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Old 11-09-2010, 10:03 AM   #11 (permalink)
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The leading edge flap pic was just a simple instance of an extending part to create a desired aero profile. Imagine a b-segment/micromini vehicle with a deployable/extendable tail structures. Ever decreasing and getting smaller urban cars still need better aero (longer) for more efficient highspeed use. The McLaren T-25 tall but very short dimensions may benefit a folding 'baby cup' Kamm or boattail winglets. I could imagine a junkyard hack using power sunroof/moonroof mechanicals for this exercise...

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Old 01-23-2011, 12:10 PM   #12 (permalink)
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Here is concept vehicle using the devices that I was talking about in my first post. :
Shape-Shifting Hybrids - The Vauxhall Flextreme Hits 125 MPH While Getting 175 MPG (VIDEO)

QUOTE " The most surprising thing about the Vauxhall Flextreme is the fact that it shape-shifts at certain speeds. When the car goes above 30 MPH a vertical panel extends along the body and behind the wheels to make the car have more drag co-efficient."

( I see a typo there ... that should say LESS drag )

This is a low quality video of the car. Note what the announcer says about how the back end extends at speed :


Here is a much better view of the same car.
Note the use of clear inserts in the wheels between the spokes and the plugged grille up front.
Also, note the use of small cameras where the mirrors would be. They didn't talk about the shape shifting abilities of the car, but it's a good view of the car never the less.



Why is it that Opel ( a division of GM ) makes such beautiful streamlined designs, while we here in the U.S. are handed asymmetrical bricks on wheels ?
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Old 01-23-2011, 12:40 PM   #13 (permalink)
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So - back to my original question. How do you guys think that we as a group could come up with something similar ?
Imagine an extention on rails that you could control from inside the vehicle with a servo.
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Old 01-23-2011, 12:57 PM   #14 (permalink)
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Here is a another video that has some exceptional CG animation and audio.
It seems to show the extensions at 1:37
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Old 01-24-2011, 04:46 PM   #15 (permalink)
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Rear flaps/wings?

Hope it is not sarcosanct to speculate on Murray's impeccable engineering projects, but I've used his T.27 as a the basis of the extending wing surfaces/flaps (or shape shifter?). The ever shortening/tall dims for urban packaged vehicles does not have good aero properties @ higher speeds. Thus the extending Kamm-wing is an alternative solution. In a speculative design, there is a low profile roof package attached between roof rails. The extension movements are very similar to sunroof mechanicals but it extends rearward & behind the rear top quarters and then additional side 'winglets' deploy. Many 'hardtop' convertibles have engineered multiple powered hinges & panels deploy cleanly & consistently. This extended Kamm-wing could be an optional OEM part or easily added as an aftermarket part.

...had to clean up the sides too.
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Old 01-24-2011, 07:24 PM   #16 (permalink)
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I just knew you would come up with something clever like that Botsapper.
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Old 01-25-2011, 05:27 PM   #17 (permalink)
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extension

Quote:
Originally Posted by Cd View Post
So - back to my original question. How do you guys think that we as a group could come up with something similar ?
Imagine an extention on rails that you could control from inside the vehicle with a servo.
I'd be thinking safety first in the event that the car was rear-ended.You don't want to impale the car behind you.Motorcyclists?
After that I'd re-visit the Fachsenfeld/Kamm work at FKFS in the 1930s with 'extensible' aerodynamics as Hucho opined about in his section on buses and commercial vehicles.
Build to exacting aero proportions up to the truncation of the body,then continue it with an extensible structure,most likely an inflated envelope for open highway driving.
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Supercars,driven flat out on the Autobahn have drag built in as a compromise to safety.You might imagine 200-mph on wet pavement between Frankfurt and Munchen! So they're a special case requiring special considerations not encountered in the 'real' world.
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If you would like to see a mechanism,ideal for an extensible structure ( inside the envelope ) you might have a look under the dashboard of a Beechcraft Bonanza aircraft.You'll be looking for the control yoke elevator mechanism.It's absolutely exquisite! The only hitch,is that it must self-destruct upon collision.
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Old 01-25-2011, 05:55 PM   #18 (permalink)
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Agree w/ safety issues. The proposal has exaggerated extended dims. I see any Kamm-wing construction would have to be ablative, probably made of 'soft' polyurethane foam/thin clear polycarbonate sheets.
There are already plenty of large rigid/metal rear spoilers @ the cutting edge of any motorcyclist's misfortune.
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Old 02-03-2023, 02:13 PM   #19 (permalink)
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Waking this thread up from the dead to say the concept is one I tested recently.
It works !

Using drawer slides, I was able to create a compact boattail that slides into itself for driving in traffic and parking.

I hope others can get some use out of the idea.
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Old 02-03-2023, 03:24 PM   #20 (permalink)
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The retractable boat tail I designed for the VW Type II had a hinged floor instead of a sliding top; but same idea.

Also:


i.pinimg.com/originals/a3/62/32/a36232042df9bdd82157af5a68c48991.jpg

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