I have found it is incredibly difficult to find brushed ducted fans online. The average thrust is something like 500g which is clearly not sufficient for the job. 2kg is going to be difficult to lift based on the availability of fans that I have found. Am I looking for fans the wrong way or is this consist with the rest of you guy's research?
Yes, you are indeed looking at them wrong. I spent the past few weeks designing and testing the parts for the official Ward's Sci kit that will be available soon. In doing that, I looked at a variety of fans and ended up settling on a cooling fan like what you'd see as part of your computer power supply. There are a lot of types available, but the specific one I tried out is this one: http://www.digikey.com/product-search/e ... 70-1126-ND
The KEY stat to look at when you are trying to select a fan is the static pressure (for the example fan it's 300.4 Pascals). In order to levitate the device, the fan(s) need to be able to provide enough pressure under the device to counteract the weight of the device (i.e. pressure is force per unit area). Note it's force not mass, so you need to use the value of Earth's Gravity (9.8 m/s^2) in calculations.
So for example, to levitate a 250 g device with a footprint of 15x25 cm you need: 0.250 kg * 9.8 m/s^2 / (0.15 m x 0.25 m) = 65 pascals (try it yourself: https://www.google.com/?gws_rd=ssl#q=0. ... +x+0.25+m)
) Keep in mind though that assumes perfect conditions and no losses at all.
A device with max mass of 2kg would require a minimum of 8 times that, or 520 pascals. Digikey has fans like the one I indicated about that handle 1,300 pascals for $27, which with the proper design should be able to handle a max spec device.
Note I'm not saying you have to go with this specific type of fan or design, as all fans have a certain static pressure rating. Just trying to help everyone understand the physics involved.