ROCKET ENGINE TEST Review. How to see combustion instability?

[@CopenhagenSuborbitals]

Stay tuned for a closer look at the data! And thank you for watching! If you like what we do, consider becoming a supporter, we turn your coffee into 🚀 rocket hardware! Visit www.copsub.com/support-us or click "JOIN" above 👆 for more details. Our recent engine test live streams with timestamps: Day 1 (4 burns): kzbin.info/www/bejne/qGS9m4emrdV8Z6s Day 2 (5 burns): kzbin.info/www/bejne/h2TYh6qAd5aki80

[@locustians754]

Sir I have made a replica of spica rocket in a game and I want to show you but where can I show ? Please reply 😁😀🙏

[@CopenhagenSuborbitals]

@@locustians754 no need to “sir” us - We’re completely regular people. KZbin, Instagram Facebook or any other page that can show photo/video should be fine :-)

[@locustians754]

@@CopenhagenSuborbitals ok Thanks I actually like to give respect to those who do amazing things 😁😁 and also just wanted to ask how was my suggestion for the capsule?

[@locustians754]

@@CopenhagenSuborbitals umm I have messaged you both in Instagram and messenger... please do reply 🙏🙂😔!!!!

[@aarons1234]

2:02 *demonic screeching* "Buy our merch!"

[@kantt07]

I love the engine cut off sound. Really badass. And! I just got my CS t-shirt today. Glad to wear your colors!

[@ptonpc]

It was great to watch the test and yes to no explosions or setting things on fire :)

[@CopenhagenSuborbitals]

Thank you for wathing!

[@StanleyCreative]

5:23 Can confirm 😅 But also, that last test was genuinely scary in person... So loud!

[@CopenhagenSuborbitals]

It's hard to imagine something 20x more powerful that's coming soon.

[@jorgenskyt]

A genuinely "ground braking" test. Unfortunately it's only possible to get the experience of the sound, deep in the stomach and the marrow of your bone, by being there in person. Now you know one of the reasons we look so much forward to these test campaigns.

[@LarsBjerregaard]

@@jorgenskyt Still remember being there for a TM-65 test, QUITE the experience for your whole body and all senses :-)

[@thomasesr]

Are you guys going to x-ray the injectors?

[@CopenhagenSuborbitals]

We will see. First inspection under a microscope and leak tests.

[@Oplotes]

good luck!

[@burzulicious]

So awesome, guys!!!! And great choice of music!

[@CopenhagenSuborbitals]

Thank you, pleased to know!

[@TallinuTV]

Yeah, I heard that Tim Dodd music! ;)

[@ges7991]

Very cool. Enjoyed the live broadcast also!

[@CopenhagenSuborbitals]

Glad to hear!

[@tomasberger9980]

Great test campaign! Have you any ISP results? How coaxials did in compere to calibration shower head test?

[@CopenhagenSuborbitals]

Thank you. All of the coaxial swirl injectors seem to have higher performance compared to the shower head. In some cases even up to around 10% increase in ISP.

[@ryanrising2237]

​@@CopenhagenSuborbitals 10%! I can see why you're so attracted to the design with that kind of increase. Well done all, and good luck with hammering out the instability.

[@flipu2k]

Great progress, congrats! Also awesome video production quality,

[@CopenhagenSuborbitals]

Thank you!

[@Techmakerdk]

In order to combat instability you could have baffels on the injectorplate - like the F1 - or you could have a number of smaler injectors. Like the A4’s combustion chamber.

[@CopenhagenSuborbitals]

There are many things that can cause instability, so first we need to identify the problem before we come up with a solution.

[@mathboy_]

Congrats on the successful test! Very interesting results and I'm looking forward to the full details.

[@mohamedfarid7499]

Great job for 3d printing engine

[@phazix6529]

Small rocket companies are what is needed to start a space industry and increase space exploration. Wish you all the best of luck.

[@NomenNescio99]

For my untrained eye, this seems to have a lot in common with the V2 rocket. Same fuel, similar design of both the injectors and the combustion chamber. Although the ignition mechanism seems to be inspired more from the soyuz way of doing it. 😜

[@max_kl]

The V2 used showerhead injectors, not coaxial swirl injectors. The only similarity are the brass nozzles with a similar shape as CS's injectors for the fuel but they didn't have a "double wall" (which is what makes them coaxial)

[@jorgenskyt]

The A4, the booster for V2, used the same fuel. It's not the "best", but it is MUCH more environmental friendly than any other fuel. The injector though is very much different from the one used in A4, as the A4 had separate nozzles for Fuel and Oxidizer. The ignition system is more or less classic. During our development prior to the first BPM5 test we were made aware that this "old fashioned" system is still used in the Soyuz "broom stick" system. It is regarded as one of the most trustworthy systems so no reason to change that as long as the engine only has to be lit once.

[@NomenNescio99]

@@max_kl The A4/V2 actually used both swirl and showerhead injectors, search for a documentary called "A4 / V2 Rocket in detail: fuel and oxygen injectors" here on youtube, they even test, with water - an actual swirl injector from the V2 rockets at the end of the movie. It's one part of a ten part series that goes in depth into the design of the V2 rocket, I really enjoyed watching it.

[@max_kl]

@@NomenNescio99 Ah, you're right! I missed the fact that some of the fuel injectors were actually swirl injectors with angled holes. Thanks!

[@lewismassie]

You said that due to the results of the test firings that you were seriously looking to use the design in the future. Was this referring to the Brass design or the swirl injector design as a whole? And if the latter, what other ideas did you guys have for injectors?

[@CopenhagenSuborbitals]

It was referring to the coaxial swirl design in general. Coax swirlers were our main bet from when we started working on their design, but obviously, we had a lot of unanswered questions before the static fires. Now with the data on hand, we are confident we can adopt it going into the future with the BPM-100 engine.

[@lewismassie]

@@CopenhagenSuborbitals Out of curiosity, what other injector designs did you have in mind? Splash plate, Unlike quadrets, pintle, etc

[@rogerc7960]

Copper does thermal expansion when hot, could crack when cold, any sign of that?

[@CopenhagenSuborbitals]

Like Jacob mentioned in the video, no. ;)

[@CopenhagenSuborbitals]

*Upon first inspection.

[@johndododoe1411]

Brass alloy has different properties than pure copper, that's why it was invented.

[@eugenschutze5981]

Congratulation! Good job! To avoid the combustion instability may be it is necessary to increase the injector pressure drop, but slowly, step by step. On the other hand the total pressure drop from the tank exit to the combustion place should be approximately equal or more than half of the combustion chamber pressure. Good luck!👍

[@G4m3G3ni3]

Could you elaborate further why that is? Thank you for your input!

[@eugenschutze5981]

@@G4m3G3ni3 Ok! 1. If you for example have 1000 bar tanks pressure, you would have the nearly conctant propellants flowrates. The low frequency instability is damped in this case. You could use for this purpose the Venturi nozzles in propellants supply lines, but it results in the tanks mass increasing. Compromise experience solution is the total pressure drop, wich is equal or more than half of the combustion chamber pressure. Afte achievement of the combustion stability in all inlet pressure and temperature conditions combination it is possible to proof the slowly decreasing of the pressure drops. 2.The higher injector pressure drop, the better the propellants atomization and the better combustion stability, but only slowly pressure drop increasing to avoid high frequency combustion instability.

[@likesoha548]

What I need I got all of your videos thanks a lot

[@stekra3159]

Regarding the combustion instability problem do you think that is a serious concern? and do you think that you will first try to figure it out on the BPM 5 before moving to the BPM 100? please update us when there is something to take about and what steps you are going to do about it if that is neesery.

[@jorgenskyt]

Not a serious concern, just annoying. Thoroughly analyzing and meticulously discussion the several Gb of data is believed to solve the instability issues. Scaling up from 5kN to 100kN will certainly present other issues so it is probably best just to move along persistently.

[@TheSadButMadLad]

0:23 Is the whine the same as the whine from the SpaceX raptors?

[@steveadams7550]

Wow. I think I counted eight shock diamonds. Great job. If the ocilationS were a feedback, try increasing the length to make it a distructive harmonic.

[@logangrimnar3800]

Really hope you make these open source, I've got a project this would be perfect for. The ATF has a lot of resources that remain unchallenged...yet.

[@AIM54A]

Perhaps you need more delta-P across the injector to kill that oscillation.

[@aarons1234]

As someone who's not very proficient with math stuff, what's DeltaP? DeltaV's evil twin?

[@CopenhagenSuborbitals]

@@aarons1234 "Delta" simply signifies a change of a measured value. P in this case would be pressure and DeltaP would signify a change in pressure as the propellants go through the injector into the combustion chamber. Whereas DeltaV describes a change in velocity of a spacecraft, or basically energy spent needed to fight gravity.

[@cogoid]

Cool! Good to see you safe and the hardware in one piece. A 100 kN engine is a remarkable achievement.

[@LarsBjerregaard]

This was only a 5 kN test engine :-) The 100 kN engine is being worked on.

[@cogoid]

@@LarsBjerregaard Getting any size liquid fuel engine to work is already impressive. Of course, stability of the large engine will be a much more subtle problem. Good luck!

[@HansJMicheelsen]

Fantastisk projekt!!

[@CopenhagenSuborbitals]

Mange tak!

[@blameyourself4489]

Wow! Instead of turning down the volume I actually turned it up.

[@G4m3G3ni3]

Is there any chance you would make the data available to the public?

[@G4m3G3ni3]

Oh and I wanted to really say sorry for all the prophets in the comments offering primitive solutions to a problem that has yet to be unterstood by you guys as if it is such a straightforward thing to solve. Oscillations have been the cause of RUDs in almost every rocket program in its early and sometime even operational stages and requires very sophisticted planning that counts on decades of experience and thousands of tests gone boom. Even the ambition to solving it should be enough to earn the utmost respect of any fan of rocketscience out there, something youve earned many times over in my book. I wish you that the development continues without any major hurdles you deserve it!

[@CopenhagenSuborbitals]

We will present a lot of the data once we go through all of it.

[@guillaumedamartin2880]

Great video! You made a realy good job! An interesting thing that you could have talked about is the production price for these different injectors to find out if for example 3D printing is more or less expensive than conventional injectors.

[@max_kl]

AFAIK they got them for free

[@CopenhagenSuborbitals]

Häring and Digital Metal were very nice helping us out with these injector nozzles. We would need to account for the hours we put in to develop our brazing technique for the brass elements and all the time for their actual brazing, then compare it to 3D printing to come to some sort of a conclusion. But since we do this all in our spare time we don't track these hours that well and we don't really have an answer.

[@dizbeefpvdizbeliefdizzy3612]

Awesome!

[@xavermaier9625]

RIP Camera; but bautiful Mach Diamonds

[@CopenhagenSuborbitals]

Well, it did survive this time.

[@rasputinputin8103]

Mach diamonds are a sign of instability due to the nozzle being at sea level.

[@aarons1234]

@@rasputinputin8103 if the nozzle is severely over expanded then yes it can cause instability but Mach Diamonds don't inherently mean the flow is unstable.

[@desmond-hawkins]

@@rasputinputin8103 Not at all! Mach diamonds are due to supersonic gases coming out of the nozzle at extreme speeds but low pressure. Yes this sounds counter-intuitive, but this is just because there is _a lot_ of gas coming out at very high speed. The pressure inside the combustion chamber can be very high (e.g. 300+ bar with Raptor engines), but that's at the narrow throat before the nozzle. The gases expand in the nozzle and as soon as they reach the exit of the nozzle they are surrounded by air. The pressure of the exhaust gases past the nozzle is _lower_ than the atmospheric pressure, and as the ambient air compresses the flow of gas it can create shock waves that form as _standing waves_. You can actually learn a lot about the characteristics of an engine by just looking at the mach diamonds, their size, regularity, stability (which seems to be an issue here).

[@mastershooter64]

@@rasputinputin8103 RS-25, J-58, Raptor: *Are we a joke to you?*

[@noahwail2444]

Well done, enjoyed watching it (and hearing it!). Perhaps you could sell the sounds to a movie set, it would do great in a number of aplications.. ;o)

[@CopenhagenSuborbitals]

Thanks. We would love to try and properly capture the sound environment of an engine test next time with decent microphones and recorders, not a 7 year-old GoPro. So perhaps then. :)

[@take5th]

The shock pattern looked inconsistent. But, congrats!! What’s been happening?

[@jgunther3398]

what do you hope to do with it eventually?

[@_LuisFernandes_]

0:19 the MONSTER !!! XD

[@dhrumilpatadia5099]

Is there any blog abt the findings?

[@33blue]

1:57 sounds like an eva screeching

[@theaviation4240]

Man here from science to technology channel damm you people are so hardworking and passionate I have a rocket propulsion degree I hope I can help you

[@romanzaradzki1168]

4:15 wath is the music ?

[@trevorw.7739]

Helmoholz resonance? Add cavities to damp the frequencies of interest.

[@Nerdsking]

Your fuel injector seems to not use Film Cooling. How do you administrate temperatures? Just using fuel rich mix?

[@CopenhagenSuborbitals]

The outer ring of the swirler elements are slightly more fuel rich than the center set.

[@TheMarcusGomez]

Nice.

[@aizazali3240]

Are you sir use turbojet pumps to pressurized the propellent? Is it possible to make a turbojet pump for our own rocket project? Because I search but did,t find it.

[@jorgenskyt]

No turbo pumps. Turbo pumps adds complexity, costs and risks. As for now we use a so called "Dynamic Pressure Regulation System", or just DPR for short. You can learn about it in some of our other videos.

[@RocketPavitra]

'Very unforgiving environment we have in these rocket engines'🤣🤣🤣

[@ayoksusune8095]

Ijector tengah kasi agak bulat kedepan jadi semburanya menekan apinya gak neyemprot keluar

[@Avida-l7s-instrumental]

C’est beau ! 🥲

[@simostsr7034]

Why you just didn't print the whole injector at once and you choose to solder them on the injector plate?

[@CopenhagenSuborbitals]

1. The larger the printed part, the harder it is to get the tolerances right. 2. Testing this injector design for the first time we wanted more control over each element verification. 3. It is more expensive. 4. It was more risky with little real-world tested injectors that used binder jetting in general.

[@simostsr7034]

@@CopenhagenSuborbitals Thanks a lot!! :)

[@simostsr7034]

Hello again! I just read that you tried a full 3d printed injector :)

[@leshommesdupilly]

Amazing ! Do you get any help from big agencies like Nasa or SpaceX ?

[@CopenhagenSuborbitals]

We are located in Denmark, not US, so no. All the help we get is from 100's of people all over the world that donate a small to our project each month.

[@chrisbillings338]

It seems to me the problem is the way the propellants are introduced into the manifold. There's probably a lot of "Scavenging issue" type effects because of that........ or the way the propellants are introduced into the injectors causing a Scavenging issue effect. Probably just a little geometry tweek and you'll be perfect. 👍

[@chrisbillings338]

or like 100 other possible culprits lol

[@iscreamfitness]

When is the test flight

[@desmond-hawkins]

Great results! And fantastic video. It would be great to see the actual data and go more in depth, I feel like this is always behind the scenes and I find it difficult to find material that's not just a summary. I had a question though: I was wondering about the comment at the end saying that this 3D-printing process works "immensely well" for this use case, since you've only put them through a few seconds of burn time compared to the multiple minutes they would need to survive in this environment to reach orbit. I'm curious to hear how you are planning to gain confidence that they will last (maybe a long static fire test like SLS just went through?), and what you have seen about the data so far to have already reached such a high degree of confidence. (High degree, get it? 🔥 … ok I'll see myself out).

[@CopenhagenSuborbitals]

We will go through the data in more detail once we have gone through the data (possibly in a live stream, where you can ask questions directly). As for the 3D printing process, we are not reaching for orbit. Our suborbital flight requires only but a minute of burn time and between the two runs with this injector we already have half of that time covered with no indication of damage. But of course, before we qualify flight components for the Spica rocket and BPM-100 engine we will need to run further and longer duration tests.

[@desmond-hawkins]

@@CopenhagenSuborbitals Awesome, thanks for the quick reply! It’s so great that you engage with watchers online, your passion really comes through.

[@CopenhagenSuborbitals]

@@desmond-hawkins You are welcome! We try.

[@joaocoelho7799]

Hi guys. Did you made any CFD + FEM simulations regarding the thermal problems that may arise due to the temperature gradients from the liquid propellents and the hot fire gas? And if so, by curiosity, which software did you use?

[@SABlackhawk]

150 Hz for your size of combustion chamber is definitely chug instability, 1L acoustic mode would be in the kHz

[@aeris-mo]

Is Mr ballute fine ? Long time without see him :-/

[@CopenhagenSuborbitals]

As good as ever, thank you for asking! We have a parachute update waiting to be edited.

[@aeris-mo]

@@CopenhagenSuborbitals

[@ayoksusune8095]

Nah ini baru roket

[@burger__boy1659]

Thought about (you probably have) using the same method as the Saturn 5 and V2 engine did. 👌 Bro that engine test was incredible keep up the good work

[@hafizuddinmohdlowhim8426]

You will need a damper to compensate the oscillation. Contact me how we can help you to design the helium damper.

[@ayoksusune8095]

Solar jugak bisa coba aja semprot sepre lalu bakar

[@tonylorentzen]

You should rename the engine to T-REX - sounds a lot like the T-Rex in Jurassic World :-)

[@CopenhagenSuborbitals]

Hehe.

[@stanburton6224]

Instead of silver solder, you should look at nickel brazing using Wall-Colmoloy brazing compounds. The melting point is much higher and strength is better. But it needs to be sintered in a hydrogen atmosphere..

[@BasedBidoof]

So underrated. I wish I was a millionaire so I could invest into your company

[@arnavkalgutkar6169]

They are not a for-profit company, they are a non-profit passion project.

[@dannygo500]

Epic

[@ayoksusune8095]

Kalo bisa tenga agak bulat

[@piroman683]

You should just 3D print the injector as a full monolithic piece, no brazing of the elements to the faceplate. Way faster and cheaper

[@ayoksusune8095]

Mantabs

[@kusalvimukthi2386]

This is just an idea. Why don't you try slingshot your rocket when the thrust begin.? I know it can face many difficulties, But I think you and your crew can handle it. This is maybe dumb, but i have to tell you every drop of fuel is precious. Thank you...!!!

[@ud886]

With all due respect, Do you think you can get people to space? 🧐, In any case, good luck you are big Bos

[@TheDerperado]

🚀

[@NoahHagen]

I’ve decided to develop a small payload single stage rocket and balloon (or rockoon) and will be perfecting a solid rocket motor to do so. Race you to space 😝

[@aerojetrocketdyners-2538]

Lol, good luck

[@petermacris8260]

initiate new angle lmao

[@Anvilshock]

Next step: Test to destruction!

[@jorgenskyt]

Actually, in the last of the tests in this series we tried. The ground was shaking, the roaring shook our bones and made the container shake and wobble as we have never seen it before. But we did not succeed in destroying anything.

[@G4m3G3ni3]

@@jorgenskyt Wow! Thats a first in Testing rocket designs in my book and that from a hobbyist group. You guys (and your sponsors) are amazing!

[@theaviation4240]

I want to support your organization I mean I still can not understand how only 60 people did a launch abort test how you people are so close to cross the karmen line ( I imagine when you people will launch put humans above the karmen line how confused Denmark gov will be lol )

[@rasputinputin8103]

YOUR POGOING EFFECT (INSTABILITY IS CAUSED BY INCOMPLETE COMBUSTION. Oops caps off. The cure is to place a ring (wall) round the first two rings of injectors 24mm tall, then come off at 45 degree increments to the edge, again at 24mm (8 hedges) to the edge of the injector plate. Your pogoing effect will stop, and you will have now complete combustion and full stability.