I went on a field trip to NASA Ames Research Center yesterday. I haven't been there since I was in elementary school, and I am as excited about being there now as I was then. The fieldtrip was organized by the Society of Latino Engineers and Scientists at San Jose State University (SOLES-SJSU). About ten of us SOLES members got a tour of the wind tunnels at NASA Ames. NASA Ames contains several wind tunnels; some are used to test models of vehicles such as jet fighters, helicopters, and even the space shuttle. These models are tested at varying wind speeds. Some of the tunnels here at NASA Ames are used to test high wind speeds of over mach 1 while others wind tunnels focus on sub-mach wind speeds. NASA Ames claims to have the largest wind tunnel in the world. The National Full-Scale Aerodynamic Complex (NFSAC) holds to wind tunnels, the largest of which has a cross section of 80 by 120 feet. The 80 by 120 feet wind tunnel is so large that actual F-18 been tested there, in addition to other jet fighters. There is no better model than the real thing. They have tested a variety of vehicles in the 80 by 120 wind tunnels, such as actual sized airplanes, helicopters, and even 18-wheeler semi trucks. Radio antennas have also been tested, and legend says that even a submarine had been tested here in this wind tunnels. Most recently highlighted by a Nova special on PBS, the parachute for the Mars Lander was tested here a few years back.
In addition to the 80 by 120 wind tunnel, we saw other tunnels, such as the 40 by 80. According to our guide, the smaller the cross section of the tunnel, the higher the speeds of the wind you will be able to produce. This of course makes sense. In a large tunnel you are pushing more air and you will need larger forces to push large volumes of air. In you funnel or squeeze air through a smaller cross section, the same forces will produce higher speeds. The smaller diameter wind tunnels are the ones that go over mach 1. For example, the 9 by 7 feet wind tunnel has a mach range from 1 to 2.5. The larger wind tunnels such as the 80 by 120 have wind speeds of sub mach 1. But of course, in the smaller wind tunnels you can only tested models.
Our tour guide was definitely long winded about wind tunnels. The field trip lasted over three hours, and this was the abridge tour. We skipped on some tunnels. The tour guide pointed out sections of a model replica of the actual NFSAC wind tunnel. The model included in very fine detail the whole complex including the actual fans. My mind warps even at the thought that the model wind tunnel was tested in a wind tunnel.
I learned a lot from my visit to the wind tunnels housed in the NASA Ames Research Center. One thing I learned is that hearing your laugh echo is really scary. All of us, college level seniors mind you, where having a lot of fun giggling and laughing inside the 80 by 120 wind tunnel just to hear our echo. I also learned that wind tunnels don't blow a lot of hot air, they suck air. Our guide said that this concept grade school children grasp best, he joked that he often over hears them saying as they leave, "Yeah, wind tunnels suck!"