Prototyping (Tiny) Rocket Injectors

[@XMaster96DE]

0:34 "I am not an engineer", But I just happen to have access to high precision 5-axis CNC machines and Metrology equipment. This alone kind of gives him such a huge advantage over all the others he has listed.

[@scottgauer7299]

Hi! I've worked on both monoprop peroxide engines and biprop combustion engines. For monoprop, you do not need atomization, and an atomization optimized injector will give you bad performance. Atomization is only needed when you need to vaporize your propellant (to ensure efficient combustion but irrelevant in a monoprop). All you need to do with your monoprop injector is make sure it's distributing the flow over the entire catalyst bed evenly (like a showerhead) and it has a large enough pressure drop to avoid feed system coupling (chugging).

[@kenmercer2721]

Just what I was thinking. Impinging two reacting propellants makes sense whereas peroxide just needs good exposure to the catalyst.

[@DisorderedArray]

Also, for a monoprop, are impinging flows needed, or could the flow from one hole just impact on a baffle to achieve the same effect?

[@scottgauer7299]

No impinging flows at all. The best monoprop thrusters use just a showerhead with axial flow

[@BPSspace]

I could not possibly be more excited for a project! Great work on this so far, and man that high speed footage is beautiful. Also LMAO 0:35 if you don't qualify as an engineer, I'm not sure who does

[@starshiphopper7044]

You

[@BreakingTaps]

🥰🥰🥰

[@multidiamanthunter]

Im still sad you view hybrids that bad :( especially for European student groups it’s the best option - did you see e.g. the North rocket build by HyEnD. It set a new record earlier this year. Hybrids have their flaws but also some really good points in favour especially in terms of safety.

[@kineow]

We at Vaya Space will show to the world very soon how amazing hybrid rockets can be!

[@mmmmm49513]

Aerospace engineer here. Love this channel. Always a cool topic. I was terrified at the beginning of the video when you said that you were going to build a monopropellant rocket. I though that meant using high percentage hydrogen peroxide and it’s pretty nasty. The lower percentage stuff is lot safer so I’m glad you went that route. That said, make sure you read up on proper storage. I remember reading a story in my textbook about a lab technician at Purdue not properly venting a container of hydrogen peroxide. Since it’s constantly decomposing it can build pressure before “violently decomposing” which will destroy the pressure vessel and shoot shrapnel everywhere. I’m sure you already know this. But the only other thing I’ll say is make sure you build your combustion chamber out of a ductile material like aluminum. That way if it explodes for whatever reason you also don’t send dangerous shrapnel everywhere 😂.

[@Bobbias]

Yeah, I've seen what it looks like when forces are enough to literally shatter steel. Don't want to be anywhere nearby if that ever happens.

[@BreakingTaps]

Been storing it in a mini fridge, and burping it occasionally to relieve pressure (if any) 🙂 I did see some pretty wild containers for the high test stuff, which have built in expanding bellows to accommodate the decomposition. Pretty scary stuff tbh! Even if I could find a vendor for higher percentages, not really sure I'd want to. Reading through Armadillo Space's archived dev blog is equal parts fascinating and terrifying 😅 Interesting point about using a ductile material. I was actually planning the opposite, building it all out of stainless. But using a weaker material does make a lot of sense. Will think about that, and also see what kinds of pressures the electric pump feed generates. I do plan to "fire" it only inside a safe enclosure. Will probably weld up a steel box and surround it with bricks and such. I dont have a lot of background in energetic stuff, so planning to be suuuuper cautious and extra safe :)

[@mmmmm49513]

It’s not about strength! Use a good strong material! What I’m talking about is the how the material fails. Ductile materials like aluminum will pop open and vent an explosion. On the other hand more rigid materials like a hardened steel will fracture causing shrapnel (pipe bomb). The shrapnel would be the real thing to worry about. Hope that helps!

[@MrLouvillian]

@@mmmmm49513 another good approach is to have bolts designed to fail at X times MDC so that the nozzle blows off in the event of a chamber overpressure. Great place to use materials like brass (or even plastics) for the bolts

[@JaredBrewerAerospace]

Aero here too. I have a liquid 50lb biprop on my channel. I had that same feeling about the real deal High Test H2O2. Treat it like LOX. Get it and use it on the same day. Also, I forewarn that the pump will be the most difficult part of this adventure. Materials, seals, bearings, heat,... All of it. Rockets fundamentally don't have any moving parts. For your injectors the L/D ratio of your injector holes is more important than the diameter. While testing, check valves will help with consistency at startup due to their crack pressure. Welcome to boiling the ocean for troubleshooting and good luck!

[@LuizHenryBR]

Yes friends, I feel blessed to find this channel

[@omjagdeesh8731]

Same

[@raptorsean1464]

This this is basically what I just commented on the last video of his I watched. This is now my third video in quick succession. The first one was the micro spheres on micro electronics and tape, and the second one was the ion blaster. If you haven't seen those, go check them out. They're absolutely fascinating.

[@CopenhagenSuborbitals]

Nice work and amazing footage! 🚀 Great example of the intricacies of injector geometry and associated effects.

[@BreakingTaps]

Love what y'all are doing! Should have mentioned you in the intro and totally overlooked it. Been following your project for a long time now, what you're doing is amazing. And you have some very cool videos on injectors 😎

[@CopenhagenSuborbitals]

@@BreakingTaps Wow, thanks, the admiration goes both ways! 😊

[@mased-v2j]

It looks like the next step in testing will be to build a better supply for your pressurized liquid. You’re getting a lot of air in your “propellant”. I think a piston pressurized with air on one side would work better. That way you can bleed it. Great video. I’ve been thinking about doing something like this for a while. I look forward to seeing what you come up with.

[@treeman10]

He also said he plans on using an electric pump, not pressurized air, so they should yield better results

[@aaronmarkstaller]

Or a balloon sac. Keeps liquids and gasses separate. Very low friction

[@darkwater72]

Well now. Using a "piston" driven by air, instead of redesigning the airstream, is one of those "quietly brilliant" solutions. It has all the best qualities: 1) Simple to manufacture using tools you already possess. 2) Does not REQUIRE (and I stress the word "require") redesign of any of existing components. 3) does not REQUIRE changing the design or principles of any other part of the system. At this stage, all you are trying to do is drive the propellant through the atomizer at the required rate. I have seen teams disappear down rabbit holes of ever more "brilliant" designs requiring ever more complicated and time consuming machining which, for this purpose, was completely unnecessary. (Ask me how I know.😢) This is design and trial. The ONLY part that has to look like the final product is the part under test.

[@Conorsev]

I have been making a peroxide rocket at home. I made my own 90% peroxide. I used a vacuum distilation set from Ali Express and a refrigeration vacum pump. Ended up being alot easier then people said and was a fun project. I'm using stainless steel nozels from a misting fan. They attomise great and come in heaps of sizes.

[@WyrdieBeardie]

I love how everything seems to "change" when you start to deal with the "very"... The very fast, the very small, the very high power, even the very low power, the very high vacuum... Suddenly, issues that previously could just be ignored suddenly become relevant or even dominating! This series is going to be very, very, interesting! 😃 Thanks for sharing!

[@PatrickKQ4HBD]

What a great observation! 👍

[@charlvanniekerk8009]

This is going to be an incredibly interesting build!! I cannot wait for the rest of the development.

[@luizgustavoschultzsenko5860]

You can use an Agricultural sprayer nozzle for that, it atomizes very well, and you can choose the shape of the sprayer, from a triangle to a hollow cone, and the materials too, up to ceramic nozzles 😊

[@TimeLapseRich]

Sprayer nozzles are used in may sizes and mist/spray patterns in the industrial food market. I uesd them in systems that sprayed baking pans mostly.

[@JCisHere778]

When filming stuff like droplets and jets, you could try putting some white acrylic (or something similar) behind your experiment as a diffuser and illuminating it from the back, in my experience that gives better contrast and introduces less heat. Very cool project :)

[@BreakingTaps]

Will give that a shot next time! Getting good high speed footage with enough contrast was _super hard_

[@1Happy_Singh]

​@@BreakingTapsCan We Just Put A Metal Net Of Some Durable Material 😅??? Or Can We Put Spraying System And Catalysing System In One Unit In Which The Sprayer Is A Cylindrical Structure Inside The Catalyser ??? And Then We Angle The Nozzles Of Sprayer So That Tiny Water Droplets Are Formed ???

[@ciaduck]

This is a good idea. I've also seen really cool water-droplet photography using 2 colored lights at 90 degrees from each other.

[@aaronmarkstaller]

No black background and light from above or below

[@aaronmarkstaller]

Can use a reflector sheet to diffuse it, or diffuser cotton cloth

[@ehdeesign]

Always impressed with your effort level & build quality. Couple things. 1. BI-Prop injectors use different sized holes AND impingement angles from inner-outer rows. 2. There is no benefit of impingement for a mono-prop. Impingement is for mixing fuel and oxidizer for more efficient combustion. With a monoprop, the catalyst releases the oxidizer stored in the fuel. 3. Hybrids have thier place in propulsion, there is not a one tech solution in the rocket-world. There are always trade-offs.

[@OtherWorldExplorers]

Not to be a snob But according to This Old Tony... When a machinist is pointing at something you need to point with something technical. In other words when you were pointing at your 3D printed model of the rocket. You should have used the back end of a Mitutoyo digital calipers, or a ruler that measures down to tenths... All joking aside, I'm very excited to see where this is going. Rockets are cool!

[@BreakingTaps]

Or a sharpie marker that teleports through time throughout the video 😁

[@OtherWorldExplorers]

@@BreakingTaps Touché`!! Score is one nothing your favor :)

[@Engineerd3d]

You should look at diesel injectors in this case for inspiration. These are designed to aromize fluid to a very fine degree and their tip design is very well studied and researched.

[@BreakingTaps]

Will take a look!

[@42468]

@@BreakingTaps from my experience, two things might be worth trying from the diesel world: pintle-style injectors (which can be turned on a lathe-no microdrilling) and voice-coil based injection (where a vibrating membrane is used as a pump and to break up jets into a steady stream of droplets).

[@Elitesniper257]

I’d also take a look at using automotive fuel injectors and components. If you want a full system it’s going to be easier as well since it lower pressure and components are easier to get.

[@Vi_Renders]

0:34 "I am not an engineer" then why do I hear Team Fortress 2 music every time you're in frame?🧐

[@1495978707]

8:00 you may want to consider using a mirror to film with the high speed camera, so that you don’t have to worry about damaging it, only the mirror

[@alexandregb566]

Imagine the life of this man. "Oh boy, I'm so bored. Let's make a rocket engine to liven my day up a little". It's awsome.

[@randomname4726]

Awesome series. You've finally convinced me to buy Nebula on payday. I love watching your channel, but it makes me feel very unaccomplished, lol. I used to make candy motors a long time ago before i had kids, i really must get back into it. Time to find a lathe.

[@BreakingTaps]

Hah, I feel the same way when I watch other creators on YT like Shane at StuffMadeHere or Joe at BPS 😅 Like how tf do those guys get so much awesome work done?! The struggle is real🙂

[@lewismassie]

This might be some of the best injector plate footage out there. I've seen animations for the doublet impinging injectors, but to see them really happening is very cool. If you have the free time I'd love to see some exploration of some of the other injector designs

[@SarahKchannel]

my gut tells me, that attaching a ultrasonic transducer to the nozzle plate could help disperse the liquid even better. Also it could help in cases where individual nozzles plug. Thats just my instinct, never seen it, never tried it.

[@undeadarmy19]

The size difference between 1mm and .2mm is only about 5x smaller in diameter, but its about 24x smaller in area, that's why it looks SO much smaller.

[@Slim821]

I have led and also supported designed various hybrid rocket motors from very tiny up to 80,000 lbs thrust(SS1 and SS2)with burn times exceeding 60 seconds and are all powering manned astronaut application. I have also developed liquid rocket engines with more than 50,000 lbf. Each tech has it place depending on the application, performance requirements, and budget. After doing this for over 30 years, I still swing back and forth on which will support my application. Some of my applications are drag racing with burn durations under 7 secs and quick reusability and reliability are paramount!

[@GerinoMorn]

Now, I'm also not a rocket scientist, but if I wanted to do a monopropellant rocket I'd probably not worry that much about injection, and just have series of fine silver(ed) meshes to pump peroxide through. Possibly by using the pressure increasing due to boiling to push peroxide through finer and finer catalyst meshes/sieves it can create sort of feedback loop...

[@ungoodwoodworker]

The low fps camera footage is so great. With those small holes you might need to change the name of the channel to breaking end mills.

[@tireballastserviceofflorid7771]

Cool project my friend One suggestion I would highly recommend it play more with pressures. Think about fuel injection. Old stuff like the early 70s used 30psi stuff. My 6.4 diesel uses 28,000 psi. The more pressure the better the spray. Really below 100psi I don't think you will ever get reliable atomization. And I do think you will find better atomized peroxide will relase more energy. Each droplet will have a surface tension and will be spinning. Theoretically it will give better contact to the catalyst. And for nozzle testing try a bigger tank to give you more time to study the spray. Anyway will be really cool to see how it progresses.

[@TheEmptyHoliness]

Fantastic video! This was amazing!

[@WRRocket9999]

If you increase the pressure drop across the injector, it will even out the flow rate through your injector elements. In your case this will probably mean you will need a larger diameter feed line for your injector feed or reduce your hole size. This pressure drop through the injector will also help you significantly when you actually go to run your engine. Your pressure drop is essentially your safety margin. If you have a combustion pressure excursion and your pressure drop is too low it will cause your combustion pressure to exceed your injection pressure which will stop or even reverse your propellant flow. In practice this will result in whats called pogo or chugging instability because it causes a low frequency oscillation of combustion. As the flow slows down from the high pressure, then speeds up again as combustion slows and the pressure drops back down and keeps repeating this cycle. I've done some work with 90% peroxide, and it is indeed its own special animal.

[@ExcessiveOverkill]

I have been working on a similar project only with goal being parallel extremely laminar streams. I built a much larger fuel tank I could pressurize that prevented air from mixing with the fuel. I used cam lock fittings so it’s easy to refuel. I also found smaller holes are way way better for getting good streams. I started with .003” sapphire orifices but found that the .1mm PCB drills on Amazon also work quite well. They are also super cheap and more resilient than i expected. Adding a super fine SS mesh filter screen is also a must since any small particles will clog the nozzles. I tried polypropylene filter fabric but the tiny fibers can come loose and cause clogs themselves.

[@joelstienlet1641]

In what material(s) have you drilled these 0.1mm holes, and how deep? Thank you.

[@beautifulsmall]

0.2mm thats about the smallest mechanical via size before laser vias take over. Repairing my oil boiler , the nozel was amazing, 60 deg cone , three spiral jets. Beautifully made. You can dismantle them easily. £9 Danfoss. maybe some bits you could use. Fascinating as always. Nebula sounds worth a look.

[@almosthuman4457]

that's some great highspeed footage. rockets are fun, I'm here for it.

[@KallePihlajasaari]

Great project. You will probably run into pump cavitation at some point. You may get better results if you ignore the nozzle plate and simply fill all your sections with catalyst bed. Round disks of silver (plated) mesh filling the whole cavity probably easiest. Look at what the H2O2 tip jet helicopters and jet packs have done, a lot of the hard work has been done for you. Your impinging jets were beautiful but somewhat overkill for a mono-propelat that has to pass through a catalyst bed afterwards.

[@Amberlynn_Reid]

Well done making a shower head

[@BreakingTaps]

🚿

[@johnhosky2931]

You should look at the nozzle on standard garden hose sprayer. One of the settings in those little 6 position ones is usually a mister that atomizes the water quite well. I wonder how that one functions.

[@npip99]

9:58, remember to not consider 0.2 vs 1, but actually consider 1/25 and 1. Because you have to square it. A 0.2mm hole is 25 times smaller than a 1mm hole.

[@Flare1107]

So I wanted to try building a monopropellant engine using a modified Ranque-Hilsch vortex tube. The design was to run the injector partially reacted into the offset intake side port, and use a catalyst mesh wrapped around an adjustable, perforated, "cold return" tube through the center of the body. The "cold" air is redirected 180 degrees back over the body, and both hot and cool air are used as thrust.

[@the_normal_guy9308]

What about a pintle injector? It should be easier to tune and throttle.

[@NoblePineapples]

This is insanely cool and I am all for it. Absolutely love learning about anything aerospace related.

[@jan_the_man]

It's great to see your channel getting more into rocketry stuff. We do, of course, have a lot of very high quality DIY rocketry content on KZbin, but your machinery experience and tools shows this from a completely different view. Would love to see more of this!

[@bearnaff9387]

Watching your video I was reminded of two names - Richard P. Speck of Micro-Space and Dr. Adam London of Astra. Both are/were professional aerospace providers (We sadly lost Speck around 2010) with maverick outlooks. Speck ran a successful(!) aerospace company with some of the most gonzo engineering I've ever seen. His low pressure liquid-fueled motors used unconventional materials like fiberglass and resin, and his design for a minimalist lunar launch platform used angle aluminium framing and medical rubber tubing in the shock-absorption system. It was terrifying when compared to more conventional design, but when I met him he also had more than a few of his commercial launches (sounding rockets for the weather service) at hand to show that the principles were not nearly as insane as they looked. He was the kind of guy would makes world-record smallest/lightest orbiters in Kerbal Space Program, but did it in real life. Dr. London is an MIT grad who founded Asta. His post-grad work isn't nothing, but it's what he did at MIT that really made his name. The interest at the time was in micro-rocketry systems. Some principles of semiconductor MEMS design could be adapted to handling combustibles and could theoretically be used for ultra-small probes or station keeping for satellites. The top of the line at the time was a solid-fuel array on a chip. Essentially, it was a bunch of explosive wells piercing a conductive sandwich with traces to allow specific wells to be detonated at will. The wells were separated enough to prevent chain firing. It was a good way to store a small amount of delta-v for long periods of time without worrying about the vagaries of pumps and the behavior of liquid fuels in microgravity. The downside was that it was a chip die with tiny firecrackers in it. The delta-v budget sucked, especially compared to its mass. When Dr. London did his work, a MEMS pressure pump had recently become availble. So, he decided to see if he could use semiconductor tech to make a MEMS-scale rocket nozzle. It was cool AF. It looked like a little almost-2D bell nozzle made of layered metal and was _tiny_. I have to assume it didn't work because Astra doesn't mention it, and there are a tremendous number of applications for a chip-scale turbopumped liquid-fueled engine. There were discussions of building orbiters with the mass of a small car that could deliver 13-oz payloads to LEO and the linke, it was wild. Even though Speck is presumably designing sounding rockets in heaven (one of his non-commercial sponsors was a Baptist church!), we still have Dr. London. You might consider reaching out, or not. Either way, you're doing something cool and have cool peers.

[@psychosis7325]

Makes me love being Australian, 50% H2O2 is like $30 a gallon on Ebay here.... Mind you last one I ordered was shipped in an oversize reused box of a non hazardous chemical and had leaked causing me to have to track down a delivery driver, had all decomposed but was still not cool. Contacted supplier and they put in some new practices to ensure similar does not happen again. Kinda glad that come to me and not someone else that would of thought less of it.

[@wolpumba4099]

*Overview* - The video focuses on prototyping rocket injectors for a monopropellant thruster using hydrogen peroxide. *Background* - Monopropellants decompose and provide thrust, typically with the help of a catalyst. - Hydrogen peroxide is used as the monopropellant, which decomposes into oxygen gas and water vapor when it contacts a catalyst. *Design* - The thruster consists of an injection chamber, a catalyst chamber, and a rocket nozzle. - The injection chamber will have nozzles of different sizes and geometries to spread the peroxide into a fine atomized spray. - The catalyst chamber will be packed with a silver catalyst to decompose the hydrogen peroxide. *Injector Test Stand* - A CNC-made test rig was used to try out different injector geometries. *Types of Injectors Tested* 1. *Showerhead Injector* - Array of holes to spread the liquid. - Tested with 1mm and 0.2mm holes. - Atomization increases with pressure. 2. *Impinging Injector* - Angles two holes towards each other so the streams collide. - Tested with 1mm and 0.2mm holes. - Atomization is much better with smaller holes and correct angles. *Observations* - Full showerhead behaves differently than a single row, merging streams at low pressures. - Impinging injectors need to be in perfect order for effective atomization. *Conclusion* - Both types of injectors have pros and cons. - It's unclear which will work best in the final thruster design. *Additional Content* - A companion video with more technical details is available on N_b_la. *Positive Learnings* 1. *Effective Atomization with Impinging Injectors:* Using smaller holes and correct angles resulted in much better atomization, which is crucial for efficient fuel mixing. 2. *Showerhead Simplicity:* The showerhead injector's design is straightforward and could be more robust for consistent performance. 3. *High-Speed Camera Insights:* The use of a high-speed camera provided valuable real-time data on how the injectors behave under different pressures. 4. *Modular Design:* The thruster's design is modular, allowing for easy swapping of injector plates for testing different geometries. 5. *CNC Test Rig:* The CNC-made test rig proved to be a useful tool for trying out different injector geometries. *Negative Learnings* 1. *Impinging Injector Sensitivity:* These injectors are sensitive to alignment and hole size, and any imperfection can lead to ineffective atomization. 2. *Flow Rate Issues:* The full showerhead emptied the tank quickly at high pressure, introducing air and complicating the results. 3. *Unclear Optimal Injector:* Despite the tests, it's still not clear which injector type will work best in the final thruster design. 4. *Material Sensitivity:* The video mentioned that high-test peroxide can be sensitive and potentially dangerous, limiting its usability. 5. *Complexity of Variables:* The number of variables like hole size, pressure, and angle make it challenging to pinpoint the optimal injector design.

[@nerdgarage]

The reason the 0.2mm holes look so much smaller than you'd think relative to 1.0mm holes is because we're talking area here not just diameter. While the ratio of the diameters of the two hole sizes is 0.2/1 or 1/5 or 20% depending on what measurement means the most to you, the AREA of the holes tells a very different story. The 1.0mm holes have an area of (about) 0.8 sq mm while the small 0.2mm holes have an area of only (about) 0.03 sq mm. No that's not a mis-shifted decimal. Thats a ratio of 3/80, or only 3.7%. A much much smaller ratio than that of the diameters, which fits the much smaller visible size of the small holes vs the large holes.

[@BreakingTaps]

Oh yeah, when expressed as area that makes a lot of sense why it visually looks so much smaller! Felt like I was going insane at first when I was looking at them 😅

[@TheToric]

I would take issue with the statement that bipropelant is the most common rocket. For orbital boosters, maybye, but keep in mind that most payloads boosted into orbit have a ton of little manuvering thrusters that are all monoprop. For example, the dragon spacecraft launches on a booster with 10 bipropelant engines (9 first stage, 1 second stage), but the capsule has 18 draco engines for manuvering and 8 superdracos for LES, for a total of 29 monoprop thrusters. Other orbital systems have similar number of maneuvering engines. And solid rocket boosters, while not as popular for orbital and launch applications, are extremely popular for military applications, and are used for most military missiles, from ICBMs to air to air missiles. Im pretty sure that military stockpiles mean that SRBs are easily the most common type of rocket engine.

[@forrestglenn2520]

YESS! I'm very excited to see you doing rocketry!

[@SlickMona]

Could you make an impinging injector with 3+ streams colliding? That would presumably help with reliability in the face of clogging.

[@gsuberland]

That's a standard geometry called an unlike triplet :)

[@zyeborm]

As above and you'll still have issues with clogging. It's normally used when you're using to mix liquids with different volumes, like you have 4x as much fuel as oxidiser.

[@Jack_Of_Some_Trades]

@9:00 (1mm Showerhead High Pressure). THAT IS WICKED COOL. You're feeding so much air pressure into the system that the air exits WITH the fuel. I think the air is forming a sudo-solid center channel almost as if the pressure is somehow still high enough (despite it expanding and moving faster) that it forces the fuel to the walls of the drill hole where the air is relatively stationary. This might be making a cylindrical venturi tube which is why it's atomizing the fuel so damn well! @11:10 Contrast this to the 0.2mm where the air cannot make it through the drill hole since the viscosity of the fuel blocks the smaller hole. In this case the air pressure is more so acting as a piston on the back of the fuel forcing it through the holes. While you may be getting more fuel through with the smaller holes it just will not react as well as the better atomized fuel. If you could find the smallest size diameter hole that still has that boundary atomization you will have your best possible fuel injector. After that you would need to tackle how to maintain the larger volume of compressed air the fuel injector will need in order to completely inject/(eject) the fuel in the reservoir. @13:08 DUDE YOU CAN SEE THE HARMONIC OSCILATION. You just need to fine tune the reservoir size, feed line length, and plenum size to get it to work better!

[@markp5726]

For diesel injectors, K-factor (hole taper) makes a large difference. Similarly with geometry of the orifice inlet - smooth, radiused edges mean much greater flow. I suspect the same would be true here. You'd have a much easier time creating taper than they do with injectors, since you can actually access the inlet side; no need for exotic stuff like reverse-taper edm. Given the scale, smoothing and radiusing would still be difficult. If you were determined to, I'd look into machining with an abrasive fluid (aka hydroerosive grinding). Think diamond powder in fluid; different applications use different viscosities, and it can range from the same viscosity as your target fluid all the way up to that of barely-workable pottery clay.

[@BadPractices]

This may be my favorite channel on the entirety of KZbin. I love this.

[@OrenTirosh]

I don’t see why you would need a spray injector. Spraying increases liquid to gas surface area - but you want maximum liquid to catalyst contact area. Having gas here will DECREASE it. Just feed the peroxide into the catalyst in the liquid phase. It will introduce the gas and atomize remaining liquid by itself.

[@jacklav1]

This is very cool, I love it. I don't know why you say you're not an engineer. I recommend you check out photo etching. A sheet of pretty much any metal eg. 0.2mm Inconel is chemically etched from a precise mask. You can get holes and cut-outs and partial etched areas too. No angled holes though. I bought a 1m x 0.5m sheet for £200 and on to that sheet you could fit hundreds of test pieces or finalised parts.

[@KegRocket]

Nice work! Keep this up and we're going to need you to build an impinger for the KegRocket!

[@BreakingTaps]

I will absolutely and happily make any parts you need for the KegRocket! 🤩

[@rgloria40]

I don't know if old CNC machine, I notice some new precision CNC machine can drill holes at micro degree angles cause the injection of fuel to spiral. This cause the flame to spiral. Another ideal was to divide the manifold into four section.and allow for time injection to cause a spiral burn.

[@PROSCO_in_Space]

Hey, enjoyed the vid. I have worked with HTP and here are some advices. I recommend to use showerhead injector for the catalyst bed and design the orifices so that you would have a pressure drop across the injector about 20% of your cat bed pressure. Use transverse injector for the fuel injection. You would need enough chamber length and pressure for the autoignition of the fuel.

[@sgtjan5241]

I think you need a smaller diamater nozzle. like 0.1mm and much, much more pressure. A common-rail diesel system has about 3000 bar, or 43511 PSI for atomizing the fuel well.

[@captainscarlett1]

I wish I had the time and the money and the smarts to do stuff like this. Unfortunately I have none of these but I do enjoy living vicariously. Really fascinating stuff that I mostly understand. People like you enrich my life. I have pet cats, I try to enrich their lives by doing things they don't really understand but captures their attention. Same thing.

[@Guds777]

Instead of inventing the wheel, you could use a known device called fuel injectors, drill few holes at an angle and screw in few injectors. You can get injectors that are very small. You can also get used injectors take out the nozzle and use only the nozzle to safe on weight and bulk...

[@GreenGj-]

As soon as I heard "Monopropellant" my reaction was immediately thinking he would end up with chemical poisoning

[@badsamaritan8223]

Give smarter every day's carberuator video a watch. Really neat look at the way they work, and how they're basically tiny rocket engines.

[@1kreature]

Try drilling with a bit larger (say 0.5mm) almost all the way through with a 0.2 final to try and make a narrow channel that tapers on bottom and ends up 0.2mm dia at the end. The constriction before opening should really make the output more turbulent.

[@sssfsfdfsdsdffsfsdf4]

If you want to learn more about peroxide rockets. Look at the engines that were used on the british Black Arrow rockets in the 1960s. Apart from the project beeing a political tragedy, it used peroxide and kerosene, and the cycle is brilliantly simple but effective. The use the catalyst to react the peroxide into steam and oxygen, then used that to power the turbopumps to pump the kerosemse and peroxide, then combined the catalysed products with kerosene to make it go boom. A very simple but effective cycle that I believe didnt have a single notable Failure throught the entire development cycle. If any liquid rocket cucle is going to be done by a hobbyist, thats the one i would recommend. And you can build off your experience with this project.

[@hamiltonjames4]

i love nebula it supports all my favourite channels

[@robertheinrich2994]

maybe a stupid question, but: high test peroxide and kerosine form hypergolic fuel. you have showed PLA 3d-printed engine models. since PLA is just another hydrocarbon, once the system is sufficiently hot (either with decomposing H2O2 or with an injection of a fuel like diesel), you could just burn PLA as solid fuel, essentially making a hybrid rocket that is hypergolic. of course, if anyone would use that thing in the wrong way, it turns into a fireball. and no one wants that.

[@Bigman74066]

It always amazes me how well a simple plant spray bottle atomizes the water. I don't really know how the atomizer works, but it looks like a good place to start(?)

[@AstroCharlie]

This is some of the best injector footage I've seen! Super cool video and I'm excited to see how this turns out!

[@BreakingTaps]

Thanks Charlie! And appreciate all the help you've given so far! 🥰🥰🥰

[@Hansengineering]

One day I will be bored enough to build a browser plug-in that listens to video and quits when it hears .

[@HM-Projects]

Hah this is going to be an exciting series. I haven't dabbled in rocket making after I got grounded in high school due to a candy accident You fellas are making me interested again 🤣

[@superdave6889]

Breaking Taps, google something called "Rocket Candy" it is usually a sugar, or sugar alcohol mixed with an oxidizer such as Potassium Nitrate (KNO3) and can be made easily at home (with proper safety procedures of course) it is a good beginner's rocket fuel if all safety procedures are followed.

[@tommybronze3451]

nozzles should be designed that way that: - oxidiser hit fuel stream to allow mixing and more effective burn - a row of fuel nozzles on the outside spraying directly at the walls of the combustion chamber to create a protective blanket, preventing meltdown - same head shall feed fuel and oxidiser through adjacent nozzles. - nozzles shall narrow at the tip to improve ejection speed

[@TheHuntermj]

Get some silver jewelers wire and make it mess it up into a disordered ball, like steel wool, that should produce enough surface area combined with enough fluid flow for your "combustion/reaction chamber"

[@msmith2961]

Some of the turbine engines I work on have fuel nozzles with jet holes drilled at an angle around the rotational plane so that it sets up a swirl pattern with the fuel. Maybe try an inner ring of straight exiting holes with an outer ring of rotationally angled holes that impinge on the straight exiting drops.

[@Taco__Ray]

I’d love to see a collar between you and integza since he’s always doing 3d printed rocket projects

[@zlm001]

Would you want a cone shape going from the pump outlet to the backside of the injectors? In all the diagrams there are manifolds to guide the fuel to the injectors.

[@joetaylor486]

This was a fascinating video for me. I have heard of impingement injection nozzles in relation to rocketry for decades but have never had a clear understanding of their function. Well, until now. Thanks.

[@adityawalimbe]

Man i really graduated from youtube video documentaries, Myth busting, learning physics, youtube shorts to god damm rocket science. id really love to see you guys collaborate and launch one together.

[@davidcora2751]

Awesome! Thanks!

[@jmirodg7094]

You might try to look at swirl injector, you put a swirler (just angled surfaces) followed by a convergent section, the fluid will keep the rotation velocity on a much smaller diameter generating a nice attomization when exiting the hole.

[@jet_mouse9507]

Maybe you should try coating steel wool in the silver! That might give more surface area, and produce a better result if the wire mesh doesn't work well enough

[@cwbh10]

Another aerospace guy here working on a pretty cool engine at work (albeit the electronics) and this is almost cooler than that. Awesome stuff dude, can’t wait to see where it goes just always remember to take safety 1st!

[@elijahf111]

should try using espresso filter baskets for fun

[@GodlikeIridium]

9:49 discovering Pi 😀 Any geometry is so simple but so interesting. And I'm from chemistry, not math or physics. But those easy facts show in so much day to day things are are so influential!

[@loopie007]

Consideration: You have a rocket nozzle to increase velocity at the output of the completed engine. What about making micro nozzles for your HP to enter the chamber. As the micro-streams exit the nozzle, the fluid should be ripped apart as it expands to fill the exit of the nozzle. Naturally, this will take some custom-shaped micro drills that are made to look like the expansion nozzle exit, but I think it may be worth a try. The holes need to be as small as possible.

[@GENcELL2014]

You might want to look into a magnetic pin finisher to burnish and debur small parts like this with many tiny holes.

[@BreakingTaps]

It's been on my radar! Definitely thinking about it, a few of my watch-making friends say they are great for small parts

[@GENcELL2014]

They truly are, I have one for finishing a fiberglass product that is a carrier for a specialized cylindrical electrical contact. Carrier is 4mm diameter, 1mm thick with a .6mm hole in the center. Can easily do a batch of 100-200 and after 20minutes they come out of with perfectly rounded edge and polished flat surfaces.

[@GENcELL2014]

@@BreakingTaps fyi the burnishing compound and stainless steel pins that work in a separate plastic container are stuff to be sourced, but the pin finisher machine truly is nothing but a couple capable magnets spinning on a platter with speed adjustment and a timer, could easily be made instead of bought.

[@lasskinn474]

how does the chamber before the catalyst mesh not fill up with the fuel as pressures go up on other side?

[@zyeborm]

That is a legit issue with catalyst based rockets especially when testing horizontally. For this kind of thing the injector is generally more of a baffle to spread the propellant across the whole catalyst bed and to help with instability (pressure drop across the injector helps reduce "chugging" where the liquid sits on the bed until it decomposes all at once and the resulting pressure spike can push back up into the feed system that process builds into a cycle.) Honestly though I think it might be useful, if he really wants to use 35% I think he'll wind up needing the purple menace of potassium permanganate to get it to cook off. That could be interesting in an impinging injector and would make for some very pretty video. Especially filmed in someone else's shop 😂

[@cescohenrichs2655]

What would be really cool and impractical is if you made a piston head that injected fuel into the engine

[@eugenew2]

I was thinking of an atomizer that would inverse the flow at greater resistance in the center and decrease resistance as the diameter increases. Kind of like how the throat would work if perforated.

[@seancollins9745]

you should look at carburetor discharge booster technology.

[@Jay-qs1ef]

When's the next rocket video coming out? I'm really excited to see it

[@m0nologger]

you might have some success looking at espresso machines, and how they evenly distribute liquid flow through the group head.

[@carrotman135]

I wonder how well an espresso portafilter basket would atomize the liquid

[@ahfreebird]

One way to reduce the amount of air getting in to the injector that I can think of is to pressurize the tank before the test, then open a valve to release the liquid. That way you don't have pressurized air coming in and 'pushing' the water out of the way. Something else to consider is the difference in viscosity and surface tension of hydrogen peroxide compared to water, even a small change can have drastic results when talking high pressure fluids.

[@BreakingTaps]

Ah yeah that would have helped a lot. Will see about incorporating a solenoid and more automated testing in the next round (I want to get the sensors working soon anyway, so will have a microcontroller in the loop soon). 35% peroxide is a tad more viscous than water but not much (1.1cP vs 0.8cP for water), so I'm mostly hoping it behaves near enough the same 🤞

[@namenotshown9277]

You forgot to mention the V2 turbo was powered same way, hydrogen peroxide and silver iodide. Or maybe an interesting side note if you weren't aware.

[@zyxwvutsrqponmlkh]

O rings make the world go round.

[@Zaniahiononzenbei]

That's an interesting crab shirt, cool to see Ferris show up here.

[@BreakingTaps]

I don't do much programming any more, but when I do I try to write it in Rust! 🙂🦀

[@sywaddr11]

Could you please put in a double-slit-experiment in this project and electrified the water droplets

[@tomholroyd7519]

It's oscillating at high pressure, yeah. I have trouble understanding how they keep prop pressure high in zero g

[@Gameboygenius]

Re: 1 mm vs 0.2 mm holes. This is obvious but I'll point it out anyway. The area is relative to the square of the diameter, so 1/5 diameter will give 1/25 of the area.

[@honkabooly]

Great stuff! Facinating

[@rossrobinson7943]

For 365deg catalyst coverage on a mesh or foam, plating will work much better than sputtering. Sputtering or evaporation is pretty much line of sight. You would need to rotate your substrate in the vacuum to get complete coverage. Did both the 90's when I was a kid. During HS did plating at Hughes Aircraft. Did sputtering in college. Coated EUV mirrors for NASA mission.

[@joebanks1866]

I like the channel, but this video is the best thing I've seen you do. Love love love this footage.