Interesting rocket launch

[Tembaco]

Good evening everybody!

I am in my exam year of high school and it is required that we write a pretty in depth research article about a subject of choice that falls within the courses you take. I follow a beta course at school (math physics chemistry etc.) so I choose the subject of rocket engines. I have come up with a couple of points I am going to research:

How does a rocket work? (sec, focusing on the principles of rocket engines)

What are the different fuels used? (liquid, solid etc.)

Different nozzle shapes

future projects (non-scientific, but looking at the (near)future of spaceflight)

if anyone has good source material (scientific please) on these that would be awesome but what the reason that I write this post is for the following part of the essay. To take all the things we have learned and apply it to a real life example.

I want to take an existing launch and analyze it focusing on the engines and fuels used. Basically looking at the rocket ascent into space analyze why it is using a certain engine with a certain fuel, and why on the next stage this is completely different. The only problem is that I am pretty new to the subject and I do not know a lot about rockets and launches. So can anyone recommend an interesting existing launch that has a lot of different engines and fuels uses for reasons I discus earlier in the essay?

Thanks in advance!

Edited February 13, 2014 by Tembaco

[SargeRho]

Wikipedia is a pretty good source for such things actually.

The principle of a rocket engine is rather simple: Take a propellant, and accelerate it. Ion engines use Xenon, Caesium or Argon, ionise it, and accelerate it using electromagnetism/electrostatics. Liquid fuel rockets combine fuel and oxidizer, burn them, and use the nozzle to direct the resulting hot gas out the nozzle. Thermal rockets work similarly, but they heat the propellant without combustion. Nuclear thermal rockets (would) for instance use a nuclear reactor of some shape or form to heat typically hydrogen or water. Rocket engines are a rather diverse category.

[Ralathon]

Well there are quite a few interesting historical rockets that used different configurations for different stages.

The classical example would be the Saturn V. It had 3 main stages, a service module and a 2 stage lander and it used 3 different fuel mixtures:

First stage used RP-1 (Highly refined Kerosene) as fuel with Liquid Oxygen as oxidizer. This is essentially the baseline fuel mixture for launch stages because it has a pretty good density and packs a lot of power.

Both the second and the 3th stage used Liquid Hydrogen with Liquid Oxygen. This mixture is highly efficient (very high specific impulse) but it is also very light. So this means that you need very big tanks to carry any significant amount of it.

The service module and lander used Aerozine 50 with Nitrogen Tetraoxide as oxidizer. This is because those 2 fuels spontaneously ignite when you mix them, that way your engines become more reliable (Don't want an ignition failure trying to escape the lunar surface...)

If you want a good book on the history on rocket fuels (and the crazy kerbal style shenanigans they ran into along the way) I can recommend Ignition! It has gems such as this section on Chlorine trifluoride (a possible oxidizer):

Chlorine trifluoride, ClF₃, or, "CTF" as the engineers insist on calling it, is a colorless gas, a greenish liquid, or a white solid. It boils at 12° (so that a trivial pressure will keep it liquid at room temperature) and freezes at a convenient -76°. It also has a nice fat density, about 1.81 at room temperature.

It is also quite probably the most vigorous fluorinating agent in existence - much more vigorous than fluorine itself. Gaseous fluorine, of course, is much more dilute than the liquid ClF₃, and liquid fluorine is so cold that its activity is very much reduced.

All this sounds fairly academic and innocuous, but when it is translated into the problem of handling the stuff, the results are horrendous. It is, of course, extremely toxic, but that's the least of the problem. It is hypergolic with every known fuel, and so rapidly hyperbolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water - with which it reacts explosively. It can be kept in some of the ordinary structural metals - steel, copper, aluminum, etc - because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however this coat is melted or scrubbed off, and has no chance to reform the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation I have always recommended a good pair of running shoes.

I'm less versed in the area of rocket engines themselves. But the main difference between lower stage and orbital engines is efficiency - thrust balance. For a lower stage engine thrust is way more important than efficiency. A 10 minute rocket launch with an ISP of 300 takes more fuel than a 5 minute rocket launch with an ISP of 200. Upper stages don't care how long they have to burn, so much more focus is placed on efficiency there. This means large bell nozzles to optimize the gas flow and usually pretty low thrust.