Quote:
Originally Posted by JulianEdgar
You keep talking about wing profiles having the ability to develop zero lift at certain angles of attack. That's fine - there's plenty of data that shows that. Trouble is, it's another of your argument red herrings.
For example, let's give The Template a negative 5.6 degree angle of attack (as you nominate for the Clark Y) and then let's add a suitable underfloor profile (red).
I'd be pretty confident that lift would now be waaaay down. Trouble is, it's also now a completely different shape... |
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* Finally, after a year or so, you publicly announce that all wings are capable of zero-lift. This is real progress. Thank you!
* I've provided the underbody profile. It's basically flat until the long, 2.8-degree diffuser completes the belly. The rest of what you see is the wheel fairing package. SAE 'approach', breakover', and 'departure' angle limits for a passenger vehicles are respected.
* As to a car-width 'wing section' for an automobile, this was tested by Kamm at FKFS and returned Cd 0.21 as a lange-heck.
* Adding tumblehome reduced the drag to Cd 0.1764.
* Adding body camber and boat-tailing produced Cd0.1481.
* And the long diffuser takes it to Cd 0.1231 ( Template car measured Cd 0.1201 with crappy wheel fairings ).
* In front elevation, the 'template' car approximates a semicircle in cross-section. There isn't a flat surface on the car anywhere. It's all compound surfaces.
* A couple of 'wingtips' joined together would be a more accurate characterization of the form. It's a streamline half-body.
* The sides mirror the top contour.
* Pressures alongside are very close to up above.
* There is no vorticity.
* Boat-tailing creates continuous cross-sectional contraction and surface area reduction, all the way to essentially zero, over the latter 2/3rds of body length. That doesn't make for a very good 'wing.'
* Passive pressure acting over the aft-body would be at the highest positive values observable.
* Active suspension and reduced ground clearance offers opportunities.
* Active suspension offers body inclination opportunities.
* The tail can be 'deployable' as with Hucho's Figure 8.63.
* Static wheel loading due to travel weight may make the whole 'lift' issue a non-starter.
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As a piece of crap, Spirit is quite stable at 108- mph. In crosswind, exposed ,on an elevated interstate highway. With wind tunnel tuning I would venture that it could perform any 'normal' driving functions without drama.