Introduction: Add a Jet Engine to Your Project
So you want to add a jet engine to your project. Naturally. Who wouldn't? After several popular youtube videos have gone viral showing jet engines attached to bicycles, canoes, and even someone rollerskating with a jetpack Wile E. Coyote style (surprise: it's me!)... you start to wonder... what else could I attach a jet engine to?
It's a dangerous hobby, and I'm suggesting that you do not attempt any of these things, but if you are absolutely determined to do this, it's better for you to have the following safety info than to not have it.
I'm the rollerskating jetpack guy, here to share my safety secrets with the curious and bold. Want to know how to buy a jet engine, handle jet fuel, and how to think about safety? Read on, adventurers!
Step 1: Decide How Much Thrust You Need
Before you can buy a jet engine, you need to know what size to get. Jets are sized by how much thrust (push force) they produce.
I recommend buying a spring scale, and use it to pull your go-kart, canoe, or whatever you want to attach this to. If you will ultimately be sitting in the go-kart (etc) then sit in it and have a friend pull you, while watching the spring scale to see how much force it takes to get moving.
How much did it read? Ten pounds? Fifty pounds? Write that down. This is the minimum jet engine thrust you should be looking for in the next step.
Step 2: Buy Your Jet Engine
There are several companies manufacturing small jet engines for use in radio-controlled model aircrafts. Swiwin, JetCat, and KingTech are just a few of the top names.
The main things to look for are:
1. Thrust - does the jet engine have enough thrust to move your contraption? Thrust is often measured in kilograms, so multiply by 2.2 to find the force in pounds.
2. Fuel Types - depending on the model, your jet engine might run on kerosene, diesel, and/or jet fuel. Generally diesel is safer to handle, while jet fuel will produce the most thrust.
3. Auto Start - some jet engines you'll need to start using air power or propane before you can start burning your primary fuel. These are slightly annoying to deal with and I highly recommend buying a jet engine that has an electric starter motor, which is often advertised as "auto start"
For my project I bought a Swiwin SW300B which has 30 kilograms (66 pounds) of thrust, uses any fuel type, and has auto start built in. It's a great jet and I didn't have any problems using this.
Before moving on to the next step, read the manual several times until you really understand how to operate the jet engine.
Step 3: Buy Some Jet Fuel
Your jet engine may be able to run on several kinds of fuel, but for me the most fun comes from jet fuel. Think about telling your friends that you're going to buy jet fuel. It sounds cool, right?
So here I'm going to share a little secret. Jet fuel is nothing more than kerosene that's been refined a little more. It sounds dangerous, but fire safety experts will tell you that gasoline is much more dangerous because it has a higher vapor pressure and lower flash point.
Let's say you do want to get jet fuel. Buy a blue container that's designed to hold kerosene. I recommend a 5 gallon Scepter SmartControl container because in my experience their safety spout leads to the fewest spills. Use a permanent marker to label it "Jet A-1" so that you don't confuse this for any other fuel.
The jet engine pump nozzle is too big to fit into your jet fuel container, so you're going to need to also buy a funnel or a wide-mouth can with a flexible spout. I highly recommend this 4-quart galvanized measuring can with a flexible spout.
Search online for private airports near you, and call them to find one with a self-service jet fuel pump. These pumps are much more complicated than the gas pump for your car. Watch this video several times and mentally prepare yourself for using all the knobs and levers before going to the airport.
Dispense your fuel into your measuring can, and then pour that into your kerosene container. Be careful not to smoke or cause any sparks during the process. Be careful not to spill any jet fuel. If you spill a few drops, don't worry - it will evaporate. If you spill a lot, you will need to use the spill kit which should be nearby.
1) If the credit card machine asks for your "tail number" leave this blank and wait or hit enter to get to the next screen. Do not worry about the ground strap, you have nothing to connect it to.
Step 4: Test Your Jet Engine
Before you attach your jet engine to your final project, I highly recommend building a quick test stand so you can practice operating the jet and get familiar with it. I made mine out of steel but you can also use wood. The nozzle gets very hot but the mounting bracket should stay fairly cool. Do not stand behind the jet!
You'll find that as the jet builds speed, the combustion becomes so efficient that it's invisible. Don't let that lull you into a false sense of security. The jet stream is incredibly hot! If you put your hand in the jet stream for even a moment you will get a very bad burn that will probably require you to go to the hospital. Your jet engine user manual will tell you the danger zone behind the jet engine. Don't allow any person, pet, or cherished object to enter the danger zone, no matter how excited this Kenny Logins song may get you.
Step 5: How to Not Get Burned
The primary burn danger comes from the jet stream. Be very, very careful not to let anything enter the jet stream exiting the nozzle. Think about how you will prevent your helpers or audience from coming into contact with the jet stream. Will you use caution tape, safety barricades, or something else? Have a plan and stick to it.
The secondary burn danger comes from touching the nozzle while it's still hot. Even if it's not glowing red, it may be very hot. Give it at least 5 minutes to cool down after each run before you think about touching the nozzle or the metal body of the jet engine.
Make sure to have a fire blanket and a fire extinguisher nearby. I recommend a nomex fire blanket for its burn resistant characteristics and a CO2 fire extinguisher because it won't ruin your jet engine like the ABC powder type extinguishers will.
You may want to wear a fireproof underlayer like racecar drivers wear, such as this set. Over that I would recommend dense cotton clothing like denim, and avoid fabrics like polyester that do not self-extinguish.
I recommend starting with full-length clothing that covers as much skin as possible. If the flame somehow briefly touches the clothing, it will really help prevent you from getting a severe burn.
Step 6: Attach Your Jet Engine to Your Project
Consider these important safety topics as you design and build your project around your jet engine:
1. Use a roll cage - If your jet engine crashes into something, the hardened metal turbine blades that were spinning at nearly 100,000 RPM can come loose and fly out, potentially injuring you or a bystander. Build a steel cage around the jet engine to take the force of any impact that may happen and save your jet engine from destroying itself and potentially injuring someone.
2. Protect yourself from the inlet - The inlet of the jet engine is going to be sucking in an incredible amount of air. Make sure the operator's hair and clothing can't get near it.
3. Use a heat shield - The fire emits a lot of thermal infrared heat. This is the radiant heat that makes your skin feel warm when you are near a campfire. Aluminum will reflect nearly all of this heat, even if it's a very thin layer of aluminum. On my jetpack you'll notice an aluminum heat shield after the nozzle to reflect this heat away from my body.
4. Use lots of failsafes - Think about what will happen if you crash. Will the jet stop automatically? It will if you use a "deadman" switch, which is any switch that turns things off if it is released. What happens if you start to catch fire but you can't see it because the jet engine is behind you? If you have a friend with an emergency remote stop that operates over a radio link, your friend can turn off the jet remotely when they see that happen. What happens if that remote stop is out of range? If your system automatically stops if it's not receiving a signal, then that's a fail safe. What happens if your controls come loose? Use pull-up resistors in your electronics or some other feature that will turn things off if the controls come off. What happens if the code in your microcontroller fails for some reason? If your "deadman" switch cuts the power to the microcontroller, then your code does not represent a single point of failure - you can disable the jet even if the microcontroller freezes up.
Step 7: Have Fun Safely
Enjoy your new jet-powered project!
Over time as you become more comfortable operating your jet engine, it's easy to forget how dangerous it can be. Don't disable any safety mechanisms, and always make sure to have several helpers on site to hold the fire extinguisher, remote stop, and to help as well as having fun.