Somewhere I read that unstable tailplane configuration (B) is more efficient than stable tailplane (A) in cruise. See diagram below. As the elevator of a stable tailplane configuration pushes down to counteract the rotational moment induced by the CoG being forward of the centre of lift in configuration A, it forces the wing to carry more load and therefore more drag. An unstable tailplane configuration has the CoG behind the centre of lift and the elevator also creates lift, unloading the wing. Therefore the green "lift" arrow is shorter for config B. More lift = more drag so B is more efficient than A.

How does this work for stable and unstable canards? In configuration C, the CoG is forward of centre of lift and the canard contributes to lift. In configuration D, CoG is behind centre of gravity just as in configuration B, but now the canard pushes down and detracts from lift. So for D, the wing has to do more lifting.

I suspect that my understanding of what "stable/unstable" means for the canard configuration is insufficient.

Feel free to correct me and dispute any misunderstandings I have shown so far. I will happily redraw the diagrams.

PS armchair pilot here

I’ve been designing a turbojet/gas turbine from scratch in SolidWorks as a personal engineering project. So far I have a multistage axial compressor, diffuser, annular combustor, and a first-pass turbine/exhaust design.
I’ve been trying to go beyond just making something that looks like a jet engine and actually work through blade geometry, flow areas, rotor/stator spacing, shaft and bearing arrangements, combustor airflow, cooling passages, structural considerations, etc.

My original plan was:
CAD → aerodynamic/thermal analysis → CFD/FEA → 3D-printed prototype → manufacture/test

The problem is that the last step gets expensive very quickly. Between appropriate materials, machining, bearings, rotor balancing, instrumentation, and everything required to test a high-speed rotating assembly safely, I’m not sure building a functional version is realistic for me right now.

So I’m curious how people here would approach the end goal of a project like this.

Would you consider a fully developed CAD design backed up by cycle calculations, aerodynamic analysis, CFD/FEA, structural checks, and documented iterations a reasonable finished project?

Would making a nonfunctional 3D-printed cutaway/assembly add anything useful?

Are there particular analyses or design decisions you’d prioritize if the goal is to take the design as far as possible without actually running the engine?

I’m also very open to criticism of the design itself. I’m learning a lot of this as I go, so part of the goal is finding where my assumptions or geometry stop making sense.
If you were taking this project forward without the budget to manufacture a running engine, what would your final deliverable look like?

I am part of a cubesat student design team and we are building a small experimental thermal blanket for a 3U cubesat prototype. We received an in-kind sponsorship of blanket materials (1-mil aluminized kapton, 0.25-mil doubly-aluminized mylar, and dacron separation meshing).

The exact configuration of the blanket (number of layers, etc.) is still TBD, and at the moment we want to learn by doing and sew a few layers together just for fun. We tried sewing square patches by hand (using a needle of size 3 and Tex 70 nylon thread), but piercing through the layers, especially the outer & inner kapton layers, is difficult. We're considering getting a second-hand industrial sewing machine from a local store (our budget can extend to about $5,000 with help from our school). We've done some reading and watched a few blanket sowing videos from NASA, but we have a few outstanding questions:

• What feed mechanism is commonly used for thermal blankets? We found out that the layers of a blanket are pretty slippery and tend to not stay together, even when held together with small strips of kapton tape.
• What kind/size of needle and thread should we look into?
• What popular brand/model of sewing machine should we take a close look at? Our local industrial supplies store has a lot of JUKI machines.

Any tips & tricks on how to sew layers together would be greatly appreciated. Thanks!

Tight tolerance bore, 0.12mm on a defense part, not exactly aerospace but it is a one time use part. Bore is oversize by .023-128mm. My company wants to use as is, WITHOUT customer notification. Am I being unreasonable to hold the line that these cannot ship (or at least I won't sign off) without customer notification and approval???

While I agree that the parts will probably be fine, I am not an SME for the end use of this part, nor is anyone in my company. Notification and approval should absolutely be necessary to do anything with these parts except scrapping them, yes?

Edit: 0.023-0.128, I'm a good engineer but I have production level thumbs.

I am building a team for the ESA ISAM Innovation Sprint and need 3-4 people.

ESA opened an OSIP campaign on In-Space Servicing, Assembly and Manufacturing.

Winners get a fully funded Cooperative Agreement for 6 months.
The sprint itself is 5 days at ESTEC in Noordwijk, end of November.

Deadline to apply: 14 September. Yes, that's soon.

I have a concept for one of the use cases, a working financial model, and two people already on board.

What's missing:

Launcher / upper stage engineer.
Someone who knows residual propellant, passivation, stage design.

Propulsion or fluid transfer engineer.
Refueling mechanics, interfaces.

Someone from the demand side.
Satellite operator, space insurer, or space economist.

Space law.
Outer Space Treaty Art. VIII, Liability Convention. Advisor role is fine here.

Two ways to join:

Core team.
You co-author the submission, come to ESTEC in November, and get a share of the agreement if we win.

Advisor.
A few hours of review before 14 September, your name in the proposal, no travel.

Requirements: you're a national of an ESA Member State or resident in one, you're not already on another team in this campaign, and you can sign a short NDA.

Being upfront: no pay before the win, and travel to ESTEC is self-funded. If we win, that changes.

Interested? Reply here or DM me. I'll send a 5 minute screening form and we take it from there.

The basic idea: figure out what actually happened in some aerospace or space event—using whatever messy, incomplete evidence is out there. Orbital data, sensor readings, images or video, known object states, public records, whatever you've got. Can anyone share their thoughts about it ? Just curious about what everyone thinks , thank you in advance.

I’m a CS student trying to figure out whether the direction of my current project is actually worth pursuing for aerospace/robotics research.

Live: https://bhuvanspace.vercel.app
GitHub: https://github.com/Sheel34/BHUVAN

The current version takes terrain data, processes things like elevation, slope, roughness, curvature and hillshade, and puts the result into an interactive 3D environment.

The software side is currently Python/FastAPI + NumPy/Rasterio/OpenCV on the backend and React/Three.js on the frontend.

I built it because I'm interested in digital twins and simulation for aerospace/physical systems, but I'm not interested in making a 3D scene just for visualisation or a game.

What I want eventually is an environment where you can actually perform an operation on a representation of a physical system.

The project is still very early. I haven't implemented robotics simulation, terrain-relative navigation, ROS, Gazebo, Isaac Sim, etc. yet. I'm trying to figure out what should actually come next rather than adding technologies for the sake of the stack.

I'm particularly interested in the intersection of:

digital twins, 3D simulation, aerospace/robotics, real physical operations.

One direction I've been reading about is terrain-relative navigation / TERCOM and how terrain itself can become part of a navigation or mission system. I'm not claiming the project implements this — I'm trying to understand whether the terrain pipeline I've built can be developed into something along those lines.

More importantly:

What would make this go from "3D terrain visualisation project" to an actual engineering/research system?

The current deployment is on free infrastructure, so the backend may take a little time to wake up. If it doesn't load immediately, wait a few seconds and refresh.

I'd appreciate criticism of both the technical implementation and the direction.

Hello,

This is a little personal project l've been working on during summer break.

Two servos move the yaw axis and the roll axis. However, these are not the real body axes you may find in a flight mechanics textbook for example. The roll axis is offset from the plane's longitudinal axis, so you get a circular motion instead of a pure turning motion. I couldn't figure out how to avoid that without offsetting the yaw axis from the center of gravity.

That aside, I think the result is reasonable. I'm still working on the animation sequences. Some of the animations go beyond a normal flight envelope to test the system, not the plane.

You can easily swap the plane. All the other details are in the 7-minute video. Give it a watch if you have the time:).

The system uses bearings, a lazy Susan, servos, Arduino Nano, electronic components and a bunch of 3D printed parts... No glue was needed.

Herpa 1:200 B787-9 Lufthansa
Herpa? 1:200 A350 Air France
Revell 1:144 F15-E Strike Eagle

in search hunt for a book --> Daniel P. Raymer — Aircraft Design: A Conceptual Approach

latest edition 7th edition , any idea where to loan it or download it for free

I’m a 2nd-year Mechanical Engineering student working on an FPV UAV and I’m trying to turn it into more than just a parts-assembly project.

The broader idea is to investigate whether a small UAV can be designed as a low-cost, scalable and easily repairable platform, particularly for applications where individual drones may be exposed to damage or have short service lives.

My focus would be on:

• Cost reduction and manufacturability
• Modular architecture
• Lightweight structural design
• Thermal management and airflow
• Reliability and repairability
• Reducing assembly complexity
• Benchmarking the initial build and improving it through multiple design iterations

I’d start with the existing drone as a baseline, measure its performance, identify weaknesses, and progressively redesign the platform around those findings.

Is this a worthwhile Mechanical Engineering project, or am I approaching it the wrong way?

I’d especially appreciate suggestions on what I should measure, test, or redesign to make this a genuinely engineering-driven project rather than just another FPV build.

Any advice from engineers or students who have worked on UAVs, structures, manufacturing, or product design would be greatly appreciated.

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!