I wish to develop a platform for geophysical work. The problem is that suitable geophysical receivers are copper coils with a weight in excess of 5kg - with ancillary electronics the total payload would likely be 10kg.

In addition, an air coil receiver would need the largest possible cross sectional area to be carried horizontally, whilst a ferrite core receiver would be a longish (0.6 m) cylinder to be carried vertically.

Model airplanes are generally smaller than this, whilst ultralights/para-gliders are considerably larger. Does anyone have any suggestions for a suitable airframe to get started with?

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I think the 3 hour flight time begins to make it a big machine, along with the 10kg payload.

You will struggle to get that out of an ultralight.

The helium for a balloon would cost a small fortune there.
I had come to the same conclusion! I considered hydrogen - but generation of hydrogen on site would take too long (using 20Amps.)

If I could cut the receiver to 5kg - would this be more feasible? I can obviously spend more effort tweaking the geophysical receiver in order to reduce the size of the airframe.
Yeah 5kg would make more feasible.

I think you might be best off expecting 3, 1 hour trips or just over, airframe tasking from a single point.

You'd have to remember 5kg is more weight than most peoples complete systems.

Things like a prepared runway are going to start to be required, not too much of a drama if you can use a bush road.

Not sure how much they can lift, 5kg might be a bit much but you might have a look at a 12ft Telemaster.

Petrol engine on the front, lots of fuel


I think I would be buying 3 at a time, getting another or spares would take forever.

Might not be quite upto the job, maybe somebody here has a better idea of what they can carry.

They are not sexy delta/circular/vertical solutions but for plodding around with a package they might do the job.


Thank you for the information - I needed this kind of advice to put me on the right track.

What is the max. flying time with a brushless motor?

How would the plane handle a copper coil strung from wing tips to tail tip?
Maybe you could add a picture of that coil, my instant thought is that the results from it might be skewed if the coils is distorted downwind.

Maybe the coil could be built into the wings??
Coil would have to be rigid - a typical example is attached. This could be mounted onto, or towed by a conventional airframe, or could be built into the wing of an unconventional (delta wing?) airframe.
Is the red box all the recording and power gubbins?

What's the total weight?? Still 10kg??

You might be able to build a really big flying wing, it would be hard to store though.

It will get to the point of how much do you want to spend.

The benefit would come if you managed to get two or three units flying and sold.

But for a one off, an ultralight might be cheaper.

Would be fun trying to lift a 1m coil.

You could incorporate it as a training hoop for a big RC heli.

The several hours and large distances wont happen then though.

Also the heat and dust of the bush would be a nightmare in a complex machine. Miles from workshops.

An interesting problem.

To put it in perspective, my current work in progress is to get 1kg lifted for 1 hour. Seems simple but its not!!
The red box is probably a pre-amp - typical coils weigh 2.5 - 5.0 kg. Many of the full size (manned) systems are deployed either hanging from a helicopter, or as a 'bird' - towed behind an airplane. These systems use larger coils, and also include the transmitter which is even more massive.


The idea behind the UAV system - that lighter ground based receivers could be used since the UAV can fly close to the ground.

I am beginning to think I will be constrained to alternative geophysical systems where the receiver is 1 - 2 kg - and see what can be achieved, as I am no aeronautical engineer!
Hi matabele,

Fugro used a scaneagle for survey however they ran into serious interferance probems. The biggerest issue is you need to build a complete composite airframe to ensure the interferance is the lowest possible.

We completed many trials for such work and they varied in results based upon the payloads that were fielded. The copper surveys were very successful and geophysics were amazed at the results.

Further the UAV were able to complete surveys a night for extended hours in comparison to fixed wing aircraft as they didn't need to deal with thermals in late morning and afternoon, so the UAV kept very percise altitudes.

If you are interested in the surveys drop me an email.


I have a platform (AI-extended) that is based on the senior telemaster, it uses a MicroPilot autopilot we have it done numerous test flights and have the flying parameters dialled in for quick use. It could also easily be transferred into the larger telemaster platform if required.

If this is something that interests you please let me know.

Greg Lewis
I have considerable experience with TDEM in the field with fixed and rotary wing. In your words: "you are a geophysicist - not an aeronautical engineer," and need a turn key solution that is available and affordable. I would prefer to go offline with you to discuss your needs. You can reach me through my email at thorpe@seeop.com or 480.355.2435 (USA).

Sincerely yours,


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