Quote:
Originally Posted by JulianEdgar
I quoted in my Veloce book some tests carried out by a major magazine using an "unnamed aerodynamicist in an unnamed wind tunnel". From what you've said since it appears those tests were done in one of the tiny wind tunnels. Had I known that, I wouldn't have put the material in the book!
Easy - car manufactures and professional race teams don't build enormous wind tunnels with moving floors because they like spending money. If a tiny wind tunnel and a fixed floor would do, they'd be using them. They don't.
|
1) It's given, that 'tiny' wind tunnels will generate perfectly acceptable data for streamlined cars, at zero-yaw, with the condition that a blockage correction factor ,from a large wind tunnel is provided.
2) The Toyota Prius provides the large tunnel blockage correction factor. We have Cds from Toyota, A2, and DARKO for that specific car.
3) Professional race teams wouldn't necessarily be germane to ecomodding.
4) For a couple of decades, the USEPA has required cross-wind-averaged Cds from automakers, from which they can set proper loads on the dynamometers used by Mobile Sources to establish compliance with federal emissions standards.
5) Market demand for higher profile vehicles such as SUVs and pickups has changed the degree by which vehicle wheels are 'integrated' into vehicles ( or not ), making wheel drag an issue, whereas before these vehicles existed was not really on he radar.
6) Obama-era CAFE standards drove aerodynamics, of which they've now been rolled back under the present administration.
7) The cost of the tunnel is passed onto the consumer, and is a complete tax write-off, so it really doesn't hurt the bottom line.
8) Are they 'better'? Only re-testing of earlier vehicles, with and without the rolling road is the only way to quantify that one. Some of MIRA's testing showed that in some circumstances, drag due to stationary vs rotating wheels are a 'wash.'
9) Gene Haas Racing offers a rolling road tunnel to all comers. $ 4,000 / hour. DARKO, @ $500 / hour was all I could absorb.