Above: A petrol-powered-leaf-blower-powered skateboard!?

Whilst skateboards are traditionally powered by the rider, using their feet, it has long been dreamt about by many a 'boarder to have a 'board which doesn't need to be pushed back up a hill! There are many possible methods, and I have considered just a few in order to go into more detail.

## Basic Overview

Propulsion MethodElectric Motor
Jet Engine |
OverviewAn electric motor is mounted as a replacement for the bearings, in order to provide extra power.
A jet engine is attached to the rear of the board's deck (either on top or the underside) and is fired to boost power. |

## Before we get started... Useful Links...

Wikipedia - Electric Skateboard

Elektro-Skate

EightballBoards - Wireless Electric Skateboards

RokitScience - Electric Skateboards

Elektro-Skate

EightballBoards - Wireless Electric Skateboards

RokitScience - Electric Skateboards

## ...And a couple of videos:

## Powering a Skateboard with an Electric Motor

An electric motor is a relatively simple way of powering a skateboard. An electric motor is powered by a rechargeable battery, and connected directly to the wheel or via a gearing system to increase torque or power. For a reasonably powerful and therefore speedy board, a 400W motor is the most effective (prices in the region of £100). The required battery for the motor should have at least 12V, and these cost around £50. However, we need to take into account the current that will need to be supplied to the motor. The amps required equal the watts divided by the volts, so:

So, we need a 34 amp battery to power our board - quite a lot. Another problem with this powerful of a battery is that they aren't the smallest of things - most are around 120mm X 180mm X 200mm. This is going to substantially increase the weight of the skateboard and therfore lower efficiency. There are two ways we can combat this problem, because there are two parts of this equation we change - the Wattage and the Voltage. We need to either decrease the number of watts our motor needs of increase the number of volts being supplied. The voltage is the easiest thing to change, so we'll try that first. Let's say we double the voltage:

And we have successfully halved the needed number of Amps. A 17 Amp battery, which provides 24V can be found with dimensions as little as 110mm X 70mm X 390mm; whilst being considerably longer it would be a much better fit on a board. The battery I found provided 17 Amp hours, or Ah, which means it can provide 17 amps for one hour. Similarly, it can provide 34 Amps for half an hour, 68 Amps for 15 minutes etc. Using this, we can calculate that this battery could power our board at 17 Amps for one hour of continuous usage at full power - not bad when you include time when you may not need full power, account for time when you may be stationary and other time when you may not be at full power.

## The Basics of Jet Powered Skateboards

The jet for a 'board needs to have enough thrust to push the board - which means at least the mass of the board, plus however much extra the rider needs to reach their desired speed.For example, the average 'board has a mass of about 3 or 4 kilograms. Now, to calculate the thrust that our jet will need, we will use the unit of Newtons. 1 Newton is the force required to accelerate 1Kg by 1 metre per second, every second. So, if our 'board has a mass of 4Kg, then an engine which produces 4 Newtons will cause our board to travel forward, on a perfectly flat surface, at a steadily increasing rate of 1 metres per second squared. This means that after 10 seconds, the board will theoretically be travelling at 10 metres per second, as shown in the graph below.

Whilst this may seem relatively simple, it doesn't work. If you had a perfectly flat surface, in a vacuum, with no gravity, and a riderless 'board, then you would be nearly there. The final problem is the most annoying - the jet needs air to work so these conditions are purely theoretical. This is all a bit of a pain, because it means we actually have to do much more complex calculations.

So our earlier speed/time graph should be more along these lines:

And then we allow for the jet itself. For ease of calculation, let's say it has a mass of 6Kg.

So we evidently need more thrust, or else our 'board will take 3 minutes and 20 seconds to accelerate to 10 metres a second (0.6kph - an average person walks at around 5kph and our board needs to go up to 25!). The graph below shows the projection.

## A final thought...

There are people who think that alternative propulsion will be too difficult to handle, or too unsafe to use on board commercially and everyday - so here is one final video to prove you all wrong!

The electric commute - faster than a car, a bus, the tube, your feet, and in some cases a bicycle - brilliant!