Of course, it’s an unproven theory, but I suspect that I am the "graduate student" that Mr "Blue" Ahlstrom wrote about in the following post.
Yes, Graham, you are the graduate student I referred to. I did not use your name to avoid a public confrontation, and you are welcome to contact me at my e-mail address or by PM; both of which you have access to since you have registered on this site. I am only too happy to keep a dispute of technical theory private until someone challenges me in public. Having exposed me to public criticism, you are now vulnerable to the same. BTW, I publish too, am a guest lecturer, and write my own code; you could've found this out with a proper search. This doesn't make my work (or yours) any more valid, it just means that it passed technical review and is worthy of discussion.
You were far from the worst example of "help" that was offered to us. By far the worst was someone claiming to have the "secret" of using electromagnetic vehicle and exhaust plume charging to create a "gravity well" and an over-unity effect. Your work stays within the limits of the second law of thermodynamics and was worth consideration. I reviewed your e-mail to Craig, you never contacted me, so I do not understand where this "avoidance of contact" idea comes from. In your e-mail, you
postulated that your research with un-validated CFD "proved" that "shock waves" lifted the back of Sonic Arrow and caused the 1996 roll. You were
specific in your insistence that your TBD "test" would "prove" your theories.
This is the basis for my dismissal of your attitude and work.
Whether or not you have accurately modeled transonic and low-supersonic objects and vehicles in intimate ground effect of a porous and plastic surface is not apparent from your research. What is apparent is the following:
1. No known CFD solver has been validated for ground effect.
2. You are one of the few researchers exploring intimate the science of ground effect on transonic and low supersonic objects.
3. Your work does not account for decay of shock reflection via a variable density, variable porosity, and variable structure surface (welcome to playa, a VERY non-linear group of effects). In addition, the explosive disassembly of the surface by the shock requires the surface ejecta to be included as significant to the model.
4. Your work does not account for the detailed mechanical and aerodynamic features of TSSC and Sonic Arrow 96. For example, rolling tires, local surface alpha, suspension deflection, gross vehicle alpha (controlled vs. actual), louvers and negative Cmu on TSSC, aft separation and its effects on transition to terminal shock and stagnation, etc. These are major, not minor effects for shock formation and decay, as well as all pitching moment, stability and control effects. FYI, no models or drawings exist of SA-'96. The die cast model is ~95% accurate for SA-'97 and less than 60% accurate for Fossett LSR-'08.
5. At the speed of the 1996 roll, the car was only traveling at 675 mph, or ~M.89 for the temperature. The leading edge sweep of the struts is 75 degrees and would not create a compression wave until M3.8! Yes, the root interface and the un-sweep at the strut to wheel fairing interface would create a shock, but Breedlove had cambered the leading edge down so that the lower surface achieved a negative alpha so no shock was present between the interface and the ground. This increased the strength of the the upper surface shock. Tehrefore, there is a downforce based roll component, but not a lifting force based roll component. Did you account for any of this?
6. Like many proponents of the flat-bottom cars (I'm not saying you're one), you made no distinction in your e-mail between blunt-fat vehicles like TSSC and high fineness ratio vehicles like Sonic Arrow. Strength of a compression wave is proportional to the first and second order of displacement: max cross section and fineness ratio. This is linear wave drag theory that I am sure you are familiar with.
It is for these and other reasons that Dr. Hal Ahlstrom and myself believe that CFD is not useful in this instance. In fact, it is detrimental, in that it will create a vast volume of questionable data that will probably lead in the wrong direction due to its volume. A better course would have been to ask us if we could add some aerodynamic sensing to our data collection along with detailed 3D vehicle coordinates so that you could validate your modeling with our data. As you embark on your career in aerodynamics, try to remember that it's not real until it's tested.
Don't guess, TEST!and this doesn't mean CFD.