My home made copter balancing rig

Discussion in 'Cinestar Misc' started by Dave King, Feb 16, 2013.

  1. Dave King

    Dave King Well-Known Member

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    I wanted a precise way to balance the copter while suspended so I could get the most accurate balance reading. I've seen guys use bungy cords and anchor them from the battery tray but I didn't think it would be the most consistent way to go about it. So I took the stock battery tray measurements and created an aluminum plate that would bolt on top of the existing battery tray. MSC had the biggest selection of standoffs that I could find but even they didn't have anything longer than 24m bolts so I decided to just take 2 of them and stack them to give me enough room for the batteries. For those interested I used M3X25MX4.5m standoffs MSC part #77124410

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    I'm using 80 pound fishing wire and a fishing sinker with a loop under the plate for the mounting point. The hole in the aluminum plate is exactly in the center of the copter. I used the center of the battery tray for reference.

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    As you can see my copter isn't very weight balanced because I have my FPV transmitter, Voltage regulator for the orientation lights, and Xbee all toward booms 2 and 3. I will temporary balance the copter by putting the lipo on booms 7 or 8. The FPV camera isn't mounted on here yet as well which will affect the balance point slightly. I'm going to try to balance it without the camera gimbal in case I want to flight it without it. I will then balance the gimbal and then with the gimbal bolted on the copter it should be very balanced.
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  2. Jim Swanson

    Jim Swanson Member

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    Nice Job Dave. For any newbie or stubborn oldie, balancing the props, gimbal, AND the final set-up is super important. This will sound silly, but I would have bought a "balancing system" from Freefly (with instructions or videos) if it was available. What we have now is a collection of ideas, which is great, but for newbies a set of plates, bubble levels, strings, weights, etc might be nice.
     
  3. Pavlos Antoniou

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    Thas how i balance my gimbal..! i put a wire on the center hole and then i put helicopter shaft and i balance the gimbal..!

    I will try the copter too :) :)

    Why you put a second plate and you dint use the battery plate itself??

    Also how can i undestand if the lipos must be one near the other and not one above the other??
     
  4. Dave King

    Dave King Well-Known Member

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    I used a second plate to get the true center of the hub/copter. I've seen people use bungy cords and several mounting points that join to one mounting point above the battery plate. The only way I can see this being accurate is if the mounting points on the battery tray where spaced exactly the same distance away from the center point and that all cords have exactly the same length. With the second plate I can put a mounting dead center of the copter with one single mounting point and not have to worry about mounting points and lengths etc.

    As for the batteries, I mounted them side by side to keep the center of gravity low. I don't think it matters much though.
     
  5. Pavlos Antoniou

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    it matters a lot...! the thing is to have the CG on the center and not low..!

    So if the gimbal is heavier you have to put one bettery above the other in order to have th CG on the sender of the copter ...!

    What you think?
     
  6. Jim Swanson

    Jim Swanson Member

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    I've noticed that my GH2 on a 2axis Freefly with Radians has slightly less shake when running dual lipos side by side. My unscientific guess is that extra weight on top helps steady the copter and makes the cg better.
     
  7. Pavlos Antoniou

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    Hmmm yes...! but on the same SHip if you put a 5D??? what would be better???!
    Side by side or one above the other??!
     
  8. Dave King

    Dave King Well-Known Member

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    I used to think like yourself but I don't think it matters because if look at the guys using the red cameras, their CG is way below the hub and they fly fine. I think the biggest thing is to make sure the copter and gimbal are both balanced. There's plenty of room for 2 batteries on the stock tray, many people fly with thati successfully and I like repeating successful combinations.
     
  9. Dave King

    Dave King Well-Known Member

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    It doesn't really matter provided both the copter (AKA ship) and the gimbal are balanced. Here's what I have done.
    Step 1 Balance the copter with no landing gear. My copter was slighlty off balancle because of the FTP camera, and navigation mounted on boom one. I counter balanced this by putting my FPV transmitter, wireless USB, and step down regulator on boom 5 as well as used a smaller/lighter camera on boom 1. You won't believe how even 20 grams changes the balance of the copter.
    Step 2. Balance the gimbal.
    Step 3. Put the gimbal on the copter and recheck. After I did this I didn't have to make any balance adjustments.
     

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