Starting Teardrop At Nose?

[Jenn348]

I'm wondering if it would work to start the teardrop shape early on the car, at the nose, by redirecting air flow upward at the nose. That way, the teardrop would be formed in the front, and a shorter, more reasonable boat tail could be formed in the back.

Thoughts?

[Ecky]

You could lower the coefficient of drag that way, yes, but total drag is equal to coefficient of drag * frontal area, or CdA. So, by increasing "A" to lower "Cd", you might actually increase overall drag. Generally, aero mods that increase frontal area are to be avoided.

Edit: the flip side to that is that if you can make productive use of all of that extra area, it could be close to "free" aerodynamically.

[kach22i]

Originally Posted by Jenn348

Attachment 22367

I'm wondering if it would work to start the teardrop shape early on the car, at the nose, by redirecting air flow upward at the nose. That way, the teardrop would be formed in the front, and a shorter, more reasonable boat tail could be formed in the back.

Thoughts?

Blank sheet design or modifying an existing vehicle?

I posted a few ideas on modifying an old Pontiac TransVan from the 1980's.

I left links in the thread, but the images do not show up on the page because Photobucket sucks.

http://ecomodder.com/forum/showthrea...t-34980-3.html

If you do a Google image search "Transvan kach22i" you might see a few of the thumbnails.

[freebeard]

Here's a study I did:



It doesn't consider sight-lines and refraction. It might be worth considering the roof edges as blisters on the actual Template.

[aerohead]

Originally Posted by Jenn348

Attachment 22367

I'm wondering if it would work to start the teardrop shape early on the car, at the nose, by redirecting air flow upward at the nose. That way, the teardrop would be formed in the front, and a shorter, more reasonable boat tail could be formed in the back.

Thoughts?

In plan-view,The Schl'o'rwagen begins it's taper with the first few feet of the body and comes in at Cd 0.186.
The original 1987 GM/AeroVironment Impact began it's plan-taper in the middle of the door.
The conventional wisdom for early low drag bodies was,follow the fast pelagic fishes and marine mammals.Make the largest cross-section of the body within the first 33% of the body,then use the rest of the 66% for the aft-body pressure recovery.
Cambridge University's CUER,Cd 0.11 solar racer is a good recent example.
To modifying an existing vehicle would be limited to a body-on-frame type,discarding the entire body,narrowing the rear axle,then building a body to enclose it based upon a streamline body.
You'd be looking at many years of fabrication.Millions of dollars if you had to pay someone to do it.

[freebeard]

Here's an example where the template shape starts at the cowl. The front fenders are their own Template shape blended into the overall body.

And an example that uses a reverse tricycle layout, and flat glass to reduce refraction and lensing in the windshield: