Quote:
Originally Posted by winkosmosis
My point is that the shape used in those overlays appears to be arbitrary.
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Copy- Pro will be closed this weekend for the 4th of July celebration,so it will be the following weekend before I can post any new images.Without Hucho's book,it's probably counter-productive to discuss the "template." Without a handle on "ground-reflection" or "mirroring" it will be impossible for anyone in the aero forum to grasp the premise of the template.----------- I will venture that there is nothing arbitrary about it.Once everyone gets a look at their own car on top of a mirror,they'll immediately see how really "blunt" their car appears to the air.------------- Due to ground-reflection,and respecting that a 2.5:1 teardrop body of revolution has the lowest drag of any form investigated,it will become obvious to everyone,that to achieve the lowest drag in ground-effect,a vehicle would have to be 5-times as long,as it is tall ( including it's ground clearance).This IS Hucho speaking.You can ignore me,I'll just play messenger.---------------- Since the 2.5:1 teardrop has the lowest drag,and especially no separation whatsoever in it's all-important aft-body,when it is represented in ground-effect,it has no peer as an example of ideal aerodynamic low-drag form,bar none.---------- Anything "faster" will suffer separation and higher profile drag.Anything "slower" and it will suffer increased skin-friction and consequently higher drag.---------------------- The reason it is chosen is because it works.Any contemporary automobile (save some vans and SUVs) has undergone most of the mods CAR and DRIVER came up with in 1974.You would have expected that.And modern automobiles do not have separation at their fore-bodies.The challenge remains in the automobiles wake.And to do the full meal deal,as Darin says,a full 66% of a car's body must be "aftbody",in order to provide the gentle deceleration ramp necessary to allow the air to come to rest,losing all "motion",and without turbulence.That's all streamlining is.-------------- And it's worth repeating.The path used to displace the air,must be at least two-times longer in order for it to regain it's static pressure,re-assuming the position it had before your vehicle disturbed it.------------------------ The template provides a no-brainer architecture to follow in creating aft-body mods.It's a go-no-go if you will.If you're above or below the line,you mod at your own peril.No one is obligated to use it.And please,if there is one of you that can develop something easier to use that's risk-free,go for it! ------------------------- I'll get the images up in a week and a half.In the meantime,if you like,take a gander at the back of a every commercial jet which flies over.Look at the back of every nuclear submarine.Look at the back of every fast torpedo.Goodyear Blimp.FUJI Blimp.Met Life Blimp.Orca.Bottlenose Dolphin.------------------------ Not arbitrary.