Typical energy ratios to get into orbit? (height, friction, velocity)

[Stargazer19385]

I realize the answer depends how where in the atmosphere speed is increased more, and whether a higher orbit or lower orbit is desired, and the shape size and weight of the craft. But I'm just curious about typical ratios.

About what fraction of the fuel goes to lifting the weight of the craft? The weight of the fuel? (giving them potential energy)
What fraction goes to giving the craft the kinetic energy (final speed)?
What fraction goes to just overcoming friction through the atmosphere?

Thanks. lots of math with the atmosphere thinning and the reynolds numbers changing and fuel mass and speed changing.

 

[mfb]

Most of the energy goes into the velocity and heat of the fuel, most of the interesting energy goes into the kinetic energy of the rocket (for low Earth orbits), and some smaller fraction (I think it was something like 10% compared to the kinetic energy) into potential energy.
For higher orbits or even escape routes, the initial part is the same. Gravity exchanges kinetic energy for potential energy afterwards.

For a given rocket, it is easy to calculate the final potential and kinetic energy of the rocket. Atmospheric drag is hard to evaluate, but it is a small contribution.

 

[Stargazer19385]

That all makes perfect sense. I kind of should have known drag would be a small portion, since it only goes 400 miles up, and most of that is through very thin air. Only about 3-5 miles of the air is remotely thick. However, high velocity through thin air could still mean high drag.

So kinetic energy is the hurdle...

I guess the reason we don't have large telescopes hanging from balloons instead of in orbit is the telescopes are too heavy and would need a very big balloon. The balloon blocking the view could be solved by suspending the telescope well below the balloon so it is angularly small at that distance.

 

[mfb]

So kinetic energy is the hurdle...

Right.

Balloons are also unstable.
For small telescopes, the atmosphere is not so problematic, and large telescopes are really heavy.

 

[PJC01]

I can provide a general response to this question based on theoretical calculations and observations from past spacecraft launches. The typical energy ratios required to get into orbit can vary depending on a variety of factors, such as the desired altitude and speed, the shape and weight of the spacecraft, and the atmospheric conditions during launch. However, a common ratio for reaching a low Earth orbit (LEO) is approximately 10:1:1 for potential energy, kinetic energy, and overcoming friction, respectively.

In order to reach orbit, a spacecraft needs to overcome the force of gravity and the resistance of the Earth's atmosphere. This requires a significant amount of energy, which is primarily provided by the spacecraft's engines and the fuel they carry. The fuel is used to generate thrust, which propels the spacecraft upwards and helps it reach the necessary speeds to enter orbit.

Based on theoretical calculations, it is estimated that about 80% of the total energy required to reach orbit is used to lift the weight of the spacecraft and the remaining 20% is used to overcome atmospheric friction. This means that the majority of the fuel is used for potential energy, while a smaller fraction is used for kinetic energy.

However, it is important to note that the actual energy ratios may vary depending on specific launch conditions and the design of the spacecraft. For example, a spacecraft with a more streamlined shape may experience less atmospheric friction and therefore require less energy to overcome it. Additionally, different types of engines and propulsion systems may also affect the energy ratios.

In conclusion, while there is no definitive answer to the energy ratios required to get into orbit, a general estimate is that about 80% of the energy goes towards potential energy, 19% towards kinetic energy, and 1% towards overcoming friction. These ratios may vary depending on launch conditions and spacecraft design, but they provide a basic understanding of the energy requirements for reaching orbit.