Electric Beach Luge project

John Dingley, Swansea, United Kingdom. Featured on Hackaday 24th Aug 2017: Click Here

BACKGROUND: This project is an experiment to build an electrically powered thing (top left above) for use on long stretches of firm flat sand that will be a cross between a downhill luge board (see example below), a kite surf buggy, a go kart and a Star Wars Land Speeder.

Why do this? I used to own the yellow sand rail above many years ago which had a V8 in the back. Back then you could drive on beaches like Pendine Sands (South Wales, UK) which is several miles long. This was a big deal as historically several land speed records were set there by brave men such as Sir Malcolm Campbell in his beautiful Bluebird series of cars or John Parry-Thomas who lost his life in 1927 in the 27 litre engined Babs. Here is a Top Gear episode filmed there: https://www.topgear.com/videos/top-gear-tv/monaro-vs-300c-vs-s-type-r-part-12-series-5-episode-1

At the time I noticed that despite the off road tyres, if you built up some speed, the car would start to plane on the surface, only slight steering changes could make you drift gently sideways. An old video of this car (aggressively rather than gently drifting) is here: https://www.youtube.com/watch?v=bl2XDJrXTnQ

I now build electric vehicles, especially one wheeled versions like the one above, which are much slower but also great fun on beaches. For a lot more information on these, go here: https://sites.google.com/site/onewheeledselfbalancing/

Above is an example of people on downhill luge boards. These are like long skateboards and can reach speeds of around 60 miles per hour or more. A dangerous sport, even by the admission of those who do it. One of the best designs apparently is the board made by the Rogers brothers, example shown above right.

Here is my basic frame welded up. Tubes shaped using a DIY hydraulic pipe bending machine.

Example of a kite buggy above. Also a land speeder from Star Wars on right.

The plan is that this will use a lot of spare parts from my previous projects. My early projects used go-kart parts and these parts are also available second hand at reasonable prices on ebay, including part worn tyres.

The front wheel will be steered using my feet, like a kite buggy. Foot pegs not welded on yet. The rear wheels are close together because this thing will mainly go in straight lines, the turning circle will be pretty big, which is OK, that is the plan. I will lie down on it like a street luge board, for minimum wind resistance, so the motor and batteries etc will be mounted as low as possible under my head and shoulders. This also keeps the centre of mass as low as possible for stability. I could move the rear wheels outwards of course but I do not want to build a trike, I want it to be long, sleek and pointy. Ground clearance will be minimal, the wheels will plane along surface of sand not sink in. Go kart wheels seem about right for this experiment and the use of slick tyres will add a little drifting fun I hope!

Here is the (LiFePO4) battery (shiny thing on left), battery management system (black box on right), golf kart motor 500Watt 24V. The little box with the ventilation holes contains an OSMC robot combat power controller which can take around 160 Amps continuously without burning out, a 24V fan, and this is sent a control input by an Arduino Uno microcontroller, which reads a potentiometer in the hand controller to set the speed you wish the motor to go at. There is no brake at the moment although I will leave the axle slightly over long so I can add a kart disc brake later if I feel the need to. As you see everything is as flat as possible so I can lie down on the machine, very much like on a luge board.

Short video showing the drive train, battery pack, hand control etc.

Wedge shaped alloy box had to be made to seal the electronics from water and sand, and yet still allow the fan to circulate cooling air over the OSMC power controller. The motor and chain was in separate enclosure to limit the amount of sand coming in off the chain to the lowest amount possible.

Sir Malcolm Campbell setting speed record of 130mph at Pendine Sands.

18/07/17: It now has hand rails each side and a back/head rest.

The backrest folds forwards so you can get at the electrical parts easily. It unbolts fully if required. The support strut at the rear is also completely removable. Just waiting for steering bearings to arrive now.

22/07/17: The image above was poor quality because it was taken in the dark! Machine had first test on driveway at 11:30pm. It seems to work really well. Much time taken today to protect the main electronics from water and sand ingress. A whole load of minor jobs to do tomorrow morning, including a proper headrest, then might think about going for a beach test run.

23/07/2017: Photos from first beach test. Youtube video at top of this page. The trigger device on right hand rail now sets the speed from zero to maximum. Apart from burning out the main power switch and having to hot wire the machine with a big connector block, everything worked fine. Turning circle is around 15 feet, better than I thought. Front mudguard was essential to reduce the amount of sand and grit flung in our faces and goggles also a must for same reason.

Factoid on the prone (face down) riding position we tried in one of the videos at the top:

Before the invention of trousers that stopped blood pooling in the legs when pulling out of a dive, the Gloster company in the UK built an experimental jet, the Gloster Meteor (Prone), that contained a regular pilot in the rear position and a prone pilot at the front to investigate whether it was possible to fly an aircraft in the prone position.