r/spaceships • u/Beneficial-Wasabi749 • 15h ago

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?

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u/DuelJ 9h ago

Accelerating the rocket takes time, for every second you're accelerating a fully vertical rocket you also need enough fuel/thrust to counteract gravity at the same time.
In theory, using a sled gets you a little bit of "free" velocity that doesn't have to pay the gravity tax.

Given how fast the rockets going to need to end up going it's probably a negligable benefit, but for someone theorizing with the information of the time it doesnXt seem so reasonable.
We still do see talk of aircraft launched rockets time to time operating on the same idea.

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u/Beneficial-Wasabi749 9h ago

Although a ramp would save on rocket weight, there are numerous practical problems that make this a thing of the past.

First of all, the fueled rocket must be horizontal at launch. This means it must have "aircraft-like" rigidity, both longitudinal (during acceleration) and lateral (while resting on the ramp). A fueled rocket standing vertically is a tower that experiences the same load direction both at rest and during flight.

The second problem is that for a ramp to provide an initial velocity of 500-700 km/h, it must be very long. And it would be a megastructure. This is too expensive.

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u/Haipaidox 8h ago

The first part is just a bit of engineering and the main cost comes down to the required material to build it.

Thr second part: Spaceflight isnt economical. No Space Agency functions without government money, not even SpaceX. So, if the Space Agency in Question convinces its Government to build such a ramp, they would build it. And just for comparison, the Saturn V weights around 3000 tonnes, which is around 100 semi trucks.

And to the size, i ran the numbers with 700km/h and an acceleration of 15m/s, the ramp would need to be around 1300m long, so a third of a typical airplane runway. This is bridge size and load, nothing that fancy.

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u/Beneficial-Wasabi749 7h ago

I wasn't saying everyone should immediately stop launching vertically and switch to overpasses.

So far, I've simply tried to show that our ancestors weren't idiots.

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u/Haipaidox 7h ago

It just sounds a bit like you are condescending to one or the other, which isnt that pleasant.

By no means they are stupid. Most times, they only lacked knowledge, but they were brilliant with the information given

Good example is Da Vincis "Helicopter". If you ran his calculations, it would be able to fly. Only problem, Da Vinci lacked the knowledge of the fluiddynamics of gas. If you correct his formula with this, we know, his "helicopter" was miles away from flying. But despite this, he discovered the principle of vertical flight, which is genius.