The letter is to a witness to a recent mishap here, and I am chairman of the investigation board. The letter has to look nice and professional. The committee won't meet again for a few more days, but I have to do my homework. After mailing off the letter, I settled in to evaluate a technical proposal from a small company. I won't say much about it, because it involved trade secrets and all, but it involves blade tracking in helicopters.
Helicopters get lift from their rotor blades.
They seem like very flimsy items to be holding up an aircraft, when you see one sitting on the ramp, but they get very stiff when you spin them around. When these two forces are in balance, the blade flies at a shallow angle above the horizontal. Anyhow, even the most finely crafted rotor blades show slight differences in shape and form that result in small differences in the lift they generate. Therefore, the angle may vary from blade to blade, and the blade tips will not fly at the same height. This company has a bright idea about how this may be done more easily, but I can say no more.