continued from above
In NASA Time Trial we are only limited on wing mounting to a height of up to 8" above the roof, which is WAAAAAY up there, and FEET higher than what the 3D wings were really designed to be used at. A 2D wing is simply more efficient than a 3D wing, when mounted above the roof. This means: they produce more downforce (negative lift) and less drag at a given speed and angle.
I spent most of a day on 4/19/14 making cardboard mock-ups for the 6 mounting pads, then making the trunk profile for the uprights
Since we weren't restricted on mounting the wing anywhere close to the rear trunk lid, we figured we would see more downforce with a 2D wing mounted at or near the upper limits for NASA TT. The higher you can mount the wing, and the farther behind the car, the less turbulent the air will be that is going over and (especially)
under the wing. We had originally looked at making a wing that met NASA American Iron and NASA TT/ST rules, but they were conflicting. TT specified a maximum height but AI specified a maximum of 1.5" behind the car.
I transferred the cardboard to thin sheets of wood, cut those out for prototype templates and then bolted up the wing
My first mockups (above) were both AI/TT legal, shown above in wood. After staring at it for a while it just didn't...
look right to my engineering eyeball. It was too vertical and not swept back enough.
If we see any trunk deformation at high speeds we will add tubing to brace to these two plates (at right) from the ballast weight bracket
So when I gave the upright layout to Jason I told him to just centrate on the trunk shape and approximate height (we pushed it up to around 6" above the roof, within 2" of the TT max height). He transferred the trunk shape into SolidWorks then moved the actual upper wing mounting portion rearward about 8 inches, which put the wing too far behind the back plane of the car to be AI legal. I kind of knew this first aluminum unit we made would be a prototype that we would later need to tweak, so we will go back and make "production pretty" wing mounting kits for AI and another for TT/ST use on the 2010-14 Mustang trunk.
Check out the video above showing the CNC plasma cutter making a wing upright in about half a minute
After Jason had turned the trunk shape into a CAD drawing I ran to our metal supplier and picked up some aluminum plate in two thicknesses, then rushed over to Friction Circle Fabrications in Lewisville. There Todd Earsley used his brand new CNC plasma machine (see video above) to cut the aluminum I brought into the shapes from the files we sent to him. He cut the six mounting plates and two uprights in less than 35 minutes on his machine, and I was loaded up and racing back across town with the parts still hot.
Once we got to Vorshlag the crew cleaned up the edges and started mocking up the mounting plates. We were super busy that week on customer cars and it wasn't until Friday afternoon that everything was finished, welded, painted and bolted together. We set-up the upper mounting holes with 3 initial Angle of Attack (AoA) positions: 6, 10 and 12 degrees from level. We left the wing at the lowest angle setting we made, 6 degrees, for our first TWS laps with NASA.
Me (at left), AJ (middle) and Jason (right) posing for a quick pic with the new wing when AJ Hartman stopped by Vorshlag
A couple of weeks after we built this wing, just after our TWS race, AJ Hartman happened to be flying through Dallas after a test with a customer down at CoTA. He stopped by the Vorshlag shop to check out our prototype mounting for our first AJH wing. He pointed out a few things we could tweak to make it better, but overall he liked the set-up. We showed him two more cars in the Vorshlag shop that need to get AJH wings, and he is making those for us now.
That's all we have time for in this installment. Tune in next time when we cover the NASA TT race at TWS with this new wing installed. This Saturday is
Five Star Ford at ECR - see ya there!