Gathering Required Parts
The same ducted fan model I mentioned in my post on 1st July is also sold in a bundle with an appropriate 80A ESC (Electronic Speed Controller). As far as I can tell, this makes it around £2-10 cheaper than buying an equivalent ESC separately (just going by amazon listings at time of writing) and ensures correct compatibility with the EDF.
The product listing shows a wiring diagram, including connecting the ESC to wired and wireless control systems. I'll need to look into how to connect the ESC to an Arduino or similar microcontroller so I can control the thrust output using my own code.
I will also need a battery, helpfully the listing for the fan and ESC lists an appropriate compatible LiPo battery model: “4S 3500MAH 35C”.
Some preliminary research has revealed that this means the appropriate battery pack will need to have 4 cells in series (to produce the appropriate voltage) and a safe continuous discharge rate of at least 35 times its theoretical capacity of 3500mAh (around 122.5A).
If the battery in question was to be discharged at that rate continuously, it would only last around 1 minute and 45 secoands before running flat. It is probably sensible to purchase at least two battery packs so I can continue working while one charges.
Searching that model on amazon shows battery packs with voltages listed as 14.8 volts. This is what is considered the nominal voltage for the battery pack, but when fully charged, the pack can output as much as 16.8 volts, the amount listed as the maximum for the EDF.
The principle is shown in the following graph from a dataset collected by Matteo Galeotti et al. and published in science direct. It shows the voltage curve for a similar single lithium polymer cell while discharging:
It shows the voltage output starting high at around 4 volts before sharply dropping off and then following a shallower curve (around the nominal voltage) before dropping off steeply again as it finishes discharging. This graph also shows the change in that voltage curve over a number of charge-discharge cycles, but i don't expect that to be of significant concern over the short period of time I will be conducting my experiments.
Of the listings shown on Amazon, almost all of them come in bundles of 2 packs. All these listings range from around £50-60. This listing has appropriate battery packs available for £52.43 for a bundle of 2.
This should be enough parts to build an initial test assembly and begin experimenting with writing code to control the EDF's thrust output. I'll need to purchase a second EDF and ESC in order to construct the carriage for the 1D linear test track setup I proposed in my previous post on 4th July.
I have put together an initial BOM which I will send via email to request the uni purchase the required parts:
I have also updated my Gantt chart, and I'll start including the most recent version at the end of my blog posts going forward:
