Black Bullet - fast 280 racing quad w tilted arms!

by RCSchim | December 3, 2015 | (0) Posted in Reviews


Get the Quad here: www.Globe-Flight.de

This is my first really fast Quadcopter. The Tricopter was quite fast also, but this smaller one 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 motor arms straight or angled (3 steps: 0°, 10° or 20°). 
The build was fairly easy, you have a good amount of space in the quad. The battery compartment is large enough to hold a 2250 4 cell - maybe even larger. But the best performance is achievable with small and extreme Lipos (1300mah Gensace 75C).

And that's already the first flight video:

ESCs: 4x 12A SimonK Maytech (without BEC)
Motors: 4x T-Motor MN2206 - 2000KV 
Props: 6 x 4.5 ABS Gemfan Carbon reinforced
Battery: 1300mah 4 cell Gensace 75C (3mins) / 2200mah 4 cell Turnigy 45C (6 mins)
Weight: 720 / 820g (with either Gensace or Turnigy)
(Vendor): 620g (3s1300) - 700g with 4s1300 and Mobius
Separate BEC for powering the Naze32 board
Flight controller:  Naze32 with Cleanflight 1.10 and Luxfloat PID controller
https://quadcoptersenzo.nl/en/Flightcontrollers/naze32_acro_funfly

PID Tuning:
BLHeli FW / ONEShot125
Current PIDs are not tuned out yet, I changed to BLHeli lately but need more flights with it.
My starting point
Cleanflight 1.10
Oneshot125 enabled
Controller 2-Luxfloat


P
I
D
Rate
Roll
0,5
0,10
20
0,40
Pitch
1,6
0,10
30
0,40
Yaw
4,5
0,20
0
0,30
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 one):
Reproduceable - on 45° dives from some altitude and with some speed, you "feel" that yaw gets unstable and suddenly it snaps 90° (or more?) to the right (most of the time).

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.

The first set of props were normal, plastic Gemfan 5 x 4 (balanced with sandpaper) and the new ones were also Gemfan 6 x 4.5 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 RCGroups.com Thread

Android App for Cleanflight
FPV-Community Cleanflight Thread
PID Tuning Knowledge:
https://github.com/cleanflight/cleanflight/blob/master/docs/PID%20tuning.md
http://open-txu.org/home/special-interests/multirotor/cleanflight-pid-tuning/
 
Build pics:

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Black Bullet - fast 280 racing quad w tilted arms!