Aero Design Progress 2014

Earlier this summer, I did a lap time simulation study earlier this summer to understand the sensitivity of lap time on a number of parameters (including mass, power, downforce, drag, and mechanical grip).  The results of the lap simulation showed mechanical grip to be the most important parameter, followed by downforce and then mass.  Since there is a limit as to what can be achieved with mechanical grip, past those limits aero is still the biggest enabler for decreasing lap times.

2014 Architecture

After about 3 weeks, we have a basic vehicle architecture for 2014.  This has been a pretty intense period, as three weeks ago the car was a blank assembly.

The highlights:

• 10 inch wheels - affects packaging for WHUBs, suspension, and frame primarily
• Narrower track (~46", front and rear)
• Smaller wheelbase (60")
• Complete frame redesign - no rear box
• Lower occupant positioning - CG focused
• Lots of downforce

Once again, the focus will be on mass, aero, and mechanical grip.  All of these need to be understood on at least a high level to design an architecture, as many of these enablers and decisions will drive packaging.  For example, originally I started with a rear box because I thought diffuser design would dictat my suspension points, but with CFD I've found that I can actually get better downforce with a shorter diffuser (more on why that is in another post).

So let's take a walk through how to set up an architecture:

Recap of 2013 Motorsports Car: Intake

I must say that I still haven't full recovered from the tornado that was the month prior to competition, which is why I haven't had the opportunity to update the blog. However, we did take a lot of pictures of the design and fabrication processes, so I would like to go through all of the progress we made as a team building our car, named OD-13.

Just a quick note: I apologize for any redundancy regarding the pics that may occur...I just want to make sure I cover everything, because there is a large gap in the blog.

I'll start with the intake:

Suspension packaging

The great thing about a brand new design is the design latitude.  The bad thing about a brand new design is... the design latitude. Making everything fit properly is never an easy task, and often requires you to take a step back and look for some very creative options.

With the help of susprog, I think I've finished the first iteration of the suspension packaging. 

The front was relatively easy - I was able to get the motion ratios required and the ARB packaging with pullrods without too much issue.

 The rear on the other hand is much more difficult because of the addition of a driveshaft, frame limitations, aero limitations, and rim clearance.  However, everything fits, the min clearance at static is slightly less than 0.1" (cutting it close, I know), so a lot of the success of this design relies on good tolerances and properly jigging parts during construction.

Design Progress

 Design is moving along at lightning pace right now, with the whole team contributing now.  With lapsim analysis we've been able to figure out what to focus on for this year - the main goals are (in order) to 1) improve grip, 2) improve aero, and 3) reduce mass.  We might be shooting for a narrower width as well due to the nature of the Michigan course, but not sure if a narrower track is worth the reduction in aero area.

A lot of goals 1 and 3 will be accomplished via the 10" Hoosier LC0's (we think - tire data analysis is currently ongoing to verify).  Also, we're looking for significant reduction in CG via driver positioning and packaging optimization.  Weight reduction is looking for a lot of creative design, better analysis to enable less over-design, better CAD accounting for mass, and better manufacturing methods.  CFD analysis has just started today to optimize the aero package for this car, so there's lots of work to do still on that front.

Some teaser shots of what the car might look like next year: