Know How...

Jan 18th 2018

Know How... 365

MultiRotor 101 - Part 2

Prop balancing, InSpectre, and the Nebula Capsule projector.
Although the show is no longer in production, you can enjoy episodes from the TWiT Archives.
Category: Help & How To

Want an easy-to-use tool to see how vulnerable you are to Meltdown and Spectre? Tired of "Jello" videos from your drone? Feel like building the 2018 Alien-X? Need a soda-can sized, Android-powered pico projector will full-size features? -- Padre and Jason have the answer to all of these questions on this flu-ridden episode of "Know How"!


  • Written in Assembly by Steve Gibson
  • Only 125k (would have been much less except he had to include a picture to make it a legit Win10 app)
  • NO INSTALLATION (Runs directly from the executable)
  • Will examine your vulnerability to both Meltdown and Spectre
  • MAY cause false positives with AV suites b/c it allows you to enable/disable protection (malware behavior)

Prop Balancing
Unbalanced props are the #1 reason for "jello" video.

  • They can also cause premature wear on the multi-rotor's motors and frame
  • Not to mention that the excessive vibration can cause innacuracies in the FC's sensors

Spinning at a few thousand times per second can turn even a small imbalance into a major vibration

So what we need to do is to balance the prop so that weight is as equally spread around the blades (and hub) as possible

Tools and Materials:

  1. A prop balancer
  2. Level
  3. Tape or Sandpaper


  1. Assemble the Prop Balancer
  2. Place the prop balancer on a level surface, then level the prop balancer with your bubble ruler.
  3. Mount the prop on the beam, making sure that it's snug in the holder. Turning the prop should turn the beam and vice-versa. -- If the prop isn't properly secured, it will wobble, which will invalidate the balancing.
  4. Place the beam between the arms of the balancer, making sure that it freely turns.
  5. Spin the prop/beam assembly and watch for wobbles. If it wobbles, the prop isn't properly secured. 
  6. Set the prop so that both blades are equal distances from the table surface, then release.
    • The heavier side of the prop will fall.
  7. Add tape to the lighter blade, or sand the heavier blade. -- Repeat the test.
    • I prefer to add no more than 2 pieces of tape, always on the underside of the blade. 
  8. When you can position the prop in any position and it stays in that position, then it's balanced.
    • It's possible that the HUB is unbalanced. If so, you'll notice that the prop tends to balance with the heavier side of the hub down.
    • If that's the case, you can sand the heavier part of the hub.



  1. Power up Craft
  2. Enter "Receiver Test" on Flight Controller
  3. Test all inputs. Reverse channels and/or swap cables as needed
  4. Set Subtrims
  5. Set motor layout to "QuadCopter X"
  6. Calibrate ACC
  7. In "Mode" set "Self-Level" to "AUX"
  8. In "Self-Level" set P to 30 and I to 20
  9. Check motor rotation. Flip pairs as needed
  10. Calibrate ESCs
  11. Install props
  12. Balance Center of Gravity

Syma X5c

  • Hovering above the ground effect
  • Nose Out
  • Circle of Death
  • Nose In

Nebula Capsule

  • DLP 100 Lumen (30,000 hours)
  • 854 x 480 Resolution
  • 4 Hours Battery Life
  • 360 Sound (has Bluetooth conenctivity)
  • Can be controlled via a phone)
  • Android 7.1
  • 1 lb
  • Input: Wireless, HDMI, USB, Bluetooth
  • Up to 100" size (Really best around 30")
  • AutoKeystone

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