The cosmos should better ...

This experimental kit is in itself a good thing. The wind energy is very tangible and vivid. The large wind turbine with more than one meter in diameter makes what already therefore, that when assembled the right wing (which is not explicitly stated in the instructions), it already turns at moderately strong wind.
But that is precisely the problem of the box. The axis of the wind turbine drives a generator via a step-up transmission, gears are operated with a diameter of about 3 mm in the smallest plastic. Now you can imagine what effect stress on this weak transmission when the wind turbine at (only) moderate winds running a few hours - because only then the battery is also charged.
Now, with us the fun after about 2 hours had passed since widely made in the transmission of the first "tooth loss", and the whole generator unit so that was out - a shame.
Here cosmos must make improvements, so that this crucial part of the experiment box is something more durable - at least I know from the past of the cosmos as a better quality.
That's too bad, because the box itself is a great thing with which one could have fun and knowledge truly sustainable - who has already its own wind energy plant in the planter ;-)