Question on designing Wing on Solidworks (or any CAD)

[Heisenberg]

Hey guys,

I'd like to know if anyone can share their experiences in designing a wing. Being in charge of the aero component of my formula student team, I was wondering if designs go something like this: Put a wing on a car via solidworks, and then generate airflow. Certain parameters on the wing (i.e. the curvature?), can be changed and the setting that allows the car to produce the most amount of downforce is calculated.

If not, can anyone suggest an overview anyways? Anything would be appreciated

Sorry if this sounds like a silly question, but nobody else in my group has had good amount aero experience and I really want to learn what I can do to make it work.

Cheers,
Luke

[Lycoming]

How are you going to make it? How will you mount it? Do you care about drag? Or is downforce the only relevant design parameter? Do you intend to design your own foils, or use stock profiles like the NACA series?

It sounds to me like you need to learn more about aerodynamics before you dive into this. I would start with Racecar Aerodynamics by Katz.

[Tim.Wright]

First step, forget solidworks... Designs don't start in solidworks, or Catia, or ProE. This is a typical student mentality. The design process for a wing is the same as any other part on the car:

First you need some targets. e.g. some idea of your downforce and drag targets, weight targets etc (any aero element has a weight limit above which it is using more grip to push itself around than it actually generates from downforce)..

Then you need to choose a suitable concept: i.e. which profile shape, number of elements, interaction with the body + tyres.

Then you can start in Solidworks with your models and CFD and whatever...

If you really are in charge of the aero group, you also need to make your other guys do the same. If you all jump into solidworks and CFD from the start, you are guaranteed to come up with a complete design that just doesn't work because the rear wing guy designed for max downforce, the front wing guy designed for min drag and the body guy designed for max cooling...

[Heisenberg]

Thanks for the replies guys.

I have read the aero book by katz, and in the process of reviewing it so I fully understand it. So, maybe I'll make sure I make the review one of my priorities.

Tim.Wright, that looks like a good mentality to have for the R&D of the aero. But, to get the downforce and drag targets etc., I would need to first test the schematic in solidworks anyways wouldn't I?

As for profile shapes, are their schematics of wings posted somewhere which I can make adjustments off of? Or do I typically start from scratch after knowing what my goals are?

Thanks again, I hope to get a step towards the right direction,
Luke

[Tim.Wright]

See, if you didn't mention that you are doing formula student I'd have said nothing more. But ffs man, you are supposed be be an engineer, not a CAD operator, so I'll bite.

Tim.Wright, that looks like a good mentality to have for the R&D of the aero. But, to get the downforce and drag targets etc., I would need to first test the schematic in solidworks anyways wouldn't I?

No, again, forget Solidworks... What I said is not an R&D process, its an engineering design process valid for every part on the car. What I'm trying to point out is that "engineering" something does not start and end with making pretty shapes in Solidworks. You can train a monkey to do that. P.S. your downforce and drag targets have nothing to do with the wing shapes. The come from the tyres, the engine power, cooling requirements and the handling/stability of the car.

If you you have no idea of what downforce, drag, weight, rules, manufacturing or other constraints there are on your system then you are not an engineer... you're just playing games. If you don't have the info above, then find it.
Talk to your VD guys, ask them about the tyres.
Don't have any VD guys? Then estimate the cooefficient of friction of the tyres yourself using track data and use that to figure out the performance sensitivity to downforce.
Find out what the current balance of the car is before you start messing about with the tyre forces. 2 tons of downforce are no good to any body if its all on the front axle.
How is the car operating noe in terms of stability? Is the aero kit going to help or hinder this? Might you need to trade off some overall downforce in order to get better stability?
Have you talked to the powertrain guys to see what kind of power output they can give you? since your work will be basically undoing theirs if you have no idea on an acceptable level of drag.
Do you know what kind of heat rejection power you need your cooling ducts to be capable of providing?

This is the engineering bit. The calculations, the discussions, the ideas, the compromises. This all needs to be known before you can start a single sketch in Solidworks. Contrary to what you said, if all you want to do is draw in Solidworks and make CFD plots, that is an R&D project which is of very little use to actually building a fast car.

I hope this gives some perspective...

[Lycoming]

People designed wings for years for both cars and aircraft without the use of solidworks. And there was nothing wrong with the way they did things. Oh, and if you want to dive down the rabbit hole that is CFD, make sure you know what you're getting into.

[munudeges]

Get out a trusty pencil and paper and think through what you are doing first.

Alas, I have seen too many people throw stuff into CFD applications expecting to get some kind of meaningful result, as if by magic. Unfortunately, I've seen a Formula 1 team operate like that. No prizes for guessing that they have fallen a long way down the grid.

[flynfrog]

I found this book useful

http://www.amazon.com/Competition-Car-A ... 0857330071

To echo what Tim said you need to look at the complete system of the car. How much unused HP can be burnt up pushing wings around. Can you afford to limit your top speed if you can make it up in the corner.


For airfoils you can start here

http://www.amazon.com/Theory-Wing-Secti ... g+sections

One other thing to keep in mind is construction techniques. I am a big fan of wetlay over foam for FSAE. You can hot wire cut and layup a wing in a matter of hours. Its possible to go from CAD to car in one day with this method. For the all important testing.


look up drop boom hot wire cutters. You can build a variable power supply with a battery charger and a dimmer switch.


To address your original question. wings are pretty easy to draw in SW. But I would look at doing some 2D sims in ansys or star SD you can easily eat up a semester learning the software.

You could also build a real world wind tunnel of few load cells and proper use of the shop truck can tell you quite a bit. Throw some yarn in the mix and you can almost get away form CFD and the wind tunnel

[flynfrog]

there is also the brute force method

[Greg Locock]

I bet if you used that approach and combined it with active struts you'd beat many CFD designs!

[Heisenberg]

Thanks again for the replies guys,

I just ordered those two books on amazon. I'll discuss it with the engineers in my fsae group keeping in mind all the different dynamics of the car.

Sorry for my ignorance, but my degree is in computational chemistry. I've just been thinking about going into auto engineering, so I read books on the subject since May. I'm in the process of doing my damn best to make the aero section work as no one else in my group really knows how to go about it.

all the responses are sincerely appreciated,
Luke

[Jersey Tom]

Or in this case, the aerodynamics. The science. To the points mentioned above, step 1 is to determine what it is you're after and then you can move onto step 2, figuring out how to achieve it in some conceptual or fundamental way. Drafting it up in SolidWorks is the almost most trivially easy stage of it all, IMO. Once you're at that stage the piece has basically designed itself and everything is already in place. Getting the fundamental understanding of things upstream of that is really the crucial part that requires the thinking.

To the point of Step 2, getting / making a sandbox tool of sorts might be helpful. Say you start with 4-digit NACA airfoils... as you vary thickness, camber, etc. how does that affect lift? Drag? Sensitivity to AoA? Might even be able to dig up measured performance curves of these things to save yourself some time and effort.

[Lycoming]

One other thing to keep in mind is construction techniques. I am a big fan of wetlay over foam for FSAE. You can hot wire cut and layup a wing in a matter of hours.

With or without vacuum bag, and with or without spar? If you're bonding in a spar thats minimum another day or so of cure time. And how much sanding is required to finish it up for even just testing? Depends somewhat on the skill of the people doing the layup, I suspect...

[Greg Locock]

". And how much sanding is required to finish it up for even just testing? Depends somewhat on the skill of the people doing the layup, I suspect..."

Make the guy who did the core and layup do the sanding. The second one he makes will be much better!. Anyway, less than a day, coz you can bog the low bits with cellulose filler.

[flynfrog]

One other thing to keep in mind is construction techniques. I am a big fan of wetlay over foam for FSAE. You can hot wire cut and layup a wing in a matter of hours.

With or without vacuum bag, and with or without spar? If you're bonding in a spar thats minimum another day or so of cure time. And how much sanding is required to finish it up for even just testing? Depends somewhat on the skill of the people doing the layup, I suspect...

The foam is the spar. Without a bag I could get a pretty good part. This is the method that the long-ez, cozy ect all use. If you want paint smooth add a resin wipe once the first coat of resin gels. Not sure I even have pictures any more but we could get a pretty good surface finish without any touch ups. If its for testing drywall compound makes a smooth easy to sand surface in about an hour for a good size wing