3689648757?profile=original  Part 1 .. DIY Giant Octocopter Build designed for Magnetometer Surveying

Here is my first attempt at building an octocopter. I will post images as I build it.

I built a budget 960mm hexacopter in my spare time last year while working for uranium, copper and gold exploration companies in Africa. I made it out of aluminium and it was a dismal failure and freakin heavy. I am building a giant Octocopter, final design will be 1400cm-1300cm motor to motor .. I can decide later down the road.

My ultimate goal is to create a bussiness where I am contracted to Mining Exploration Companies to fly Magnetometer Surveys  ,Lidar and whatever else I can manage to lift safely.

A magnetometer Survey may sound impossible to do "the motors create their own magnetic fields" but I have a lot of experience mounting High End magnetometers "$12000 US each" on everything from a LandRover to 4X4 Quad Bikes. The data is perfect so long as I stick to the rules of collecting Magnetic Data. The distance from sensor remains constant throughout the whole survey, the metal you are wearing and the metal on the quad bike must remain constant throughout the whole survey and the sensor should be as far as feasible from metal or magnetic source.
To be honest if I can do it on a quad bike I can easily do it on a large octocopter. Advantages are the slow speed "or fast", speed dictates how detailed I will survey. Flying 5km taking readings every .2 seconds will yeild very detailed survey data.

The quad bikes survey took 3 months in a desert in Namibia. I had 2 quad bikes, 2 African drivers, 2 magnetometers, 1 base station magnetometer and each quad bike had a spectometer attached to the front.

******************* OFF topic now sorry, back to this build blog*****

I bought 90% of the items from Foxtechfpv "Excellent good fast service and delivery".

I bought CNC items from Infinity Hobby " I like what they sell and will use more of what they offer next time".

I bought my carbon fiber booms and folding arm assembly from brushlessgimbal " I got the parts fast enough but next time I will cut out this middle man"

Part 1 complete .. Next Part 2 .. Parts List

E-mail me when people leave their comments –

You need to be a member of diydrones to add comments!

Join diydrones


  • Maiden flight should be this week but had to go with cheap props and 9000 mah battery until my bank account is replenished.

    I will be doing a comparison between a walking mag survey and my drone survey on the same area on a gold/copper project in a couple months or less depending on how fast the bush lines get cut.

  • Thanks

    I looked at shielding earlier but the options add weight and mu-metal would hurt the budget.

    Shielding will not be needed however, the magnetism from the magnets remain the same. A slight secondary magnetic field may be created by the motors but using Mission Planner the speed will be set at a constant rate and as smooth a flight as possible. If it does look like I am getting noisy data in my tests then I will lower the sensor further down. Right now the plan is for the console to be mounted 640 mm below the Pixhawk which is on the bottom plate "the batteries are on the top plate" and the sensor towed 2 1/2 meters below the console. That should be just enough but if not I will be towing the console and sensor to whatever height is needed or create taller landing gear to hold console. Lots of testing to do once I finish building it and buy/rent mags.

    Today I made my FPV wiring harness for OSD telemetry and non OSD Video. tricky for a first timer. 

    My folding arm kit came in, I made a bad choice with this particular purchase because now I have to make a bunch of changes in design. Folding Arm Mountings are 45mm tall ... My Tarrot aluminium pillars are 37mm tall .. Measure three times cut once tomorrow.

    Chinese Folding Arm Kit had no measurements on their web page .. Next time without posted measurements on a website I will not make a purchase.

    Taranis X9D and X8R Receiver came in today as well .. sexy looking Transmitter. Nothing else to buy but Batteries and Propellers now. sadly that must wait.

  •  Hey Ron, you could use mu-metal for shielding around your motors, mu-metal was designed to obsorb magnetic fields. Also look to carbon fibre for your skin / framing, with 8 motors most of your weight will be in LiPol batteries and motors. Hope this helps 

  • Typically Helicopter Airborne Mag Surveys tow the sensor "the bird" underneath itself.

    I believe their are many advantages of using an octocopter for magnetometer work.

    A:  slow speed equals data taken every half meter oe less versus an a plane who must fly faster. Slower speed means the magnetometer can be set to spit out data less often which also increases the quality.

    B: I can truly fly the canopy just above the trees because of the slow speed, a fixed wing aircraft can't do that. Surveying closer to the ground increases the resolution, flying higher/faster just melts those small weak anomalies into the background.

    C: I know nothing about making a plane, I did not research plane because in my head I could not understand where and how it would land.

    D: I have many more carrying options with an octocopter, I am basically building a carbon fiber box underneath the octocopter

    E: I am doing this for fun and I have wanted to make one for this exact purpose for a couple years now. I have some unwanted downtime.

  • Why not a fixed wing?

    The site you linked to has this.


    With sensors on the wing tips they can be a good distance away from the motor.

    Are you going to dangle the sensor from the bottom of the quad?

  • The magnetometer I normally use "GemSystems GSM-19W" weighs is 3.1 Kg according to their website  but I can reduce that further by shedding some items like sensor poles, harness, battery belt and may even create a carbon fiber housing for the console.

    Ideally I really want a potassium pumped Magnetometer because they are even lighter.

    My motor and prop configuration can handle that.

    My frame is likely on the heavy side but I have plans to reduce that weight as well.

  • Developer

    How much does your magnetometer weigh?

This reply was deleted.