Sonntag, 22. November 2015

Black Bullet

Aus Black Bullet
Get the Quad here:

This is my first really fast Quadcopter. The Trincopter was quite fast also, but this smaller one here has tilted motors - which makes all the difference! It's just so cool to feel this "urge to fly forward fast" from the quad! Nice option here to change a few screws and have the motorarms straight or angled (3 steps: 0°, 10° or 20°). 

The build was fairly easy, you have a good ammount of space in the quad. Battery compartment is large enough to hold an 2250 4cell - maybe even larger. But the best performance is achievable with small and extreme Lipos (1300mah Gensace 75C).

   ESCs: 4x 12A SimonK Maytech (without BEC)
 Motors: 4x T-Motor MN2206 - 2000KV
  Props: 6x4.5 ABS Gemfan Carbon reinforced
Battery: 1300mah 4cell Gensace 75c (3mins) / 2200mah 4cell Turnigy 45C (6mins)
 Weight: 720 / 820gr (with either Gensace or Turnigy)
620g (3s1300) - 700g with 4s1300 and Mobius
 Seperate BEC for powering the Naze32 board
Flightcontroller:  Naze32 with cleanflight 1.10 and Luxfloat PIDcontroller

PID Tuning:
BLHeli FW / ONEShot125
8.12.2015: Updated the PIDs below after some testflights with the new setup. Flies quite stable and smooth now!
Cleanflight 1.10
Oneshot125 enabled
Controller 2-Luxfloat

feature RX_PPM
feature FAILSAFE
feature ONESHOT125
set looptime = 2400
set rc_rate = 110
set rc_expo = 60
set rc_yaw_expo = 0
set thr_mid = 50
set thr_expo = 0
set roll_rate = 40
set pitch_rate = 40
set yaw_rate = 30
set tpa_rate = 53
set tpa_breakpoint = 1500

Issue with Yaw on fast miniquads (not only this here):
Reproduceable - on 45° dives from some alt and with some speed, you "feel" that yaw get's unstable and suddenly it snaps 90° (or more?) to the right (most of the times).

I tried so many things (mostly PID tuning and trying different PID controllers in Cleanflight 1.9.0) but nothing helped. After I changed to DIFFERENT PROPS!  the problem went away.
First set of props were normal, plastic Gemfan 5x4 (balanced with sandpaper) and the new ones were also Gemfan 6x4.5 carbon reinforced ones.
I think with the weight of around 800gr the quad was too heavy for the small props.

UPDATE: my friend Prometreus was also testing this quad and found that moving to BLHeli ESC firmware and using Onshot and Active Damping help to get the quad stable.
=>Video tutorial how to flash the Maytech ESCs to BLHeli

Links, Tips:
Black Bullet Buildlog (GERMAN) from Prometreus
Black Bullet Thread

Android App for Cleanflight
FPV-Community Cleanflight Thread
PID Tuning Knowledge: