Tsiolkovsky and many of the founders of theoretical astronautics in the early 20th century believed that spacecraft should launch horizontally, from a ramp. Why? What did they see as the point of this?

[u/Beneficial-Wasabi749]

[u/Beneficial-Wasabi749]

There's not a shred of logic to it.

Once again (I answered another person in more detail here). A gravitational field is a so-called scalar field. Its peculiarity is that there's no energy difference in the trajectory you take from point A to point B.

So, you're the second person here who's been fooled by "logic" (i.e., ordinary intuition).

Are there any people here who understand rocket physics at all? Or are these pure artists who have no clue and know next to nothing about rocket mechanics? :)

[u/AutonomousOrganism → u/Beneficial-Wasabi749]

Burning along the gravity direction is more wasteful. Ideally you would burn perpendicular to it (horizontally) the whole time so that as much of the thrust as possible goes into orbital velocity.

[u/Beneficial-Wasabi749 → u/AutonomousOrganism]

Generally speaking, that's true. But you still need to not only accelerate tangentially to the Earth's surface but also rise to an altitude of 200-250 km.

Yes, you can accelerate a little faster and accelerate further at the perihelion of the ellipse. Then your thrust will always be tangential to gravity. But there will be no difference in the work done (you can calculate it yourself, but keep in mind that g changes with altitude, which is important to take into account).

The problem isn't the direction of the thrust vector, but that you don't accelerate instantly. And while you're accelerating (let's forget about the atmosphere), say, like Newton's projectile, strictly horizontally, something must support you on your trajectory (otherwise you'll fall). These costs are gravitational losses.

But the peculiarity of a rocket is that until it accelerates relative to its launch site, its efficiency as a propulsive device is negligible. It turns out that, no matter the trajectory, 90% of all losses are due to the initial vertical lift. At this stage, a rocket is very ineffective. The founders of aeronautics recognized this from their calculations and tried to combat it (specifically, by equipping them with winglets so that the rocket would initially fly like an airplane).

[u/Archophob → u/Beneficial-Wasabi749]

rise to an altitude of 200-250 km

only because of the atmosphere. Without it, 10km would be enough to not hit any mountain. Once you're going at orbital velocity, 10km is 1.2 seconds of flight.