I think that aerodynamics and lift would be the internet itself, along with the various technologies that bitcoin is dependent on. That would be bitcoin’s environment, so to speak. 

And you could say that when altcoins do things like massively raise the block size, they crash and burn because their hubris leads them to ignore these “physical” constraints of the environment.

Mapping the analogy:

* Aerodynamics and lift = The underlying networking, computing and cryptographic primitives that Bitcoin relies on (internet, CPUs, bandwidth, storage, etc.)
* The 737 airframe = The core Bitcoin protocol itself
* The engines = Scaling solutions like Lightning, Liquid, etc. that need to be integrated carefully

However, this highlights the issue with arguing by analogy. You really have to make sure your analogy is apt, otherwise it creates more confusion than clarity. 

...And, for someone like Saylor, with the gift of gab, analogies can be effectively used for sophistry.