Hi RC people,

I have built my first ever drone and had gone through a maiden flight, result was a crash land. I'm pretty sure that the base parameters needs some serious fine tunings and tweaking, suiting my drone. My drone should possess smooth maneuver, stable Altitude hold & Loitering and RTL during fail safe – these are my expectations and I request your suggestions from your experiences and knowledge.

Suggestions and advice are requested:
1.   What kind of tuning is required for smooth maneuver, stable Altitude hold & Loitering and RTL?
2.   How do I start with the tuning process and what to be tuned?
3.   Is any pre-set values to be revisited initially, before tuning?
4.   Is indoor tuning with strings, help ? (https://diydrones.com/forum/topics/arducopter-tuning-guide)
5.   Will Autotune be helpful for smooth flights, what needs to be done before performing auto tune ?
6.   Also sharing any feedback/ advice/ personnel experience can help me to improve myself ?

Drone Configuration:
•   Purpose:    Photography
•   Frame type:   X- Frame – Quadcopter
•   Frame size:    680mm
•   GVW:       2.8kgs (Drone + 4K camera)
•   Motor:      EMAX MT3110 700Kv
•   ESC:      EMAX BLHeli 25Amps
•   Propeller:    1238 CF propeller
•   Battery:      ZOP 14.8V 4500mAh 45C Lipo
•   FC:      APM 2.8 + Ublox M8N GPS + 3dr Power module
•   Firmware:   Arducopter V 3.2.1 (Last update for APM 2.8 board)
•   Radio:       FrSky TH9X – 8 Channel
•   Telemetry:   3dr 100mW Telemetry – 433mHz

First Maiden Flight:
I had the drone out for a maiden flight with the existing PIDs and the default parameters in the APM 2.8. I had setup only Stabilize mode in all the 6 flight mode options, since I'm not sure how the drone responds to the other modes. And most importantly, I wanted to see the drone's performance in Stablize mode.
It was a mid noon in an open residential plot, the wind was very mild and I had the take-off. The drone lifted-off from the ground at nearly 60% of the throttle. But the wind was carrying away the drone. Since, I was in Stabilize mode – I tried to keep the drone in position. But the drone responded too aggressive to my roll and pitch sticks. I somehow tried to land the drone, coz I do not want to loose it in the wind. I lowered the throttle stick very slowly, but it happened to be a crash land and my propeller got damaged. Then, it was time for the propeller change and I decided to tweak the base parameter (PID gains, Pitch/ Roll tilt angles and any other required fine tuning) before taking them up in the air.

Changes done to the base parameters:

ANGLE_MAX (cDeg): Default value=4500 ; New Value=1000 ; Comments:Difference in tilt angles observed - 10deg
ACRO_YAW_P: Default Value=4.5 ; New Value=1 ; Comments:Now the Yaw rate is smoother and not aggressive as was in default values

Background on the Quad build:  (I've put this session at last, since I do not want to bore anyone with bla.. bla.. stuffs in the first)
I am Arunkumar from Chennai, I am a Mechanical engineer by passion and an Engine calibration engineer by profession. I am so much fascinated to build a drone rite from my college days, but never found time and budget. Its been almost 5 years after graduation now and I decided to pursue it. I started surfing on the web regarding building a drone by late 2018 and almost touched upon every basic topics. And finally came up with my requirement for building a drone, I wanted to see how things look from above. Yeah, I decided to build a drone with capability of carrying a camera payload of 0.5kg or atleast an action cam with Gimbal.
I decided to build an Quadcopter and started to begin with the GVW calculations, with the help of 3D CAD modelling (Calculation part in the next paragraph). I liked the design of Tarot-680 and Alien H4 680, mainly their looks and portability. I wanted the drone to be very portable and have space to mount the camera equipment. I started looking deep into Alien H4 680/ DAYA H4 680 designs and modelled a 3D CAD respecting the basic symmetrical rule for X-frame, i.e. when the axis of the motor mounts are joined by lines, looks like a square whose diagonal length measures 680mm.

I finally built a 3D model of my frame after multiple iterations, which respects both symmetrical rule and fold-ability. I wanted my complete frame to be made out of Carbon Fibre (CF), but considering the availability of CF here in India – I decided to go with Glass Fibre (GF) for the base plate, CF tubes for the foldable arms, aluminium motor mounts, TAROT mounting clamps for the CF tube and a wider landing skids. Since I had the complete 3D model, I was able to specify the density of each material (CF, GF and Al) and could finally get a very closer estimate of my frame weight (~700 grams). Believe me, my drone now weighs the same as the estimated weight. I felt this is quite heavier for a frame along with landing skids, but this was due to the high density of Glass fibre and the M3 Carbon Steel bolts (nearly 40 numbers).

Then proceeded to look for the available Flight Controllers (FC) in the market. Researched on that topic, finally decided to go with APM 2.8. Because, I liked that had a open source platform, compatible for other types of RC vehicles and mainly the budget. Further looked upon for the type of Motor – Propeller – ESC – Battery combinations, considering their own weight that adds to the GVW and matching the thrust provided by the combination. After many iterations, my calculated GVW of my drone was 2.3 kgs without camera.
GVW: Drone = 2.3kgs | Drone + Action Cam = 2.3 + 0.2 = 2.5kgs | Drone + 4K Camera = 2.3 + 0.5 = 2.8kgs
I decided to have my thrust to weight to be 2:1, which is the thumb rule. I chose EMAX MT3110 700kV motor which provides a maximum thrust of 1.4kgs @ 17.3Amps in combination with 14V battery and 1238 CF propeller. The total thrust provided by the motors shall be 1.4kgs x 4 = 5.6kgs, this shall be an exact match considering the critical GVW=2.8kgs (i.e. Drone + 4K Camera = 2.8kgs).

Then, I started procuring the materials and components required for the build (both from India and China). Out of which 90% of the electronics were procured from Aliexpress and the building materials from India. It took almost 6 months for me to collect all the components. Finally my drone configuration was supposed to be as below;
Now, once after collecting all the components, I started to fabricate the frame first, next the wirings, setting up the motor configurations. Fabrication and wiring were one of the very trickiest part in building the drone, my personnel opinion. Because even a single wrong solder can ruin the complete setup. I referred to the "Flight Setup" from the Ardupilot website https://ardupilot.org/copter/index.html and after few reworks, I finally built the complete drone. Yet, the calibration part was left out.

I started referring to the below tutorials for each;
Radio TX/ RX Setup:
TX/RX – Flight mode switch setup: https://www.flitetest.com/articles/Turnigy_9x_and_Arducopter_flight_mode_setup
ESC Calibration:
APM Setup: All the 8 parts of Painless 360 channel

Firmware uploading, Compass Calibration, Accelerometer Calibration, Radio calibration, Fail Safe setup and other Mandatory calibrations were done. Successfully !!!

Hi
This was really fun to read! I see you've put in a lot of effort and there is a lot of excitement !

Coming to the problem
1) Always power up your multirotor on a level surface and do not touch it until the initialization has been completed.

2) the reason I suspect that you've seen aggressive behaviour is because your gains in the flight controller is high. If you notice oscillations happening while giving stick input that means your gains are too high and they need to be turned down till the oscillation are gone.

3) the best way is to auto tune your setup so that you get the best possible gains, you'll need an open space and really calm weather to do it, kindly refer to painless 360 videos on auto tune. Moreover his videos are really helpful for APM and PIXHAWK.

Finally answering your questions

Suggestions and advice are requested:

1.   What kind of tuning is required for smooth maneuver, stable Altitude hold & Loitering and RTL?

A. Auto tune is the best way to go, you'll need an isolated and a open field for testing, follow painless 360 video for how to auto tune.

2.   How do I start with the tuning process and what to be tuned?

A. Follow painless 360 video for how to auto tune.

3.   Is any pre-set values to be revisited initially, before tuning?

A. I would say start from the pre set values (default values) and work from there.

4.   Is indoor tuning with strings, help ? (https://diydrones.com/forum/topics/arducopter-tuning-guide)

A. Highly not recommended. Multirotor are very dangerous to work with in confined and close proximity. One small mistake and you could injure your self.

Always remember propellers should only be attached when you intend to fly, otherwise remove them.

5.   Will Autotune be helpful for smooth flights, what needs to be done before performing auto tune ?

A. Auto tune will give you the best gains to fly, but it doesn't guarantee that you'll have a rock solid stable aircraft, follow painless 360 video for how to auto tune.

6.   Also sharing any feedback/ advice/ personnel experience can help me to improve myself ?

A.
1) Always remove props and work with the quad when indoor and not flying.

2) Never fly indoors or in very close proximity of people and property. Don't fly over people, even professional drones fail and people get hurt.

3) if you feel for any moment that the aircraft is doing weird thing land immediately and don't be a hero.

4) following are the things I noticed front he picture of your quad:
A) the telemetry is close to the GPS, kindly move the telemetry far from the GPS, there are chances of signal interference.
B) your ESC has 3 wires signal (yellow) , +ve ( orange ) and ground ( brown), only the ESC connected to OUTPUT chanel 1 of your APM should have all the 3 wires of the ESC connected, for the remaining three ESC you should remove the +ve wire ( orange ) wire . This can be done by lifting the flap of the connector housing (black ) and then removing the said cable and insulating it with heat shrink or insulation tape. The reason for doing this is to prevent brown out from taking place. Brown out is basically the APM rebooting itself due to spike in voltage , during the reboot you'll be unable to control your quad and it's get really ugly. Since you are using a power module , find only one ESC ( all 3 cables ) to the output channel 1.

5) I would suggest you have another friend / family member act as a spotter and also record flight videos, these videos help analyse problems with quads during a crash.

6) test in increment, understand the type of flight modes, see when to you use what and understand their drawbacks.

7) start flying with stabilize mode, get comfortable with that , then move to altitude hold get comfortable with that and so , but  keep RTL for the end. Only if you feel confident move on to the next flight mode.

Coming to another thing
Be it APM or Pixhawk these flight controller require a lot of patience to read the documentation and understand it, if you rush or take shortcuts thing's go bad really quick.

If you are looking to fly manually and just want to do photography and no auto mission flight then the DJI Naza m lite is best. The stability is just too good and the RTL mode is just amazing, you can get it working in very less time compared to the APM and PIXhawk


I see I've given you a huge write up and i apologize for that !

Have fun and keep us updated on the forum

Regards,
Naveed

Quite good. Having worked on apm on a 450 sized frame, I would say, the write up is pretty huge. Kudos bro.

Dear friend,
Your post reminds me, myself about 5 years ago. Asking for help those days, though not as descriptive as you have written. The situation was same except, in my case it was a TREX 450. LOL. After 2 months of building the copter it was crashed in less than 5 seconds. Before I could realise what stick to push the copter takeoff and flip on nose, crashed hard. That evening I was crying over the helifreak fourm, asking expert advice for the tuning of the helicopter.

In few days, I managed to gather a tons of tuning parameters, hundreds of advise what to do and don't, etc.

Loaded with those and the rebuild TREX 450, I was on the field with a new hope to see my helicopter flying, and to my surprise, the history repeats itself. LOL.

Another few days of my research reveals that, quads are right stuff to start with. Bought a F450, a KK 2.1.5 from eBay and I steps ahead myself with my dream to fly RC model.

After some days of work, I was in the filed with the quad, this time on stabilization mode. It was on air for 20 second or so before it does some crazy maneuvers and crashed. I was so frustrated, asking for help, over helifreak and rc groups. Started reading the tuning stuffs, the PID logic and tuning different parameters that controls the behaviour of the quad.

After few months of doing research on rc models, I have build up a sound knowledge on the control systems. But those seems worthless when I am in field with my quad.

One day, reading some post on helifreak, I came across one post about how to train yourself to fly a rc helicopter. On that day onward, my view of flying a RC model has been changed, and today I can do some crazy maneuvers, I ever dreamt.

In short I would like to say two lines.

1. Most of the flight controller's default settings are more than enough to keep your model in air.

2. Buy yourself a good simulator (not those available in Google Play Store), and practice their first before going to the filed with real one.

Flying a RC model is similar to learning riding a bicycle. You can't blame the bicycle if you fall first time.

Hi Naveed,

Thank you so much for your valuable feedback and sharing your key points from your experience. I shall place the telemetry away from GPS, look into Brown out and also refer to Painless 360 for auto tune.

I appreciate you for spending your time giving out such good valuable suggestions. Thank you once again.

Regards,
Arunkumar

Hi bro. Do you mean to suggest me, to work with 450 quad ?

Hello brother,

Yeah, I agree with you. The bicycle can't be blamed for one's first fall. One should know how to ride it.

Can you please suggest me a good simulator ?

You're welcome,
You can learn how to fly on your quad itself, flying a 450 size won't make a difference, since your setup is almost beginner type and the flying weight is reasonable .

You can check out for flight simulator locally
They are called real flight 22 in 1 flight simulator.

I've actually found the quad flight simulator are more difficult to fly since there are no limit on the attitude ( basically no restrictions on tilt).

Regards,
Naveed

Dear Arun Kumar,
Naveed sir, has suggested a good simulator, and it is also available with some local hobby shops. You can try that.

Regards
Pradeep

Thank you Naveed. I shall try the simulator and will keep updating the progress.