Dean
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| posted on 14/7/05 at 05:15 AM |
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HP VS Aero
Can hp over come the aerodinamic flaws of the locost. Could a locost ever reach 170+ ?
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silex
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| posted on 14/7/05 at 06:57 AM |
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Yes is the short answer (in theory) - but you probably wouldn't want too. In standard trim the car would become quite skittish and you would
probably turn your cycle wings into ear warmers.
Keeping the car on the floor is your concern, but with enough power you could push a 7 style body that fast.
Murphy's 2 laws
1. If it can go wrong it will
2. In case of emergency - refer to rule 1.
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Hellfire
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| posted on 14/7/05 at 07:08 AM |
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You could always put a Merlin engine in. Bags of HP don't thinkit'd be too much fun though...
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smart51
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| posted on 14/7/05 at 08:01 AM |
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the amount of power required to go at any given speed is, simplistically, divided in to two parts: aerodynamics and rolling resistance. All you need
to overcome these is power. this is the american way. the other thing that you can do is make your car lighter and more aerodynamic.
power required at the wheel to overcome rolling resistance
P = SQR( mph ) x F where F is a factor for the weight of the car and the stickiness of the tyres
Power required at the wheel to overcome aerodynamics
P = mph x mph x Cd x m2 x 0.0085
Cd is the coefficient of drag (to do with the shape of the car) an m2 is the cross sectional area of the car.
Baically, the 7 has a Cd twice as high as a good car. this means that twice as much power is needed to overcome aerodynamics. Basically, if you
replaced the bodywork on your seven for something good, the top speed would go up a lot. Except on my car where the gearing limits the top speed.
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scoobyis2cool
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| posted on 14/7/05 at 09:08 AM |
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Although the Cd of a 7 is about twice that of a normal road car, the frontal area is about half, so when you multiply them together you actually end
up with an overall drag value pretty similar to a road car.
Pete
It's not that I'm lazy, it's that I just don't care...
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Bob C
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| posted on 14/7/05 at 11:24 AM |
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I beleive it's more extreme than suggested above, aerodynamic DRAG is proportional to speed squared so power required to overcome that drag is
proportional to speed CUBED.
extra power needed to take top speed from 150mph to 200mph is x2.37
Bob
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smart51
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| posted on 14/7/05 at 12:05 PM |
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quote:
Originally posted by Bob C
I beleive it's more extreme than suggested above, aerodynamic DRAG is proportional to speed squared so power required to overcome that drag is
proportional to speed CUBED.
Having worked throguh this, you are right. The drag in Newtons is proportional to speed squared. Work done = force times distance. As you are
traveling more distance at higher speed then power = speed cubed. Blimey.
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smart51
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| posted on 14/7/05 at 12:35 PM |
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a quick bit of typing into excel gives horsepower vs speed for a typical BEC
MPH BHP BHP for aerodynamic car
100 75 50
110 97 65
120 124 82
130 155 102
140 192 126
150 233 153
so if your car makes 125 BHP and you want to go 20 MPH faster, either make your car more aerodynamic or get another 70 horse power!
[Edited on 14-7-2005 by smart51]
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