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How to Build a Jet Engine!

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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/
 
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JediDude62056 months ago

do you think this would work in a rocket? and how much newton thrust does the engine itself produce + how much does it weigh?

fozzy13 (author)  JediDude62056 months ago
A rocket works much differently than a jet turbine engine. I haven't measured thrust, but the thing is pretty heavy, and I don't think it would fly under any circumstances safely.

How about for a bike? Im designing a jet combustion chamber and I might use this your Instructable for the turbine of the the engine. (A turbo might work as well or better but Its cooler if you say that you built the whole thing)

fs2-7.jpg
JediDude62052 months ago

About how much time did this take to assemble?

rimar20002 months ago

Very good work, congratulations.

fozzy13 (author)  rimar20002 months ago
Thank you!
waldosan3 months ago

just as a suggestion: if you look at diagrams of get engines as they are professionally made the compression stage uses moving left handed blades and stationary right handed blades to form the compression, basically something looking like this \ / the compression occurs when the moving blade slides over the stationary blade. the stationary blade interferes with the forward moving current causing it's direction to change from moving rotationally to moving forward.

just something you might think about if you're trying to increase compression, the trick might not be to add another fan blade but might be to add a stator. also you're design is kind of funky having three different flame tubes being fed by a centrifugal fan you might decrease the tolerances by adding a stator and a sheath to keep the compressed air compressed.

waldosan waldosan3 months ago

also: you can still use the rotor stator setup with your centrifugal intake if you pay attention to which way it's spinning, you want the stator to slice the air current being produced by the rotor so the stator being on the outside you'd want something like this: \(/ /)\ where the backslashes are the stator and the forward slashes are the rotor represented by the parenthesis. imagine it spinning clockwise. i would imagine if you build a manifold on the outside of the stator you'd be able to supply all three flame tubes with constant air pressure.

fozzy13 (author)  waldosan3 months ago
Thanks for the comment! I'm aware of stator veins, and the body of the engine itself is shaped in such a way that everything comes very close to being aligned perfectly as stator veins would align them. That's not to say it couldn't be improved though; in fact that's one of the thing I will be implementing in the future.
dsherman15 months ago
An easier shortcut would be to take automotive turbo chargers and superchargers to make your routers and stators and shroud your combustion area to make an anular combustion chamber.
erronius6 months ago

I'm certainly not an engineer, but if you are really going for the centrifugal compressor, why not cut off your existing fan blades, mount radial blades on the remaining fan disk (maybe even spiral them outward) and put a cowling (a plate with a hole in it) on the front to mitigate pressure loss? I've seen electrical submersible water pumps designed in that manner (with water channeled between the motor housing and the outer housing); and squirrel cage fans work in a similar manner. I may be full of pewp, but it seems to me that maybe you could push more air into your combustion chamber that way???

fozzy13 (author)  erronius5 months ago
This "cowling" was made in Step 11: Finishing Pieces.  I didn't use it in the test, because as air was blown into the engine at the compressor, it could be felt with the hand at the exhaust side in the appropriate places.  That said it will certainly be considered for use in future testing.
iwantanto6 months ago

Sorry, I don't have experience with jet engine. But it looks like you weld the flame tube in wrong way. If you like to compressed the air, then the wide-side of the flame tube should be at the intake fan (bigger one) and the narrow-side at the exhaust. That's I learned from the gif animation.

Oh wait, the smaller end was intake?

fozzy13 (author)  iwantanto6 months ago
The smaller end was indeed designed as the intake. During testing, the engine naturally wanted to operate the opposite direction, likely because I had no effective way to get the compressor spinning to speeds in which it would actually compress, if that makes sense. Because of the circumstances in this first round of testing, I allowed the tests to happen backwards, as they were want to do.
Daemoncoder6 months ago

Should be titled " How NOT to make a jet engine"

AJMansfield6 months ago

It looks like the fins on the intake rotor are backwards. You should try flipping it around, using the jet end as the intake and the intake as the propulsion end; that way you could install a stator underneath the rear rotor, and modify the fin pitch to force air laterally into the channels. You could get some major improvements to compresion efficency that way.

Wait, the larger end was the intake, right?

astral_mage6 months ago

shop vac will give you the volume that u need.

jacobkoski6 months ago

May I ask what type of welding table is that with the holes? Is it a strong arm table or another commercially available one? Or is it custom?

they are commercially available but will set u back up to several thousand or so. but u can make yr own tho. try to find a local make it space that has a plasma table. learn how to use. then make yr own table threw layering of 1/4 to 1/2 in. steel plate. then assemble your layers. and legs that will support the table top.

dpagan126 months ago

jknickel is right ,the speed necessary is too high for your mechanics and the air flow drive your using has to go the other way or you don't get compression . How about scaling it down , it would be safer and you can build the high precision parts easier and a dremel would work for startup . my 2 cents

zikzak16 months ago

As others have said, Balance. VERY important! That thing will become quickly uncontrollable and / or fly apart, if it's not balanced and starts to drive itself hard. As you know, jet engines run at a very high RPM. None of us here want to see you hurt yourself or anyone else! Nice project though. Would like to see the next revision of this after you put some more R&D time in. CAD will help you a lot!

masynmachien6 months ago

Great to see the Ible on your "baby" I saw getting "born" this summer.

Good documenting of your learning experience and promising results!

I see some helpful comments appearing below (and more will probably follow). Apart from important safety tips, I think the "cowling" on the front compressor fan to force the air into the combustion area, is the first next thing to try.

With this kind of work I expect the better it starts to work, the more dangers will appear.

fozzy13 (author)  masynmachien6 months ago
Thanks Yvon! When I get back to testing I'll be putting everything people are saying into consideration, putting on the intake cowling that I made, and have better weather to modify things and get some better runs done.

A few tips for drilling holes in round stock. First off, use a V-block to hold the stock. This prevents it from spinning/rolling and also keeps it straight up and down.

Before you start drilling, use a punch to center mark the stock. This will keep the drill from wandering when you are first starting the hole.

With any drill size over 1/4" in diameter, drill the hole first with a smaller drill as a pilot. For a 3/8" hole, I would drill a 3/16" hole first, though the drill only really needs to by slightly bigger than the web of the larger drill.

Be sure to use the correct speed for the size drill you are using. An easy calculation is to take the cutting speed of the material you are using (measured in surface feet per minute (SFM), found in a machinist handbook or online) multiplied by 4, then divided by the diameter of the cutter you are using. This also works for speeds of end mills and other tools that spin. So a 3/8" drill in steel would be 130x4 / .375 = ~1300 RPM. Keep in mind this is just a starting point and may need to be adjusted up or down.

If you have access to one, use a lathe to drill the holes. Mount the stock in the chuck of the lathe, then put your drills in the tailstock. Don't center punch it though. Instead, use a center drill to make a dimple in the stock. Then go to your normal drills.

If you are unsure of some of the terms I used, google them and it should become apparent what I am talking about.

Properly done, you should NEVER break or burn up a drill.

Good tip NRD, drilling thru a rod was always a pain in the neck.

xarlock6676 months ago
Hi, you are going to kill yourself if you dont lock that nut on your fan down. Also, balancing your blades is a great idea. If you ever get it going hard it will vibrate apart. That said, enclose your fire to build more pressure for more power. Have fun and try not to die!
gdecol6 months ago

I like the idea of a homemade or DYI
turbine.

Very nice job so far, I'd like to point out a couple of things that may help.

After studying your design and putting some thought to it it
seems as if your igniters might be relocated out of the tubes and into a
funneling combustion chamber built around the shop vac impeller with
the igniters at the escape end.

At their present locations you are
igniting your fuel in the tubes/ fuel lines which is not allowing a
build up of pressure. Sort of like lighting a fuse inside a firecracker
with open ends or just the powder by itself or igniting gas inside the fuel injector
instead of the piston cylinder.

Having some pneumatic and hydraulic
background I've learned that a container volume under pressure is more
powerful than a tube under pressure.

Combustion in this
application needs to be a controlled, contained explosion in a partially
enclosed volume with a directed pressure escape.

Or I could be completely off base and may just need a beer:)

Nevala6 months ago

People have covered most of everything I had to add, but I wanted to suggest that you consider balance in your further progress. When you get one to kick off proper, you're going to want to ensure that it doesn't shell out. Balance is the key in that case. I would presume that any automotive engine rebuilder would be able to balance your shaft and turbine assembly pretty easily.

TwinMustang6 months ago

Also, as I see you noted in a further step, steel doesn't hold up particularly well under jet combustion conditions. If possible, I recommend using Aluminum and Titanium in the construction, as aluminum disperses heat well, and titanium has an extremely high melting point (both are used in commercial jet engines specifically because of these properties).

TwinMustang6 months ago

As an Aircraft Maintenance Engineer I don't really have much to add to the comments, except to emphasize Eye Protection, and the shaft was far too small for safety. In the future, you might try using 3/4" aluminum round stock, and using a die to cut the required threads. This will ensure the integrity of the shaft by minimizing stress concentrations. Something else you might consider is that a jet engine works on a pressure differential. By this I mean that once ignited it should need nothing more than a fuel source in order to run.

In aviation, jet engines are run up before igniting the fuel. I would advice caution in doing this, but you will likely have better results if you do. I recommend using a dremel, drill, or angle grinder to spin the impellers up to a minimum of 2500 rpm before igniting the fuel source. Higher is better in this case. I'm uncertain as to the viability of propane in an experiment like this, but I would also recommend priming the engine before ignition, and lighting with the modified stun gun you mentioned

Hope that helps

Hazmatt6 months ago

This will be a major rework but I think you need the exhaust outlet from the combustion chamber to be larger than the intake. For the gasses to go the correct direction the air intake has to be a higher pressure than exhaust. The exhaust is lower pressure with a much larger flow

loachridge6 months ago

Wow. Nice work for what I would say is a hand built turbine.

I would like to direct you to Tesla for smaller turbine designs.

The only thing I would suggest that hasnt been said already, is work out a system for centering and getting a more circular rotation.

dhanhurley6 months ago

Hi from Tübingen University,Schwaben,S. Germany...You should check-out V. SCHAUBERGER (Austria) and his VORTEX RESEARCH... Also maybe you should use PULSES ... Ciao ... Dhan Hurley

Bill WW6 months ago

Here are comments from a retired mechanical enineer:

Just keep doing what you are doing. New engineering graduates with practical
hands-on experience are rare. Your enthusiasm and curiosity are admirable.

I am not convinced that AutoCAD skills are essential for your current projects or your future career. I now use cad, but did not in my career (hey, I started with a slide rule!).If I were now starting out, I would learn software intended to convey concepts and ideas to others, such as Adobe Creative Suite.

The impeller you are using appears to be from a Shop Vac. If so, it is likely aluminum, not stainless.Also, I measured my Shop Vac motor speed with a digital tach: 30,200 RPM!

Use eye protection and think about how your creations would disintegrate if they fly apart. Then don’t stand in the way of projectiles.

For one thing, you need a cowling on the front compressor fan to force the air into the combustion area. It has to come in pretty close around the intake area to keep most of the air from leaking. Take a look inside the vacuum cleaner to see how this is done. Also there is going to be a lot of turbulence where the air gets forced into those 3 square tubes. If you take a look at successful jet engine designs, they use a ring that goes all the way around the outside of the fan. Think like a pipe inside of a pipe. http://www.youtube.com/watch?v=cUnUsPxvrSw

darkmf6666 months ago

I'd have to agree with jknickel. Although i am in no way an
engineer, i think the main thing this setup lacks is a combustion
chamber. Merely burning gas in front of a big ventilator is not gonna
work. So first of all a more closed design should be required. Inside
there you can combust the gas.

Also the way the fanblade moved up
and down the axis as you spinned it up is very scary if you ask me. You
might wanna fix this issue by using a jam nut thats tightened next to
the first nut. That way you'd already decrease the chance of the thing
blowing up in your face.

Also i think that you wanna make such an setup where you use part of the exhaustgasses to drive the compressor once its running. To get it running in the first place you indeed might wanna use a leave blower, or you could try spinning it up with something like a batterypowered drill.

Bard6 months ago

Based on the video it looks like your rotor is a little off center. this was evedent by the slight wobble and the back swing when the power source was removed.

Marsh6 months ago

I would think a leaf blower to be a better source of impingment air to get it going

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