The fastest ground vehicles on earth are not driven by their wheels but by an aircraft jet engine. At world record speeds, they run on an aerodynamic razor’s edge between downforce, which limits speed, and liftoff, which can result in death and destruction. [rctestflight] wanted to see what it takes to run an RC car at very high speeds, so he built a ducted-fan powered car with aerodynamic control surfaces and an aircraft flight controller.
This high-speed car is built on the chassis of a 1/14th scale RC buggy, powered by 4 EDF (electric ducted fans) mounted on a very long aerodynamic foam board shell. It also has an aircraft-style tail with elevons and rudders for stabilization and control at high speed using an ArduPilot flight controller. The flight controller is set up to stabilize in the roll and yaw axis, with only fixed trim in the pitch axis.
[rctestflight] got the car up to 71 MPH (114 km/h), which is fast for most RC cars but well short of the 202 MPH RC car speed record. It was still quite hard to keep in a straight line, and the bumpy roads certainly didn’t help. He hopes to revisit the challenge in the future with larger motors and high voltage batteries.
If you want to do more than just go in a straight line, or drive upside down maximum downforce is your friend. This can be done with careful aerodynamic design, or just add fans to suck the car onto the ground.
I’ve had Traxxas trucks with Traxxas motors and speed controllers hit gps-measured speeds over 80mph on city streets.
There’s a lot of room to squeeze out performance if he only hit 71mph.
My biggest problems going faster were always the wheels disintegrating or the car doing a wheelie as the aerodynamic pressure reached parity with the torque.
Still fun to see a car with active aerodynamics though.
Yeah… Centrifugal forces will kill foams.
If bumpy roads are upsetting it, more suspension? Perhaps scaling this up to 1/10th might not be a bad idea.
I love the ducted fan setup.