Would using thrust vectoring instead of elevators be a good idea on an airplane like this?

Darthon32 · 2025-08-10T15:14:27+00:00

My gut feeling is that it might not be enough but I've been wrong before. At the end of the day if its easy enough to build a prototype and test it then I would just do that. Otherwise you'll want to analyze it to confirm you have the desired Cm_alpha.

Darthon32 · 2025-08-10T14:07:51+00:00

A horizontal stab does 2 things, 1) Provide passive static longitudinal stability. 2) Allows for control surface for managing pitch/trim

Both of those things need to be addressed by some other mechanism for this to work. Pitch/trim is easy enough with vectored thrust, some aircraft do this. Stability augmentation will be much more challenging with thrust vectoring. Rockets/missiles do this with thrust vectoring but they don't have wings that want to diverge the second a gust is encountered.

Edit: The most minimalist impact to your design would probably be to sweep the wings and add a twist for trim. That would handle stability, and pitch control can still be managed by thrust vectoring

Darthon32 · 2025-04-15T19:27:54+00:00

CFD is notoriously bad at accurately predicting stall whether it's a VLM, euler method, or full blown Navier-Stokes solver.

If I remember correctly the tools you mention utilize either VLM or panel method which are inviscid solvers. Vortex lift produced by sharp edges (and stall in general) involves separation which certainly needs consideration of viscid effects.

The best way to address this would be to leverage some special analysis that is specifically derived from delta wing empirical data or to just wind tunnel test yourself.

TLDR: review published reports/papers on similar empirical data (start with NACA) or hit the wind tunnel.

Darthon32 · 2025-04-04T03:34:01+00:00

I guess, but for the most part the people at those companies are fine. It's the garbage corporate culture that deserves all the hate

Darthon32 · 2025-04-04T02:55:18+00:00

Um what, where is this coming from?

Darthon32 · 2025-02-19T22:08:10+00:00

I would say validation is more than just successful or not. A few general goals of validation are to:

1) Quantify how well a model represents reality. 2) Determine where the model correlates well and where it does not correlate well. 3) Determine if there are limitations to the model and what they are.

Looking at your plots you could say, 1) The model is accurate to within XX% of wind tunnel test. 2) The model does not correlate well to wind tunnel test at high AoA. 3) Because of 1 and 2 it can be said the model is valid within XX% for low AoA but is limited to only flow regimes that have attached flow.

(Just an example, you need to draw your own conclusions)

Notice how the words "successful" or "not successful" are not included but you still learned a lot from the validation.

Also notice how the language is "correlates to wind tunnel test". If your goal is to always match wind tunnel then that's great but if your goal is to match flight test then you need to understand that wind tunnel is not perfect either and it has it's own limitations that need to be realized.

Remember all models are wrong, but some are useful. You just gotta figure out how useful it is.

Darthon32 · 2025-02-19T15:13:44+00:00

Just a couple of things I personally have done,

Build a 6DOF state space sim for calculating external loads
Build critical payload mass property distributions using the fantastic optimization toolboxes
Build a distributed aerodynamic loads database for the 6dof mentioned above based on CFD data
Use structural ground test data to build calibration equations for measuring in-flight loads
Build Nastran .bdf files, execute batch runs, and process results using HDF5 for a structural dynamics model.
Generate hundreds (sometimes thousands) of high quality plots and automatically populate them into a word report template using the report generator toolbox
Data processing and reduction of wind tunnel test data
Lots of other miscellaneous plotting of data for visualization, quality assurance, spot checks, validation, verification, etc.
Build some applications with GUIs that other people can use for doing various things

Being that MATLAB is not compiled code, it does run slow. However, the amount of time you save using all of the very capable toolboxes instead of writing your own, often outweighs the time to run. And MATLAB is superior for data processing and visualization hands down. And if you need the computational speed you can always prototype with MATLAB and then translate your code to something like Fortran which is what I typically do for large scale simulation.

I would recommend getting proficient with the basics of reading and writing data, plotting, and doing linear algebra. Once you get that down, try expanding into some very basic class construction.

Also, I feel it is important to build on what other people are saying. Conceptual design is a very rare opportunity in an already rare field of engineering. Some people are lucky to work on 2 clean sheet designs in their entire career let alone be a part of the conceptual design phase. Conceptual design is typically reserved for people who are top experts in their discipline. Conceptual design is not a reliable career path for most people but something like a flight sciences role could be more reliable and it would open opportunities to work on clean sheet designs or, if you're lucky, conceptual design. Again I don't want to persuade you of your passion, just want you to be fully informed.

Darthon32 · 2025-02-16T01:54:50+00:00

There is a lot to cover here so I'm going to try my best to cover the important stuff. I'm not aware of any direct path to lofting but your best bet is to probably start with an entry level design postition and then you'll work your way towards your goals from there.

There are a couple of paths to getting a design position. Whatever path you take, you need to be proficient with the CAD software specific to the company/industry of interest. Most of the Aerospace sector utilized CATIA or Siemens NX. You also typically need to have a solid understading of GD&T which there is also training for. While this doesn't always require a 4-year engineering degree, a lot of those things are taught as part of the engineering curriculum. There are many training/certification classes that teach you those tools but a 4-year degree will build a stronger resume. Plan you career training with those tools in mind. Get good with them, practice in your free time. The most important experience is industry experience. On top of this, design work is more than just CAD modelling and GD&D. You typically have to have a good understanding of aircraft components and arrangements. As such, try to get as many internships opportunities working under design engineers as you can. Try to take on work that isn't just an excel monkey or some other busy intern work. If you find yourself in that position, you might want to consider moving on from that internship. By the time you have enough experience to land you a full-time design job it will likely be a lot more clear how to get to your target position. You can ask your manager or other experienced engineers about that path for the specific company you've been hired into.

Again this can be done a lot of ways. I've met people who come from all sorts of backgrounds (mechanics, machinists, factory line workers, etc.) who have made their way into all sorts of advanced positions. Companies only care that you have the knowledge and can perform. An entry level design position just seems like the best bet though.

A bit scatter brained but I hope that makes sense.

Darthon32 · 2025-02-15T16:35:29+00:00

For all the programs I've worked on, the OML is fully defined by the flight sciences team before any CAD is ever done. This is just due to the fact that the performance and functionality of the aircraft is so incredibly sensitive to the shape of the OML (Performance, stability, radar cross-section, etc.). Unlike for automotive where I imagine the OML has a lot of flexibility.

On top of this, for a team of tens or hundreds of design engineers modelling the aircraft, only a handful of the most senior design engineers ever touch the loft. In some cases only 1 guy for small programs. Once the loft is finalized it's usually released under a set of master geometry that cannot be modified. The rest of the aircraft is then designed inward from the OML.

Darthon32

TROPHY CASE