200mph RADIO CONTROL CAR
Pocket rocket A
One tenth scale model of the JCB Dieselmax record holder targets 200mph
n accident in the desert on a motorbike gave Ford model maker, Nic Case, something of a wake-
up call. The American was taking part in a desert race, and while he was uninjured in the shunt, a sense of his own mortality came over him. Case stopped riding his bike,
and instead turned to racing radio-controlled cars. That new- found passion evolved into an attempt on the radio-controlled speed record, which he now holds at 161.76mph, and Case plans to crack the 200mph record with his new creation, the SR11, an
BY ANDREW COTTON
extreme evolution of the original record holder, based on the JCB diesel speed record machine. ‘The original V1 body was
inspired by the JCB Dieselmax,’ says Case. ‘The general curves and basic layout was gleaned from them, and that holds the record. For V2, we received some key CFD support from CD Adapco in 2009, and ended up with a drag coefficient improvement to .201! That body worked well until we started going to 175mph plus, and then a blow-over condition reared its ugly head in September 2010.’
BODYLINE Flying cars are a phenomenon that has been experienced by Le Mans Prototypes, but the RC car clearly had a different problem. A frame-by-frame analysis showed that the nose of the car was actually deforming at speed, and
that the carbon fibre and foam reinforcements were not enough. Version four of the body
features a complete carbon fibre body structure with an adjustable splitter and wheel exhaust vents for the front wheels. Adding weight to the nose helped too, and the overall weight of the car increased to 13lb. That has put extra pressure on the driveline, but the team is confident that it can set a new record with the car. ‘The big unknowns right now
are the aerodynamics,’ explains Case. ‘Even though the car has been in CFD, it is not real-world conditions, with weight transfer and body deformation. The CFD didn’t really pick up the potential problems, or maybe it is my lack of experience, because the more I learn about aerodynamics the more I realise how incredibly complicated it is. ‘Additional aerodynamic support was contributed by Dale Beever, a co-worker, who has had a lot of experience in the wind
tunnel with production vehicles. I’m pretty sure that the body thing is taken care of, but we won’t know for sure until we go above 180. Right now we have only done 167. Even if it is just 186, 300km/h, I want to make sure we get everything out of the car that we can because we have never fully wound the car up yet. At these speeds, it is still accelerating, even on a full size drag strip.’ One of the problems that faced Case while developing the car was actually seeing it at those speeds. He came up with a fixed Long View Camera, which is used to monitor the car as it sets off at the start of the drag strip. Case then takes it up with the naked eye at full speed. ‘We looked at putting the camera on the car, but it is not realistic because, while it sounds like a good idea, the camera is two inches off the ground and the perspective is so incredibly heightened in terms of difficulty.
“the nose of the car was actually deforming at speed”
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www.racecar-engineering.com • January 2012
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