straight line race (stem racing) i want just a quick check up from some of you before going in the simulation about the chassis. someone have some ideas to make it better? thanks in advance

Bonjour, est ce que quelqu'un pourrait m'expliquer comment (et si c'est le cas) un moteur à distorsion d'espace temps pourrait théoriquement aller à des vitesses hypersoniques sans produire de sonic boom?

Title. The reynolds # should be from 250K-1.3M (estimate). I plan to have fowler flaps for increased clmax at stall. I can't find a good compromise that performs well in stall (Laminar seperation bubbles at low RE, good Cl) and cruise (low Cd at cruise cl). Any help is greatly appreciated!

Hey everyone I'm working on a supersonic rocket with an apogee of around 10 km, and I'm trying to determine the drag coefficient of our elliptical parachute for OpenRocket simulations. What value would you recommend, and are there any reliable sources or experimental studies we could refer to? Also I want to know what are the essential essais and tests I should do with the parachute (except deployement and shock)? And my last question is in a Rocketry competition report what do I have to focus on and what the juries will also focus on?

I’m looking for aerodynamic CFD vids, mainly on cool or unusual objects, animals, vehicles etc aha!

Does anyone have any favourites? Or any links or suggestions where to find them!

Thanks for your help :)

Could anyone guide me on the ideal sizes of my wind tunnel’s sections? It’s already 7ft after making compromises and being conservative. I plan to use it to test a custom wind 1:10 rc car. I’ve been getting most of these messages through Claude so it really feels like I don’t know what I’m doing.

I've been working on this race car concept for a while and I'm mainly interested in the aerodynamic side of it.

The idea is to keep the very reduce wind turbulence, teardrop-shaped upper body of the Volkswagen XL1, but combine it with extreme race-car aero: large Venturi tunnels, active floor, huge diffuser, massive rear wing, front splitter, active aero and even two rear fans inspired by the Chaparral 2J.

I'm wondering how far something like this could realistically be pushed. Would the XL1-style body actually help with airflow, or would the extreme downforce devices completely defeat the purpose? Where would the biggest aerodynamic problems appear, especially with ride height, pitch, yaw and aero balance?

I'm mostly looking for people who understand this stuff to tell me where the concept makes sense and where I've completely fucked up the physics. The drawings are just a rough representation of the idea.

(I used a translation tool for this because I don't speak English, so some points might be off. The key points I want to highlight are that the car isn't designed for maximum aerodynamic efficiency or low drag; instead, the goal is extreme aerodynamic stability, achieved through the teardrop shape of the XL1 Sport Concept. This shape keeps the car stable at speed and helps manage airflow to generate active downforce—specifically at high speeds on straightaways. It’s a damn fast car, but it also handles corners incredibly well. Sorry about the phrasing.)

Simulation suggestions

Hi, I'm gonna be writing my bachelor thesis on the topic of CFD in OpenFoam. The practical part should be focused on a flow around some part of an aircraft (jet). However I'm still thinking about which part should it be. That's why I'm writing here for inspiration, so if anyone has any ideas... :D. It could literally be anything, for example one idea I had was how the frosting affects flow around wings in cold weather

I highly reccomend these set of video lectures produced decades ago from various academic institutions. They are old but very well made. I remember studying these as part of university courses and really enjoyed them.

Here is the playlist: https://youtube.com/playlist?list=PLfF--3o8i4r82vJ0kjCVYgqKgyVM5QwN0&si=bR3oI2ubVOyPVuqn

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!

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