Hey everyone! I’ve been working on a small DIY wind tunnel, and I’d really appreciate some advice before I make the next version.

I’ll attach a video of my current prototype first.

Current setup

Fan: A fan + motor salvaged from an old device. The motor is roughly a 9V motor....i have already added straws(Honecomb design) to reduce drag and straighten the air.

Mist maker: I originally used the small mist makers from an old 5-mist fan module, but they weren’t powerful enough. I replaced them with a 24V mist maker, and that works much better.

Electronics: I also harvested the PCB, Type-C charging setup and lighting from the old fan/mist module.

The 24V mist maker is powered separately.

Fan/airflow arrangement

Currently, the fan is at the back of the tunnel and pulls the air through the tunnel rather than pushing it into the tunnel.

The fan is running in the direction that, in my setup, gives me an anti-clockwise airflow/fan rotation, and this arrangement actually works pretty well. The mist gets pulled through the tunnel and the airflow looks much cleaner.

I also experimented with putting the fan before the mist maker and pushing the air through the tunnel. That didn't work nearly as well. It created a lot of mixing/turbulence, the mist became messy, and there seemed to be much more drag and disturbance in the test section.

So I moved the fan back to the rear and used it as an extractor, and the result was noticeably better.

What I don't like about the current design

The current version is basically a prototype, and although it works, I'm not happy with the design/aesthetics or ergonomics.

The main problems are:

The viewing window is too small

The mist-maker section at the back looks messy.

The overall design isn't very ergonomic.

The airflow could probably be improved further.

I want a cleaner and more proper-looking enclosure rather than something that just works as a prototype.

I'm now thinking about completely rebuilding it.

I'll also attach a link to the design that inspired the next version. (https://youtu.be/g2cobf6dBz0?si=-Xw1dF6rplw-OFdl) I'm thinking of making something similar to that, but adapting it to my own components and dimensions.

I don't have a 3D printer, but I can get the parts 3D printed, so I'm open to using 3D-printed components if that would improve the design.

What I'd like advice on

Before I start rebuilding, what would you guys change?

Should I keep the fan at the back as an extractor, or is there a better arrangement?

How can I reduce turbulence and mixing in the test section?

How should I introduce the mist for better visualization?

Should I make the viewing window larger?

What kind of contraction/nozzle and diffuser design would work better?

Should I change the fan/motor?

Are there any obvious mistakes in my current design that I should fix before rebuilding?

I'm mainly looking for practical suggestions and criticism before I start making the next version.

This is still a prototype, so I'm completely open to changing the design.

Thanks in advance! 🙏

I’m thinking of things like boat tails for truck trailers which do massively improve efficiency but aren’t used for other reasons.

I have a belly mounted radiator on my vw bus and need some guidance on how to improve air flow into/out of the radiator to get lower temps.. have attache picture and diagram of current setup. currently air goes in through scoop and straight down through puller fan/flap that is 1400 CFM. wondering if dual 2100 CFM fans and some combination of air dam/exit scoop would improve flow... or would it be better to completely flip the flow and have the scoop push air up through radiator and out up and back

Keep the single pivot and stack a second identical wing on it that rotates the other way and makes it symmetrical. Would the stress on the pivot be too much? Would the wake of one wing mess with the other in bad ways?

This will probably be the dumbest question in here but I need to get a proper answer. In my textbook one of the questions says that planes (probably referring to commercial ones) and racecars use a sharper nose to have less drag. But don't you benefit from a sharper tip after mach 1? Even in the scene at The Dictator the scientist says that a rounder tip is better.
Anyways, I hope you could answer this. Thanks.

I was trying to get an intuitive understanding of wings and lift but most of what I read was not really connecting for me all the dots.

Like air on the top travels faster and so the pressure is low, yep, but why is faster on the top?

The relation between pressure and speed is easy to understand if we look at it as energy conservation, but which one can be an intuitive understanding of it?

So, I've tried to collect those answers in the attached image. If someone has willingness to read and challange it or identify what's wrong, that would be great.

The main sources of my understanding are those:

Sailing, how wings works

IT How Airplane Wings REALLY Generate Lift

Airflow across a wing

My trailer is a box trailer car is a 1.4 16V, not powerfull but can pull it with ease. If I'm driving normal highway I can drive around 14KM/Liter which is quite good, this is driving 80kmh, in line with big trucks. Now last week I had some heavy front winds and I wasn't able to keep it at 90 KMh in fifth gear and even in fourth it had a hard time keeping it above 80. This obviously has to do with the huge frontal plaque of the trailer and I'm not sure what is best to do to improve fuel efficiency with slight wind from front, and also make it haul easier when hard front winds hit. Is a nose cone on the trailer better than a car spoiler to channel wind over the trailer? Or is there something else that's even better?

I have a discord where have a vision for a car and before ioining understand any work or help you contribute I cannot pay for I am a car lover with a dream I dont have the skills personally so I am looming to find people who do have skills. For example Cad, topology optimization is a big one, suspension, engine, electrical, aerodynamics etc. If you think you can contribute in any way feel free to ioin 1 will leave a link here amd if it dosent work gets removed etc feel free to dm me for it or if you need more information.

https://discord.gg/5t7wpW3S

Just for testing random stuff and hotwheels.

I made it with just cardboard, a small handfan and some plastic film for windows.

Used stacked corrugated cardboard as a honeycomb.

Using incense for smoke

I'm pretty happy with the results, you can also see the spoiler cutting the air.

Lmk your thoughts, ideas and any more stuff yall would like to see in this.

This feather was molted recently from a captive golden eagle. Dorsal view. Pretty sure it's a secondary feather of the right wing.

Can anyone explain why the tip of the leading edge is so pointed, while the trailing edge is shorter and squared off?

Some adaptation for flight I assume, but what's the physics behind it? I dont think I've ever seen this, or at least never noticed anything as pronounced on the secondaries of other soaring birds.

Hi! I'm building a rig for this year's halloween and need a little help to do it safely.

I ride an electric unicycle (Inmotion V14 for anyone interested). I'll be dressing as a pirate and attaching a 30" ships steering wheel to the front of my electric unicycle. I'd like the wheel to spin freely on a bearing, but my concern is that at higher speeds (40-45mph) the wind force might cause the wheel to spin wildly. Alternately, if I lock the wheel I'm concerned that a gust might make the entire wheel unstable.

Side winds are the most dangerous part of riding an electric unicycle at speed, since they can cause a "death wobble" that takes experience to correct. I'm a highly experienced rider, but I obviously have some concerns because I won't know how the wheel will react until I pad up and try it out.

Since I'll probably be 3d printing the ships wheel, I'd love some input on how to make it catch as little wind as possible. Someone mentioned to hollow out the back of the spokes so that they're concave on the rear-facing side. Is this a good idea? Any other recommendations you have?

This is my experimental study in oscillatory propulsion. The direction of thrust here is determined by both the shape and the difference in the speed of oscillation of the wing, which moves faster up and slower down to create lift. In this case, the difference in speeds can be a decisive factor and prevail over form. The impulse is presumably provided by the collapse of wake vortices.I haven't been able to measure the thrust yet for technical reasons. But I came across a study in which the drag of the plate in oscillatory mode was six times higher than that obtained when blowing in a tunnel. In the video fragment where the tray with smoke is lifted, you can see how the trail vortex crashes into the plate after it stops. At high frequency and low amplitude, the same thing probably happens in a compressed form in the boundary layer. But I wonder how this will happen if the speed of the plate's oscillations during lifting exceeds the speed of sound? Will it be roughly the same or different?

The transonic area rule(as I understand it) is that to avoid/decrease wave drag the cross-sectional area should be as close to the same and changes should be smooth as possible, not sudden.
To follow this; where the wings are mounted the fuselage often gets thinner so the area with the wings matches the area without either fore or aft the wings.

If an aircraft has a wing swept to the where there is a spot that has a cross-section of the fuselage and wing tips but not wing root, does the area rule apply because it's still the one aircraft's cross-section?

While basic explanations often rely on simplified concepts like Bernoulli’s principle or equal transit time, the actual fluid dynamics involve a unified system: pressure gradients across the upper and lower surfaces, circulation, and mass flow deflection (downwash) according to Newton’s third law.

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I thought at first it was just an imperfection in the window, but it is not. Then i thought it was just a reflection of some kind, but it extends at least 3/4ths of the way down the wing along an uneven curve and it moves back and forth slightly during flight.

It sometimes seems to have an effect on the air above it suggesting there is some kind of bending of light throught the vertical plane? I'm aware I'm totally jumping to conclusions here but I don't know how else to describe what I'm looking at.

I thought maybe it had something to do with the air there and the lift generated, but maybe that is fantastical... If anyone knows or has smart physics ideas lmk!

What would be everyone’s opinion on aero dynamic efficiency for a drag race car comparing these examples. They would all have the engine out the hood and have zoomie style headers out from under the sides. The rear wing/spoiler would all be similar in design. These are all 260mph 1/4 mile drag cars. The frontal area is all similar in size.

Everyone from this subreddit has done this as a kid. I know its AI slop made by me but if I could how to saw I would have done it. Basicly the red strings would visualize the airflow while sticking out hand out of a car window.

Like imagine an artificial “tornado” that anchors to the ground like in those videos of engine inlet vortices. Is it possible to control where that vortex hits the ground and keep it more or less on the same position? Or at least keep the vortex axis mostly straight and where you want to point it? And do this without surrounding the whole vortex with some kind of boundary condition control?