DA3 Space Program (CAT 7), including a functional orrery.
About this creation
The Brewtopian Space Agency was set up almost a century ago with the goal of unlocking the mysteries of outer space. Unfortunately, because our telescope lenses are usually covered with beer foam, it has taken us all of that time just to discover the inner planets of our own solar system. Based on that knowledge, out scientists have constructed a working model of the solar system, an orrery.
Here is what our scientists currently know about our universe: The DA3 home planet, Planet Guinness, is the second planet from its sun in the Goldman system. Planet Guinness has a unique climate that causes a tan cloud cover in the northern hemisphere and a black one to the south. For this reason, Planet Guinness is sometimes known as the "Black and Tan" planet. Planet Guinness has one moon, the Barrett Moon, which makes almost 12 revolutions per year. Closer to the sun is Planet VAkkron, a verdant green planet full of interesting life forms. The Brewtopian Space Agency is actively trying to determine whether its atmosphere is suitable for growing hops. Due to the fact that Planet VAkkron is a captured planet, it orbits the sun in a direction opposite that of Planet Guinness.
[ I hope that was enough sucking up to the DAS to score a few brownie points. ]
Because I was building digitally, where it is a real pain to mesh gears together, I tried to go for a solution that involved as few gears as possible (which, hopefully, should make it easier for the DAS to confirm its functionality as well). There are two key elements in the design of this orrery:
A central gear train based on a large Technic turntable, with a 24-16 tooth differential going up through its center.
A simple, secondary gear train based on the large planetary gear set that came with the Bucket Wheel Excavator. This secondary gear train provides the motion for the moon without adding complication to the central gear train.
Here is brief description of how the orrery works, starting with a listing of the moving axles, and the gear ratios between them.
CENTRAL GEAR TRAIN
Axle 1: Crank
Axle 2: Vertical axle with stacked 24T and 40T gears
Axle 3: 8T idler gear between axles 2 and 4
Axle 4: Inner orbital axle (the differential)
Axle 5: Outer orbital axle (the outer section of the turntable)
There is a 16T gear that meshes with the 16T end of the differential (the top end). That gear is fixed to the pair of 4L half-thickness liftarms immediately above it (it cannot rotate with respect to the liftarm). It serves only to transfer the differential's rotation to the smaller, upper orbital arm. The gear ratios for the central gear train are as follows:
Axle 1 to Axle 2: 12:12 or 1:1
Axle 2 to Axle 3: 40:8 or 5:1
Axle 3 to Axle 4: 8:24 or 1:3 (0.33:1)
Axle 2 to Axle 5: 24:56 or 1:2.33 (0.42:1)
For every clockwise turn of the crank, the green planet revolves about the sun 1.67 times in the counter-clockwise direction and Planet Guinness revolves about the sun 0.42 times in the clockwise direction.
SECONDARY GEAR TRAIN
Axle 6: Vertical axle with 12T gear making contact with planetary gear
Axle 7: Horizontal axle near end of larger orbital arm
Axle 8: Vertical axle at end of larger orbital arm
Planetary gear to Axle 6: 140:12 or 11.67:1
Axle 6 to Axle 7: 12:12 or 1:1
Axle 7 to Axle 8: 12:12 or 1:1
The moon revolves around Planet Guinness 11.67 times for every revolution of Planet Guinness about the sun.
GEAR TRAIN PICTURE 1: The picture below shows orrery with most of the supporting framework removed. What is left is the gear train, plus the orbital arms.
GEAR TRAIN PICTURE 2: The picture below shows an even more stripped-down version of the orrery. The larger orbital arm is removed, except for the gears and the planet/moon at the end.
GEAR TRAIN PICTURE 3: The picture below shows the gear train from below, showing the idler gear that is part of smaller orbital arm's drive train.
For the sake of the following two positional examples, consider the starting position of the orrery to be shown in the following picture:
Turning the crank 90 degrees clockwise, the green planet will revole 150 degrees counter-clockwise (looking down) and Planet Guinness will revolve 38.57 degress clockwise. The moon will revolve about Planet Guinness 450 degrees counter-clockwise (i.e. retrograde motion). The following picture shows the position of the orrery after a clockwise 90-degree crank turn from the starting position (above).
Turning the crank 90 degrees counter-clockwise, the green planet will revole 150 degrees clockwise (looking down) and Planet Guinness will revolve 38.57 degress counter-clockwise. The moon will revolve about Planet Guinness 450 degrees clockwise (i.e. retrograde motion). The following picture shows the position of the orrery after a counter-clockwise 90-degree crank turn from the starting position (above).
And finally, the required picture of a downed space capsule being discovered by our military forces. A squad of Brewtopian commandos have discovered an alien space capsule containing gallons and gallons of the greatest substance known to man: BEER. The commandos are struck with awe and feel the need to enshrine this great discovery and bow to it - definitive proof that there is intelligent life out in the far reaches of the galaxy.
If you like this MOC,you might also like some of my other DA3 MOCs:
Quoting Stuart Lucas
Welcome back to the site's finest digital orrery!
Thanks. Technic in digital is definitely no picnic. I'm anticipating some difficulty with the missile launcher for the same reason, even though I have a pretty good idea of how to implement the working features.