- Travelling speed in water is 200 mm/s (1 meter in 5 seconds)
- The total weight of the boat is 295g and both vessel & floaters displace 63,000 mm3 of water when submersed to full capacity.
- Propeller rotates at 6,800 RPM
- Project is ready to accommodate Radio Controlled circuits for operation at the distance
HOW IT WORKS
NOTE: operate SLOOP only in swimming pools or bodies of water from which the boat can be easily retrieved.
S-LOOP is a boat formed by a hydrodynamic vessel and accompanying side floaters that is powered forward by the action of a 4 blade propeller. The motor of the propeller is spun at 6,800 RPM at a supplied voltage of 4.5v coming from the series combination of 3xAA batteries. A lifting force acts on each spinning blade as a result, thus pushing the propeller and attached vessel forward.
The direction of the boat is controlled also by lift acting on two airfoils (rudders) located at the rear of the hull. Through a gear reduction, a motor rotates the rudders’ axes changing the angle of attack with respect to the mainstream of air that exits the propeller. The action of the motor is set by means of a mechanical switch that is operated manually and then locked into position to prevent further rudder rotation. S-LOOP will only go in circles, however in further projects at LAYKANICS, we’ll replace this switch by a Radio Controlled unit to able to control S-LOOP at the distance and expand it’s functionality.
The operation of S-LOOP as a whole is achieved through 4 modules, each with functions that are explained below:
FLOTATION MODULE:This is comprised of the main hull (11-SLOOP) and side floaters used from project STRDR (04-STRIDR). The side floaters connect to the hull through a fixture & arm (14,13 – SLOOP) that can be retracted (for storage) or set at different heights to minimize drag. The floaters can be snapped on to the arms at any axial position for proper balancing when into the water (S-LOOP will always trim by sinking the back of the hull).
POWER MODULE:it powers the propeller and the motor rotating the rudders. It’s made out of the battery holder (12-SLOOP), switch stator (10-SLOOP), lock (09-SLOOP) and multiple wires and contacts. The diagram explains how the batteries are connected in series to provide a voltage of 4.5v to the motor of the propeller and 1.5v to the motor acting on the rudders. The clock and anti-clockwise rotation of the rudder motor is achieved by switching polarity at the motor terminals through a clever arrangement: one terminal of the motor is permanently connected to a contact that is common to the positive (+) of battery2 and the negative (-) of battery3. Then the other terminal of the motor is taken to a switch that connects it to either the negative (-) of battery2 (rotation is in one direction) or to the positive(+) of battery3 (polarity is inversed and rotation is in the opposite direction).
STEERING MODULE:is used to give direction to the hull. The rudders have a symmetric airfoil profile around which the air coming out of the propeller circulates. As you’ll see in the LEARN section, when the airfoils are NOT aligned to the flow out of the propeller, a force is generated at their “suction” surface pushing the back of the hull and forcing it to rotate about its own axis. The larger the angle of attack, the larger the force and hence the more pronounced the rotation of the hull and the tighter the loop followed by SLOOP.
The steering module employs a motor housing (04-SLOOP), a securing ring (06-SLOOP) and a speed reducer (15-SLOOP) as printed parts. Motor K1-M1 is meshed to the rudder axes through gears K1-G10 and K1-G60 to reduce the speed of rotation and increase the torque output so that the rudders don’t rotate back at the action of the flow. When setting the position of the rudders, the angle of attack can be measured by marking the gear and comparing it to the graduated scale in the hull. This will allow you to set different loop diameters. The speed reducer at the top has a screw that presses right onto the shaft end of the motor. When screwed in, the load on the rotor is increased and the rotation of the axis made slower. This helps to slow down the response of the rudders as a speedy rotation might be difficult to control.
THRUST MODULE: produces the thrust force required to move the boat forward. The motor spins at a very high speed, creating a lift force on each of the four propeller blades. The blades push both hub and motor forward and with them the whole boat. To achieve a high speed, the motor most be supplied with 4.5v. Because fast speeds can produce an injury, a casing (03-SLOOP) and a mesh (08-SLOOP) enclose the propeller. NEVER run your fingers across while the motor spins!! Also notice that a small weight difference in any of the blades can produce an imbalance which at high speed will result in high vibration. The structure of the casing is made therefore springy to isolate such vibration from the rest of the hull. The strut in “A”-frame shape fixes the module on to the boat. The small lugs on the side are used to secure the wires that feed the motor of the steering module. The axial location of the casing with respect to the strut, can be adjusted by pulling back or forward. This will help balancing the hull and adjust the intensity of the flow over the rudders (slow or fast control). The “T” slot at the bottom of the casing fits the nut for the securing screw that fixes the casing to the strut.