Who was “ amateur aerodynamics?”

[Phase]

I’m tempted to enter next year. Even without a full boat tail. He only got 69 mpg and they won’t even let you go above 55mph during the event. I get in the 80s for mpg when going 55 steady state lol

[M_a_t_t]

I thought about it as well, but it's quite a drive. Even farther for you.

[Phase]

Yeah super far for me lol. But I’ve done plenty of east coast road trips. Would be a fun and interesting trip. New York State is pretty ( not as pretty as Oregon though lol)

[Vman455]

Apologies for not replying here sooner. I haven't had much interest the last few months in commenting on this forum, but I've been checking in from time to time to see what's going on. And it's always just what I expect. Today it looks like we have someone misreading a Green Car Reports article and attributing the Lucid Air's drag coefficient to the new Prius (and others drawing conclusions from that without bothering to check the source and verify that it's true or not), yet another claim that aerodynamics is so complicated that you're better off just following a template, and a grossly oversimplified claim of the relationship between drag coefficient and base area. *sigh*

Yes, Amateur Aerodynamics is my site. You all are free to comment there or even send me a message--it's right there in the sidebar menu--so I'm not sure how you think I'm commenting without facing "the pointy arrows of the public's feedback." But whatever; the reason I don't comment here anymore (and end up venting a lot of my frustrations on my own site) is because the community here is so insular and believes such weird things that just about any attempt at non-conformity is met with unproductive personal attacks. That's why aerohead refrained from commenting on this thread beyond his cryptic posts; he devolves into ad hominem attacks far too easily and is probably afraid he'll be banned. Again. You've successfully built this forum into your own echo chamber, aerohead, so comment away.

As far as my ego: I am not a professional aerodynamicist. It's right there in the name. I have an associates degree in engineering, and I am currently applying for a bachelor's program in aerospace engineering, but I don't have experience in a wind tunnel or aero lab (although I will if I get into this program, which is one reason I decided to apply to it). I haven't misrepresented myself on my site; you can read about how I got here and what my experience is under the "About" tab. What I do have are an extensive and up-to-date library on car aerodynamics and a lot of experience now testing things on my cars in the real world, and I conclude many of my posts by encouraging readers to do the same: read, test, measure things, figure out how to see what you're looking for, learn something. Don't believe me, or Julian, or aerohead, or a textbook. You don't have to! If you read something that sounds outlandish, verify it for yourself. If you're wondering what a modification to your car will do, design a test that will show you. If you try a test technique and it fails, figure out how you can improve it or be critical and honest with yourself about what you may not have done well enough the first time and try it again (for example, I had to attempt throttle-stop testing several times before I was able to figure out what to do to get consistent results that I could actually trust). As Julian said here quite often, and which very few of you appear to have taken to heart: I don't have a monopoly on testing.


Tested this last week.


A few weeks ago; I was very wrong in my predictions about what these changes would do.


Earlier this summer.


Coming up, once it stops snowing here.

I expect I won't come back here. There's no point; if you all want to learn, the resources are out there, and trying to have any reasonable discourse here just turns into shouting at a wall of inanity. If I get into this aerospace program, I won't have time to write much anyway, and I might shut my website down then--so, if you find something useful (I think "Practical Guidelines," "Tuft Testing," and "Measuring Aerodynamic Pressures" are the three I would choose--well, those and the pipe organ voicing post, since that's a subject only a handful of people know anything about and I thought I explained it pretty well), please copy it and save it for future reference. And most important, go test! Buy some cheap equipment and measure pressures, get your cellphone camera or a GoPro or a friend and tuft test your car, figure out how to measure changes in drag (just this month, Julian and I have talked about two new techniques that may allow measurement of drag changes on hybrids and EVs. You may be able to come up with your own, and if you do please share it).

I'll end by quoting Sovran's concluding address at the 1976 GM conference on aerodynamics. I think it's very relevant:

"We have explored the heretofore distinct possibility that answers to some of the key questions about the three-dimensional flow fields of road vehicles lie, for the taking, in the vast bluff body literature on simple, aeronautical and architectural configurations. Is it possible that the knowhow already exists and all that is necessary is to pose the proper questions to the right people? I think it is now clear that this is not the case. We might have hoped for better, but at least we can check off that possibility and get on with the specifically directed research that is required" (Aerodynamic Drag Mechanisms of Bluff Bodies and Road Vehicles [1978], 370).

That research is ongoing, and you can join in.

[freebeard]

...trying to have any reasonable discourse here just turns into shouting at a wall of inanity.

Why are you picking on Xist?

I see Ecomodder as a refuge. Once you are shouting, you've lost the high ground.

[aerohead]

* '[T]he drag of the ( Cd 0.09 ) basic body ( of revolution ) is achievable. To what extent this can be approached in the development of a production vehicle is therefore more a question of the balance of the requirements of the specification, than of technical feasibility.' Hucho, page-209, 2nd-Ed, 1987.
* 'lower values ( below Cd 0.30 ) are possible. Whether or not they are feasible for any particular car is more a question of consistency with the vehicle's design concept than it is of aerodynamic capability.' Hucho & Sovran, Annual Reviews Fluid Mechanics, 1993, page 531.
* 'The greatest potential for aerodynamic improvement is at the rear.' Dr. Teddy Woll, Mercedes-Benz, 2014, ATZ Online.
* ' The main contributions to the drag force originate from the rear part of the body.' Hucho, page-61, 2nd-Ed.
* 'The wake flow generated by a blunt ended cars typically causes more than one-third of their aerodynamic drag.' Adrian Gaylard, PhD thesis, page-2.
* '[I]t is very important to design a rear body surface which brings the divided streamlines smoothly together.' Hucho, page-61, 2nd-Ed.
* ' Optimum shapes are 'streamlined bodies having a very slender rear part.' Hucho, page-61, 2nd-Ed.
* ' The perfect aerodynamic shape is a teardrop.' Dr. Teddy Woll.
* ' The design of a perfectly aerodynamic car would need to head in this ( teardrop ) direction.' Dr. Teddy Woll.
* '[T]he optimum shape in terms of drag is a half-body, which forms a complete ( streamline ) body of revolution together with its mirror image- produced through reflection from the roadway.' Hucho, page-15, 2nd-Ed.
* ' A long and tapering rear is still good for the vehicle's aerodynamics.' Dr. Teddy Woll, Mercedes-Benz Group ( the new A-Class ), 2018.
* ' Steep tapering... is limited as the resulting flow separation increases air drag.' Hucho. page-282, 2nd-Ed.
* ' flow separation should be avoided all together.' Goro Tamai, The Leading Edge, page 11.
* Recovery of the pressure... can be achieved with boat-tailing.' Hucho, page- 144, 2nd-Ed.
* ' As a result of (a) bent roof, the flow is exposed to a deceleration that further increases the static pressure at the back.... Simultaneously, the influence of the ( base ) pressure was reduced by the downsized effective vertical area at the rear end. The result is a significantly lower air resistance force...'. Mario Hirz & Severin Stadler, Graz University of Technology, Variable trailer design drastically cuts aerodynamic drag.' SAE Technical Paper 2013-01-2414, 11- February-2014.
* ' the drag reduction from an elongated tail varies almost linearly with the reduction in cross section area.' Jeff Howell et al., SAE Paper 2020-01-0673.
* ' It is remarkable, however, how little data is available on the effects of streamlined tails on non-axisymmetric bodies, whether representative of road vehicles or not.' Jeff Howell, et al.

[aerohead]

I 'went by' your school today and took a look at the curriculum.
Looks like it will be the 1st semester of your third year when you'll get incompressible flow Fluid Mechanics. That's good!
Presently, their using Munson, Young, and Okiishi's, 'FUNDAMENTALS OF FLUID MECHANICS, by Andrew L. Gerhart et al., 9th-Edition, Wiley, ISBN: 978-1-1195-8 as their class textbook.
Currently unavailable at the UIUC bookstore ( available on Amazon, $ 129.55 ).
The 7th-Edition is available online in it's entirety for free.
I scanned the book, and anything automotive related didn't begin until page-511.
Page- 527 begins dedicated auto-related material, however I didn't notice any material that would 'move the dial' as far as new material. Hope the latest edition expands on this when you get to it.
Your school has done some research on 'motorsports aerodynamics' in the past, but there wasn't any specifics about it at the Aerospace Engineering website.
-------------------------------------------------------------------------------------
The school's largest sub-sonic wind tunnel at the Aerodynamics Research Laboratory ( which you'll have a class at in your 4th year ) is 2.8-feet height, by 4.0-feet width, with a test section length of 8-feet. It's 150-hp, MACH 0.2, with 160 measurement ports, and a wake rake with 52-ports. They say it's primarily for airfoils and wings, at 2-D flow.
You'll get some free electives your senior year, maybe they'll let you do some small automotive work.
You will have access to world class CFD.

[Vman455]

Originally Posted by aerohead

I 'went by' your school today and took a look at the curriculum.
Looks like it will be the 1st semester of your third year when you'll get incompressible flow Fluid Mechanics. That's good!
Presently, their using Munson, Young, and Okiishi's, 'FUNDAMENTALS OF FLUID MECHANICS, by Andrew L. Gerhart et al., 9th-Edition, Wiley, ISBN: 978-1-1195-8 as their class textbook.
Currently unavailable at the UIUC bookstore ( available on Amazon, $ 129.55 ).
The 7th-Edition is available online in it's entirety for free.
I scanned the book, and anything automotive related didn't begin until page-511.
Page- 527 begins dedicated auto-related material, however I didn't notice any material that would 'move the dial' as far as new material. Hope the latest edition expands on this when you get to it.
Your school has done some research on 'motorsports aerodynamics' in the past, but there wasn't any specifics about it at the Aerospace Engineering website.
-------------------------------------------------------------------------------------
The school's largest sub-sonic wind tunnel at the Aerodynamics Research Laboratory ( which you'll have a class at in your 4th year ) is 2.8-feet height, by 4.0-feet width, with a test section length of 8-feet. It's 150-hp, MACH 0.2, with 160 measurement ports, and a wake rake with 52-ports. They say it's primarily for airfoils and wings, at 2-D flow.
You'll get some free electives your senior year, maybe they'll let you do some small automotive work.
You will have access to world class CFD.

Why do you presume I'm entering as a first-year?

UIUC has several student motorsports teams for which aerodynamics is a primary focus, including a solar car, Supermileage car, Shell Ecomarathon car, and Formula SAE. The aerospace curriculum includes incompressible flows, compressible flows, viscous flows and heat transfer, aeroelasticity, computational aerodynamics, and applied aerodynamics. I'm excited for the opportunity to get as much hands-on experience as I can to complement and expand on what I've already been doing on my own.

[freebeard]

Why do you presume I'm entering as a first-year?

Have, or will you, confirm or deny?

[aerohead]

Originally Posted by Vman455

Why do you presume I'm entering as a first-year?

UIUC has several student motorsports teams for which aerodynamics is a primary focus, including a solar car, Supermileage car, Shell Ecomarathon car, and Formula SAE. The aerospace curriculum includes incompressible flows, compressible flows, viscous flows and heat transfer, aeroelasticity, computational aerodynamics, and applied aerodynamics. I'm excited for the opportunity to get as much hands-on experience as I can to complement and expand on what I've already been doing on my own.

That's good to hear. You've easily got enough time in for a master's. Seems like cutting you at least a two - year break or somethin' would be considerate.
--------------------------------------------------------------------------------------
That's really funny about solar, Supermileage, SHELL, and SAE.
The website mentions 'motorsports' as if it were just a footnote, from some previous, random research. I would think that the department might play that up their automotive activities some. The only reason I ever went to school was to learn about automotive-related engineering. 'Solar' didn't even exist until seven years after I graduated.
--------------------------------------------------------------------------------------
* As far as car stuff is concerned, I would think that the 'incompressible' flow regime fluids would be the most applicable, unless you're gonna get into transonic speeds.
* Viscous flows, ditto, 'cause that's what we drive in.
* Computational aerodynamics is ( has been ) the future. Love it!
* Applied aero, especially if they get off into automotive material.
-------------------------------------------------------------------------------------
All of it sounds great.