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Old 07-26-2017, 04:56 AM   #76 (permalink)
Velos Rotors
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Join Date: Apr 2015
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That is a really cool application Allan. Now I Imagine your Velos like a fire fighting machine taking out fires in difficult to reach places.
Instead of water tank it will be connected to a big fire extinguisher..

There are many ways to increase the flying time of a helicopter.
The one I prefer is to make it more light weight but that is not an option here.
So bringing the rotor rpms down will certainly help to increase the flight time and particularly by increasing the gear ratio or bringing the motors KV down.
For example 400kv motors will bring the rpms down by 450 rpms compared with 500kv motors.

450kv motors will bring the rotor rpms about 230rpms lower compared with the 500kv ones
The above values are approximations when using the 22T stock pinions that come with the Velos.
Regarding the pinions 2 teeth less will be equal to about 50kv less on the motors.
But having the motors spinning at lower rpms is the best way to do it. And reducing the throttle on the ESCs is the worse way to do it.
Also larger batteries can help a lot with the flight time.

Now what is the ideal rotor rpms? This is not a fixed number. It depends a lot to the maximum take off weight. But values of about 1500 rpms are good to start the experimentation and from there you can adjust up or down accordingly.
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