Just before stepping through the hatch of our five foot diameter bullet, I look behind the craft at the 165 foot diameter fan stretching above and all around me and I realize more than I had ever before, that I would be sharing space with this huge mass of turbulent energy as we both accelerate into the common 5 foot diameter tunnel just ahead. Although invisible, I could feel the airstream converging in on itself, and me, creating a pressure difference across the pod.
We take our seats, which are highly reclined to minimize the pod and tunnel diameter, and fasten our seat belts for the non-stop trip. This is no ordinary craft. There are no wheels, no bearings, no engine, and no brakes. This pod is a pressure vessel with forward and aft regulators to balance the inside environment at a comfortable pressure, temperature and air circulation. Forward and aft circumferential hydrodynamic seals turn the cylinder into a piston, a very fast piston, driven at cruse by pneumatic pressure.
As the hatch is closed, I sit uneasy. I look out through the mostly transparent tubular walls at those who we leave behind and it occurs to me that in a moment, they will be many, many miles away. My eyes scan from the right, over head and to my left, taking in the exciting moment, and then after a brief wink at each member of my family, I look straight ahead and become acutely aware of the small hole which is to be our immediate destination. The ALL CLEAR indicator illuminates on the front console, a small bump sounds from below, and we move out at a brisk 1/2 the acceleration of gravity, 15 ft/sec2.
v = a*t
x = ½ a*t^2
(constant acceleration equations with zero initial velocity and position)
At this rate we reach 100 miles per hour in 10 seconds (not exactly a drag race car), having traveled a quarter mile. After 20 seconds, we pass 200 miles per hour and just over one mile. This constant acceleration continues as the air behind us converges and we approach the throat, minimum tunnel diameter, and 640 miles per hour…