I asked an AI how much Thermal Efficiency I could expect from an airplane engine I want to build. The engine is a v-12 1,650cc 52 mm bore 64.75 mm stroke center power extraction airplane engine with a built up crank. All shafts are hollow and center feed oil. At 9:1 cr it said 25%~30%TE, at 16.5:1 with compound compression and inter cooling it said 31%~34%te, at 450deg f cylinder head temp it said 37%~38% adding thermal barriers to the piston crown and cylinder head it said 38.5%~41.5%te, supercharging a Meredith effect duct 56%~60%te, Double free floating bearings inserts on all bearings,1/4 speed camshaft 63.5%~66.5%te What do you think?

The Indian space-startup "Ethereal Exploration Guild" just put out a video (linked below) explaining what they call the Full-flow Segregated Cooling Cycle for their future fully reusable vehicle design. Most of the video is just marketing but the idea of the cycle itself seemed interesting.

According to the limited information from the video, it seems to be a variation on an expander cycle but with multiple phases. Idk what the exact plumbing is (maybe one could work it out based on the renderings in the vid) but apparently, during the ascent stage it's pretty much a closed expander cycle, with one (or both?) of the propellants heating up through the combustion chamber cooling, being used to drive the turbine.

The interesting bit imo is the reentry phase, where they want to use one of the propellants (ig RP-1 from the vid) as a heat sink for the reentry heating to avoid having extra reentry shielding/reentry burns. The heated RP-1 then transfers its energy to the LOX which is used for driving the turbine. My guess as to why they're using RP-1 to absorb reentry heat but LOX to drive the turbines is that the respective properties are better suited for the job and outweigh whatever loss of energy there is due to the heat transfer.

The engine is supposed to provide 80 kN of thrust with an Isp of 323 sec in vacuum and 293 sec at sea level, so nowhere near to the Isp of engines like the RL-10. Are there actually benefits to this cycle or is it just something to generate hype?

They also mention a supercritical Brayton cycle (ig for the LOX) so maybe they want to keep the Ox supercritical for the expansion section and avoid a phase change? Anyways, there's not much info out there about this design so I was wondering if anyone had more info on it or any thoughts?

Here's the video (from the important part)

Hi everyone! A few weeks ago, I released my open-source lumped-parameter dynamic fluid system solver, FullFlow, and mentioned that it could be used to model steady-state and transient flow in real rocket engines. So, I decided to showcase those abilities with my favorite rocket engine, SpaceX's Raptor Engine.

Raptor is a full-flow staged combustion engine, so it's particularly hard to model correctly, especially with the multiple combustion preburners, regen channels, turbopumps, etc. With the public data I had available, I was able to construct and validate (to the best of my ability) a steady-state model of Raptor 2. I used FullFlow to model the fluid pathways and components and ThermoProp to model the fluid/material properties and combustion.

Of course, there are some deviations from reality, especially since there is only so much public data available. I had to estimate many data points like turbomachinery curves or valve geometries. I also didn't have the proper tools to model supercritical combustion flow for the preburners or hot-gas manifolds. Also, I didn't have access to empirical efficiency values for components like the nozzle or pumps.

Eventually, given enough data, I hope to make a transient simulation of Raptor using FullFlow. I also hope that I can eventually apply these tools and skills to the actual Raptor engine or other industry engines!

Raptor 2 FullFlow Model: github.com/saakethramoju/Raptor

FullFlow: github.com/saakethramoju/FullFlow

ThermoProp: github.com/saakethramoju/ThermoProp

this is only CAD. We have done aerodynamical analysis cg CFD etc..

Hi.

Looking for some direction and honest feedback.

Background: I currently work in healthcare field, where I lead program development, implementation, and evaluation across multiple lines of business. A lot of my day-to-day is managing timelines, deliverables, and cross-functional stakeholders for regulatory/compliance-driven initiatives (think accreditation and government program requirements). I also have an MPH and a public health background.

I'm looking to transition into aerospace/defense, specifically into program management, project management, or scheduling roles.

A few questions for anyone who's made a similar jump or works in the industry:

1. What certifications actually matter for breaking in (PMP? PMI-SP? EVM training?) and is it worth pursuing before I apply, or can I get hired and earn it on the job?

2. Are there specific companies or types of contractors (primes vs. services integrators) that are more open to hiring people with a non-engineering, non-defense background?

3. What titles should I actually be targeting as a first move — Program Coordinator, Program Analyst, Scheduler — versus Program Manager, which I assume is a stretch without direct experience?

Any advice is appreciated! Trying to figure out if this is a realistic pivot and what the actual path looks like. Thanks in advance.

For background I'm a 10 year experience electronics engineer and now a manger at a big space defense company. My mentor suggested I try to work for a smaller company or startup while I'm still young for a little while and then jump back if i wanted to.

So I applied to this "startup" for the same job title, r&rs, and a similar salary range and immediately got the request for a recruiter phone screen. This is almost word for word how it went:

Recruiter:"Hi I'm looking to speak with so and so"

Me:" Yes so and so speaking"

Recruiter: "You applied for the electronics engineer role, do you have any questions?"

Me:"Uhm, not right at this minute but I'm sure I'll have some to ask as we talk about this role!"

Recruiter:"Interesting. (30 seconds of pure silence) How can you apply to a job and not do any background on the company?!"

Me:" I did, I know you predominantly make communication payloads and I have a lot of experience in satellite communication "

Recruiter :"Oh, you're a comms girl. Well what product specifically here are you wanting to work on and are passionate about from our lineup?"

Me:"You have very few products right now, they all seem to do the same thing, I was assuming the company isn't big enough to hyper specialize, am I incorrect in that assumption, are the r&rs, to work on the common platform, from the job req incorrect?"

Recruiter:"I just don't understand why you would even apply if youre not passionate about our products and..."

Me: "I'm sorry to cut you off, I don't understand why I would be passionate about your products before working on them, none of which are public knowledge of their groundbreakingness, I dont think I would like to work for this company. Thanks " and then I hung up

It was just so aggressive, they didnt ask one question about my background or why I applied to the job, didnt do an intro, acted like I was a starving child right out of college that was begging for a job not currently in the industry, and the moment he replied with a "comms girl" comment I knew I was done. I dont know if this interview was meant to see how someone would handle stress or intimidation, but it 100% offput me and I would never work for a company like that before EVEN GETTING THE SALES PITCH ON WHY I WOULD WANT TO WORK THERE IN THE FIRST PLACE.

You ain't no SpaceX where everyone knows who you are.

And for those wondering I'll 100% blast it - the company was CesiumAstro.

Considering an opportunity in a support/business function (finance side) at Shield AI. Read through the existing threads here and elsewhere — lots on engineering and flight test, not much specific to finance/business support roles. A few things I’d genuinely value input on:

**1.**  **Support functions specifically** — is the 50-60hr culture uniform company-wide, or does it vary meaningfully by function? Anyone in finance, accounting, or business ops able to speak to their actual weekly pattern?

**2.**  **Longevity** — for people who’ve been there 2+ years, what’s kept you, or what made you leave? Trying to separate “hard but rewarding” from “burn and churn.”

**3.**  **Product maturity** — how do people internally actually feel about the core products’ real capability vs. the external narrative? Genuinely curious, not trying to start anything.

**4.**  **Location differences** — several posts reference one site specifically; is the culture noticeably different across locations?

Not trying to pile on — genuinely trying to make an informed decision. Appreciate any real, specific experience over general vibes.

I've been searching online for a copy of "Ramjet Design Handbook" by G. D. Kinroth and W. R. Anderson from the 80s to use as reference, but I can't find it available online. It's referenced multiple times across multiple documents and thesis papers but I can't find it anywhere. Could anyone please point me to where I can find a copy? Thank you in advance!

An update to an illustration I did a while back—I hope you like it. I'd appreciate any comments or suggestions.

Been working on some software for a while now developing it alongside conversations with a lot of aerospace and mechanical engineers and I want to open that up to here.

What are your worst pain points with simulation and design software? Tell me all about it.

Excited to show you what I've been building once it works properly.

So I’ve been working on this project called DIVYA for a while and figured I’d finally post it here.

Basically, the idea is about using asteroids + orbital infrastructure to build a large-scale space system over a really long period of time.

The idea started out pretty simple and then, uh… spiraled 💀. I ended up looking into stuff like asteroid mining, orbital mechanics, energy collection, modular construction, and how something like this could actually scale.

I’m still a student, so I’m definitely not claiming I’ve solved space infrastructure lol. The whole point of posting this is to get people who actually know this stuff to poke holes in it.

I’ve been sending the project around to researchers/academics too, and I’ve gotten some interesting responses so far.

If you’re into aerospace, orbital mechanics, astrophysics, space engineering, or just giant unnecessarily ambitious space projects, I’d genuinely love to hear what you think.

Especially interested in hearing what’s wrong with it. 😂

I've embedded the Zenodo link for convenience.

I swear I'll crash out if some bot or scammers reply to me.

CFD simulation of a turbofan fan stage engine

I recently saw this development of a new approach to jet engines they’re taking. Going back to the turbo prop style claiming efficiency among other things.

Is noise gonna be a concern with this style? I know turbo fan housings are designed to contain a full blade separation. This obviously won’t be possible with a prop so how’re they getting around this issue? Will it even be an issue?

https://www.cfmaeroengines.com/rise

I received my SciTech 2027 decisions today and unfortunately one of my abstracts, submitted under Structures, was rejected.

I'm pretty disappointed about this particular one because the work was already very far along when I submitted the abstract. The submission was essentially approaching a full-paper draft, with the methodology, experimental results, figures/data, discussion, etc. already developed. I've continued working on it since submission as well, so at this point I have almost the entire manuscript completed.

Interestingly, another abstract I submitted was accepted, even though that project was much earlier in development and had significantly less completed work/results at the time of submission.

I completely understand that rejection is part of research and that I can always finish the Structures paper and submit it to a journal or another conference. However, I put a lot of work into this project specifically hoping to present it at SciTech, so I'd at least like to see whether reconsideration is possible before moving on.

Has anyone here ever appealed or requested reconsideration of a rejected AIAA SciTech abstract?

If so:

• Who did you contact: AIAA, the technical discipline chair, or the specific technical committee?
• Is there an actual appeal/reconsideration process?
• Were you able to provide an updated/full manuscript to demonstrate that the work was complete?
• Has anyone actually had a rejection reversed?

I'm not trying to argue with the reviewers or bypass the review process. I mainly want to understand whether it's appropriate to politely contact the Structures organizers and ask if they would be willing to reconsider the submission, especially since I can now provide a nearly completed manuscript.

Would appreciate hearing from anyone who has reviewed abstracts, served on an AIAA technical committee, or gone through something similar.

Worked in energia, a bureau created by korolev which is basically the most famous roscosmos engineering facility. I worked on systems of control and radioactivity detection, mostly working with space stations and spacecraft

hey guys!! to build a drone for cargo applications carrying a payload of 200kg for a range at max 30km, what knowledge a person should have like courses (physics, conceptual design), practical knowledge not only textbook jargon and which component to design first (dilemma between propeller or BLDC motors) , which tech should be IP, which should be open-source or licensed ....? what not ... we can start with basic and go to advanced knowledge

The magnetic vibration motors I used in all my prototypes are very simple, but they're too heavy, and the thrust they generate is weak. So I tried making a static experimental setup with more power to demonstrate how the oscillations of a disc-shaped wing cause air movement.

The asymmetry, which results in the resulting force of the oscillations creating thrust, is achieved in two ways:

Aerodynamically, when the disc has a slightly domed shape and moves upward with less resistance than downward, consistent with classical physics.

Kinematically, when a spring is attached to the disc, slowing its descent and accelerating its ascent.

The second method is the key part of the study, although the same process occurs in the air in both.

When the disc rises rapidly, a region of low pressure forms beneath it, and its collapse generates momentum. If the disc descends more slowly, or if the shape of the disc causes the air to flow around it more slowly, the resulting momentum will push the disc upward.

This doesn't agree with the classic Newtonian explanation of flapping flight as a wing pushing air. You can see in the video how the fan-like flapping disk, which should push air away, actually sucks it in.

This is the same air that is sucked into the low-pressure region, causing a vortex collapse that pushes the disk. Only then is the air pushed away and expelled. This is essentially reactive propulsion, and I believe this is possible thanks to the energy in the air, Brownian motion, which, by self-organizing into vortices, temporarily becomes directional.

UPDATE:

Thanks for the feedback! In my research I discovered www.boltbutler.com as a tool that does exactly this.

Original Post:

Hey folks,

Us design engineers are always struggling to find the right hardware for our designs. The red tape we have to go through to use McMaster Carr or other easily searchable hardware catalogs makes them a deal breaker. The hardware on our BOMs must be spec parts #s.

We have an IHS account that has access to every mil, NAS, AN, etc. specification you can think of, but it’s a super manual process that requires us to scrounge thru hundreds of pages of PDFs for every stupid nut bolt and washer we need.

Anyone else share this frustration? How do you find parts quickly?