The Airbus A319 saga - epilogue

Here, here, and here I've posted about various data-gathering exercises and calculations regarding the Airbus A319. The data was gathered on two flights, one on takeoff from Laguardia in New York to O'hare in Chicago, and the other on landing from Chicago at John Wayne Airport in Orange County, CA. I mentioned that the calculated landing speed seemed too low and that the landing roll seemed too short.

As it happens, my office window overlooks Long Beach Airport where Jet Blue provides service using the very similar Airbus A320. Rhett Alain over at his Dot Physics blog posted an article on an iPhone 4 app from Vernier Software and Technology called Video Physics. It allows the use of iPhone videos to do rudimentary analysis of the physics (position, velocity in the x and y axes) involved and to email the data files to a "real" computer for further analysis in Vernier's Logger Pro software.

I took video of a couple of Jet Blue's A320s on takeoff and landing and used the Vernier products to determine the speeds. As I suspected, my estimate of 152 knots for the A319 takeoff speed at Laguardia compared fairly well with the measured speed of 167 knots for the A320. The landing speed was another story. My accelerometer measurements and numerical integration with a taxi speed assumption let to a calculated landing speed for the A319 of 99 knots. My measurement for the A320 was 129 knots. This comports much more favorably with my knowledge of aircraft operations and what I've seen on the web.

I'll be travelling to Houston in November; I suppose it's possible that my iPhone will accidentally be measuring acceleration on takeoff and landing on that trip as well.