First Flight
Ok so, if you haven't heard of it before, KSP is this fun little game where you run a space program and try and launch spacecraft to other moons and planets in a scaled-down solar system. Despite being the first game I ever bought, I never really spent a significant amount of time playing it.
I figure it'd be fun to share my experience trying to play it, and talk a bit about rockets. I decided a good starting point for my game would be building a general-purpose, medium-sized launch vehicle for putting cargo and crew into orbit.
I decided to base it on the Zenit-2. The Zenit is a very interesting launch vehicle with quite a history, which I'd like to explore in a future post. Skipping past that, we get to the last variant: the 3SL. It was operated by a multinational (American, Russian, Norwegian, and Ukrainian) Company. The main body of the spacecraft was manufactured in Ukraine, while the engines and the upper stages came from Russia. Boeing provided the fairing and integrated the pieces. Finally, the Norwegians provided the launch infrastructure, which was by far the most unique part of the rocket. See, the company, named Sea Launch, unsurprisingly provided one of the only sea-based launch services while it was in operation.
The rocket was launched from a "self-propelled semi-submersible mobile spacecraft launch platform converted from a mobile drilling rig" called LP Odyssey. The whole thing looks like something out of a spy film, and it's honestly hard to believe this was a real thing. Because no one could be on the platform while it launched a rocket, it was paired with a combo rocket carrier/mission control center ship called Sea Launch Commander. In Captain America: The Winter Soldier, the ship in the beginning that is hijacked (Lemurian Star) is the same ship.
In the movie, it's launching the satellites that provide the targeting data for the hellicarriers which I think is pretty neat.
Here's my approximation of the rocket in KSP, during its first ascent. The bottom looks like four rockets but is actually a single large one called the RD-170. It's probably the most interesting part of the rocket as it represents the high water mark of soviet rocket engines.
If you're familiar with KSP, you might not remember there being an RD-170 equivalent, we have one because I'm running a heavily modded version of KSP. (Restock + Near Future + Utility Mods)
Here's the engine IRL. Pretty neat. The RD-170 has an even more interesting history than the Zenit booster it mounted on (it inherits many design elements from the soviet N1 moon rocket)
To get into orbit, you need to be traveling horizontally at about 2 kilometers per second. However, if you tried to achieve these speeds near the surface, all of your energy would quickly be lost through drag, so you first must ascend through the atmosphere before your upper stage turns horizontally and circularizes your orbit. If you need some more info I have attached an article from NASA explaining the whole thing in depth.
The rocket's payload, in this case, a satellite, is often not aerodynamically sound (and even if it was figuring safe flight profiles for each payload would become quite complex) so it's enclosed in an aerodynamic fairing. Popping it off to save weight once the rocket is out of the atmosphere is always the highlight of a launch. Real rocket fairings are typically two halves, to save weight and complexity, but I find having multi-part fairings more fun. If you look at the end of the rocket carefully, you'll notice the engine bells are moving around. This is because during ascent, one of the primary ways that the rocket controls itself is by making adjustments to the direction of its exhaust.
Here we see that the upper stage trying to circularize its orbit. Unlike the lower-stage engines, which are optimized for pure lifting capacity, the upper-stage has a much larger nozzle to propel the rocket more efficiently. You can see how the lack of atmosphere means that the plume can expand much more easily than in the lower stages where it was squeezed into a narrow jet. (ksp doesn't fully simulate this, but it ends up being right a lot of the time)
Unfortunately, the lowered thrust came back to bite me. Although the rocket had more than enough energy to reach the needed orbital velocity, it simply did not have the necessary thrust to reach those speeds before it began to reenter the atmosphere and burned up.
My second attempt used an engine with roughly twice the power output and was a lot more successful. The blue line represents the current trajectory of the rocket, while the orange line represents the rocket after the planned burn. I'd like to say I planned such a perfect circularization burn, but I actually used an external tool to do so.
Here we can see our rocket doing that injection burn, with the higher thrust engines. On real rockets, these burns can take a pretty significant amount of time
Here you can see the satellite getting deployed by the upper stage.
Typically after a satellite is put into orbit, each functional element is slowly deployed, then verified one by one. But since this is KSP, we can have fun with a one-button deployment sequence.
I'm going to take a moment here to say that Tumblr's 10mb limit on gifs is driving me nuts. I can't even use an external host cause the GIFs don't autoplay.
The main advantage of sea launch was you could launch anywhere on earth. This typically was used for an equatorial launch because the equator provides a minor speed boost and makes achieving any inclination easy. For pretty much every sea launch, these strengths were used to put a cable or telecom satellite in a geostationary orbit. This one isn't based on anything in particular, I just slapped it together based on the first satellite I found on google. The main advantage of sea launch was you could launch anywhere on earth. This typically was used for an equatorial launch because the equator provides a minor speed boost and makes achieving any inclination easy. For pretty much every sea launch, these strengths were used to put a cable or telecom satellite in a geostationary orbit. This one isn't based on anything in particular, I just slapped it together based on the first satellite I found on google. I guess the next step will be to put up some real telecom satellites.