Aero Design

[Steve H]

My school has never even looked at an aero design in the past and I would like to do some basic design work to determine the effectiveness for our team and if it is something worth pursuing in future years. I have no idea where to start and was hoping someone familiar with aero could point me in the direction of a good reference book. I'm hoping for something that is more application based than theory, in other words, something I can wrap my head around without too much of a struggle. I need to learn just about everything, starting with developing design metrics through to implementation. I found "New Directions in Race Car Aerodynamics: Designing for Speed (Engineering and Performance)" by Joseph Katz and it looks pretty good. Has anyone read it?

[JulianH]

Hi Steve,

the book from Katz is really a good starting point to begin with Aero but for a FSAE car, I think the best thing is just try and error.

If Aero helps you (and how much Aero you need) is answered with a lap time simulation.

There are a lot of papers (on FSAE cars and on simple wings / diffusers) that might help you in your design. Just use Google Scholar and jump from paper to paper.

Regards,

Julian

[onemaniac]

http://www.optimumg.com/software/optimumlap/

Try the link. It's a lap simulation software (free) by Optimum G.

[Kevin Hayward]

Steve,

It is not very hard to make a set of wings (or other aero devices) especially if their purpose is for validation and testing. Just wire cut some profiles out of foam, wrap in fibreglass, smooth them a little (not as important as you may think for a FSAE car) and mount them to the car. End plates can be a simple as plywood, or if you have access a bit of aluminium honeycomb panel. No need to go crazy with the first set of wings that you test. You will have a lot to learn about manufacturing, mounting and tuning the car with aero that will mean the first aero package wont be ideal.

You will find that the lap time simulation will tell you a certain amount of info, but it will not give you the complete answer. Virtually all lap time simulations will tell you a "perfect lap" this is where the driver has no influence. Aero packages have a large impact on the way a car drives and will impact the drivers confidence. It also allows you to do things that you cant do easily on a non-aero car.

For example you have an option to run a mechanically oversteering car with a rearwards COP to bring in understeer at speed. This can be used to your advantage on FSAE tracks.

Simulation and calculations should certainly be a part of your decision, but do not get caught over-simulating and under-testing.

Kev

[Rex Chan]

I started with the Monash SAE papers, the 2 books (Katz and McBeath).

However, the best thing to do is start emailing people who are doing it in FSAE, as I found many people were willing to chat about how they do things.

In practice, manufacture and mounting were the biggest problems. And the damn front wing scraping. And getting the wings level. Just remember you're hanging a lot of mass off the car.

[Steve H]

Thanks for the replies! I think I'll go ahead and order the Katz book and I'll definitely look at some papers. I doubt our team will have the resources to actually use anything that I design but I'm interested in learning the basics of aero design so I might as well use the opportunity. Out of curiosity, any idea how much weight a full aero package typically adds? Our car is already pretty heavy this year (figuring on something like 500 lbs w/o driver).

[Kevin Hayward]

If you do a big wing package with wrapped foam expect anywhere from 13 to 20kg without a floor. Floors can start weighing quite a bit. I have seen well built floors weighing 20kg or more.

My take is unless the car is built to get the absolute best out of a floor I would start with big wings to get an idea of what you are dealing with ... definitely for the first test.

Kev

[JulianH]

As Kev stated, it depends on the size of your package.

If I remember correctly the small wings of Karlsruhe 2012 weigh about 8kg, our 2012 package (with floor) weighs 11,5kg. Monash is probably in the 25kg region...

But you can get a lot of performance due to these kilos http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Tim.Wright]

Originally posted by JulianH:
As Kev stated, it depends on the size of your package.


Hehe...

[AndrewTC]

Try Competition Car Downforce by McBeath. Excellent introductory book with many real world examples.

[AlexL]

Julian,
after Austria our second, bigger wings were about 7kg, including all bolts, wires etc.

Alex