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Old 03-03-2018, 04:39 PM   #61 (permalink)
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Concave as well as convex?

I can see that eventually you get into filleting and interference drag, but I see an overall similarity to Luigi Colani's work.

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Old 03-03-2018, 04:42 PM   #62 (permalink)
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similarity

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Concave as well as convex?

I can see that eventually you get into filleting and interference drag, but I see an overall similarity to Luigi Colani's work.
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Old 03-06-2018, 03:13 PM   #63 (permalink)
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Raising the tail is fine, you actually should follow the line of zero lift, which will appear to be negative angle of attack. If you dont do this you will have some interesting times at highway speeds in the proximity trucks (FOR INSTANCE) driving either way.

Zero lift can be drawn at the chord, taking the halfway point of the mean aerodynamic chord, and drawing a line to the trailing edge.

But I would also suggest chopping the latter part off as these boat tails seem excessive in length and impractical on the road
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Old 03-06-2018, 03:29 PM   #64 (permalink)
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Quote:
Zero lift can be drawn at the chord, taking the halfway point of the mean aerodynamic chord, and drawing a line to the trailing edge.
Does this produce a datum line or the actual angle of attack?


Choose your tolerance for pain.
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Old 03-06-2018, 03:34 PM   #65 (permalink)
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Quote:
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Does this produce a datum line or the actual angle of attack?


Choose your tolerance for pain.
yes
but what you needed in the first place is a straighter roof with more bottom camber, then the line lifts at the tail to what appears to be negative lift (by AoA). Symmetric foils will not get you where you want to be

Last edited by sidecar; 03-08-2018 at 10:06 PM.. Reason: correcting a mistake
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Old 03-06-2018, 04:07 PM   #66 (permalink)
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On the aerocivic I worked up a design(not built yet) to address the non-optimal bottom angle of my boattail without damaging the underside on steep angled approaches. I would have a frame piano hinged at the bottom front of the boattail going out at the proper boattail angle. This frame would have compression spring's at the back end allowing it to move upward and then recover when making contact withe a steep surface. There would be two small castering wheels on the back underside that make contact with the road surface. The sides of this lowered boattail extension would be hinged to allow upward movement of the boattail.
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Old 03-06-2018, 05:58 PM   #67 (permalink)
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I drew something like that, but with the piano hinge at the top edge.Even that left the lower fron
t to scrape the ground.
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Old 03-06-2018, 06:32 PM   #68 (permalink)
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I put the hinge line 6-8" above the bottom. It isn't posed correctly, but there are arms outside the hinge-line:




This is to reconcile the curved valance and the straight hinge-line. The leading edge moves down and forward to match up to the diffuser.

Also I would consider an hinged and extended diffuser with skegs that have skateboard wheels on their tips (else titanium skids for sparks) that retracts up into a half-circular tail ala Morelli. Per 'D' at Permalink #44.
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Old 03-08-2018, 05:18 PM   #69 (permalink)
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Found this surfing though the Random Wind Tunnel thread (page 14).
Random Wind Tunnel and Smoke Pictures Thread
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Originally Posted by kach22i View Post

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Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
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