# Confusion with the $\lambda$ in this experiment

I am still having trouble seeing why on this manual for experiment ideas, that they say the $$\lambda$$ is constant. My question is, how do we find this value of lambda or why can it be kept constant? If so what would be the constant value?

I will appreciate the clarification.

• I think this is engineering and should be addressed there engineering.stackexchange.com – anna v Jan 27 '19 at 5:18
• This is presumably explained in the article at the Physics Teacher linked at the end of the quote - and that link has been lost in the screenshot. – Emilio Pisanty Jan 27 '19 at 5:28
• – Farcher Jan 27 '19 at 12:29
• It is certainly not about engineering. The context is a home-experiment, but the question is about the meaning of a parameter is an expression for the rotor-wing lift. Which means it is not even really a [experimental-physics] question, but instead a [fluid-dynamics] one. On the experimental side, the set-up displayed in the image is problematic insofar as the results will be affected by a non-trivial ground-effect. Attaching the drone to a latticework attached to the scale would yield slightly better results. – dmckee --- ex-moderator kitten Jan 27 '19 at 17:53
• @dmckee also, the rotor downwash hits the plate, and it's not at all obvious to me what the effects of that will be. – Emilio Pisanty Jan 27 '19 at 19:09