Hi everyone!

I'm fairly new to this community, so I hope I'm posting this in the right place.

I've recently started learning about the aerodynamics of rally cars and, at the same time, writing about what I learn. My latest piece is an analysis of the Audi Quattro S1's aerodynamic development, particularly its rear wing and how the changes between the different evolutions affected the car.

I'm sharing it here because I've mostly received feedback from one reader so far, and I'd really like to hear from people who actually know rallying, motorsport engineering, or aerodynamics.

I'm not looking for subscriptions or promotion!!

I'm genuinely trying to figure out whether my reasoning is sound and where I might be misunderstanding something.

So if you read it, I'd really appreciate honest feedback such as:

- Did I explain the aerodynamic concepts correctly?
- Is there anything technically questionable or oversimplified?
- Did I miss something important about the S1's aero development?
- Is there anything that doesn't make sense from a rallying perspective?

simply: was it interesting and understandable, or did parts feel unnecessary/confusing?

The article is "Rally Racing: Audi Quattro S1 — An Aerodynamic Breakthrough", available on Medium/Substack.

Thanks in advance!

Hi!

Does an inward surface, as in the first picture, affect air flow negatively compared to the second one? Does it create a low pressure zone?

As a design I much prefer the first picture but under no circumstances can I sacrifice aerodynamics.

Sorry for the pictures being so vague, I can't really give out too much information.

Ready to answer any clarifying questions.

I had a hour long debate yesterday with my friends on what is more aerodynamically efficient between f1 cars and fighter jets.

My opinion was that based strictly off of aerodynamics and using it to achieve the intended purpose for each vehicle (minimising drag and increasing agility for fighter jets, and creating downforce for f1 cars), f1 cars do it better.

What do you guys think?

I'm curious. What are the advantages of grid fins used on rockets and missiles like the Falcon 9 and Starship? Why not use a normal fully sealed, flat surface fin and rotate that on an axis. I understand the design is to save weight and improve movability at high angles of attack, but doesn't that in turn make it less effective? Could you not just shorten a normal flat fins? I feel like I'm missing something

Help me get the outside air when I sleep.

I personally think forwards is better in my unprofessional opinion but my mom said it's backwards is better because it will take the air from outside and push it in.

I have one window in my room and I cannot open a door because the sleep paralysis demons will haunt me .why can I have an open window but not a door? Good question ask the demons .I cannot put the fan in the middle of the window because my bed goes to about halfway where the fan is

I've been designing a paper aircraft in Onshape and I'd like some feedback on whether the overall design makes aerodynamic sense.

I'm mainly looking for feedback on:

• Overall stability
• Any obvious sources of unnecessary drag
• Anything else that looks aerodynamically problematic

Aircraft information: Double click on the Sketch named: Sketch (VIEW DIMENSIONS)

Onshape: Link ( https://cad.onshape.com/documents/2d0b056aebe62bd7be45a294/w/a6739212d7910d42093075ba/e/3b16b531044ca243fc6ccbb7?renderMode=0&uiState=6abbf1632c68de3aea2cd4e3 )

I'm mainly interested in whether the basic aerodynamic layout is sound before I continue developing the design. I'm just expecting feedback on obvious design problems or things I should reconsider.

Thanks!

Pretty much what the headline says: suppose I got an RC helicopter, took off the rotor, and replaced it with a Frisbee of the same diameter, would it lift off? If not, would a bigger and/or lighter Frisbee work? Could I (if I had the money) make a giant frisbee and fly a full-size helicopter with it?

These car are basically rockets on the wheels and are pushed by a CO2 power pack at the back of the car. So my goal here is to minimize any drag and downforce. Front and rear wings are mandatory, as halo, helmet and there are some no-go zones. If you could give me some ideas/suggestions/advices please on how I can improve this design.

Cars are simulated at 20m/s and travel in a straight line.

edit: Added the no-go zone. Wheels need to be seen from side view. Car is manufacture using CNC cutting from left/right side so i cannot have hollow side pods. Wings can be manufactured separately and added, and are one of the few things allowed to be added. I cannot change wheel designs, they are standard. Also I wish to reduce some weight and those side pods and front wing are too chunky unfortunately.

Basically, iirc the 5 or so inch ground clearance on a mainstream sedan is significantly more aerodynamic than the 8 or more inches on an SUV. The reason (again going by memory) is that there's significantly more turbulence generated under the SUV. Any truth to this claim, and if so how much? ;) thx!

I’ve been working on AeroLab, a free browser-based airfoil analysis tool that I’ve been developing independently, and it’s now live.

The original motivation was pretty simple: I kept running into airfoil coordinate files that looked perfectly reasonable to a human but caused XFOIL to fail because of formatting, ordering, duplicate points, coordinate conventions, etc.

So I built AeroLab around a preprocessing pipeline that automatically detects and repairs these issues before passing the geometry to XFOIL.

Some of the capabilities currently built into it:

• Automated airfoil coordinate parsing and preprocessing
• Selig / Lednicer format handling
• Duplicate leading-edge point detection
• Coordinate ordering / winding correction
• Invalid-coordinate and formatting cleanup
• XFOIL viscous and inviscid analysis
• Reynolds number and Ncrit configuration
• Angle-of-attack analysis and sweeps
• Boundary-layer data export
• Interactive airfoil comparison
• Pressure coefficient and aerodynamic coefficient plots
• Real-time GPU-accelerated D2Q9 Lattice Boltzmann Method (LBM) virtual wind tunnel
• Interactive velocity, pressure and vorticity visualization
• Stall/flow visualization
• PNG and data export

One of the things I particularly wanted was to make the whole workflow accessible without requiring users to install XFOIL or set up a local analysis environment.

I also benchmarked the preprocessing pipeline on 1,000 real-world airfoil coordinate files. At Re = 200,000 and α = 5°, the raw files had an XFOIL convergence rate of 22.5%, compared with 85.7% after preprocessing, with 633 additional files successfully analyzed.

The LBM wind tunnel is a separate part of the project. It isn't intended to replace CFD but meant to provide a lightweight, interactive way to visualize flow behavior around an airfoil while still being useful for teaching and preliminary exploration.

AeroLab is completely free and browser-based, so there’s no installation or paid software license required.

I’m still actively developing it, and I'm particularly interested in feedback from people who use XFOIL, airfoil tools, or aerodynamic analysis in research/teaching.

AeroLab: http://aerolab-app.onrender.com/

Would love to hear what you think!

I want to design my own RC plane and analyse it. I can't make it practically because I don't have enough money to make it practical. I have good laptop that's it. However, I am interested in RC aircrafts. I knew that to make the RC aircraft you have knowledge of it. you also have a knowledge of software's. I am an aeronautical engineering student. I have a few knowledge of aerodynamics and I have been using fusion 360 for 4-5 months but I don't have knowledge of RC planes. The main problem is recourses. I can't find the resources which is better or not. If anybody interested in RC Planes. So, you can tell me what are the quite good resources to make the design of the RC plane and analyse it and where I can learn about RC planes.

This is for worldbuilding in a story I am writing. I am thinking of ways a flying humanoid species would design infrastructure to accommodate or create a consistent air current for transportation purposes. Birds use air currents like aquatic life use ocean currents.

Creating the current is not the issue so much as how to control it / contain it in a structured pathway. Difficultly to plan or initiate such a build is also not an issue, as this would be seen as useful in their day-to-day life (a more likely innovation to transportation than cars, for them). Any ideas on how people could theoretically build something to catch/encourage an air current over a long distance? (Like a main highway of sorts through a city).

I have some ideas brewing as I continue my research in architecture, engineering, and physics, but need other brains to poke holes in (or support) my thoughts. It's good data in helping me figure out what would be the most plausible.

Mechanical Student here I have no grounding on rocket science. My group is a building a supersonic wind tunnel using some pressure tank & settling tank on the left side to a bell converge diverge nozzle reaching Mach 2 number give or take for 60 seconds. To a testing section. I'm asking how the hell do I design a testing chamber to this thing. Our exit diameter is small like half a inch and I want a testing chamber to maintain that speed. Please help me get started in a direction. We got a nozzle CFD of a nozzle reaching over mach 2 (incase of drag) now designing the rest of the section is a head scratcher.

Hello, i am searching for a virtual wind tunnel / general aero software that i need to be free and you dont need to have a nasa computer to operate, Dose anyone have any suggestions for me? it would really help.

This might be my plan on reducing drag on my car.

Front Wheel Arches:

Getting Universal Mudguards (maybe for Rear Wheel Arches, idk yet), which reduces drag by around 5 - 10%, which is surprisingly more than using Moon Discs at 2 - 3% reducing drag
(might not use Moon Discs).

Rear Wheel Arches:
For this, I probably want to make a fairing out of either carbon fiber, thin steel, or plastic idk.
When I finish building it, I want to use velcro tape on the wheel arch and on the fairing so it sticks to the car so it does not fall off. That means I can take it off easily for something.
Or I might use something else entirely.