there is no substitute for experience ...
Anyhow I am in Texas with a 'big boobed blonde' and drinkin Tequila shots so I really don't give a **** Y'all ...
Cheers