January 27, 2008. As a result from experiments with collective and cyclic control in helicopter rotor heads, Some one pointed out to me that there is a similar Lego challenge in the simulation of a Voith Schneider propellor for ships. A nice explanation with an interactive animation can be found on: the website of Voith Turbo . As a start, I have tried to simulate the cyclic control. This means that the magnitude of the forces applied on the water can not be controlled in this creation. I hope that the pictures are self explaining.
A Lego "ship" with Lego VSP's at he front and the back side
Bottom view of the propellors. A gear ratio of 1:2 is needed to make each blade rotate 180 degrees during one full cycle of the propellor.
Close up of the propellor. The movement direction is fixed with a pin.
The ship moves in a straight line forwards
The ship moves sidewards
|Th ship rotates counter clockwise (bottom view)||The ship moves straightforward to the right (bottom view)|
The next step is to built a nice ship and to test it in a bath tub.
July 22, 2008. I managed to make a nme of movie recording with this ship in a bath tub of a friend. The rsults were a little disappointing. The following movie files show three movements: 1. rotation, 2. forward and backwards, and 3. left and right sidewards. I think that these results can be explained for by slipping of the belts.
August 17, 2008. The following pictures show the new boat with a number of improvements/
There are two geared motors in the bottom of the plastic body of the ship. The geared motor on top in this picture, underthe crown gears, controls the phase shift between the rotations of the blades and the propellor asemblies. The geared motor below drives the rotaion of the propellor assemblies.
The following picturs show the connections of a VSP with the two different driving axes.
The right picture shows the mechanism for driving the propellor assembly. The left picture shows the control of the phase shift between the blade rotations and the rotation of the propellor. The yellow handle on top used to be for manual control. Now it is used for showing the direction of the force on the boat.
The boat can make translational movements in all directions, and rotations as well. In order to avoid the use of a third motor,I have applied a trick. One rotation direction of the motor drives both propellors in the same direction. The opposite direction drives both propellors in different directions. The following pictures show the mechanism that works with a sliding wormwheel.
This time I have used for testing an inflatable swimming pool for (very) little children. The results are shown in a movie.
Right now, I don't have any future plans for LEGO VSP's. However, I like to know, and learn, about the efforts of other people. Therefore, your email is always welcome.