The Aerodynamics of Speed 

Impeccable shaftsmanship at the end there, solid 10/10. The video was pretty good too.

My neighbour is nearing 90 years old, he's an aero engineer who has consulted extensively since his retirement in his mid 70s. He's sharp as a tack and still gets calls from DoD colleagues when they are stuck. I was stunned when he told me about some of his colleagues in the 1950s joking about their previous work... "Ze guidance has to be so accurate now, my last boss vas happy as long as ve hit London"

About 20yrs ago I cut up 200 ft of 1/4 clear vinyl tubing and ran it from inside my 66 Belvedere hardtop to points all over the body. Base of the windshield, grill, fenderwells, area behind rear window, and like that. Then I had my buddy Sam drive me around on I-81 at 80mph while I hooked up each tube to a furnace exhaust stack vacuum gauge and wrote all the results down. My plan was to figure out where the high and low pressure areas were so I could see if there was any way to duct the high pressure air to the low pressure areas to reduce drag or make it rain behind the car or something. The only thing the experiment indicated might be helpful was to remove all the glass from the car. I still have the notebook with all my "data" and handrawn outlines of a mid60s Mopar intermediate. I think writing this comment is the first time I've gotten any benefit(?) from all that "research". Thanks. All hail

I burst out laughting everytime you showed Kermit flailing his arms around to display turbulent flow. This is one of the best, most visual descriptions I've head and I'm going to use it from now on!

I'm wholly impressed by how you wrapped up a very serious dissertation on aerodynamics with a dick joke.

Everyone always asks if I ever took an aerodynamics class in engineering school. Of course I tell them I did, but the class was not whatever they imagine aerodynamics to be. It is a dark art, with understanding inversely proportional to knowledge.

Just discovered this guy and he's the first RU-vid car guy I've seen caveat literally every idea for car aerodynamics. When he introduced who NACA was instead of just saying a NACA duct sucks in air, I knew he's the real deal.

I enjoyed the longer video immensely but I have this weird feeling that I actually learned something. I'm sure it will pass.

I'm beginning to think every car Matt works on needs to have a hidden phallus somewhere.

17:00 if you're in the UK the custom is to attach a small bell at the front to get a sense for how much the air is flowing, this also helps you remember which end is the front. It's the bellend.

The Dodge Charger Daytona and Plymouth Superbird, Chrysler's NASCAR homologation efforts around 1970 used textured vinyl on their roofs. This served two purposes, first the rough texture did have a "golf ball" effect which helped stabilize a shape that was never designed to go 200 MPH. And second and perhaps more importantly, it covered the slapdash bodywork done to the 2500 street versions they had to try to sell. NASCAR banned vinyl tops for 1971.

Probably one of those things that is significantly different between hydrodynamics and aerodynamics, but one of the things we have found in racing sailboats is that a slick, glossy hull surface is often slightly less performant than a sanded, matte surface. Something about the roughened finish wetting, making the dominant interaction be water on water instead of water on fibreglass. The Olympic Soling class used this to great advantage; you could tell pretty quickly who sanded their hulls and who polished them. The sanded hulls were usually a boatlength or two ahead consistently.

Engineering humour is rarest humour . . . . next to accounting humour. Also, drag is caused by exposure to feather boas, sequins and stage makeup.

I’ve watched probably 100+ aero videos, and this is hands-down my favorite, ever. Thank you for that.

The transition from aerodynamics to bio mechanics is incrementally subtle.

So glad we never have to experience childish humour on this channel. Cheers mate. 🍻😁👍

Your intro regarding confidence in aerodynamics applies to just about anything complicated: Cyber security, data analytics, AI, environmental science, etc. I find that entertaining

First off, maaannnn, Matt: I always absolutely love your deadpan humor and delivery. It gets me everytime. Second: All of this footage of Bonneville makes me sad. I moved to SLC for 2.5 years, but both years I lived there, the salt flats were too wet to run (and I had to leave before the third one ran) so I never got to go. Still though, I love getting this insight. Thank you!

After reading up on theory and (tested) examples on an ecomodding website, I made some aero mods to my 2005 Accord to reduce its drag (for fuel efficiency reasons, not speed). I did A-B-A-B testing during relatively stable weather. Runs in both directions, straight level road, no traffic, using cruise control with the car left on for consistent speed. Short airdam w/ curved lip connected to a partial undertray under the engine bay, partial grille block, side mirrors folded back. Could add/remove all at the side of the road with simple tools. Got ~4.25% fuel efficiency improvement at 55mph. Pretty happy with that.

That diagram at the end made my Monday, thanks Matt 🤣🤣

Your drawing shows that nature knows the answer to everything.

This feels like it addressed everything I ever cared to know about aerodynamics minus all the math. great video!

About NACA ducts: they are only made for high-throughput airflow, NOT for static pressurization as is what you want for a ram air for the intake of jet or other engine. They work well for that for which they were designed, and static pressure is NOT it. If you need static pressure, you use a scoop or other forward-facing inlet that is preferably located in clean air, such as the front of the car or a scoop well above the boundary layer.

I fucking love this channel! From beginning to thankful ending. It's always just the best from Matt.

I love your content, you’re one of the only content creators I have the bell on for.

A belly tank racer with a small hole for a ram air scoop explained it to me like this: He calculated the volume/mass of air going into his intake hole as a cylinder of air extending from the start line to the finish line. He calculated the diameter of the intake hole based on that. At 200mph, the hole was slightly larger than a quarter.

My best example for how unsure we are about aerodynamics is that some guy put a spoiler on and started getting better mileage. People were saying he was an idiot, probably had tail wind or some other thing was causing it because spoiler causes drag. Nowadays, we know very well spoilers can be used to reduce drag but it still does depend on the car, a speed record car probably won't benefit.

i see Matt, i click. i am a simple schnitzl.

I'm glad that i found your channel, i'm learning more about understanding things in general on the point where my default answer changed from "yes/no" to "Maybe, idk really, oh might aswell try ". Thank you 😂

Thanks for not conflating fast with quick. Traditionally of course, you just made your vehicle light, and put the most powerful possible engine in it. Aerodynamics was what you had to resort to when your car wasn't fast enough!

you'll love this story: My engineering teacher in flight school was once a part of a team designing a new kind of wing. it had a dip or groove of some kind in the middle of the beam that produced a laminar bubble. it would have let planes fly with much less drag. only one problem, which apparently took them years to find out. when it gets wet it stops working. and sometimes in real life, water falls from the sky.

Tamper throwing toddler takes tons of torque! Totally true! :D

This is pretty much the extent I remember from my one aerodynamics lesson at university 15 years ago. Now my 6 year old son is into drawing cars and keeps asking if this and that are aerodynamic, and I can only answer "yes, but not how you think." I'll have to show him this vid to confuse even more.

As hydro and aerodynamic engineer at marine industry, I could not agree more with you. Salesmen and managers keep demanding answers to issues that I just cannot give at conference room. "Why can't you promise that we'll have perfect wind shelter in the back seat of bow rider..." when the boat can move anything between 20 to 50 mph, can have wind from any direction, can have a trim of 1 to 4 degrees, people sitting there may be anything from 4 to 6 ft... Like open top vehicles' turbulent airflow was easy to manage even before.

I was thinking about the golf ball aerodynamics all along the video. Never saw the Mythbuster episode but I saw a research video on golf ball aerodynamics that compared even dimples vs random size and distribution of dimples. Very happy that you saw the question coming.

I love the baby and the panicked Kermit the Frog for unhappy airflow! (Former Aerodynamics Engineer here) I also love the MythBusters reference!

Tip for the Jag Add one of those luggage racks that you see on similar old cars , position it so that the top rail can hold what will effectively be a spoiler that will duct the air in the direction you want. You could just fit a spoiler but it would look out of place . A trick with aerodynamics is to get the turbulence that would normally cause drag to work for you by deliberately making in happen where it can do something useful like feed the engine or cause a low pressure area under the vehicle. The down force that causes the least drag is obtained by creating a low pressure area under the vehicle.

All hail the algorithm. John Britten ducted high pressure air from the front of his bike to the radiator under the seat for the max DP that he could get and he successfully used a radiator half the size that everyone else was. The drag reduction was impressive. I highly recommend reading what you can about his engineering methods. Also I highly recommend reading "Doing More With Less" by Paul Ciotti for the same reasons. Edit: The title of the book is actually "More with less: Paul MacCready and the Dream of Efficient Flight" ( ISBN-10:‎ 1893554902 )

The tire thing hit me hard. I went from 18x8 tires to 19x10.5/11 staggered on my mustang and my mpgs on trips from California to Texas went from 30.9 to 27.5 at 71mph

I am a huge fan of your channel, I just want to leave you some love. Thanks for making your videos incredibly entertaining and educational. It’s like a perfect balance with pacing and your presentation style is really fun. I really appreciate your work!

I'm really interested to see your real-world ram air test results! Great video, thank you.

Absolutely enjoy your channel and content. Thank you so much for sharing.

Very informational and I appreciate it and I had a good chuckle at your last diagram

An extremely interesting video. I have a friend who, after servicing his CBR, found that it would run perfectly at low speeds but lose all engine power above 80-100 km/h. After taking apart and cleaning the fuel system to no avail, he gave up. Some time later, he saw another stripped-down CBR somewhere, and noticed a piece of rubber that was missing on his bike. Turns out that without that piece of rubber, air that flowed into the fairing at the front at high speeds would affect the air pressure in the carbs or airbox. "Automotive aerodynamics is difficult because there are a lot of complex shapes and a lot of moving parts." -- This reminded me of a book on motorcycle engineering that I read once. That section boiled down to "we just don't know so pick a drag coefficient and roll with it". Cars are relatively predictable since the shape stays at least somewhat consistent, put a flailing human that makes up a quarter to a third of the total weight and all that goes out of the window. Since bikes don't have windows [citation neeeded], this is not an issue.

Your channel has the unique effect that even for the subjects that I'm not sure how much interest I have at the beginning, I always end up watching all of your videos through to the end, and I'm glad that I did. Feeling informed, with a smile. I know that I may be kidding myself, as I will probably forget most of the facts (and all of the numbers) in less than a day. But that's OK, because it is entertaining. 🧐😊

You are seriously gifted for presenting complicated concepts, understandably while entertaining.

One other trick to keep airflow attached is to blow pressurized air from a grid of small holes in the airfoil, that was popular for a while for aircraft flaps. The problem is that when the engine quits, the blown flaps quit with it leading to an extra problem on top of an already hairy situation.

What you said in the beginning about how the more you learn about aerodynamics the less certain you are about it seems to apply to a lot of engineering on account of the close relationship it has to physics. I noticed the same thing with electrical engineering. When you learn the engineering side of things, everything's all idealized and simplified so you can learn the basics. Then you get into the physics side of things and learn that everything you were taught under engineering was wrong and dumbed down and this is how it really works. Which is much less than idealized and as a result, a lot more complicated and more difficult to analyze accurately. I think this was actually one of the first things Feynman addressed in his lecture series. Sort of. That when you first start learning physics, everything's idealized and simplified until you understand the fundamental material, then you get into the real world stuff and learn that none of the math you learned is accurate at all and that no matter how hard you try, you can never get it perfectly accurate, anyways. But in most contexts, it's good enough. In others, you can always shoot for the highest precision reasonable.

ha ha at the end there you made me spit out my coffee , great stuff thank you for making incredibly complex stuff understandable on a sunday morning

🤣 Thanks for going over shapes and dimples. Very great content here. Aerodynamics are definitely complicated and very interesting!

I met a fighter pilot a few years ago and he said going through school to be able to fly his jet and I quote from the pilot “I learned enough aerodynamics to be dangerous” 🤣

I stuck for whole day on your videos! I love your sense of humor! Thanks for sharing all your incredible projects!

About the engine intake from the front : (a) some race teams tape over eg cooling ducts for qualifying laps because this reduces drag. I vaguely recall someone saying because it reduces effective wetted area, orthogonal to any change in airflow over the rest on the car (b) in a previous video you mentioned you thought there would be a be a gain despite the losses from the pipe back to the engine by just letting the inlet pressurise the entire inside of the car removing the need for the duct would have less losses. But viewed another way a much higher wetter area but much lower flow rate. So who knows. But it will cool the driver a bit and help fan the flames backwards if the engine catches fire. Testing. The opposite if the same question .. where will you dump the exhaust, out the side, top bottom or at the back ?

Yay ! Welcome back !

Awesome! Loved everything about this clip. Keep rockin’!

So much valuable insight in this. Thank you!

When using ram air induction remember to tune your engine to handle that extra air to get any benefit. You could also use a tool to monitor your engines computer (if it has one) and watch your manifold pressure to see if that goes up at speed to see if it’s working.

That closing image was epically hilarious

love how informative your videos are!

Amazing video all round, explanations, jokes, points made... liked it all

I designed a vehicle as per your specifications at @17:08, great design! However, I was cleaning it with a fine shammy the other day and all the sudden it started to leak turn signal fluid out of the front nosecone. Then it wouldn't start at all for like 30 minutes afterwards! Do you have any advice?

Gotta say... I don't know that I'd fully discount the aero work that was done 50 years ago. After all, they did produce the SR-71 and other extraordinary aircraft using that same imperical methodology.

ty for the upload n_n Always enjoy your videos. Wish there was more :D

Love your work 👍

Great video 👍 So would a shark skin texture finish on a vehicle be a good aerodynamic choice in regards to laminar flow ?

"Matt hasn't uploaded in a while" Google knows.

love this channel, thanks for the content/knowledge/humor

This is an all time great video. Fantastic information, well laid out, with one of the best outro cards I’ve ever seen 😂

There's a channel where the host takes 3d print designs from viewers and turns them into PC case cooling fans to see who can make the best. Someone did the golf ball dimple thing in the logic that it'd increase the airflow through the fan, but in the end all it seemed to do was disturb the air more than create better flow. My thought at the time was even if it did work the way Mythbusters _suggested_ it might, it'd just be disturbing the air as it spun or creating pockets of turbulence rather than pulling it through the fan blades. But I'm no rocket surgeon.

The more you know the less you know... Ahh classic Dunning Kruger effect 🤗 Algorithm 🙋‍♂️!

I just found your channel. Amazing content. Educational and Entertaining. You actually explain the science in the most understandable way. and I respect that you also do your own wrenching. Cheers!

Your channel is an amazing discovery! Thanks, algo. Subbed.

So, on your final shape drawing, do you think that shape is optimal when discussing the subject of water as well? What if it rains?

A month later... 💀💀💀

I have a good friend who has spent years as an aero engineer, and from our many, many beer fuelled chats I can say I'm very glad I don't work in the field. He talked about making a change to a splitter to increase front downforce, except it tilted the whole car downward at high speed, the ground effect sucked the front harder and exaggerated it, this meant the rear wing wasn't at an optimal angle and was slowing them down while providing less downforce than before while the rear diffuser became much less stable. So they reversed on the splitter, worked on Venturi tunnels and vents up front instead, which messed up the airflow over the top of the car and meant redesigning a lot of the wing shape as well as potentially screwing with body lines. So they fitted 10mm wider front tyres and left it all alone

2:33 "it all just trickles down bro" 16:50 This video is unironically really good, including exceptions nicely and explaining things in a way that makes you understand and the humour, sometimes subtle, sometimes not so much...

The wildest thing I learned about aerodynamics in the past year-ish is how unbelievably UN-aerodynamic motorcycles are. To a fucking bike, they're all worse than a full size truck from the 80's. This is why my KLR, while it had a favorable power/weight ratio for around-town hooliganery, flat out could not pass a car at 70 MPH.

This is my favorite RU-vid channel, every time I see a post I watch the whole thing right away, great stuff 👌👌

This is the first video i have watched from this channel and I'm already in live with it, damm your production quality is great

love to watch you videos ...one thing do ....THE JAG LOOKS SOOOOOO F GLORIOUS :))) love the shape and the presence

I love your signature at the end. Subscribed. All hail algorithm!

İ was just thinking yesterday about when you would have a new video and there you go !

Just came across your channel this morning, and wow! I really like your subject matter and how you present it.Interesting, different than the typical regurgitator, and very much a pleasant surprise (especially your venture into flooded Death Valley.)

I was thinking about dimples and myth busters the whole episode! It was satisfying to see it at the end. Excellent as always!

This video is remarkably good! Thx!

I could endlessly watch videos just like this one. I look forward to more like this. Especially the ones that educate people on how *little* they actually know.

Thanks for explaining the golf ball dimple thing. That helped.

Love the final design 😆 Thank you!

@3:43 those exhaust pulses hitting the ground is a cool shot!

The sides of NACA ducts are designed to generate vortices in order to draw in laminar flow from beyond the surface boundary layer, in the same way ram air ducts are often raised off the surface they are mounted to to get above the boundary layer. This means they should be sized and shaped to suit the application, boundary layer thickness etc. to work as intended (this is also true of ram ducts). They would still work otherwise, but not as well. They generate fairly good flow, with a little ram effect, but obviously much less than a proper ram duct. However, they generate less drag than a ram duct. Best choice depends on your application...

Aaaaaaand the ending got a subscribe from me. Great stuff, Matt, looking forward to more!

I have no university level training but several decades as a motorcycle mech involved in road racing then a career switch to aviation let's me have an opinion that ram air is of benefit at the speed your going to go ,and yes, your placement right on the nose is the sweet spot. Those other scoops you showed on the dorsal, hanging out in the breeze, are counter productive. The intake cross section does not need to be as big as you would imagine and the plenum size at the engine seemed to be agreed as at least 10 times engine swept volume. Cannot remember where the plenum data was published.

Educating and entertaining. Loving it

If you like aerodynamic physics controversy, look no further than DDWFTTW. It's effing amazing and I love it. A "sail" vehicle going directly downwind, on wind power, but way faster than the wind. Also works directly upwind, like 2x wind speed, upwind, so 3x wind speed sortof. Downwind, 3x wind speed with 2x air speed.

Awesome work mate

The engineers of your 1950's Jaguar knew a LOT about aerodynamics and drag, they did the C and D types, after all, using only scale wind tunnels and visual observations

Recent subscriber here. Loving this content. It tickles my brain.

I will forever see turbulent flow represented as Kermit the frog now. All CFD modeling and analysis should have it, I like it.

I really enjoy your delivery.

That silence after the "wing it" joke got me! 😂😂😂 cheers for the in depth info 🤙