Beginning a Long Explanation

“First of all,” my sister writes, “you should post on what your project is/is trying to accomplish.” … All right, my objective: Characterize the behavior of dual flame fronts in gelled MMH/gaseous NTO as NTO diluent partial pressure and type vary.

This is the simplest way to summarize my project while still preserving the technical aspect. It does, however, lead to a slew of questions: What is involved in “characterizing”? What is a dual flame front? What do MMH and NTO stand for and what are they? Why would you gel them? Why is diluent involved and what am I using? And how does this help babies in Africa?

I’ll start by summarizing very generally: I’m burning rocket fuel.

There are several types of rocket fuel. The most familiar are solid rocket fuels, which are used in hobby rockets, airbags, some missiles, and larger rockets such as the Space Shuttle boosters (the rockets on the sides of the big orange tank). You light them and they burn, and they don’t stop burning until the propellant is gone. Solids can be monopropellants (composed of only one chemical) or bipropellants (composed of two chemicals, fuel and oxidizer). Most solid rockets are bipropellants, and also have other chemicals mixed in to either act as binders (glue) or enhance burning properties.

The other general category is liquid fuels. As liquids, they require systems of much greater complexity, such as pumps, turbines, and heating or cooling mechanisms. However, they tend to deliver more thrust for a given amount than solids, and they can be throttled, or controlled. Liquid rockets can also be mono- or bipropellant. The Space Shuttle main engine, for example, is a bipropellant liquid rocket engine that runs on liquid hydrogen (the fuel) and liquid oxygen (the oxidizer).

My work is done in a specific class of liquid bipropellants known as hypergolics. A propellant combination that is hypergolic ignites on contact; when the fuel touches the oxidizer, it bursts into flame. No fancy ignition mechanism, such as spark plugs or a torch, is needed. This is extremely convenient. If you’ve ever played with rockets, or even tried to light a candle, you’ll know that one of the most critical and uncertain parts is trying to light them.

One of the most common hypergolic combinations in use today is monomethyl hydrazine (fuel) and nitrogen tetroxide (oxidizer), referred to in our highly acronymized (is that a word?) world as MMH and NTO. These are the chemicals that I’m working with. They can be stored at room temperature for a really long time, which is advantageous. Unfortunately they’re also pretty toxic.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s