Tutorial : scaling a custom RC hovercraft

To build a custom RC hovercraft, first of all, you need to determine the scale of your model and the power it needs.

If you don't know much about hovercrafts, I recommend you to read this page that contains a bit of theory.

Let's say you want to build a RC hovercraft, based on a real recreation hovercraft having these specifications :

Dimensions : 3 meters long, 1.8 meters width, 1.5 meters height
A total weight of 260 kilograms (180 kilograms dry weight, 10 kilograms of fuel, 70 kilograms for the pilot's weight)
a single engine with a power of 30 horsepower

1 - Determine the scale of your RC model

To get a compact RC hovercraft, we'll say its lenght will be 50 cm. Therefore, to go from a lenght of 3 meters

to a lenght of 50 cm, the RC model scale will be 1/6.

According to this scale, its width should be 1.8 meters / 6 = 30 centimeters, and its height 1.5 meters / 6 = 25 centimeters.

2 - Determine the power needed by your RC model

Do the power conversion from horsepower to watts. As 1 horsepower = 736 watts, 30 horsepower = 22080 watts.

Calculate the cube of your RC model scale : 6 X 6 X 6 = 216.

Then, use this result to divide the number of watts : 22080 / 216 = 102 watts.

3 - Determine the maximum weight of your RC model

Like before, we will divide 260 kilograms by the cube of your models scale : 260 / 216 = 1.2 kilograms.

This is quite a heavy weight, giving you the possibility to set a heavy NIMH battery on your model.

That's it, the final specifications of your RC hovercraft are :

50 cm lenght, 30 cm width, 25 cm height, a power of 102 watts and a maximum weight of 1.2 kilograms

To go further, let's compare these results with the specifications of our BR6 model :

50 cm length, 25 cm width, 23 cm height
A power of 122 watts at maximum speed, measured using a clamp ampmeter (17 amps X 7.2 volts)
A weight of exactly 1 kilogram

The BR6 does not exactly match the 30 horsepower hovercraft mentionned earlier - proportionnally, it's a bit lighter and a bit more powerful. Still, it's close enough to show you that these calculations make sense, and that they will result in a functional RC hovercraft.

Warning : keep in mind that a too light hovercraft might overturn and get upside-down easily - you don't want that to happen when your model is running on a waterplan... We actually recommend you to get as close as possible of this maximum weight, or decrease the power proportionnally.

You can now have fun and make another round of calculations, using Formula 1 hovercraft specifications (180 horsepower, 3.5 meters long, 350 kg).

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