Building a turbojet engine from scratch - was it worth it? 

This is what kids should be using internet for. Not social media but research and experimentation. Man i miss early internet it was much less anti human

Airline pilot and RC turbine guy here. I'm extremely jealous you were able to pull this off when 25 years ago I was struggling to even make one of those car turbocharger "jet engines" back when they were just starting to become an internet fad. My biggest concern I can point out is that it looks like your starting fuel is extremely excessive, there really should not be huge flames shooting out of any sized turbine like that especially during start (afterburners excepted of course), and the turbine wheel and stators should not be glowing like that unless the turbine is close to full power. Yes, you'll see some videos out there of RC turbine engines doing it, but it's usually the older/cheaper ones/the owner screwed up, and it's still usually minor. Try being much slower and progressive with the introduction of fuel. At worse you should just see the faintest flame, but no glowing of metal. Everything from my little 45N Xicoy RC turbine to full scale works that way. I'm sure if you had done that, you would've avoided a lot of your warping and damage, and not have needed to resort to additional spacing between components which would kill efficiency. You probably know but newer RC turbines use kerostart, so no need for LP gas bottles, basically a single larger fuel injector (more like a torch) will be ignited initially by a glow plug, and as the engine gains speed by the electric starter, the rest of the annular "normal" injectors will come online as they ignite by the larger torch injector. Xicoy turbines excell at this. Some of the newer jetcats too. I'm assuming that one syringe is oil. Getting proper lubrication to your bearings is critical for cooling. RC turbines use 3-5% oil mixed into the fuel. Look for Mobile DTE Light R&O oil. It's what's used in full scale powerplant turbines. Do NOT use full scale aircraft oil as its really toxic when burnt or in aerosol (look at the NTSB reports on oil fume events). I would avoid the temptation of using diesel. It smells horrid, makes a lot of soot and can ruin the turbine internals in the long term. People at my RC field always eventually have issues. Use heating k1 kerosene, which burns really clean or if you're lucky and live near a smaller airport, you may have access to self serve Jet-A. Look at airnav (dot) com website in the fuel section for where to get it near you, and call the local FBOs for access. You'd be surprised how easy it is to get, and much cheaper than heating fuel and burns just as cleanly with not much worse of a smell. Lastly, RC turbines are much cheaper nowadays, I would never trust my beloved jet planes with one of them, but the cheap chinese brands like swiwin have some for $1500 a pop (these are the ones a bunch of youtubers keep getting for free to do stupid stunts with). Look in facebook marketplace for RC turbine jet sale groups, there's 4 big ones and every once in a while some older or crashed cheap turbines show up for sale, for a few hundred bucks. Or you could make an offer and I'm sure somebody would take you up on it. Merely as a way to reverse engineer and tinker with.

Try using Inconel for the stator and rear turbine. It is not cheap, and it is really tough to work on, but it will also withstand the heat. Also use ceramic bearings, and make sure the rotating assembly is VERY balanced!

Great work! keep in mind that most jet engines deal with heat by running very lean with air to fuel ratios above 50:1 all the way to 130:1. All that extra uncombusted air helps to cool all internal components and lowers egt significantly

One of the biggest flaws I keep seeing with homemade turbines is that most don't seem to use any amount of bypass air for cooling. In order to keep the main shaft and often the turbine itself cooled air from the compressor is allowed to flow through the shaft and is released either through the blades themselves or just ahead of the turbine to help cool it. Bypass air is also pushed in through small holes in the main flame tube to keep a thin film of relatively cool air in between the fire and the walls at all times, the lack of this feature is what caused so many failures around your exhaust. Finally, one of the methods I have seen other youtubers gain some success with is using ceramic coatings, namely fireplace sealant, to coat the heavily heated areas such as the turbine wheel and pretty much the entire hot end where bypass air is normally used.

These small turbine engines use the fuel from the turbine to lube the bearings. Using traditional lubrication will usually causes it to seize

What a great video! Good job throwing this together using stuff around the house. I'm in the engineering industry and have helped design things like pressure chambers to 30,000 psi for testing. Keep this in mind please: be safe! With the turbine turning at probably 100 of thousands for RPM's and your metal starting to melt you could have had catastrophic failure of the internal compressor to the point of it coming out of the engine bay travelling at very high rates of speed! When building the pressure chamber, I had to think of "how could this fail" multiple times thru out the process and and how could I get injured if it did. Keep that in mind, and keep building better turbojets!

This is just too cool dude! Hoping to see more

Good work my friend, you're on your way to building a functional jet engine. I look forward to seeing future improvements to your design.

I like the suspense with the intense music, as fire and sparks are released back into the world. You should allow for much bypass air, possibly just by making your nozzle act as venturi and through welding fins to external housing of preferably light weight material. The fins will conduct heat from nozzle and help cool with air on it's surface area, all of this without needing a bigger compressor fan, but radial holes with bent aft angle can be drilled if venturi effect isn't super effective

3 things: 1 - Don't skimp on bearings and making sure they are aligned and appropriately lubricated. Check out SKF's 6201-2Z/VA201 or similar. Regular "High" temperature bearings are only rated up to 150°C whilst these are rated for 350° which you can get to much easier with your cooling than to try and get your housing temps all the way down to 150°C. They're like £50 each, which is expensive compared to $10. But a $100 punt that might help you remove an issue/variable is worth it in the name of progress. 2 - Have you considered fuel cooling? Not as in cooling your fuel, Not sure the speed of your pump, but you could get some "Free" cooling by using your fuel lines as a heat exchanging medium. It also heats it up making it easier to ignite kerosene? 3 - Keep doing what you're doing. Progress doesn't come from academia. It comes from people doing stupid stuff in sheds.

Ima need a follow up video NOW, great stuff.

This is insanely impressive! Keep it up mate!

You won me over with this video. Subscribed. Keep up the amazing work, and STAY SAFE!

definitely subbed, great work man.

Very nice my dude, nice video, keep up the good work!

Very well done! An enjoyable watch.

You made a subscriber out of me. Very impressive work!

Way to go! This is awesome!!! I wonder if a turbofan design would help keep the nozzle a little cooler by means of forced convection. Either way, this is an awesome project along your way! Thanks for sharing!

Good lord man, fantastic work!

Good job on that build!

Good job on the project AND video! You got a new subscriber here!

One of my schoolmates on high school built a jet engine from scrapyard turbo. It had plain bearings (no issues with centrifugal forces on the balls) and oil pump which was slowly pumping oil into them (extra fuel)

nice work!

Back when I was building mine, I ground a deep groove radial bearing to become a pseudo angular contact bearing, then fill it with silicon nitride balls completely with no ball retainer. They are so hard and slippery, no retainer or separation is needed. Then like others said, cut a bypass channel through your diffuser and allow some bypass air through your bearing tube. Hypodermic needle teed off from your main fuel supply and run fuel/oil mix through your bearings for lube and cooling. Maintaining a tight tip clearance with the turbine is essential. Of course the hot spots are your enemy with the tight tip clearance and rubbing occurs. Fun stuff. I built one with a 1.5" turbine wheel. Would self sustain around 60k rpm.

Congratulations! Thrilled that you actually got it self sustaining. Finding some of those precision parts surplus was very lucky, that's not to say what you have done isn't impressive though. But those parts are definitely not manufacturable at at our diy scale! Like other commenters, I'm also really keen to see what decisions and calculations went into designing the engine.

Awesome, Good work! Keep refining it and keep it cheap. I like that it burns propane, but understand the temp issue. I believe LPG would serve as a coolant upon injection due to phase change, so it might be a better fuel if you are trying to decrease combustion temps.

Keep it up man!! LIMITLESS POSSIBILITYS ahead in life for you...

Love your video editing

Way to go, very cool!

I'm an airline pilot, an would like to say it's really cool you have the interest in this kind of engineering and follow through to complete projects like this. its refreshing to see there are some people who are still mechanically/scientifically minded :)

Very impressive. Your neighbors must luv u.

You will also need to use multiple smaller nozzles to spread the fuel fully and avoid the hot spots

Great job , be safe.

You should consider adding an additional outer shell and turbine. The outer shell would go around what you currently have with a consistent diameter until you reach the beginning on the nozzle where it would have a short conical section to divert airflow around the nozzle. The additional fan/turbine (correct my verbage?) would go in front of the compressor wheel to match the diameter of the new outer shell. This way the shaft now drives a controlled outer flow of cool air around the body of the engine. You can play around with the larger pre-compressor wheel design to get sufficient airflow for cooling while minimizing parasitic loss on the engine. While suboptimal when considering placing the engine into a craft, you could consider also adding high pressure injectors to the outer shell which inject a fine atomization of a cooling fluid/gas. The simplest that comes to mind is distilled water but there may be a better option like C02 that provides fire suppression and is simpler to inject or creates more even and efficient cooling. As an additional note, I noticed you had hot spots around the nozzle area. This may indicate uneven combustion. Perhaps adding fins or shaped blocks inside the engine, somewhere between the compressor wheel and fuel injectors, could help. Here the fins/shaped blocks are angled/shaped to direct a circumferential swirl in the airflow for better fuel air mixing. Of course, I am not sure if this would interfere with the operation of your flame catcher. Thoughts on this? A potentially simpler solution, either replacing or complimenting airflow swirling, could be to adjust your fuel injection. Angling the nozzles more tangentially may improve fuel air mixing. Increasing fuel pressure could improve atomization and provide the necessary force for a tangential injection angle to stratify the fuel. Of course, none of this will negate that heat tolerance of your post-combustion internal components needs improvement. Though, a more even burn and outer cooling flow will help your nozzle and shell to withstand. If heat tolerance of your stator and turbine remain an issue, you may consider adding fuel or coolant injection just prior to the stator; assuming you can come up with injectors capable of withstanding the heat. Consider ceramic injection nozzles for this application? The additional fuel or cooling liquid (water?) will vaporize on the hot stator and turbine to remove some accumulated heat. Tuning this to remove just enough accumulated heat without reducing the efficiency of your jet would be required. Should you choose to implement both post-combustion injection and an outer cooling shell with pre-compressor turbine, the changes set you up for an afterburner in the future. All you would have to do is extend the cooling shell into an afterburn tube and use fuel as your post-combustion/pre-stator cooling fluid. This way you get vaporized fuel and air delivery. Perhaps additional fuel injectors in the afterburner would help here as well, so that you can independently optimize the quantity of cooling fuel and afterburner fuel/air ratio. IE if the afterburner requires more fuel than would be optimal for stator and turbine cooling.

Kudos ... you made it running for at least 3 minutes. Now I understand why people are using ceramic bearings ... maybe this and some cooling could prevent the from turning into scrap.

Congrats on a good effort, having been through an almost identical experience many years ago I am surprised you achieved self sustain at such low R.P.M. Your source of such a low cost turbine wheel is envied. As suggested by others below, the overheating is probably because of the low volume of air flow due to those relatively low impellor revs.

I'll watch more jet engine stuff. Subbed

310 stainless would be a good option for high temperature applications, 253MA is even better but expensive and difficult to work with but holds its shape very well at elevated temperatures. We use it for equipment that typically operates between 800 and 950C so it should work very well in your application. From the sound of your voice I would say you are quite young, very impressive what you have done! Keep up the good work.

Insane, ill buy one from you if you ever make more.

You're doing great. Less fuel might lean out that engine richness as well.

This is awesome, nicely done! I saw the engine was on a slide track, were you able to measure thrust output?

Oh my, those materials you are using are clearly not able to withstand the heat. There is a reason for jet turbines arent made from pots and scrap. Other than that, excellent video. Im amazed you actually made it work for a while, really cool. 👍 Now lets build a cruse missile, i think i got a few pots somewhere. 😀

I'm amazed this DIY jet ran for so long with essentially molten metal dripping into it's casing. 🤔 Good wholesome (if somewhat precarious) entertainment. 😉👍

I really want to see more. I think there is very little time left for you to build a functional jet engine.

Outstanding

Very impressive.. but why the music tho seriously.. Everyone wanna hear the sound of the Engine❤.. anyway Goodjob man.. would be nice to see the full construction process..

You could consider ceramic printing of the engine body and other stationary parts sensitive to high temperatures.Such printers are not expensive. For example, Tronxy Moore 1 or 3. The issue of choosing the right ceramics.

Your neighbors must love you building a loud experimental jet turbine

Nicely done! Might I suggest looking into some kind of research grant to pay for better parts? You'd be amazed what money is out there, and you've got solid proof of concept already. Think of some novel application for the engine, emphasizing the ol' Better/Faster/Cheaper - Pick Two angle.

The hard part is building a combustor that mixes in cold air so the flames don't ever directly touch any metal without cooling, that is how big airline engines can work many hours without melting

Great Effort. Have you got any oil mist lubrication for the bearings, also Preload the bearings with a preload wavy springs, as both elements will cool the bearings and prolong the life of them by removing very unnecessary stresses. I was a member of the GTBA (Gas Turbine Builders Association) for a while but have no idea what they are up to now, but I'm sure their knowledge can help with previous papers etc Well done on your efforts. Rome wasn't built in a day, stick with it and you will get there. Good luck my friend.

so cool!

Love the music.

The old Electrolux vacuum cleaners sounded just like your engine. I think it was the same as what Adam Savage nearly sucked his lips off and did "trim" off some of his mustache with on a Myth Buster's episode.

Still, VERY cool project!

RIP Integza. this is the future

316 is only less prone to cracking, you'll need to compare the melting point of 316 vs your egt i suspect it still won't stand up against that heat, try titanium 🤞🏽, we'll be waiting for your next attempt looks good so far 💯👍🏽💪🏽

I miss the time of step-by-step tutorials, then an even simpler one can be with the separate compressor, more step-by-step

I am really impressed about the air eqalization it the engine. How did you make the proper calculations? I am really curious if you have ever used some good driven software. Like I can just tell you that these steel ball bearings won't work. I've never used hybrid ceramic bearings, but I think it's your job to try them. You can also try not attaching the exhaust deflector to the outside, so the termal sensible material will last longer if a proper spare radius is set and if you make it just a bit thicker (1.5x i guess, but you should do some proprer calc, to determine the thermal factor). The best thing I can recommend you for the testing (if you can, and the reaction wheel is inside the turbine) is to dismount the nozzle.

GU10 type LED bulbs are possibly the way to go as they are unidirectional.

Cool dude 😎

Amazing

Figure out those sparks.most likely when warping its hitting the casing but that’s causing a lot of unwanted heat and damage to the motor

Try to use ceramic bearings if you decide to build another one, they can endure harsh conditions.

Music don't need.

I always wondered if you made it a high bypass turbofan with heat sinks around the nozzle if you could solve your overheating.

you could probably put in two fuel injectors, spool it up with the propane, and then switch over to kerosene once it's hot enough. Similar setups are used in oil burners, since oil itself is absurdly hard to get burning.

I think this should be done in diesel heaters and it can charge your battery while running

I love the compressor wheel you used, where did you source it? Alibaba?

Sir Frank Whittle was incredible

Ceramic bearings are costly, but are worth the investment.

a lot of anti ship cruse missiles have turbine engines that last about as long as yours dude and they cost 2 orders of magnitude more than a regular rocket motor due to increased range

Dont use inconel or dental equipment look into growing the metal crystals yourself to have the blades made from single of metal and make sure they have correctly sized expansion joints

nice video, im concerned about the flames shooting at the back and of your neighbors

If you are able to recreate it according to plan, you will get an excellent engine. Otherwise, be creative with the compressor wheel/turbine wheel (it is cheaper) and stick as close to the plan as possible. And remember, it's a lot of work to build a DIY turbine - you don't have to reinvent the wheel! " Good luck and have fun Thanks to: Gerald-Rutten Turbines

How do you go about balancing the rotating assembly?

Would it be feasable and helpfull to use ceramic ball bearings?

Where did you get the turbines

Nice

there will most definetely be a GE recruiter spawncamping your school from now on

Currently I’m trying to make a jet engine without power tools and with just 20€ budget, which sounds like very little but it’s kinda working so far

Having demonstrated ability to throttle your engine, maybe it would be worth the effort to implement a feedback loop with one or more pyrometers sensing the temperature different key points of your engine and reducing the maximum fuel input. And given that you are looking at using other fuels, that could also be part of a system that uses the temperature as an indicator to switch between fuels : propane to start until it gets to a certain temperature then switch to kerosene but switch back to propane if it cools down too much to the point of threatening a flame-out. Better heat resistance and active cooling looks like the obvious path as heat was what killed this engine. Yet going for automatic controls might take less effort and allow your prototypes to stay alive longer and make prototyping an active cooling design easier.

The turbine and the stator is simply far too hot. The combustion chamber is not working correctly, you need to get more air to the rear of the chamber. I built one with only stainless steel for the turbine which still lives to this day if the jet pipe is in excess of 600c you will have problems.

water cooling could be your friend if u want to use sheet metal and propan gas

but how much thrust did it generate?

927th subscriber!

Inconel, and yeah ceramic bearings. But so cool keep going roght now a hobby will turn into a career thats easy as u love it

This is insane for a hobbyist! I would see if anyone would be willing to donate!

hi, i was wondering how do you make/where do you get the turbione wheel and is there a cheap whay to make them with basick equipment?

Also one of the easiest subscribes in a while

Where did you get the turbine wheel from ?

What did you use for fuel just Kerosene?

might i suggest using propane to start the engine and once it's up to speed moving to kerosene or jet fuel

Hi, where have you bought that turbine disk ?

im just curious where you got the turbine and stator from

It seems most of the air in your jet engine gets mixed with fuel and combusted and this causes the over heating and also uses more fuel. Only about 10%to 20% of the air should be mixed with the fuel and combusted, the rest should be used to cool the combusted air before it hits the turbines

It's easy to light diesel just a glow plug and a screen

How much did the tools and test bench cost?

What kind of scrapyard sells excess turbine blades that cheap? I have been looking for one of then and have not found anything for under €400