Not Enough Thrust Produced

ArduCopter
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1

In our project, we assembled a drone with:
6x Turnigy Multistar 4225-610Kv 16Pole Multi-Rotor Outrunner
6x 13x4 propellers
6x Aerostar 50A ESC
1x Cube Orange
1x CubePilot Power Brick Mini Soldered
1x 14.8 (4s) 10000mAh Lipo battery
and other GPS, radio, etc.

However, during the testing flights, we had a total take-off weight of 6kg, and it showed a thrust loss error after one and a half minutes without the battery getting too low. Based on the specs provided by the motor vendors (https://hobbyking.com/en_us/turnigy-multistar-4225-610kv-16pole-multi-rotor-outrunner.html), it should produce about twice the thrust force needed.

We also reduced our take-off weight to 5kg and it showed the error after about 5mins with 15% battery left. We think it means the current drawn by each motor is about 17A (85%10000mAh60min/5min/6 = 17A), but it didn’t produce the corresponding thrust as it should. One of the possibilities we are thinking of is just the provided specs are not correct, but we would like to hear some comments before we head to buy new motors.

Here is the log from one of our test flight: https://drive.google.com/file/d/1l2Ndc9OnTymz4r7ZriY94In9VxdR33pu/view?usp=drive_link

Any comments are appreciated!

2

Remove the access requirement in the link for assistance

3

Thanks for the heads up, it should be good now.

4

This craft is grossly underpowered with a predicted Hover throttle of ~74% and thrust to weight of 1.3:1 (at 6kg) With 6S battery power it would be about right at the same weight assuming the components could handle it. And you need current logging.

Maxed out outputs.

RCout
RCout1163Ă—399 113 KB

5

u must make certain your thrust-to-weight is above 2 (even at low batt).

otherwise, your copter can suddenly lose altitude due to: AP_MotorsMatrix: prevent altitude loss when thrust-to-weight is less than 2 by 117-MasterChief · Pull Request #23512 · ArduPilot/ardupilot · GitHub

(unless you like this tradeoff…)

edit: assuming you increase the T/W, but it is still less than 2. the current hover throttle is practically unusable. unless you have some vtol plane, even then its gonna b real janky.

6

No Trade-off would make this turkey fly…I think it’s worse than I suggested. More like 1.2:1

7

i was referring to if he improves the T/W, but still less than 2. definitely the current hover throttle is no bueno for a regular drone.

2 Likes
8

Thank you very much for the discussion here. I think we will look for more powerful motors and make sure the T/W is above 2, even at low batt.

9

nice. assuming the pic above is of steady hover, it seems that you also have a massive attitude imbalance. might be roll + pitch imba. something to consider in your rebuild.

1 Like
10

Consider 6S battery power. It will be much easier to get to the Thrust/weight for a 6kg craft if you do.

1 Like
11

Will keep that in mind!