RC Submarine 5.0 – moving weight (2/10)

Let’s start by building a moving weight apparatus for pitch control. Calculations Here is a diagram of the relevant forces. The moving weight changes the center of gravity (G), while the center of buoyancy (B) always stays in the middle. The offset between G and B determines the pitch angle θ. We have three ways to improve the effectiveness of the pitch control: 1) increase the movable mass m 2) increase the travel distance d 3) reduce the height h between B and G The first two are limited by the free space inside the hull, while the last one would cause instability (e.g. from propeller rolling torque), which we don’t want. As usual, we need to compromise. Let’s calculate a rough estimate on how big the moving weight needs to be. target pitch angle: 20° travel distance: 5 cm height between COB and COG: 2 cm hull displacement: 3 kg moving weight = sin(20°) * 3 kg * 2 cm / 5 cm = 0.41 kg Ok, 400 grams should be enough. Let’s build that. Build I bought steel washer plates to use as the…