Carbon sideskirt extensions
- Thread starter dubsesd
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dubsesd said:
aero kicks in at about 180km/h. Looks great!Has anyone got a real flat undergrad? I keep spotting fabulous ground aero on Porsches and Lotus and am wondering how to get about it.
ChawenHalo said:
Aerodynamics operates at all speeds and not just at any specific speed and is proportional to the square of the velocity of the car relative to the air through which it moves. The formula is P = rho x v^2 where P is the pressure, rho is the density of the fluid and v the velocity of the body.
The OEM air intake operates on exactly the same principle of an increased pressure of the charge relative to the speed of the vehicle and it happens at all speeds.
exdos said:ChawenHalo said:
Aerodynamics operates at all speeds and not just at any specific speed and is proportional to the square of the velocity of the car relative to the air through which it moves. The formula is P = rho x v^2 where P is the pressure, rho is the density of the fluid and v the velocity of the body.
The OEM air intake operates on exactly the same principle of an increased pressure of the charge relative to the speed of the vehicle and it happens at all speeds.
For downforce to properly operate (as opposed to overall aero dynamics you're talking about) on a roadcar around corners yes it does, unless the 2 DTM engineers I spoke to 3 months ago are wrong...
ChawenHalo said:exdos said:ChawenHalo said:
Aerodynamics operates at all speeds and not just at any specific speed and is proportional to the square of the velocity of the car relative to the air through which it moves. The formula is P = rho x v^2 where P is the pressure, rho is the density of the fluid and v the velocity of the body.
The OEM air intake operates on exactly the same principle of an increased pressure of the charge relative to the speed of the vehicle and it happens at all speeds.
For downforce to properly operate (as opposed to overall aero dynamics you're talking about) on a roadcar around corners yes it does, unless the 2 DTM engineers I spoke to 3 months ago are wrong...
So how do microlight aircraft manage to fly (i.e. lift) at around 65km/h, if aero only kicks in at about 180km/h as you suggest? Are you saying the formula I've quoted does not apply to both lift and downforce?
exdos said:ChawenHalo said:exdos said:Aerodynamics operates at all speeds and not just at any specific speed and is proportional to the square of the velocity of the car relative to the air through which it moves. The formula is P = rho x v^2 where P is the pressure, rho is the density of the fluid and v the velocity of the body.
The OEM air intake operates on exactly the same principle of an increased pressure of the charge relative to the speed of the vehicle and it happens at all speeds.
For downforce to properly operate (as opposed to overall aero dynamics you're talking about) on a roadcar around corners yes it does, unless the 2 DTM engineers I spoke to 3 months ago are wrong...
So how do microlight aircraft manage to fly (i.e. lift) at around 65km/h, if aero only kicks in at about 180km/h as you suggest? Are you saying the formula I've quoted does not apply to both lift and downforce?
Ohhhh.... Nice analogy !!
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I'm afraid Exdos is right (as usual)...It's basic fluid dynamics 
As a med student I used the same formula when investigating the mechanical effect of the increased tenacity of pulmonary secretions in patients with cystic fibrosis. Essentially, the harder you cough the more your car will weigh 
As a med student I used the same formula when investigating the mechanical effect of the increased tenacity of pulmonary secretions in patients with cystic fibrosis. Essentially, the harder you cough the more your car will weigh [/quote]aero kicks in at about 180km/h. Looks great!
Aerodynamics operates at all speeds and not just at any specific speed and is proportional to the square of the velocity of the car relative to the air through which it moves. The formula is P = rho x v^2 where P is the pressure, rho is the density of the fluid and v the velocity of the body.
The OEM air intake operates on exactly the same principle of an increased pressure of the charge relative to the speed of the vehicle and it happens at all speeds.
For downforce to properly operate (as opposed to overall aero dynamics you're talking about) on a roadcar around corners yes it does, unless the 2 DTM engineers I spoke to 3 months ago are wrong...
So how do microlight aircraft manage to fly (i.e. lift) at around 65km/h, if aero only kicks in at about 180km/h as you suggest? Are you saying the formula I've quoted does not apply to both lift and downforce?
Ohhhh.... Nice analogy !!
Sent from my iPhone using Tapatalk
Different aero calculation required for flight as the lift also takes into account the wings surface area and angle of attack into play and wings vary in shapes and sizes, hence things can fly at all speeds. The above formula is a basic calculation for expressing variation in pressure / air density with regards to velocity, this is commonly used for speed measurement devices such as pitot tubes on aircraft as there is more air density variation with altitude.
The ground effect argument for the skirts on cars is more complex as if you treat the car as an odd shape wing, we'd have to see how the skirts affect the overall lift coefficient of the car/wing and at which speed increased negative lift or downforce is obtained. As our cars are not completely flat underneath I wouldn't expect a massive difference... But then you'd need to book a session in the mclaren wind tunnel to find out
I think I can say with a fair bit of confidence that unless you were travelling bloody quickly any side skirts that size will have two-thirds of f*[k all difference to 'aero'. Hardly a microlight scale of surface area is it.
They are also probably not attached directly to the chassis but to the original side skirts so any 'lift' or 'downforce' created will probably just bend the side skirts slightly. Also being fairly close to the wheels there will be some turbulence here (although less than at the top of the wheel) which means downforce or lift would be created inefficiently if at all.
Visually I think they look well made and well fitted, and don't look out of place. Not my cup of tea though.
They are also probably not attached directly to the chassis but to the original side skirts so any 'lift' or 'downforce' created will probably just bend the side skirts slightly. Also being fairly close to the wheels there will be some turbulence here (although less than at the top of the wheel) which means downforce or lift would be created inefficiently if at all.
Visually I think they look well made and well fitted, and don't look out of place. Not my cup of tea though.
Sae said:
Obviously the shape, surface area, angle of attack affect flight (and downforce creation), but that's a digression. The basic point that I am making is that the aerodynamic effects do not suddenly get switched on at 180kmh as ChawenHalo suggests, it is a progressive and exponential effect as the graph below shows, where a doubling in speed increases the pressure on the body by fourfold.
Yep I concur with that exdos... unless dubsesd has added active hydraulics to deploy skirt extensions at 180kph
Interestingly the new 458 mad version has interesting side skirt extension with vertical winglet - will try to post pic - but the fezza will probs have full integrated undertray/diffuser arrangement but interesting on the winglet touch as winglets on planes add lift, so not sure what the objective is on that... Does look good though
http://www.autoevolution.com/news-g...eciale-breaks-cover-photo-gallery/141095.html
Interestingly the new 458 mad version has interesting side skirt extension with vertical winglet - will try to post pic - but the fezza will probs have full integrated undertray/diffuser arrangement but interesting on the winglet touch as winglets on planes add lift, so not sure what the objective is on that... Does look good though
http://www.autoevolution.com/news-g...eciale-breaks-cover-photo-gallery/141095.html
Sae said:
Those winglets look like they are an external version of the "air curtain" seen in the BMW 1M http://www.bimmerfile.com/2010/12/13/the-1ms-air-curtain-in-detail/