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Old 01-27-2013, 05:02 PM   #452 (permalink)
Vekke
Mechanical engineer
 
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Join Date: Jan 2009
Location: Kitee (Finland)
Posts: 1,272

Siitin - '98 Seat Cordoba Vario
90 day: 58.56 mpg (US)

VW Lupo 3L --> 2L - '00 VolksWagen Lupo 3L
Diesel
90 day: 104.94 mpg (US)

A8 luxury fuel sipper - '97 Audi A8 1.2 TDI 6 speed manual
90 day: 64.64 mpg (US)

Audi A4B6 Avant Niistäjä - '02 Audi A4b6 1.9tdi 96kW 3L
90 day: 54.57 mpg (US)

Tourekki - '04 VW Touareg 2.5TDI R5 6 speed manual
90 day: 32.98 mpg (US)

A2 1.4TDI - '03 Audi A2 1.4 TDI
90 day: 45.68 mpg (US)

A2 1.4 LPG - '02 Audi A2 1.4 (75hp)
90 day: 24.67 mpg (US)
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Quote:
Originally Posted by aerohead View Post
Your concern for crosswind stability is something which has attracted attention since the 1920s.
Depending upon the position of a cars center of gravity,and center of pressure,gusts and crosswinds could destabilize a car at speed.
Professor Kamm was obsessed with stability,and his last project,around 1966,was with a DKW sedan which he modified to a K-form roofline.Kamm added his signature dual,split-fin stabilizers (Egyptian round-hulled sailing ships used these 'steering-rudders' 4,500 years ago) to guarantee crosswind stability.
Ten years after Kamm's DKW,Professor Morelli determined that Jaray's downward sloping nose,rounded fenders,and Von Mises' reflexed-camber tail could easily mitigate any crosswind funny business.
General Motors Research Labs ascertained that in the United States,we experience an annual mean-averaged 7-mph crosswind condition during driving.
On My trip to Bonneville last September,I drove through a storm front in the Texas panhandle which killed a family of five.I maintained 70 mph through 50 mph crosswind unabated until I got into Santa Rosa ,New Mexico that night.Sure,at times it was 'busy',but at no time did I feel endangered.No one else kept up with me.
My opinion is that a boat tail is zero liability.
I have noticed in my lupo 3L that it more unstable at highspeeds 80-100mph in crosswinds with 800mm long kammback spoiler. On slower speeds no problems whatsoever. My car is light about 900 kg with driver and small. Without the spoiler the car goes like in tracks but with the spoiler I have to make small corrections every now and then specially in open sections and bridges etc. Its nothing that you cannot correct at least in 100mph speeds if you have done some rallying but you need to be more alert on windy days.

Just to give more info I will chop my lupo roof according to the template .
https://www.facebook.com/photo.php?f...type=3&theater

So just to be sure is that template assembled correctly?

Now that means that I will lose about 72mm total height and I need to cut about 122mm from the back to get correct angle for the roof. So I will cut the a pillar corners and tilt the whole roof from there downward...
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Vesa Tiainen innovation engineer and automotive enthusiast
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