DETROIT - Technology that helps the military develop better jet fighters is being used by Ford Motor Co. to speed aerodynamic testing and cut development costs of vehicles.
A pressure-sensitive paint lets Ford prepare a vehicle for wind tunnel testing and get the results within a few hours. That compares to at least a week of labor with the current practice of drilling holes and installing 100 or more pressure sensors in a small area such as the driver's door window.
Shaving time can save money. Sverdrup Technology Inc., which manages the Dearborn, Mich., test facilities for Ford, charges outside companies about $800 an hour to use a wind tunnel. Ford gets a better rate.
The key to the technique is a chemical element in the paint that responds to light, says Patsy Coleman, a senior technical specialist in Ford's research labs who led the effort to adapt the technology to the auto industry.
Measurement is based on the extent the paint reacts with the light, Coleman says. The reaction decreases as the amount of oxygen increases. Digital photographs of the test area taken before and during a wind tunnel test are used to calculate areas of high and low pressure.
During the test, the painted area is bathed in blue light and a red filter is used on the digital camera to record the reaction.
The paint, created by McDonnell-Douglas and now made by owner Boeing Co., costs 'hundreds of dollars per pint,' says Jack Williams of Ford.
It takes about one-half a pint of paint to test a door window area.
McDonnell-Douglas developed the paint as a way to evaluate air pressure and aerodynamics on aircraft that travel at about 600 mph.
The challenge for Ford was to adapt the technology to produce valid measurements at wind speeds of 70 mph to 100 mph used by the auto industry.
Temperature control is critical for producing good test results, Coleman says. Also, finger oil can distort the pressure reading, so workers avoid touching the test area after it has been painted. The paint is easily removed after the test without damaging the vehicle.
While both the traditional pressure taps and new paint technologies produce valid results, the paint system provides a complete view of the test area while pressure taps leave small gaps, Coleman says. It's possible to test large sections of a vehicle by using multiple digital cameras. It also could be used to measure air pressure underneath a vehicle.
The decision to use the technology rests with each vehicle team, Coleman says.