Stardust Digger

--- Update in reopened period: With the help of https://grabcad.com/marvin.green-1 who made the following simulation of the drum, a very interesting video of it can be seen here - with smaller balls the filling ratio is near to 100%: https://youtu.be/DQ-GpTodRec The video "STAR DIGGER SIM2" MP4 file is included in the entry, too. ---------- Overall dimensions, material and mass of the drum: - Diameter – 450 mm - Length – 360 mm - Material – duralumin - Mass – 4,47 kg Inside volume of the drum: - Diameter – 356 mm - Length – 352 mm - Volume - little more than 35 liters The drum is one welded or soldered construction without moving parts. It has only one scoop but it is able to collect regolith along the whole drum’s length – the outer helical blades help for that. The captured regolith distributed further, inside, to the whole length of drum’s cylinder (that helps to take out the regolith later and in the same time forms a helical guides for regolith to go to the sides while the drum collects). In fact, the regolith enters in a kind of tube folded like ring. The inlet section is a rectangle with dimensions 116x45mm and the outlet section (it is inside the cylinder) is a rectangle with dimensions 348x45mm. That is what I found would work, after many versions of the geometry – spirals, helices, shields and so on… The simulations made shows that such a solution works and meets the requirements. Something that can be noted too is that here all the captured stays inside while digging. There are three simulations with 20 mm balls as illustration of the work of the bucket drum. And there is one simulation with 8 mm balls. ------------------------ In first 3 simulations: - Speed of drum – 20 rpm - Density of regolith - 1,5 g/cm^3 or 1500 kg/m^3 - Moon gravity – 1,62 m/s^2 - Diameter of the balls used as a particles – 20 mm (density 1,5 g/cm^3) ------------------- In first simulation of filling and emptying (see included GIF files “SD5-Sim1”, “SD5-Sim2”, “SD5-Sim3”) I used a