When you see Spica's propellant tanks swelling on its launch platform in the future - don't worry, that's how they're supposed to look! 😄 You can roughly see how the Spica tanks will look like after deformation hardening in this blog post: copenhagensuborbitals.com/spica-tanks/

That bit on the work hardened tanks was super interesting

Deliberately work hardening pressure vessels is standard practice in the industry, typically called 'autofrettage' I love the depth of this video, and as always, I'm jealous of your shop!

BIANCA: Please DONT use a drill press with your hair loose!

That tank landing in the ocean was something else 🤯

Your government should appreciate for your work.

You guys are partly the reason I’ve decided on aerospace for a career. Thanks for being such an inspiration :)

Good job all of u guys, Love from India.

It's at times like these that I wish I knew Danish and ran away to Denmark to join you guys

I love that the new generation of high-tech spacecraft is going to be the same stuff we've eaten with for decades; stainless steel. I know it's been in use since the 1950s for spacecraft, but nobody really could have seen it coming. It's kind of amazing that the very material we use on a day to day basis could eventually find its way into a rocket given enough time and recycling.

Awesome explanation of your construction process! Thank you!

1:54 Sandy Munro suddenly walks in frame

Just got a Mach2 membership. I've been thinking about it for a while now, as it's a lot of money for a student living on ramen, but it's well spent

I always watch your videos. N u all inspire me to do great for humanity. Keep it up.

I had no idea this was happening - Thanks youtube suggestions

Love your work as always.Thank you for doing videos like this👍👍👍

Wow! The splashdown came in like a tomahawk missile!

Thanks for that info, I might try 304L the next time I hydroform some exhaust pipes. One advantage of causing yield on the tank is relieving stress concentrations. Stainless steel was good enough for the titan rocket tanks.

Nice to see you back!

How cool is University students drill ,screw and weld for their projects and not only solve equations . This is real engineering

I love the creative aspect of using deformation as a feature, it's really clever. Definitively keeping my eye on CS from now on!

And here I thought only Spacex were the quick and dirty ones! Keep it up!

Fascinating stuff. Just for reference, did you switch to 304L before or after SpaceX? Where they maybe inspired by you?

Stainless steel FTW ! It's great to see what high pressure you can reach with the tanks which is way higher than the required pressure.

Like I have always said.. when in doubt over build! stainless.. ask Elon... I almost just hit the "not interested" but then thought I would see what this was about... I found this very intriguing. Especially the part about deformation hardening. I had not thought of this before but it makes perfect sense.. I may hang around a bit and check out some more of your videos..

The workshop is re-open, hip hip hip hourra :)

Did you guys just give us spoilers about future CS goals?! I love it! Reusability and high volume production/launches are a fantastic idea. So... when are you unveiling the CS Cubesat delivery stage adapter? Will that be Spica II? ;) Could Spica be used as a demonstration launch to provide proof of concept, then used in applications for additional support from your regional government? The future sure looks exciting for you and the team. Congratulations and keep up the great work!

Yeah I have worked with it....I used to work as a specialist welder in Aviation working on jet engine components...

I hope your team is successful in your goals. I myself am trying to build a little liquid fuelled rocket for fun and I hope I can work on larger rockets one day. Also I would love to know what sort of tank pressures you are going for

Excellent work, hard to believe this is a DIY project, very ambitious.

Great discussion on material and tank design! We don't only want to see rockets fly; we want to know how they're built as well!

Is the plan to deformation harden the tanks before they're installed, or will they be deformed for the first time on the pad?

This comment from me, a certified welder: The attachments to the end caps are way over welded. You don't need fillets of that size on thin sheet metal - you only need fillets the same leg length as the thickness of the material to achieve the required strength. Also look at the strength requirements: do they actually need to be fully welded? I got my ass kicked for over welding stringers on a ship because of the extra and unnecessary weight (7cm beads instead of 5cm beads, on an 11,000 ton ship). Extra weight on a rocket is even more important. Also, why the heck would you not TIG (GMAW) weld this? The downsides of TIG are that it is slower and has a larger HAZ, however the control you have is far more important than both of those factors.

That metal balloon tank looks delicious

You inspired me to start making a simple liquid feul rocket at home an some parts made at work already had some results cant wait I made my combustion chamber to short so I have to macine an extension from 316l steal good luck

BPS Space on Steriods ! (although wonder if Joe's work on gimble control might be useful ?)

❤️ Nice

Lots of interesting info and a nice workshop atmosphere. Subscribed.

Very interesting

2:00 thats the intro music of MunroeLive channel

Not to mention that stainless steel also has less thermal deformation that aluminium, making it more predictable during extreme temperatures.

Amazing presentation, couple of quick questions. What is the expected shrink after a 10% pressure stretch / volume expansion? Does the material shrink back? If so, at what ratio and it it gradual over X number of days/Hours/Minutes? Once in operation, will you be then monitoring its overall stretch dimension during a mission? Cheers

Great work! Keep it up!

Thanks for the informative video! Just curious, have you guys had to push back schedule milestones due to longer lead times on parts? Any idea of when the next test fire will be? Keep up the good work!

Cool stuff. Will you be passivating the tanks?

Very insightful video! Is your website down at the moment? Edit: all good now

more of these longer videos

Awesome update. Thanks for taking the time to explain the reasoning behind using SS. Do you think the hardening will affect the welds differently? I had to close my eyes when the blade started cutting the vernier calipers. :) Good idea though.

So have you decided who it is you’re sending into space on one of these things, or is the company-wide gladiator tournament that determines that still to come?

Nowadays stainless steel may be a controversial choice for building rockets, but that wasn't so during the early days of the American space program. The Atlas Launch Vehicle, derived from the SM-65 Atlas ICBM, was almost entirely constructed from stainless steel. Though it got around the structural weight penalties by not having much structure to begin with - the fuel tanks were the fuselage, and it used pressure in the tanks to keep them in shape.

Try a nuclear salt water rocket. The only high thrust high efficiency rocket. I recommend a chemical first stage and a nuclear second stage.

If you are able to create higher pressure tanks. Is there ever a temptation to increase the chamber pressure by 5 or 10 bar extra ? Would this require an engine geometry change?

correct me if I'm wrong but 96 bars would be water pressure at 1km depth right it's amazing the steel tank could contain that level of stress. Hydraulics are terrifying my grandfather worked with hydrolics and told me stories of 400 bars it's now years later that I can appreciate what that meant.

Absolutely brilliant. Wish I'd known about this a long time ago. Need any help with CFD?

Soft aluminum extrusions on a long pallet will work-harden just bouncing down the road on a flat-bed trailer. If hardening the stainless beyond reaching an acceptable balloon distortion is desired, I would imagine that can be achieved with sonic vibratory treatment.

96 bar :-) sejt og stærkt gået, CS !

This American says - Heck of a good job!!

I am an Aircraft Design Weights engineer. I used to have a boss who was a Stress Engineer. His moto was, Thick an strong can't be wrong. For battleships yes. My moto is, Thin and light must he right. Especially for rockets. Building battleships loses you a tremendous amount of height. Use the minimum thickness that you can to satisfy your load requirements ot come up with alternative construction methods.

You are 'smart' people!! ... right on target. I am starting 2 projects right now: a Stainless Steel Alloy hydrogen-filled 'balloon' and a Vacuum 'balloon' ... both of which require 'special' mechanical design and materials processing.

F/A master wielder you guys ROCK!

one important property of 304 is spacex uses it

When do you think you will acheive the first crewed launch?

Those rollers on that sheet metal roller are mild steel. They will impregnate your stainless with metal and it will rust. Putting painters tape on the rollers will help keep your stainless pretty

Didn't expect to see MIG welding

Hi I love what you are doing, have donated, been to one of your tests though it was the one with the oxygen valve issue, but if you don't try, nothing will ever happen. So props to you and if it was not for one damn chemistry class I'd probably be at DTU now, but you never know what the future holds. I am interested in "simple" amateur model rocketry (biggest rocket I have is 70cm in DK, that can take 2 D, E, F motors with telemetry, camera, gps tracking, etc. under 400g loaded) but I cannot find any Danish regulations on the topic other than that it seems like rockets are considered drones now in Denmark. DARK "Dansk Amatør Raket Klub" seems to have stopped existing after 2016. I grew up making lots of "Estes" rockets in the US, and of course the laws are completely different. Since I live in Odense, we have quite a bit of military airspace, and I don't want to get into huge trouble. I do have access to the flight website for DK that shows the current airspace flights, and restricted zones though, and obviously check.I have a much smaller rocket, that I've just launched once, that does not have all the gismos, but uses the same dia. motors as a testbed since I'm making the motors from scratch. Any idea's where to look or who to contact if it's possible to do this hobby in Denmark? MvH -Eric

Pressure fed? No open cycle turbo pumps? Does it lose thrust at the end because the pressure would be lower? Did you work it out so that it lowers it’s thrust as it loses mass so that the total acceleration would remain more constant?

I'm amazed that a tri-clamp could hold that pressure.

I suppose the vertex point on the right side of the ballooned ruptured tank is the initial point of rupture.

Nice use of the humble 304L. P.S. at 14:00 those are digital calipers not verneir scale calipers.

The welds at 2:22 look like the kind of shit i'd put down when i was first learning to weld.

Heaven = working on rockets among the most beautiful women on Earth #CopenhagenSuborbitals Thanks for the excellent vid everyone!

About SS304... from what I have read, it does not like saltwater or chloride-rich environments. Which is why the recovery from sea has me worried. Wouldn't SS316 be a better choice, recovery-wise? (take this with a literal grain of salt, as I am no expert)

Strength vs heat is also very good in 304L SS.

I did work, for US Navy, Mid-80's , on ,1,200 psi, steam Catapult, piping on aircraft carriers, "Heat treating" Pre-heat welding, & after, "STRESS Relief" do you "Heat Treat" you're tanks.?

So cool good luck

How can I get involved with you guys? Do you need any design engineers?

Space Vikings incoming!

Ah same music as Munro live = the car guy who takes apart EV's including TESLA's and comments on their build strategies from component level. Might want to change your music? Great shot of 'spash down' - I would call it a dive entry - I gave it a 10 as there was no 'splash' as the rocket ripped the entry like a great dive, so I would call it a 'rip entry' instead of a splash down. C'mon guys - be original. Splash downs are with parachutes and splash. Rip entry is so much cooler! Fantastic presentation btw. I am subscribed. You guys are inspirational!! Well done. Problem with aluminium is you can start off with high hardness aluminium (strong) but once you apply heat, that hardness and strength is reduced significantly. Also you need thicker Aluminium so volume of material needed is higher. Stainless steel is 3x stronger, so you can go a lot thinner. 96 bar is great for 2mm plate for that size !!

approximately how long would it take to finish the full rocket?

Could you shot blast the outer surface to gain extra strength as well?

Triclamps for compressed liquid service? Or are they temporary?

Is there any commercial interest in launching the rocket? Like sending small satellites in orbit?

You guys should invest in a GTAW machine and some classes.

The British used stainless steel in it space program which they launched from bases in Woomera Australia.

I think the editor is an Alec Steele fan...

Did you consider inflatable floats for Spica's recovery, in order to shorten the time it's in salt water? Such a thing ought to be reasonably cheap and my prevent damage to the electronics.

9:05 But after the deformation hardening there is a loss of the ductility... There is a trade off.

Are you planning on having the booster come back down and land for reuse?

Can you get the same properties (thinner/stronger) simply by stretching the flat plates of stainless steel before curving it into the tank shape?

Interesting video, and a great project! I'd like to say that 304L is not the best choice as far as corrosion protection in water with high NaCl content. 316L is a better alternative on my opinion as it has a slightly different chemical (Cr/Ni/Mo) content which improves it's resistance to chlorinated solutions. Also I am curious as far as increasing strength in order to reduce weight have you considered duplex or even super duplex stainless steels?

Really interesting video! Does the deformation hardening effect the performance at cryogenic temperature?

Could you post some videos that dive in detail about the control and gimbaling software and sensors. I'm sure there are plenty of coders who are fascinated about this. SpaceX never answer questions on this, so I'm very interested in how much is classical algorithms and how much trained AI is used.

You misled me to believe that the short stainless steel cylinder had been expanded to the half tank size you showed ( btw, I find the tank shape appealing as a tank and as a part of the exterior of a rocket). In reality, you're just showing the type of steel used to expand a fully formed rank.

Yeah I understand the cost constraints of titanium but there are also some excellent aluminum alloys out there that would save a lot of weight and is far cheaper than titanium ....just a thought....anyway best of luck in your endeavours....looking forward to further updates ....

As far as I know ss 304 is banned in use in many offshore and even offshore oil and gas application /specifications. All the best.

have you thought of using metric true bore piping systems? rather than rolling your own steel. not sure if this is an option for you

why starship thickness is 4mm but they not become ballons. dont you only need 8 bar pressure so why you guys using 30 bar? sorry i dont know much but seems strange that you need such big and thick tanks. you could use thinner stainless steel if you vent when reachs certain presssure.

Why don't you use allready hardened sheet metal (feed it trough some rollers)?

Dropping stressed austenitic stainless steel in salt water is not a good idea. Chloride stress cracking can happen leading to catastrophic failure. We take special precautions when shipping stainless pressure vessels by ocean transport. This failure has occurred at relatively low temperatures, 60 deg C.

Protip for Bianca... NEVER EVER wear gloves when using a strong drillpress like that.. Just imagen what would break first. bones or gears?!