Low cost car aerodynamic testing
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- Опубліковано 14 жов 2024
- The testing you can do on the road or track to develop undertrays, wings, spoilers, wheel covers, air curtains, splitters, diffusers - and so on. Accurate, easy and cheap - and it can be done on any road or track.
Dear fellow enthusiasts: his book is cheaper than that dubious carbon fibre lip a company you’ve never heard of sells for your car.
It’ll last longer too. Just get it, I know, you’re all “is this just an add, can it be that good, can’t I figure it out from the videos?”
Get the book.
Thank you!
I don't know boss, attaching a book to a front bumper doesn't seem like a good idea
I was ready to buy about $1000 worth of chassis braces then you appeared on my feed and stopped me before costly needles mods that at best would have only marginally increased the speed at which the same handling characteristics would have happened with less margin for error and correction. Thank you.
You can still buy them, it's just that it is almost certain that money is better spent elsewhere.
@JulianEdgar my first book will be your aero book. My car is fairly well balanced by itself, but tends to power understeer. Lift off brake oversteer and has a considerable amount of lift at higher speeds.
I've done some tuft testing with a cheap action camera and some yarn. I made a camera rig from PVC pipe, to film the tufts while I drive. Less than $100 US altogether, and you get video footage to watch and analyze all you want.
First off. Thank you for this video. It helped me a lot. I have plenty of Dirt and snowy roads. So will be doing that for sure. And will defiantly look at the Magnehelic setup for finding out how to get more air out of the engine bay on my 1971 Buick GS.
What's up! Nice too see you here. I deffinetly like the way Julian explains, and provides testable expiraments.
Very interesting video, thanks for that, I'm looking for your books now. What do you think about diy flow-vis ?
I think tufts are much better.
Loving the book by the way.:)
Hey Julian, enjoying your videos. Let's say you're done prototyping and testing some aero mods and want to build them out to look more finished. Would 3D printing be viable?
For smaller items, maybe.
Hey Sir! You have great archive here! Wish I could buy some of your books, yet they're impossible to buy from Iran directly! Even though I am United Nations employee, on and off for 8 years now!
Yet, I hope we could benefit of'em very soon!
If there's a postage service, you can buy them direct from me. But it will be expensive for freight.
Hi Julian, it would be great with a link to the book, preferably as an e-book.
No e-book is available. Hard copy - www.amazon.com/Vehicle-Aerodynamics-Modification-Development-alternative/dp/B0C87VYVL8 or Amazon in your country
@@JulianEdgar Please consider publishing as an e-book, I am probably not the only potential buyer that only buys e-books to avoid the unnecessary cleanup of my office/house with piles of paper :)
And I don’t live in the US, oversea shipping fees would be very expensive
Would checking throttle position (from the ECU) to maintain a given speed be a good way to track changes in drag? If holding 75 mph takes less throttle then there must be less drag, right?
Yes but I find maintaining a fixed throttle opening and measuring changes in speed works better. But needs to be done ultra carefully and with comparisons made in the same session.
@@JulianEdgar Oh, huh. Interesting. Any theories on why that works better? Seems like maintaining specific throttle would be tougher than specific speed. If it's a streetable car, you could even have cruise control maintain speed extra steadily while logging throttle position over time. Just a shower thought on my part though. I yield to your experience.
I imagine because the inertia of the car is such that car speed at a fixed throttle opening gives a smoothed result, whereas to maintain a speed, the throttle is constantly being juggled - especially under cruise control.
Cruise control would be a bad choice, because it constantly adjusts throttle position. Your throttle position data would be all over the place. Any differences between one test and another would probably get lost in the noise.
The fixed throttle position would be more workable, but would need a long section of straight level road with little traffic.
@@JulianEdgar Ahhh that does make sense. Basically smoothing the value aerodynamically rather than mathematically like you'd have to with a throttle position plot. Thanks for the info!
8:00 What units are those in? I'd imagine kPa over Pa given how small Pascals are, but I suppose it depends on the speed?
Pascals.
Sorry, maybe I missed it, but what’s the actual method for measuring drag? Engine load?
Constant load, varying speeds.
Ok, I guess as simple as a block under the throttle on the same road then! Thanks
Yeah, but with a few more subtleties in testing technique.
Hi Julian! I'm making a front grill to (hopefully) increase air flow on the radiator - would measuring the temperature rasing time difference be accurate enough measurement? (I'm planing on ducting the air all the way out behind the wheels but for right now the duct will end on the radiator). Nice information as aways btw!
No. Why measure a secondary effect when you can so easily measure the primary? It will be far faster and, I'd suggest, more accurate to measure pressures.
@@JulianEdgar Thanks! Im working on acquiring the necessary hardware for it
Dont they spray some water based color that washes off with water on racing cars some how and watch the pattern it forms after laps?
Yes, but I have never had any success in doing it on the road. Also, from the pics I have seen, much harder to accurately interpret than tufting.
Cyclist will get meltdowns at 14:07
Yes, people calculating Cd values to three decimal places from coast-downs is one of the absurdities of aero misinformation. (At least, not without a huge number of runs, some very sophisticated modelling of rolling inertias, and use of a yaw based anemometer probe.)
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