Ok I did read the whole thing and great Alpha draft. There is still so much to figure out, but I like the open source Idea where can I download alpha 0.1
I don't know if I would say the engineering sound until it's tested, but his people have done their homework. Still WAY more to do on the safety and recover side, and I am still thinking not everything environmental (external to the tube) has been taken into affect, but hopefully some retired NASA engineers and other people that have actually accomplished things will add to the effort and make it viable.
I would recommend he go to a smaller trial system strictly for cargo to start, then take the lessons learned from it, the UPS or Fedex tube for example.
At least someone is thinking outside to normal parameters...