Design of the RR15 & RR15E
November 28, 2014
For the 2015 competition season we here at Ravens Racing have some big plans, and some big surprises up our motoring sleeves. The start of a new design cycle means the opportunity to start researching new ways to make our cars lighter, faster, and quicker around the track. With a new crop of fourth year students on the Capstone project team, and a list of required areas of improvement on the car, the fun begins.
First on this year’s list of objectives is a reduction in the total weight of the frame. Our frame in past years has been welded from 1” round steel tubes with a selection of 0.95”, 0.65”, and 0.49” wall thicknesses. We balance our frame design between stiffness and weight as best we can. Last year the RR14 featured a selection of carbon fibre stressed panels to increase the torsional stiffness of the driver cockpit and floor of the frame. Ideally we want to make the transition to a carbon monocoque, but restrictions in cost, and access to materials and manufacturing has slowed this change.
The RR15 frame will feature a mild steel tubular space frame, along with the same style of composite stressed panels. Design improvements for the coming year include increasing the number of composite panels used in the construction, and reducing the number of structural steel tubes within the frame. Every critical tube that we remove requires that we submit a structural equivalency form to the judges, and a justification of the choice during the design presentation at competition.
On the kinetic and kinematic side of things the team is looking into the implementation of carbon fibre push rods, and suspension a-arms. Ravens Racing cars have featured differential length top and bottom a-arms for a number of years, and we have used carbon fibre push rods for many years in the past, but a full jump to carbon is still a daunting engineering challenge for us.
In order to have full control over our suspension performance and carbon fibre tube quality, we have begun manufacturing and testing our own custom carbon fibre tubes. A big thanks to our sponsor Competition Composites Incorporated, who has opened up their shop, and their amazing knowledge base to help us make some awesome tubes. These are the smallest tubes CCI has ever had come out of their shop, and they are just as interested in our quantitative test results as we are.
Interesting design ideas this year also include custom shock dampers. In previous years we have used off the shelf options, and custom options from a brand called Hot Bits. Hot Bits has graciously helped us out with custom stroke length shocks in the past and last year we paired their system with our own custom designed and manufactured torsion springs on the RR14. This year we are looking into manufacturing our own dampers for full control over our suspension’s dynamic behavior.
On top of all of this we are also looking to build off of our successful powertrain from last year. Our 250cc engine, custom engine map, plasma ignition system, and excellent fuel efficiency earned us 2nd place in the FEV Powertrain Development competition at Formula SAE Michigan 2014, and 1st place in fuel efficiency at Formula North 2014. This year we plan to keep most of our major components the same, but research is being done to increase our horsepower and low range torque to decrease both our autocross and endurance lap times.
On top of our improvements to the gas design, Ravens Racing is working on developing our first all-electric car! Run through our history and you’ll find that we’ve taken on the massive challenge of a hybrid powertrain in the past, this year we’re making things a little bit greener. The RR15E will run on the same frame, suspension, and driver controls as the RR15, making it an easy change for all of our drivers and design team members, but it will be equipped with a water cooled electric motor and a large pack of lithium iron phosphate batteries.
The RR15E does come with its own unique challenges, and each of them requires a new approach to our designs. The safety rules for electric vehicles in competition are very thorough, and require a much more lengthy technical inspection to cover. On top of this, electric competition classes are not available at all Formula SAE events. This means that we will not be making a trip to Formula SAE Michigan this coming year, instead we have registered both teams at Formula SAE Lincoln, the only event in North America with a Formula SAE Electric class.
Next up, manufacturing all the bits needed to get two brand new cars off of the ground and running under their own power, testing both the RR15 and RR15E, and ripping up the track at competition. 2015 is going to be an awesome year!