Racecar Engineering - November 2005

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Hot shots With thermal imaging cameras now affordable, could they herald a breakthrough in understanding how a racecar performs? Racecar puts one to the test to fi nd out Words Images Sam Collins Collins; Woodvine/IRISYS Andy Woodvine of IRISYS demonstrating the thermal imager at Silverstone. Above, taking readings from the A1 Team France car How many tyre temperatures should you take per tyre? The man from RML said three across the tyre – ‘outside edge, middle and inside edge.’ Would any more tyre temperature information help, asked Racecar? ‘It’s not relevant because you simply can’t get round four tyres and get any more than three good readings in time before the tyres have cooled.’ That is the perceived wisdom and little has come along that can change that. Until now. Maybe. The IRISYS low-cost thermal imager could allow teams to record tyre temperatures in seconds, without the scramble round all four corners to record 12 spot temperatures. With the thermal images, each tyre instantly gets 10 spot temperatures that can be determined later on a laptop. The usefulness of this technology was illustrated during a recent club race meeting at Silverstone, where a Speads single seater showed a strange cold spot on its right rear tyre – chances are a pyrometer could easily have missed it. Other trials were conducted on the day on a variety of racecars and objects hot and cold, including a shot of the engine bay of Rod Birley’s Ford Escort WRC taken immediately after a race which revealed the turbocharger was over 100 degrees hotter (325degC) than anything else around it. Even inadequately heated cups of tea were captured, but more serious tests were required. French outfit Driot Associates Motor Sport (DAMS) offered to trial the 32 November 2005 Racecar Engineering www.racecar-engineering.com
Thermal imaging Right rear tyre of A1 Team Mexico’s Lola just after removal of tyre blankets. Uneven heating is clearly evident, with nearly 10 degrees of fluctuation. Particularly of note are the hot and cold spots left on the tyre Getting the right emissivity value for a surface is key to obtaining an accurate reading. The IRISYS thermal imager comes with a number of preset values but currently none specifically for motorsport applications Right rear tyre of a Speads RM05 taken in parc ferme after a 10-lap club race on Silverstone’s National circuit. Note the cool stripe on the left running the entire circumference of the tyre. Although it was only a two-degree difference it could point to a number of problems, including a tyre defect. Interference from the engine and exhaust is unlikely as the problem did not manifest on two other identical cars racing at the same event Taking 10 temperatures across a tyre is easy with the thermal imager. But spot tyre temperatures are perhaps redundant with an overall visual image “ EMISSIVITY IS THE RATIO OF RADIATION EMITTED BY A SURFACE ” technology on the tyres and brakes of its GP2 and A1GP Cars, offering a direct comparison with the usual probe-type pyrometers. One of the team engineers commented: ‘It is good because when you have images you can instantly view the situation. With a probe you must look at just the numbers.’ The competitive spirit was soon present as it became clear that the imager could be used to establish what the competition is up to as well. ‘It would be great in a series like GP2 because you can see what your competitors’ tyres are doing without touching them or even being that near to the car.’ Something Racecar put to the test earlier in the day, walking in the back of one team’s garage and taking temperature readings from several metres away without being challenged. IRISYS representative (and Formula Vee racer) Andy Woodvine claims ‘it’s accurate from -10degC to 300degC, so it quickly gives you a snap shot of the whole temperature range of the desired area.’ Head-to-head testing started on the A1 Team France car run by DAMS. AP Racing’s Nic Olsen used a traditional tyre probe to take readings from the car’s brake discs, registering a spot temperature of 260degC, while the thermal imager only recorded a temperature of 160degC, around 100degC out. It seemed Woodvine’s claims were somewhat optimistic, but Olsen had the answer: ‘On carbon discs it would work fine because they are a black body, but once you get a shiny steel disc it can be a couple of hundred www.racecar-engineering.com ➔ “ IT COULD ALLOW TEAMS TO RECORD TYRE TEMPERATURES IN SECONDS ” November 2005 Racecar Engineering 33
Page 1 and 2: TECHNOLOGY FOR MOTORSPORT T h e I n
Page 3 and 4: Write Line Everyone in the Racecar
Page 5 and 6: Debrief F1 to undertake CFD aero st
Page 7 and 8: Debrief NEWS IN BRIEF New FSAE anno
Page 9 and 10: Debrief Rally news with Martin Shar
Page 11 and 12: Race people LAT LAT LAT LAT Mo Nunn
Page 13 and 14: V-ANGLES By Paul Van Valkenburgh Ty
Page 15 and 16: STRAIGHT TALK By Mike Breslin The t
Page 17: Forum Formula stupid? Just some tho
Page 21 and 22: Thermal imaging Covert temperature
Page 23 and 24: GWR Predator Woodwork Ogilvie proce
Page 25 and 26: GWR Predator Tech specs: Predator C
Page 27 and 28: GWR Predator it also incorporates c
Page 29 and 30: GM Ecotec engine “ AN OFF-THE-SHE
Page 31 and 32: GM Ecotec engine The Ecotec Lakeste
Page 33 and 34: Aero tips details in relation to th
Page 35 and 36: Aero tips least conclude that ridge
Page 37 and 38: AP cushion clutch A clean getaway S
Page 39 and 40: AP cushion clutch Designers also de
Page 41 and 42: Fuel cells Fuel cells, or bladders,
Page 43 and 44: Technical spotlight Control in moti
Page 45 and 46: RACEGEAR New products and services
Page 47 and 48: RACEGEAR New products and services
Page 49 and 50: Aerobytes Figure 2: delta Cp plot s
Page 51: The Consultant identical right and

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