Whirls,
I am surprised at you! I would have thought you were devious enough to figure out how to use Bell rotor blade JuJu on the Bell 2 series of helicopters.....the ones with the two blades.
Now Nick, Dave and other techno geeks will tell you the blades react to the various breezes that blow about the head and thus one of the blades will drop to a decent level. Dave would go so far as to describe the nine thousand and twenty three different collective and cyclic settings that are required to cope with all the various possible winds and wind speeds, gusts, and vortices.
I ascribe to the use of JuJu (or as the more professional CAA folks would call it...blade psychology).
With many years of chasing about the helicopter trying to hook a blade in a manner that greatly mimics herding cats....I finally figured out the way to ease that struggle after each flight.
One should simply take the tie down into hand....walk to the blade that is the highest in the air and speak softly out loud...."I think I will tie down that blade there!" all the while looking at the opposite blade. Do not move from your spot...continue the Litany all the while looking at the far blade...even point your extended index finger at said blade. After about the three repetition, the high blade over your head will politely droop to your hand.
Should the blade remain recalcitrant and linger just out of reach....or not move at all....merely say...(out loud) "No...on second thought...I think I will tie that blade over yonder down...and take about two steps in that direction....and hesitate just a second and return to your original position. The blade will politely drop to within reach.
Absolutely fail safe .....I promise!
Ask HIHU....he is a convert to this. I taught him this techique while we were flying the Huey.
Also....stand on the upwind side when you fling the tennis ball over the blade.