Wyatt, I know you mean well, but I cannot understand what you're trying to say. You talk about zero pressure, which would imply a vacuum, and negative pressure like it is somehow less than a vacuum. Are there relationships maybe you're trying to convey?
Then you make it sound as if you will get just as good of a result by not following the template curve and just making whatever looks like it may work for an aft body. You throw around angles like flat surfaces will suffice without any real need to transition into them. These are not backed up by any logical reasoning.
Yes, putting something in to fill the space will help. But will it optimize flow? No.
I only say following the rules of the template will optimize what we want to achieve. In this thread I am trying to explain how I see it actually working. I have never been one to take things at face value, I want to understand how and why it works like it does.
I guess one of my main points, and lines of reason, is that to move an airdrop up 3-7 feet in the air (13ft for slowmover), it takes energy, actual work. If some of this energy is not returned to the vehicle, than our fuel mileage would always be crap. What mechanism could there be for returning the energy? This is how I came up with this idea of pressure pushing us along. The answers I came up with support why the Aero Template works.
Skin drag, is btw, essentially a non-issue for cars, it really applies to laminar flow systems, which car bodies are not, and only would make up a small difference in the overall drag created by going faster. Also since a car with or without aeromods will have about the same skin area, the drag would be equal. It has been brought up before, and has always been seen as a non-factor.
I still say that the density of the air, and air pressure are 2 very different things when a moving vehicle is discussed. In all the equations I see, the velocity is squared over density which is not. So twice the speed change and twice the density will yield much lower pressures. We more than double velocities all the time, so pressure drop will always win. I don't even really think the air density increases by more than 40% even under the most extreme condition, so it isn't thought of as much of a factor, yet I say it is the density change across the length of the car that I think is the mechanism for returning the energy.
If you want to make some point, please explain it logically, tell us why you think the way you do. If you can't explain it, then I have a hard time lending any credibility to your theories. You tell me I'm wrong about the pressure, but offer no real reasoned alternative theory of your own to tell me how it does work. Read the paragraph you wrote above again and try to make bullet points out of what you are trying to say, and then explain each one. I know I have done this in the past, and then I never post anything because I realize, I don't have it really figured out well enough to offer a good alternative. Several times I wanted to tell Aerohead he was nuts, well you know, like bad nuts....we all know he's nuts....but I mean like, nuts and stupid, not the nuts and brilliant I now know he is.
You say several things which imply that the template is only good for a full boat tail, this as far as I know has never been put out, and in fact, truncating the template shape will yield the best result for a shorter body length. Aerohead quantified these returns in this thread here, I refer to it often. It is a saved favorite bookmark.
Aero Drag Reduction Quantified
So, the template is a tool to be used to get the best performance out of a given modification. Will other things work, Certainly. Are they optimum, certainly not.