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I have a project to work on it (quadcopter or "drone") and for that I need to calculate the force that my system {motor+propeller} can provide in order to make the right "basement" mass .. i've searched for some few days and i couldn't really find any software or link that can give me a clue about the way i can calculate it, so i wanted to make a dynamometer by myself and then hook the motor with the the dynamometer and simply conclude the force generated .. yet i've found lately some informations about that. so i thought it could save me some time, and plus i would really know how to calculate the exact force because a dynamometer won't give me this but ll make it as near as possible to the theoretical value.

i've found this guy who nearly asked the same question Calculate quadrotor propeller torque due to aerodynamic drag

after i read his question/comment, i'd find out that he said that he was using the wrong formula, and then he corrected it like this enter image description here

now i've found the same formula in this link :

http://aerotrash.over-blog.com/article-les-helices-pour-les-nuls-88886705.html

that gives the same last formula enter image description here . this link was helpful to understand a big part of my question, but what rests is how would i calculate Ct ( lift coefficient ) because in this link, it says that's it's proposional to J (Progress Report) which is given by this formula J = V/n.D which is also propotional to the speed of movement ( speed of flight )

Ct = f(v)

which lead me to another question, if my quadcopter is on ground ( not in the air ) and i want to lift it up, but according to what i just said, the $T = 0 N$ because $Ct$ would be also equals to zero according to these diagrams.

My question is how can i calculate the $Ct$ factor?

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    $\begingroup$ There's a ton, and I mean A TON, of resources available on the web that answer this question in any detail you may wish for. Just use Google for this topic that is much more about engineering than it is about fluid dynamics or physics; or you can try Physics Stackexchange instead. $\endgroup$
    – Pirx
    Commented Jan 23, 2017 at 15:11
  • $\begingroup$ yes i know, i'm a mechanical engineer student, and this topic is just about fluid, i just wanted to know how can i calculate this factor, it's nothing about engineering, maybe it's more about fluid than any other thing, thanks anyways for your comment $\endgroup$
    – Med malik
    Commented Jan 23, 2017 at 15:19
  • $\begingroup$ @Medmalik This does seem better suited to engineering.se since it's not really a question about the physics, more about the design calculations. $\endgroup$
    – JMac
    Commented Jan 23, 2017 at 15:39
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    $\begingroup$ I've not looked at this problem before, but the way I would approach it, low budget, is construct a pendulum to suspend a single motor/fan candidate. From such a fixture you can measure the pendulum angle vs motor current and back out thrust force if that's what you are after. $\endgroup$
    – docscience
    Commented Jan 23, 2017 at 15:40
  • $\begingroup$ Finished reading your post. From theoretical calculations you would get theoretical thrust. From the pendulum experiment, actual. The two would give you $C_t$ $\endgroup$
    – docscience
    Commented Jan 23, 2017 at 15:41

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