Jet Powered Kids Sled

It seemed in 2024 Street Sledding had all but become extinct. Why? It is super fun and the sleds here in Norway even have a seat for a friend. People just seem to be addicted to their fancy electronic toys and gadgets. Instead of good old fashion fun these days. So I thought it was time to bring back some old-school fun by upgrading the street sled to the year 2024.

Supplies

Ok, here is a list of all the major component you are going to have to buy. Warning: This will hurt your wallet. I still wince at the thought of the money flowing out of my bank account into the hands of Jack Ma Yun (Aliexpress founder) but the smile this project will give you, will be worth the wallet pain. Trust me.

Major components

• 1x Kids Street Sled
• 2x 90mm 6S EDF Turbine
• 2x 150A ESC
• 1x Electronic thumb throttle
• 1x Arduino Nano
• 2x 5.0Ah 70C 6S battery
• 2x small LED lamps
• 1x kids Ice Skate
• 1m 25x4mm steel flat bar
• 0.5m 20x2mm angle iron
• 2x mouse trap
• 10x M6x40 bolt
• 10x M6 nut
• 2x M4x30 bolt
• 2x M4 nut
• 1x PLA+ filament

You will also need

• Hammerite paint
• Wood oil (outdoors)
• Wood screws
• Sandpaper
• 15x4mm pop rivets
• CA glue
• Cable ties

Tools

• Angle grinder
• Drill
• 3D Printer
• Orbital sander
• MIG welder
• Jigsaw/bandsaw
• Pop rivet gun
• Hot glue gun

Step 1: Calculations

I say calculations but if I'm going to be honest I kind of just winged it and it somehow it all worked out.

So, how much thrust will we need from our EDF turbines? Well by hooking a luggage scale to the front of the sled and dragging my son along I'd see how much potential thrust I'd need to get him up and boogying. From standstill the starting force was approximately 3,5Kg. However when he was moving the the force required to keep him moving was only 1,2KG.

I was no rocket scientist but I just figured if I doubled the amount of thrust required to get him moving from standstill (7Kg) Then that would be enough to get him moving at some speed, hopefully without killing him.

Step 2: Refurbishment

Street sledding is so dead here in Norway that I found this sled on the side of the road being thrown away. I saw its potential and couldn't bare to leave it to the trash wolves. They are vicious animals here in Norway. It was rusty and weathered but I saw its inner beauty and decided to clean it all up.

Like a sled killing Jeffery Dahmer, dismember the sled in a calculated manner down to its individual components.

With a wire brush and an assortment of other torturous abrasive tools, clean off all the rust from the skis and front bumper. Then apply two coats of a heavy duty metal paint (Hammerite) Note: Do not to paint the under side of the ski as this will slow the sled. Smooth bare metal is key here.

The wooden parts were pretty weathered and they all needed a sand to remove most of the greyness from the surface. Starting with 80 grit lightly sand each part. Then gradually work your way up to 240 grit. To finish apply UV rated oil to all the wooden parts. As you can see from the picture I could not remove all the weathering but I just say it adds character.

Reassemble all the parts with new hardware such as nuts and bolts and hey presto the cops will never know what you did.

Step 3: Brake

Not knowing the actual speed this sled will achieve. I figured I didn't really want to explain to my wife why our son was dead. So I thought it to be wise to devise a braking system. But how do you stop on snow and ice? I wasn't sure. So I went looking for some inspiration. After looking at some options I came across my son's snow racer. It had a kind of rake foot brake. I liked the simplicity of this brake system, but if you have ever tried to use it on ice. You'd know this style of brake is completely useless. I then remembered I was an ice skater in another life and If I needed to stop quickly then. I'd use a hockey stop. Perhaps I could combined the two???

The idea was simple. Create a foot brake that replicated the angle applied to an ice skate blade when conducting a hockey stop.

Find yourself a pair of ice skates with a blade that will fit between the 2 skis. Remove the blade from one of the ice skates so that all the plastic has been removed.

Using some steel flat bar. Fabricate the swing arms by cutting the flat bar to length. This length may vairy depending on the bolt height of where you attach the swing arms. The key here is to get the blade to hit the ice at an angle of 33 degrees. Once you have drilled your holes for the swing arm bolts. Trim off the the corner of the flat bar so that it does not hit the ground before the ice skate blade does.

The blade is to be bolted onto a piece of angle iron with some small M6 bolts. Cut the angle iron to length and ensure you have enough tolerance to allow for a weld in the corner (unlike me %&#). Predrill the 6mm holes for the mounting of the blade. Ensure your parts are aligned properly and then tack weld them in place. Once you have double checked the alignment. Weld them properly.

Once you have grinded back your embarrassing, horrible welds. Apply two coats of Hammerite paint to hide any other embarrassments.

Next up find yourself a mouse trap and remove the spring. Using a pair of pliers bend each end at opposite 90 degree angles. This will be to fit into the sled upright and the brake swing arm. As you can see from the picture I drilled 3x 2.5mm holes for different spring tension positions. Lock and bolt together your spring and swing arm.

Now, go test that thing out in the snow and ice. Or in my case.... don't. (Dam global warming). A warm spell came and melted all the snow and ice in the middle of January. I was forced to wait till it got cold again before I could test. Lets hope you do not have to suffer the same.

Step 4: Handlebars

To mount the new thumb throttle and give my son something to hold onto for dear life. I was going to have to upgrade the handle bars from a rickety wooden dowel to something solid.

"Borrow" your wife's handlebars from her mountain bike. You know the one you bought her years ago, cause she said she wanted to stay fit by riding to work. Now, 2 years later it has a 1 inch layer of dust on it, but she swears she uses it all the time. Yeah! that one.

Remove the brake levers and handle grips. Mark out the positions of the handlebar uprights. Carefully drill a pilot hole through the handlebars. Then double check you got it right. On the underside of the handlebars, drill the biggest hole your drill can hold. In my case it was a 13mm drill bit. Once you have the holes drilled. Enlarge the holes to fit the handlebar uprights with a round file or a rotary grinding tool.

Fasten your handle bars using a wood screw through the pilot hole and into the uprights. Be sure to predrill the uprights to prevent wood splitting.

Slide your thumb throttle on and fasten into position. Then slide on your grips to finish.

Step 5: EDF Housing

I wanted these EDF turbines to look like they were jet engines. So I jumped onto Fusion 360 and 3D modeled a housing. Below are the STL files if you'd like to use them. However, I made a mistake with some tolerances and was forced to sand a little inside the housing and print a spacer to make sure the EDF turbine fit properly.

Once you have waited donkey years for your prints. Clean up the parts by removing the supports and cleaning up any rough edges. Using a M4x0,7 tap. Tap M4 threads into the outer housing half. Note: Thread inserts are probably the best solution here. As just treading the plastic is fraught with danger. You may only get one or two tries at tightening the screws before the the threads tear out.

Step 6: Turbine Mount

As you may have seen from your 3D printed parts there is space for a 25mm square pipe to be inserted.

Cut a half meter length of square pipe with your angle grinder or hack saw. Clamp the pipe into position under the seat then tack weld the pipe into position. Remove the part from the sled and weld properly on the workbench. Apply 2 coats of Hammerite but be sure to mask off the area where the EDF housing will slide on. To finish mount it into position back under the seat and slide on the EDF turbines. Now, take a step back and admire it's beauty.

Step 7: Controls

Unfortunately the thumb throttle I bought does not talk directly to the ESC. The ESC needs a servo signal to work. So, that is where the Arduino nano comes in. It will turn our analog signal from the thumb throttle into a digital servo signal that is understood by the ESC.

The code is as follows:

// Include necessary libraries

#include <Arduino.h>

#include <Servo.h>

// Define the throttle input pin

const int throttlePin = A0;

#define DMS 6

Servo myservo; // create servo object to control a servo

//Servo myservo2; // create servo object to control a servo

void setup() {

 // Initialize serial communication

 Serial.begin(9600);

 // Set ESC pins as output

 myservo.attach(3); // attaches the servo on pin 3 to the servo object

 //myservo2.attach(3); // attaches the servo on pin 3 to the servo object

 pinMode(DMS, INPUT_PULLUP);

}

void loop() {

 // Read the analog input from the throttle

 int throttleValue = analogRead(throttlePin);

 // Map the throttle value to a range of 0-255 for PWM output

 int pwmOutput = map(throttleValue, 200, 728, 0, 255);

 int pwmms = map (throttleValue, 200, 728, 1100, 1900);

 if (!digitalRead(DMS)) {

  pwmms = 1100;

  Serial.print("DMS egaged");

 }

 // Print the throttle value and PWM output to the serial monitor

 Serial.print("Throttle Value: ");

 Serial.print(throttleValue);

 Serial.print("\tPWM Output: ");

 Serial.println(pwmOutput);

 // Write PWM output to ESC pins

 //analogWrite(esc1Pin, pwmOutput);

 //analogWrite(esc2Pin, pwmOutput);

 //myservo.write(pwmOutput);

 //myservo2.write(pwmOutput);

 myservo.writeMicroseconds(pwmms);

 // Add a delay to prevent rapid updates

 delay(50);

}

Wire up the component according to the simple wiring diagram I crudely drew in MS Paint. I suggest soldering the wires just in case the shake loose.

Step 8: Bench Testing

Now I had no idea how weak or powerful these turbines would be. But nothing could have prepared me for how much fun this would be.

Connect your EDF turbines to the ESC's then connect your batteries. Note if your EDF's spin backwards just swap 2 of the wires from your ESC to your EDF turbine and that should fix the problem.

The next step is to calibrate the throttle. The instructions to do this will come with your ESC. A note here, is that the neutral position, can not be set at zero. You must depress the throttle 5-10% to register the neutral position.

With your throttle calibrated. It is now time to bring your wife in as a test dummy. The second she mentions that those handlebars look similar to the ones on her bike. Hit her with full throttle and she will forget all about it as she is pummeled by hurricane force winds.

Step 9: Finishing Touches

Now you know everything works. It is time to put the finishing touches on this thing.

I drew up a battery box and an ESC mount in Fusion 360 and have attached the STL files below for your 3D printing pleasure.

Attach the ESC's to the mount using the screws, that most probably came with it. Otherwise just hot glue those bad boys on. Clip the ESC mount over the turbine mounting bar under the seat and secure with a cable tie. Mount the Arduino board into the recess on the draw top with a little hot glue. I added a little hot glue to the wiring on the circuit board also, to protect the soldered joints. The battery box can then to be mounted under the seat and attached with cable ties or small screws.

I found a small plastic box to mount the ESC switches and an on/off switch for the headlights. This this was just mounted by screwing it to the back of the seat.

The headlights were simply some small 3W 24V LEDs I found in my local "everything" store. These were wired in parallel from the power side of the ESC and into the on/off switch.

The emergency shut-off-switch is to be mounted on the handlebars. I found a bike phone holder at my local "everything" store as well. Which had the perfect mounting clamp. So, I bought two so that I could also use one for a phone to measure our top speed. You will just need to fabricate a small bracket to connect the switch to the mounting clamp.

Ensure all your cables and wires are fastened neatly with cable ties and now you are ready for some fun!

Step 10: Full Speed Testing

This step is easy. Make sure your batteries are fully charged and find an open space like a frozen lake or ice rink. Then unleash the fun. My son managed to 32km/h with a head wind. But this wasn't just fun for kids. I had so much fun just jetting around on the ice. Which made me reflect on this project.

I hope somehow, through building and sharing this project. I have brought back street sledding to 2024. But if I didn't at least I was able to annoy my wife and have a lot of fun out there with my son and my friends. I urge you to do the same and bring people together over a crazy project like a jet powered street sled.

Thanks for reading.

Cheers,

The Garage Avenger