Question between hardware and software

ArduCopter
1

For an experimental project I plan to get this autopilot:

https://ardupilot.org/rover/docs/common-holybro-pixhawk6X.html
(wiring cable is the part on which I have questions)

I have read also some part of the documentation here : How to add a new multicopter frame : Copter Motors Library — Dev documentation

It is exactly what I want to do a 4 downward propeller.

But for some r&d aspect I want to replace the motor and the ecs by 4 fans like PC cooling fans

What would be the best : use fans with 2 cables DC ± or fans with PWM 4 cables plug ?

What goes out of the autopilot to the ecs to the motor ? Some is digital/seria i2c/can, some is analog.

What would be in term of hardware and software the minimum effort to make fans spinning from 0 to max speed ?

The fan simulate a device that will come later to try to make it fly. The first step is just to illustrate it could work.

Full gas the 4 fans at full speed. Low gas fans stopped:-)

I will do first a basic wood frame as in the decacopter nice video on the documentation page :slight_smile:

2

I have done further reading and understood how it works now :slight_smile:

https://ardupilot.org/rover/docs/common-brushless-escs.html#common-brushless-escs

3

The challenge will be your fans.
Regular DC12V (2 wire) fans (or other voltage range) are usually brush-less but not designed to be speed controlled. In fact if you try that you will most likely burn them out in seconds.

Whilst the CPU cooling fans are speed adjustable I doubt you will find any that are powerful enough to get anything airborne.

There are industrial type of fans which can be speed regulated, but it is a different pulse form for regulation than what a regular FC produces. (FC’s usually produce a waveform pattern suitable to controlling servos & ESC’s)
So this would require some sort of frequency converter.

In a nutshell the best option would be using electric jet engine type fans which are already designed to be speed regulated using standard ESC’s

Someone done already such a similar project a few years ago:

1 Like
4

That contraption could also be called a fast battery discharge machine. Impractical in efficiency and dynamic response from the ducted fans.

5

Yes basically the idea is to play on different type of optimisation with less electric consumption multiplication of fans/turbine with a specific air conduct output design not so big as the ones tested there.

Various attempt to play on P=F/S :slight_smile:

6

Does this 4in1 ESC currently at a good discount price on AliExpress can work ?

https://fr.aliexpress.com/item/1005004677740980.html?spm=a2g0n.productlist.0.0.d7217fe5LHbfv2&browser_id=73735ee88e4346ac93e5ff4b107fdfc6&aff_trace_key=e1cbd019bc8e460ea99bcdca0f5a1466-1695804775189-03455-UneMJZVf&aff_platform=msite&m_page_id=yazhzmllscavbyjb18ad6087ba513382bb1422a12f&gclid=&pdp_npi=4%40dis!EUR!70.23!37.22!!!72.50!!%40211b88f016958079947632318e0dd2!12000030069338083!sea!FR!0!AB&algo_pvid=2a221373-b15d-4019-b807-7214ffca3c29&search_p4p_id=2023092702463412520684139857140001657261_2

7

How would anyone of us know?
…You haven’t specified what motors/fans you are going to use.
…You haven’t specified what batteries you are going to use
…Without any details we can’t help you with that.

8

It’s BLHeli_S. I would go with a BLHeli_32 choice.

?

9

Yes during a few readings on the documentation and here I read that one of the Blheli do not work and the other yes.
On the description on AliExpress it was not clear which one it is !

P=F/S
Pression = Force / Surface

As I’working on a concept of air compression that moves in a specific form factor conduct the airflow at the output will be at really higher pression and should in theory generate a higher lift.

The idea is not so dumb as one experiment has already been made according to the video kindly posted there.
I would like to avoid to use too expensive and heavy jet engine as in this prototype.

I made a very theoretical design with 16 compressor by groups of 4. And a specific airflow collector for each group of 4.

So it would require 4 4in1 Blheli 32 esc.
I would like to keep on 50A motors for the compressors.

For the battery we start with lipo but will test other alternative.
And for the motors we should replace them also.
I want just to build a test platform and have my 16 compressors blowing.
If I have not enough lift for the moment it’s not a problem.

This platform is really exciting as it enables to be ready very fast for experimentations.