I have wanted to build a functioning, jet turbine engine for quite a long time. To me, there's something awesome about the way in which so many different aspects of a jet engine come together to make a functioning unit, that is able to propel massive objects into the sky. I actually tried to make a jet engine out of tin cans years ago! It was one of my first instructables: http://www.instructables.com/id/The-Recycled-Jet-Engine/. Perhaps one of the biggest lessons from that project, was that jet engines shouldn't be made out of tin cans.
This past summer, I had the opportunity of a lifetime to be accepted as an Artist in Residence at Instructables. With all of the new resources I knew I'd have available, I thought this would be the perfect opportunity to try to do a massive project, something that I knew I wouldn't be able to do at home. I knew I had to try to make a functioning jet engine, like I've always wanted to, but knew I didn't have the resources to do so. I poured all of my efforts into the project, and learned so much by doing it.
With that said, I'd suggest you grab a beverage if you intend to read all the way through. The actual complexity of this project didn't hit me until I was discussing it at my final Artist in Residence presentation. To read more about my AiR experience, feel free to check out my forum post here: http://www.instructables.com/community/Fozzy13s-AiR-Experience/
Step 1: Testing - Video
Testing was difficult to actually do. I just performed the first round of testing, and didn't exactly get the results I wanted. That said, I filmed most of the first round of testing in eight inches of snow, so I think some credit should be granted. Further testing will be done when I'm not away at school, because jet engine testing isn't exactly possible on campus.
The engine naturally wanted to run backwards, and so in these tests, I let it run that way. In the next round of testing, hopefully with some dry conditions, I hope to have a larger air supply to help force the compressor into functioning better than it did in this first round. That said, the engine did in fact propel itself during short portions of my testing, even if it isn't completely obvious in this test.
Step 2: Theory of Operation: How a Jet Engine Works
Before one being build a jet engine, it's important to first know how a jet engine works. Luckily, the internet is a fantastic resource for this sort of thing, and one can spend hours researching and watching YouTube videos on how they work, and different homemade versions that people are showing off.
Let's break everything down simply before we proceed.
The first place I started when I first became curious about jet engines was HowStuffWorks, so I'd like to direct your attention to their article here: http://science.howstuffworks.com/transport/flight/modern/turbine.htm
Step 3: Working Design/Overview
The following explains the different components of the jet engine I built. Consider this applying what we learned about how a jet engine works in the previous step, to the more specific design of what we'll actually be making.
Don't know what a centrifugal compressor is? Check out THIS, or THIS.
As an overview, here are some things to keep in mind while we set forth on this adventure of building together.
Step 4: Main IngredientsThis step is titled "Main Ingredients", because as I keep reading and writing Instructables, a full, detailed, list of materials seems somewhat redundant. Therefore, here are main components that were used in making the jet engine.
-stun guns/spark generator
-propane source. regulator?
-probably high temperature silicone stuff for in between joints
-3 brass barb tees
-3 spark plugs
Step 5: Flame Tubes Pt. 1: Taper
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The Flame Tubes are made primarily using 1/5" diameter and 1" diameter stainless steel square tubing.
A 5" long section of 1.5" diameter stainless was cut, and each end had to be shaped differently. One end will need to be tapered, taken from a larger diameter to a smaller diameter.
In my turbine engine there will be three combustion chambers. These will be built and tested before anything else is done to make sure that the core of the engine is working.
Step 6: Flame Tubes Pt. 2: Angle
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The other end of the 1.5" diameter section needs to be closed off, at an angle to direct the air that will be flowing into the engine.
Even though all the metal was bent into place as best as possible, a multitude of clamps had to be used to hold everything in place, and squish it together to be welded. This was largely made up as I went along, and so I'd advice looking at the pictures.
Step 7: Flame Tubes Pt. 3: Burner
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The first image of this step is a good picture of what we will make in this step.
I used two one-foot long, one-inch diameter sections of square stainless steel tubing for the second half of the flame tube. These pieces are where the fuel will be ignited, burn, and be routed to the exhaust turbine.
I decided that the smaller diameter portion of each flame tube should be 5 inches long, like the former, but instead cut three 6" pieces. I decided that cutting down each completed flame tube to the appropriate size would be easier to do at the end, then try to make everything match up perfectly after all of the cutting and welding was done.
Step 8: Flame Tubes Pt. 4: Welding/Finishing
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Welding was done kind of as I went along, and so writing specific directions for this seems unnecessary. Welds should be placed:
A 7/8" hole was drilled in the center of the 1.5" diameter tube close to the angled end.
The 1" diameter end will then need to be cut/ground so that the 7/8" diameter holes are all the same height if all of the tubes are standing up next to each other.
Step 9: Build: Exhaust
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The exhaust consists of an end plate, and two sections of bar stock bend into a circle, all welded together. The exhaust turbine goes inside of that housing.
The end plate is made of 3/16" stainless steel plate. This was cut on the water-jet cutter in the Instructables shop, that way all the holes could be perfectly spaced out along the outside. The three square holes needed to be 120° apart, where the exhaust will enter the exhaust turbine.
Because the water-jet cutting didn't turn out perfectly, a few weld beads needed to be placed on the inner circle, to allow the bearings to have a tight fit.
A 6-foot long section of 1" wide bar stock was purchased, and bent into two large rings, using a combination of the metal bender in the shop, a vice, and brute force. The appropriate perfect-circle-making metal bender was not available in the shop.
The exhaust turbine was cut using the Omax water-jet cutter at the shop, after being drawn in Inkscape. It was then placed in a vice, and vice grips were used to carefully bend each blade to a 10° angle. A mark was drawn on the vice with marker to easily identify how far each blade needed to be bent. Ideally, the exhaust gases would come into contact with the blades at a 90° angle. Because this isn't possible with our design, the impact angle will be slightly wider.
Throughout this process, I kept checking to make sure everything fit appropriately. In the pictures you can see a piece of wood cut in the rough shape of a turbine in place of the actual one. This was a test piece used for sizing, to avoid risk of damaging the actual turbine while lining things up.
1. Inkscape is an open-source vector graphics creator. If you've heard of Adobe Illustrator, this is like a free version of that program. I'm using it because it's free and available, but feel free to use your vector-graphics editor of choice. Inkscpae is able to save files in *.dxf, which is the format the Omax wants.
Step 10: Build: Intake
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The intake for the engine is probably the "least clean"/"most poorly planned" part of my project.
The original plan was to use the shroud from the vacuum cleaner motor to snap/bolt on to the engine. Due to the thin walls of the shroud, this wasn't going to work. I was stuck, and kind of scrapped together a shroud using left over 1" bar stock from making the exhaust. The following are directions for what I should have done from the start, and did some version of as I struggled to fix a flawed design.
Step 11: Finishing pieces
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Intake shroud pt. 2: Pictures 1-4
Fuel fixture: Pictures 5-11
This will be used to disperse the propane to each of the three fuel inlets, on each of the three flame tubes, of the engine.
Step 12: Fuel System
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We will use propane as our fuel source for the jet engine, as explained previously. The companies who make small propane bottles try really hard to make sure you can't easily get to the wonderful flammable goodness, which makes this part challenging. I first bought a Coleman propane stove regulator, so that I would be sure no propane would leak out of the adapter at the bottle.
The regulator came with a second valve built into the end of the regulator, which I decided to use as a sort of on/off valve. This was accomplished by bending brass rod into strange shapes, and forming a sort of hook-and-latch assembly to slide into the end of the regulator and push the built-in valve open. This involved drilling through the end of a brass elbow, and using epoxy to affix a small piece of brass tube in place so that a gas-tight, yet slideable junction was made.
A variety of plumbing adapters were then used, and epoxied together liberally to form a system of valves and fittings that would regulate the flow of propane with no leaks, and end in a 5/8" hose barb adapter. This entire process was challenging, and there has to have been a better way to do it, but this is what I made work.
Step 13: Electrical System
The "electrical system" of this project is hardly of note. I chose to use an inexpensive stun gun to generate the sparks for the spark plugs to light the fuel inside the engine. Alligator clips were used to connect the output terminals of the stun gun to the connections for the spark plugs. Because the gap of the spark plug is shorter than that of the stun gun, the spark will chose the path of least resistance at the spark plug. The flow of the burning fuel will allow other flame tubes to ignite once the first one is successfully lit.
Step 14: Conclusion
This project as mildly successful. I'd like to reiterate that this by completing this project, I learned a great deal, and it was incredible to have the opportunity to do so. Some things I would have done differently are as follows:
Thank you for reading! Feel free to leave a comment, rate this Instructable, and/or subscribe. Getting feedback on my projects is always motivation to keep building and publishing. Thanks!