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  1. #1
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    Question Can I build a quad-copter with these components?

    Hello,

    My brother was doing a very "Ambitious" project in college, to make a quad-copter. He bought some parts, designed and made the frame and had them installed however never got to finishing it.

    He gave me the parts from the project as he moved and on no longer has the will to finish it due to time and money. However I do have strong will to finish. I took a picture of the components he gave me... I never worked with any RC planes or Helis... or even quad-copters for that matter so have no idea. I did however had a chance to work with arduino in college and have my own set and as far as I know quad-copter requires a arduino system to operate. As well as gyros which are missing.

    I am attaching photos of the components I got from my brother this includes:

    4 x JP EnErG brushless 600 0/R 1100 (C35-14) motors (quite big ones)
    4 x GWS GWSESC45A Servo?
    2 x Lithium Polymer Battery

    Obviously I need more components but this site seems to have a lot of tutorials that I can use to get started and I have access to CNC machinery in College to manufacture frames.

    am I on the right path?

    Thanks!

    MiloClick image for larger version. 

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  2. #2
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    Yes .. you are on the right path ..

    The 45a things that you called a servo are Electronic Speed Controllers ( ESC's ). Which may be a bit of overkill. How big of a quad was he planning on building ?!?!?

    I ask because I use 18amp esc's on my 1.5 kilo quad with 10 inch props. And a 35 on my FBL 450 single rotor ( with a rotor disc of just over 700 mm ) 45 amp esc's be better suited to swinging some LARGE props.

  3. #3
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    Quote Originally Posted by kevo View Post
    Yes .. you are on the right path ..

    The 45a things that you called a servo are Electronic Speed Controllers ( ESC's ). Which may be a bit of overkill. How big of a quad was he planning on building ?!?!?

    I ask because I use 18amp esc's on my 1.5 kilo quad with 10 inch props. And a 35 on my FBL 450 single rotor ( with a rotor disc of just over 700 mm ) 45 amp esc's be better suited to swinging some LARGE props.

    Not sure how big... apparently it was meant to lift some extra equipment. perhaps camera or anything like that.

    Do you mean these Electronic Speed Controllers are bad? will they not work?

  4. #4
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    That's not to say 45A ESCs won't work, though.

    What you need still:
    Flight controller - AeroQuad uses Arduino and shields
    Sensors - the sensors you buy (you need either 3x gyros or 1x 3-axis gyro) go on the shield that attaches to the arduino
    Power distribution - you need a way to get power to the Arduino and 4 ESCs, this can consist of a wiring harness (ex: Daedelus Power Harness in AQ Store) or something else, like a power plate (Flyduino makes one, I make my own using copper clad PCB)

    The motors you have are 1100kV motors, meaning 1100 RPM per volt, which works well with 8"-12" props. I don't know what size your props are but they look a little on the small side (also, 3 blade props are less efficient than 2 blade due to increased surface area. They do, however, pack more thrust in a smaller diameter, if you're short on space, which normal sized quads generally aren't). Here's a table of how the motor performs with different props on it. Looks to me like it works well with a 3S battery (3 cells in series) 11" and 12" props, particularly the APC 12x6 prop (6 being the pitch, not amount of blades).

    Honestly, those motors seem overpriced... There are other motors out there that are much cheaper and give similar thrust with much less current draw (aka more efficient). But, you've already got them, so ya may as well use them! However, because they draw so much current, you're going to need a pretty big battery. Your batteries look awfully small, what are the specs on them?

  5. #5
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    Each blade of the prop is 3,5 inch, the battery specs are :

    JP EnErG Pro 18 18c Lithium Polymer 11.1V 2500 mAh (3S1P) 18C Continuous 45 Amps, 30C Bursts 75 Amps

  6. #6
    Senior Pilot wooden's Avatar
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    Yeah that battery is approximately 1/4 the size you need. It can provide 45A continuous but each motor you have pulls close to 45A individually. You need a battery that can provide at least 40A*4, so 160A. This means an 8000mAh 3S 20C battery, or 4000mAh 3S 40C battery. Lower C is more efficient and generally lighter for the same capacity.

    Those props are 7" props if each blade is 3.5". Much too small for these big motors.

  7. #7
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    What would you recommend ? Do you think I should just get another set of props and batteries or... sell the motors I got and buy smaller cheaper ones, keep those props and batteries and buy the rest of the equipment?

  8. #8
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    They're also tri-blade props. They're usually worse on a quad than normal two-blade props. For those motors, you'll probably want 10 or 12 inch props or some type, and a much larger battery.

    How heavy is the frame, and what are its dimensions from tip to tip (measured going through the center)? A photo of the frame would help.

  9. #9
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    The old frame was thrown away, I am planning to make a new one.

  10. #10
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    I would probably sell those motors and props, they're VERY expensive and not very well suited to a quad that isn't huge or designed to lift heavy objects. Those batteries will work decently for smaller motors but you'll probably want a little more capacity to get longer flight times. Sell the ESCs too as they're WAY bigger than you'll need for a normal sized quad.

    I'm not sure where your brother was planning to take this quad but it looks like he didn't do enough research on how to choose motors, props, and batteries. It seems like you might just want to start from scratch, you'll likely learn a lot more as well.

    To decide what motors, ESCs, props, and batteries to buy, you'll need to know how much everything else weighs. So, you'll have to at least start building a new frame to get an idea of how much things are going to weigh, and then you can start picking motors that will work well with the weight of your frame/electronics.

    I've explained this in other threads but I'll throw it in here too as I can't find them right now:

    To choose motors, find the approximate weight of your quad without motors, ESCs, and battery. Typical motors are 40-75g each, ESCs are 20-50g each, and a battery will probably be 300g+. Knowing this, you'll need to multiply the approximate full weight by two and find four motors that can provide this thrust.

    Example: Your whole quad weighs about 1.5kg after all is said and done. Multiply this by 2 and you get 3kg = 3000g. Divide this by four and you get 750g - each motor you put on needs to provide 750g thrust at full throttle. You want this configuration because it means 50% throttle provides thrust equal to the weight of the quad - aka the quad will hover at 50% throttle, which leaves lots of head room for moving around and arresting fast descents.

    Now that you've chosen motors, pick ESCs that are rated for the max current draw of each motor + a few extra Amps (for headroom). The motors on my bigger quad pull about 22A at full throttle, so I'm using 25A ESCs.

    Next you choose a battery that can provide enough current for all four motors simultaneously. Continuing with my motors as an example, they pull 22A each at most, or 88A combined. To figure out how much current a battery can provide, multiply it's C rating (the discharge rate) by its capacity. I use 4000mAh 40C batteries - which are overkill but give longer flight times - 4000mAh * 40 = 160000mA = 160A. I could get away with using batteries with a lower discharge rate (which would be more efficient) but this is what I have.

    Finally, check out the specs of the motors to see what props work well with them. Pay attention to the thrust and current draw at max throttle.

    Hope this helps!


 
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