AERODYNAMICS FOR CARS

[sarusa]

The tear drop and or the reversed tear drop has been widely accepted as an ideal starting point. For an aerodynamic shape.

A rain drop for example has a rounded front and tapered tail, this being the ideal shape for the least resistance for that mass at that speed.
place the same droplet on say table that offers some resistance and apply wind pressure to it and it will gradually form, temporarily to that
rounded front tapered tail shape and as the speed of the wind increases it will gradually change to a reversed shape.

The speed at which this reversed shape becomes the preferable aerodynamic ideal depends on speed, with side issues.
A classic example is a yacht,where the shape is pitted against the greater resistance, water, as against air. So the reversed shape
becomes necessary at a much lower speed. look at the water line on a racing yacht.

In cars the reverse shape becomes a useful issue to a lesser degree at lower speeds but a benefit at higher speeds and highway speeds.
revers tear drop or often refered to as wedge. Not many knife edged cars around!

Reason for this outburst is. I came across a variety of bits and pieces about the merits of putting the round end forward, as in one case where they were going to change a 928 Porsche front to rear to check which is better. My guess! Yes marginal at lower speeds, at high speeds wrong!

[bumblebee]

It was done on mythbusters

[Mooman]

You don't even need a full teardrop shape to get full benefit, look up Kammback which is a car with a flat tail like a GT-40.

https://en.wikipedia.org/wiki/Kammback

[sarusa]

Yes it was also known as a cam rear end. the error was that they didn't reverse the tear drop. Finally evolving to the wedge.
Pushing on to speeds well beyond practicality for road or even race cars, the tapered rear comes back into contention, ie: Land speed records. Then go beyond to sub sonic and supersonic speeds and straight lines and angles come into contention.

Before it becomes a contentious point. An aircraft's wing, an aerofoil, appears to be close to a longitudinal tear drop split in half length wise.
This is to do with lift rather then just aerodynamics as such. Used on some rear spoilers upside down to help down force.

[Quismiff]

Then you start getting into this territory sarusa,


along with the way the evox/ralliart bonnet is designed, the front slots vent hot air up over the windscreen/fenders from the radiator, the rear one pushes air over the back of the motor, not only for cooling, but to prevent the dead spot of air movement behind the block and it runs down over the exhaust and joins the under car slip stream, vortex generators, stabilise air flow over rear wings, but only at high speeds. most cars while not the perfect aerodynamic shape, are incredibly aero efficient compared to say a holden kingswood, or chevy bel air at the same speeds. But that is mainly down to technological advances, and understanding of the mathematics behind it.

A lot of the tear drop aerodynamics that you talk about are only when you are reaching terminal velocity, the maximum theoretical speed an object can achieve, and you want to push it a bit further. For humans falling to earth that is approximately 120mph? or is it kph? It all has to do with wind resistance and friction. the surface area of an object vs density of air vs speed and it goes on and on and on... you could fill a black board with the co efficient calculations.

On your yacht analogy, a yacht will only go as fast as the wavelength it produces which is related to waterline length, so a boat that increases its waterline length on a heel will sail faster than a yacht sailing bolt upright with a shorter waterline length, unless you get into foiling like the latest round of the americas cup, then you take these calculations, and throw them out the window...

[powermad]

Two really random posts from this poster over 15 months. Nothing else. search.php?author_id=10061&sr=posts

Can anyone explain? Trying to fool search engines? Posted by a bot?

[Quismiff]

Judging by the signature being a furniture one, I'd put money on it. At the very least it is spam