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Comment by Detrytus | Hacker News Reader

Building supersonic passenger planes was never a technical problem (see Concorde), the problem is: they are too expensive to operate to be profitable. I bet this thing will never see any commercial use.

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Being "too expensive to operate to be profitable" is a technical problem.

Yep, TV's were said to be too expensive to produce to have one in every home.

Now every home has multiple TVs, with decent TVs being available for like $200

Airplane cost to operate is fuel consumption, and, by the laws of physic, aerodynamic resistance scales as a square of speed, so you can’t really work around it unless you invent some new laws of physics.

...at an altitude of 25 kilometers, where atmospheric pressure is one-hundredth that at sea level.

That's why these schemes typically envision a suborbital hop, with no air resistance for most of the trip.

Your conclusion is really a false dichotomy. The square of something very very small (close to zero) is negligeable : thus subortibal hop (Concorde was flying at 18km altitute for example).

It is a technical problem bit still with very hard limits as to how much energy it will cost minimum to accomplish. You still gotta push through the air at higher speeds which takes a lot of energy/fuel. Best case is they go high enough to avoid a lot of the air, but you still have to get yourself up to that altitude through the air to start with.

One of Concordes problems was also that it was not that much faster for how uncomfortable it was. For London -> NY, You were looking at 7 hours in a luxurious business class vs 3.5 hours in a crammed noisy shaking metal tube for twice the price.

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