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K'NEX QuadCopter Project

Posted by VINCENT Christopher on October 9, 2011 at 6:44am

Hi,

 

I'm new in Multicopter hobbies. I'm french so excuse me for my  poor english.

 

My project : Create a quadricopter with K'nex parts.

 

I have created my frame its weight : 450g.

I have 1 or 2 Lipo pack 3S 5000mAh 30C (360g each).

 

I'm searching a good motor but i think i need help..

In fact i want have 10min run time. But i can't use Motor AC2836-358, 880Kv because 450g + batterie is too big isn't it ?

 

If my total weight is 1500g :

 

i need 4 motors with max thrust 375g. Or i have seen on this forum that the best practice is to set motor at 1/3 ratio weight/thrust

 

375g x 3 = 1125g so i have choose this motor :

: http://www.hobbyking.com/hobbyking/store/__18228__Turnigy_D3536_8_1000KV_Brushless_Outrunner_Motor.html

 

Battery: 2~4 Cell /7.4~14.8V
RPM: 1000kv
Max current: 30A 
No load current: 1.7A
Max power: 430W
Internal resistance: 0.052 ohm
Weight: 102g (including connectors)
Diameter of shaft: 5mm
Dimensions: 35x36m
Prop size: 7.4V/11x5 14.8V/10x6
Max thrust: 1160g

 

Max current is 30A and i think that the average is 1/3 of this (on an normal flight) isn't it ?

 

This page  said me that my fly time will be 10minutes with 5000mAh / 30A: 

http://www.scoutuav.com/2011/05/12/calculate-flight-time/

 

Can you confirm this ? (I know it is an estimation sure :) )

 

Thanks for your reply

 

PS : i will post some photos later :)

 

Christopher

 


 


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Replies

  • VINCENT Christopher October 9, 2011 at 9:19am

    Sure i don't need to limit max thrust. Just don't push max my stick lol.

     

    I think that the AC2836-358 is a good idea :)

    I will buy it and post some picture of my quad there :)

     

    thanks

     

    Christopher

  • VINCENT Christopher October 9, 2011 at 8:06am

    I think i have found compromis :

     

    K'Nex Frame 450g

    Electronique 100g

    Lipo 360g

    Motor (AC2836-358, 880Kv) 288g

    Esc 84 g

    Total  1282g

     

    1282g / 4 * 3 = 960g

     

    With this configuration, AC2836-358 need  to thrust 960g max (with 1/3 ratio)

     

    ower out put from ESC, 3S LiPo, 12x45 Propeller

    		25% 50% 75% 100%
    Amp
    Wattage
    Thrust    		 1.5 A
    17.5W
    230gr    		 6.1 A
    70W
    650gr    		 14.2 A
    160W
    1290gr    		 20A A
    210W
    1380gr

    If i set my ESC at 75% my motor can thrust 1290 that is better than 960g.

     

    14.2*4 = 56.8A if i set full gaz constantly

     

    if i estimate that average will be at 1/3 :

     

    56.8 / 3 = 18.93

     

    http://www.scoutuav.com/2011/05/12/calculate-flight-time/ said me more than 15min fly time.

     

    I think it is a good solution.

     

    Anyone can confirme that ? Thanks for your interest

     

    Christopher

    Calculate Flight Time of LiPo Battery
    Before we can calculate flight time, we need to know the average amperage the quadcopter will draw.  Once we have the average amperage draw we can th…
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