The centripetal force can be measured by placing a strain gauge between the hub and the blade. Some may think that is measuring centrifugal force. The question is, is the blade pulling away from the root (centrifugal) or is the root pulling the blade towards center (centripetal). Since strain guages normally aren't directional, the instrument won't tell you which is being measured.
The force at the hubs is fairly easy to calculate. It will mostly be centripetal force, and I expect some other aerodynamic stuff could add a bit. The centripetal force is a function of mass distribution and rotational velocity.
Basically, you know how much you have to accelerate the blade to keep it close to the hub, since you know where the mass of the blade is located and the speed it will be spinning, you can work out what force you'll need.
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Regarding college learning, I probably didn't come across too clearly, but I essentially agreed with you. Textbook learning provides a foundation. What you actually use is subsequently learned in the real world, but should require that foundation. Not just in knowing, but in understanding.