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Old 09-10-2018, 10:37 AM   #1 (permalink)
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If The Profile Is Good For Depasrture Angle...

Could a double ended profile be better for approach angle?

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Old 09-10-2018, 10:43 AM   #2 (permalink)
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As I understand it, the pressure build up at the nose enhances air attachment on the latter half.

If the pressure is not built up at the bow, it may not cling in the aft sections, and then it becomes detached, and therefore causes turbulence - right?

Good questions.

I think this has been reviewed before, but I'm blurry on the answer - sorry that I cannot be more definitive.

Your influencing factors:

1. Speed

2. Angle of attack (cross winds and turns)

3. Deceleration including abrupt braking.

The optimum shape might be influenced by one of the above or all of the above, don't you think?

Also the center of mass could be a weighted factor....haha, but seriously.

EDIT:

I once posted on aircraft canopy shapes (blisters) after some images Aerohead posted. That thread may contain more information, look it up.
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Old 09-12-2018, 10:39 AM   #3 (permalink)
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double-end

Quote:
Originally Posted by Angel And The Wolf View Post
Could a double ended profile be better for approach angle?
The short answer is no.The template has the shortest low-drag nose which also respects SAE approach geometry.
Also,the template is at the 'sweet-spot',in the 'bucket' of the drag curve,with respect to surface drag and pressure drag.
If the body is any longer,or any shorter,the drag will be higher.
The other thing about the double-ended form is forward visibility.The windshield angle is so extreme,that we suffer light refraction through it,and internal reflections below it,such that you can't see out of the car.Hucho makes special mention of this problem in his text.
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Old 09-12-2018, 06:40 PM   #4 (permalink)
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Quote:
That thread may contain more information, look it up.
Challenge accepted:

https://ecomodder.com/forum/showthre...rag-28206.html
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Old 09-13-2018, 10:21 AM   #5 (permalink)
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Quote:
Originally Posted by freebeard View Post
Thank you for finding it, that was a good thread.

Brings to mind a new question though; when a car is lowered so much and chin spoilered so much that it almost behaves like a surface blister, does the pressure wave change enough to warrant an optimized shape change?

That is to say, the lower you go, the more slope you need at the front?

index


And in the same vein of thought; the higher you go the more important it is to curve the chin inward and not have an abrupt splitter-like "cut-off" that could cause turbulence below it.

Or are these two different phenomena?
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Old 09-13-2018, 11:53 AM   #6 (permalink)
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Quote:
Or are these two different phenomena?
[shrug] One is above the stagnation point, the other below.

Quote:
Originally Posted by OP
Could a double ended profile be better for approach angle?
This becomes true at transonic air speed.
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Old 09-14-2018, 05:40 PM   #7 (permalink)
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Quote:
Originally Posted by Angel And The Wolf View Post
Could a double ended profile be better for approach angle?
I can see the symmetrical center profile lifting at speed.

As for the windshield, do away with all windows, put a pair of video cameras on a three axis swivel in a bubble atop the roof, and wear stereoscopic display Glasses. The cameras move with the driver's head.
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Old 09-14-2018, 05:55 PM   #8 (permalink)
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To what point? [no pun]. The space in those pointy ends isn't really as usable as a blunter end.
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Old 09-14-2018, 06:06 PM   #9 (permalink)
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To the end of lowering CD
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Old 09-14-2018, 10:09 PM   #10 (permalink)
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What is the point of lowering the Cd? Top speed? Moving a volume of space through free air? Moving a volume of space down a traffic lane? Moving pianos or marbles?

Bragging rights?

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