X8 Carbon with total weight 4kg

Hi Guys,

I had first maiden with my X8 carbon yesterday. This is my spec:

800 kV motor, max 1250 watt

13x6.5 propeller

2x 4S 5000mAH 25C

Castle 80A ESC

Total weight 4kg

my X8 failed to take off... could someone help me to give advice about my spec, which part should be replaced or else?

Thanks in advance,


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    • Your propeller is on backward. The numbers on the hub need to face forward.
    • You haven't confirmed that your prop isn't on backward. That is the most likely cause.
      I agree that hand launching is dangerous, but it should be easily done with the specs posted here.
    • Iskess,

      The propeller is in correct position as your said. Tested before flying, X8 has forward thrust .

      The battery, I mean 6S 5000 mAh 25C.

    • I won't belabor the point, but just so you are aware, if your prop is on backward you will still have forward thrust, just not enough. Do you have a scale to measure how much thrust you are making? You don't need to crash the plane to determine this, just calculate the thrust:weight ratio. I'm guessing you should have at least about 2-3 kg of thrust. Just hold the plane nose down on a bathroom scale and give her max throttle for a few seconds to get a rough estimate. Better have someone help you so you can stabilize the bird with both hands. You could also measure the wattage output at max throttle and see if it makes sense. You should see around 700W+ Watts.
      Make sure you don't use a coarse pitch prop as this will limit your static thrust in exchange for top speed. A pitch of 8 might be too high, stick with the 13x6.5. 4s should be fine.
      Post some photos, maybe someone will spot the problem.
    • True.

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