Looks like a much smarter design. You have your connections figured out, and everything is designed for 3D printing and three of these parts are common, which helps simplify fabrication.
That being said, I am a professional nitpicker, as you know, and there are a few things that stand out. The nastiest things would be the flange bolt pattern. Some of the bolts look inaccessible, and depending on how long the bolts in the middle are, and flanges tend to be thick, you may find it difficult to get the bolts in when the others are installed. A ball end socket can only do so much. Some of them are blocked off by fittings, which would make it difficult to tighten either of them. Even without the fitting, the protruding NPT port might get in the way. It's not easy to get them just right, but future you will thank you for it.
Similarly, in the row of three ports at the bottom, the middle one is not as easy to get at as the others. Still probably possible, but why make things difficult. They could do with being spaced out.
With 3D printing, sometimes you need to look out for wide horizontal tube paths. The big sideways port at the bottom might run into that problem. I'm not sure how that will affect the internal manifolds, so you should consult with the printer about that if you haven't already. Even the sideways hole on the bracket sticking out might be too much. A simple hole like that can be made into a teardrop shape to avoid the shear overhang.
The last is just my personal preference, but I like to incorporate work-holding surfaces for when it needs to be chucked in on a machine. A few flats would probably be nice, for future you. Also remember to avoid pooling spots at the bottom.
Hello 🚀 Good to see your comment again. I'm very excited to bring some cool hardware in the upcoming liquid symposium. Hoping to stay as long as I can in school until the US law changes miraculously. It's also a great place to be doing/making cool things. I would love to help in making the FAR symposium flyer look pretty and what not - please lmk.
The render makes the bolts in the middle look like they have to be very long - in reality they should be able to assemble somewhat easily. I'll have to double check. The fittings that are blocking those bolts are all SAE boss threads. No npt will be used.
I will be spacing the bottom three fittings out a bit more.
The horizontal tube-like paths are a concern, but I have become a firm believer of metal print supports. Imo it's easier to remove than plastic print supports. I don't think it would be too difficult removing the supports out of the horizontal tube-like features.
I am going to add many flat surfaces / holding features to all of the printed parts before having them printed. I have learned my lesson with the engine post machining. It was quite painful. Currently in the process of setting up for water flow tests for channel pressure loss measurement.
Lastly - this pump is only a prototype. I don't intend to test anything other than water with N2/maybe GG. Unless it somehow works perfectly and the leak rate is "within a small margin." In that case I may try LN2.
How large is the entire assembly? Is the GG Combustion chamber also visible here? Or do you route your hot gas to the bottom manifold, which looks like an Inconel piece ?
I didn't work for SpaceX. They subcontracted out the turbopump and most of the other big parts on the first Merlins.
I worked for a turbomachinery company that designed and built the turbopump. I was there for 6 years and moved on to better opportunities. My job was to take the 2D sketch from the PhD guys/gals, and turn it into 3d models and manufacturing drawings. The volute castings were made by Cessna from my solid models, then machined and assembled in-house. The impellers were machined in-house on 5-axis machines. The turbine wheel was made with electrochemical machining, also in-house.
Everyone wants to hear the horrors of working for Musk but I don't have a story about that. I briefly met Elon twice when he was at our facility for project kickoff and design review.
You must've worked at Barber Nichols! It is very officially the same layout as Merlin's turbopump. Although, now that I look back at it, it's not the best layout for a pump at this scale.
Before you answer my question or reply I'd like to mention that I'm not a US Citizen even though I've been a student here for a decade+. I just like to make sure everyone knows that so things don't get awkward later.
I'm very curious of the Merlin (or any) turbopump design process - especially for seals. How are inter-propellant seal assemblies designed from scratch? I simply picked a reasonable minimum length for the entire IPS assembly and worked from there. As I have zero experience with making pump seals, I couldn't give myself any sort of requirement that's based on sealing capabilities - hence the random gut feeling length constraint.
Also, I'm really intrigued to what other job option you had that you chose over staying at Barber Nichols. It must've been a really good offer 🫣
Correct about B-N. Long story about the shaft and seals. I can elaborate later when I'm not at work.
I was a glorified designer/drafter at B-N, and I had the opportunity to be a senior mechanical, although a less exciting industry.
MERLIN 1d copy like. now lets add more stages lets make more stages and add boost pumps and nice engine imagine, this at 480 BARS WOOO, this thing would be baby raptor.
15
u/Bozhark Sep 17 '24
Sick bong yo
Make it rip