How to achieve downforce at normal road speeds - no wing needed! Note that my most recent aero book (replacing the one shown in this video) can be found here - www.amazon.com/Vehicle-Aerody... or Amazon in your country.
You run the gold standard of youtube channels. Well-presented knowledge and demonstrable experience, no fluff, no annoying advertisements, no music, and great audience engagement. Thank you.
Yes I can do that some time, but you can be basically certain that the car develops no downforce in standard form. It's normally pretty ugly underneath.
Hi Julian, Great video as usual. The book is really good too, I bought it for my brother as a present. Anyway, it would be great if you could answer a few questions below: Did you have the same measurement referenced to the uncovered underside? Did you calculate from the spring rates how much downforce such compression would equate to? How does the difference in the damping rate for compression and rebound effect the ride height while going over uneven roads? (Explanation for the question, if the damping rate is higher on rebound it takes longer for the suspension to reach the equilibrium height for rebound then for compression. So if the frequency of the bumps is high enough the suspension will start to squat. This effect is should not show up until a threshold frequency of bumps is reached be very close to linear effect with the speed once the threshold frequency of bumps was reached.) Thank you again!
I cover the development of the Insight's undertray in detail in my book 'Modifying the Aerodynamics of Your Road Car' (pages 188 - 192). As described there, ride height dropped with the fitment of the undertrays, with no change in damper settings. Above and below car centreline pressures are shown in detail in my book 'Car Aerodynamic testing for Road and Track 2nd edition' on page 30. I didn't accurately measure undercar pressures before fitting the undertrays.
Thanks good video. I have to get under my car in a few days before I'm trying to figure out how to attach the underbody flat floor. I have a 6mm sheet of alumalite I'll use.
You can use rivnuts (captive nuts) inserted into holes in the floor. You may also need to make a steel frame to hold it in place, as I did on the rear undertray on the Honda.
Just curious what the weight of your rear panel with steel bars weighs? I'm still working on my middle panels using T6061 .063 flat sheets with cutout in the middle for exhaust. Just looking for the stiffest, lightest material I can get my hands on. Love your videos. Using them now in building my panels
To your knowledge, is it true that if the undertray bends slightly down convex/concave at the front wheel section the lift will be reduced even more. Do you have a video on undertray bends at front end or anywhere else???
If it smoothly bends downwards then up, yes lift will be reduced. Covered in my book - www.amazon.com/Modifying-Aerodynamics-Your-Road-SpeedPro/dp/1787112837 And no need to guess - just measure the pressures.
@@JulianEdgar Well... It does. A live rear axle car has a drive shaft, differential, and straigh axle pieces (as well as at least two longitudinal suspension elements and a horizontal rear one) that undulate up and down, taking up a relatively large area under the car towards the rear. Not only will the tray need cutouts for these, but their movement and existence will break up flow a lot, and from what I can fathom, worst case scenario, will create parachuting instead of a diffuser effect on anything rearward of the front of the rear tires.
Yes, sorry, I thought you were commenting on my most recent video, where reducing rear lift was all done working on the top surface of the car. I don't think an undertray of the sort described in this video can be easily done on a car with a live rear axle. Plenty that can be done on the upper surfaces of the car, though.
@@JulianEdgar Well... I don't technically have a car, I have a regular cab short bed pickup truck. And, personally, I'm not to keen on adding an aero-capper or any kind of kammeback device. It already has a soft tonneau cover, and I might consider trading that for a traditional capper, but that's about it. My primary goal would be to massively decrease drag, and increase downforce across the whole truck without adding back to the drag. Hence why I'm looking at your undertray videos. At the bare minimum I want 0 lift at any point. Truck is my primary transportation, but I do like to have fun on a backroad here and there. I'm going to be lowering it for aesthetic and handling purposes and likely doing other perfomance modifications like a turbocharger and stronger brakes in the future. It's a 2009 Ford Ranger, so it _is_ light and small enough to be fun and suitable for these purposes. But I know there's more to performance than just stopping and going, so I'm looking to get ahead of the game when it comes to optimization before I even get started.
