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My original point was that pressure rise would be linear, not instant. Thus the onset of load to the vehicle would be somewhat cushioned.

LOL. Setting aside the fact that an "instant" rise is linear - it's merely a line with an infinite slope - I really don't think you can claim any sort of "cushioning" at all until you figure out just how much air is coming at you and how fast it's going. Basically, you want folks to believe that if you drop a column of air weighing, oh, 2 million pounds or so onto an object traveling the opposite direction at 8 km/s in the opposite direction, it's okay, because the rise in pressure is going to take at least a few milliseconds or so. Gotcha. LOL.

It was never my point that simply opening the end of the tube and letting air rush in was a "great idea"...

Was that really so hard? Really, now.

Mr. Boyle's law certainly states that increasing volume decreases pressure, so I think I've got that one covered.

Still didn't do the math, I see.

However, Bernoulli certainly would NOT support your original posts, which were maintaining a solid flow of air at 1 atmosphere...

They were? You must be thinking of someone else - I don't recall claiming anything specific about the actual pressure of the column, other than that it would be non-zero, and indicating that you could expect an approximate atmospheric pressure of 0.3 atmospheres at 29000 feet. Perhaps before we continue, you'd like to review what I've actually said, instead of responding to what you imagine I've said.

...as the leading edge of the wave would be moving the fastest, with incidentally ever decreasing mass. Why? Because gas molecules bounce around at random.

You can't be serious. Individual water molecules bounce around at random too, but that doesn't obviate the fact that they're all going over the waterfall sooner or later. If you'd like to try calculating the position of each individual molecule, be my guest, but I can save you some trouble by stating that the column of air is headed down the tube. Period.

You're a lost cause, arguing in vain attempt to prove to somebody that your original unfortunate comment is holds water, despite any amount of science. Its evident you don't even read my posts. Luckily you're not in charge of driving science forward. Or perhaps given our stellar success at NASA you are in charge.

Now going from a vacuum to atmospheric pressure over say 12 miles at 7000 mph would mean a cushioning of 6 seconds. If you don't think an engineer considers that significant to instantaneous onset, then again I can't help you, simply don't respond to this and finish junior high.

If you still can't wrap you mind around the concept of gas expansion as a particle to particle interaction, then I can't help you. I've made it as simple as I can. Vacuums are not a force in nature. Only positive pressure is. Particles only move when they have more pressure on one side than they do on the other side. Thus if air is moving into the tube AND moving down the tube the air mass cannot be of constant density. IT JUST CAN'T. Each element of the moving air must have more behind than in front or it wouldn't move, it would be static. ITS THAT SIMPLE.

Suggest you move on to arguing that the Earth is flat.