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How big an issue is balance?

Discussion in 'Phantom FC40 Discussion' started by 2014fc40, Mar 20, 2014.

  1. 2014fc40

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    I've noticed mine takes off forward when it should just go vert.

    I plan to replace the props with 9" CFs. I'd like to balance it if needed. Should the software be updated aside from lowering the trims? Can it even be balanced through software?
     
  2. Tahoe Ed

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    Balance is a big deal but the Phantom is pretty well balanced from the factory. Make sure that your new props a well balanced. Not all CF props are made equally.
     
  3. ericdes

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    Any weight added to the Phantom can throw off the balance, even more on takeoff. They tend to lean forward. In that case you can adjust the gain values.

    As for props, you really need to balance them. It will save the bearings, remove the jello and overall performance.
     
  4. jerrymac12000

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    Some of the experts can correct me if I am wrong.

    If you look at the FC40 from the side, you will notice the camera mount is forward of center. Therefore, the center of balance is toward the front of the quad. Just appying power for lift will move the craft forward. As the craft lifts into the air, the internal gyro and the electronic motor controls take over adjusting increasing forward prop speed to balance the front and rear of the quad.

    If you remove the camera and mount, the craft should lift up when power is applied. At this point a gain adjustment may be needed IF the craft still tends to move forward.
     
  5. ericdes

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    Yep, and swapping for a gimbal and gopro makes it much worse. You need to floor it on takeoff so it doesn't tip over.
     
  6. 2014fc40

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    OK, props; seeing as these props will have nuts like the stock props, whats the accepted method for balancing?

    Can I stick a nail through a piece of wood and just set the nut over it?
     
  7. chrisc

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    Have to agree massively. At the moment the FC40 I have is stock apart from V2 prop guards and on take off it does like to tip forward. Taking off in long grass is a complete nightmare but once in the air it is perfectly stable.

    To be fair it is obviously quite front heavy with the camera mounted right at the front. I suppose you could spin the mount around and have it mounted more in the middle but then you'd probably get its landing legs in the shot when you are videoing.

    Either way, whacking the throttle hard or just applying a bit of down on the right stick seems to work without any issues. If I jab the throttle and let give it a bit of power it doesn't seem to have time to tip over it just lifts off. If I try to go slowly then it often starts to tip.
     
  8. Shrimpfarmer

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    I agree with the advice to give it full power on takeoff to avoid tipping over. As soon as its left the ground throttle back to the height you want. They do tip forward and you just have to compensate for that until its found its balance in the air.

    As for carbon props I think they just turn your quad into a much more dangerous machine that can seriously hurt you or someone else.
     
  9. EMCSQUAR

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    Something I've found to help offset that "front nose heaviness" -> when I do an advanced IMU calibration, I raise the front of the legs approx 1 inch. I prop the front of both landing gears with 2 small screwdriver handles. Mine is extremely heavy being fully loaded w/IOSD, Gtu 10, Futaba RX, Zenmuse and 2.4 data link (all of the components are packed into P2 shell) she's in the 1500g area w/P2 battery. She's not quick but smooth as glass.
     
  10. 2014fc40

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    Everyone mentions the camera. And sure it's not centered. Not sure why that would be except maybe for visual clearance when shooting straight ahead.

    But the battery; its about %25-30 forward of center by my calcs. When I have some time I'd like to remove the cam and bracket, insert battery and see where on the craft I can find the balance point. If it happens to be center then I'll know my off-center weight is all camera.....

    But I doubt it will be center. That battery is too far forward.
     
  11. syotr

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    I have extended the battery compartment on my Phantom to shift the battery to the rear and add more room for larger batteries.
    viewtopic.php?f=4&t=7858
     
  12. 2014fc40

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    Very interesting. Not sure if an FC40 has the "slide room" to push a battery further aft though.
     
  13. dteca

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    I just got my FC40 last week and was thinking of the future with it. A gimbal and GOPro mounted will be a bit forward. So I was thinking about adding a mount for the battery behind the gimbal on the other side of center, trying to somewhat balance the FC40. Trying to stay under the body of the aircraft as not to block the airflow of the props. Then the old battery compartment could have other uses, fpv camera, pmu, other small components. Does this sound feasible?
     
  14. npalen

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    viewtopic.php?f=20&t=14933
    Here's how you can do it. The balance seems to work out great. I did mine the same way after seeing this and corresponding with FCPhantom. He is one great guy!
     
  15. darwin-t

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    I noticed that, especially when I use a GoPro. I made 2 adapters from 1/16" Kydex which move the camera back to the center of gravity. At first, I moved it back 1 1/4". Even with the standard landing gear, my GoPro didn't show the landing gear at all.

    Then I made another one which allows me to use my GoPro and also my FC40 camera. I mount it with the camera holder upside down. It sits in front of the camera door. I switched to the taller, wider landing gear at the same town.

    Any material about 1/16" thick will work.

    Oh, when I install my Flytrex, I am going to remove the circuit boards, turn the camera mount around and drill a new hole and install a bolt and nut to hold it in place.
     

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  16. dteca

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    Thanks npalen. I remember seeing that but had forgotten about it. I think that is exactly what i will do.
     
  17. 2014fc40

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    Now I'm in a conundrum.

    1. Gimbals are way cool and help image quality.
    2. Heros don't throw a good enough WIFI signal to use as FPV.
    3. Cant use a gimbal/faux hero/fc40 cam combo together because of weight and balance issues.

    Is all this correct or am I missing something?
     
  18. lake_flyer

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    Hi,

    my first post here.

    After flying my FC40 for a month I found that flying with 2 batteries gives you more stability and smoother control. Because with 2 batteries it is easier to get a good balance. Plus, the added weight makes the Phantom a bit less jerky. First I tried to attach both 2200 3S batteries to both sides on the bottom of the landing gear. This improved the handling and the video's were smoother especially when panning. But in GPS mode the pendulum effect caused the Phantom to overcompensate so I had to think of something else. And then I found a piece of trunking for electrical wiring laying around in my garage, such as this: http://www.wickes.co.uk/Mini-Trunking-25x16mmx2m-White-PK1/p/109644.

    I cut off two pieces of about 1.5 x the battery length and drilled a few holes in them and attached them on each side with tie wraps to the arms and upper part of the landing gear. This was only meant as a temporary setup, just to test it. The batteries fit tight and slide in the rails/trunks. After that I turned the Phantom upside down, on a scale, so I could find the center of balance and check the weight. I slided the batteries in the rails until I found the perfect balance with Gopro (no gimbal yet) and FC40 cam (mounted to the battery door with velcro). Then I secured both batteries with a velcro strap and I was ready to do a test.

    The Phantom rose up completely level. Flight time seemed to have improved as well. I have my Lipo alarm on 2.5 and I got well over 15min flying time with a minute to spare before autolanding. Flying was so incredibly smooth, I just can't believe it. Total weight is around 1250 grams but there was no sign of any problem for the Phantom to lift itself with the stock props. With full throttle it just takes a little longer but then she gets up in air in a straight line and she hovers completely stable. Didn't need to do anything with the gains at all, they are all default.

    This way, for just a few bucks you can get the best and most flexible dual (or triple even when you use the battery compartment as well) battery setup you could wish for. If you add weight in the form of extra camera's, gimbals, FPV stuff etc, you can just adjust the position of the batteries by sliding them back or forth. You can also easily attach other stuff to the rails as well.

    A little bit nose heaviness turns out to be best for fun flying I found out. But you can adjust so if you want the smoothest possible video you just balance the Phantom perfectly so you have the same tilt on every side. That way, when using course lock, the Phantom will stay level wherever you point the nose (depending on your flying atitude).

    I'll see if I can make a few pictures or video of the mod. Don't know how to attach a picture here right now....

    Cheers
    Jan
     
  19. lake_flyer

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    Found it! :)
     

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  20. zerodb

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    Not sure why everyone is so in love with the carbon props... even in my 1-2 days of forum lurking while I waited for my Phantom to arrive I could see that people universally have better results using standard DJI Phantom 2 props instead of third-party carbon props. Do they really look THAT cool?