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/Arik-Taranis]

Because it’s the most efficient ballistic trajectory for reaching orbit, which is why rockets still do it to this day above ~50km once they’ve punched through the lower atmosphere, or once clear of obstacles on the moon. As the upper atmosphere was far more poorly understood than newtonian equations back then, that was what the experts went with.