Sciencemadness Discussion Board

Liquid Fuel and Oxidizer for rockets

Archenemy_6 - 25-2-2017 at 23:19

Not sure if this is the right place for this sort of topic but I've been thinking a lot about model rockets and how they're all solid fuel rockets and have been researching some liquid fuels and oxidizers for potential small scale use. I was researching some hypergolic mixtures such as aerozine50(hydrazine and unsymmetrical dimethylhydrazine) and nitrogen tetroxide or Kerosene and high test peroxide over a catalyst. These all seemed fairly expensive or unnecessarily hazardous just in handling the chemicals so I tried to think of a regular fuel and oxidizer mix. The first obvious choice I found for fuel is using kerosene since many rockets have used that throughout the years and it can be obtained almost anywhere. As for oxidizers I found a list of class III oxidizers but only 3 on the list were liquids.
Hydrogen peroxide-52%-91%
Nitric acid - >86%
Perchloric acid - 60%-72%
Nitric acid seemed ok but as far as storage and injection into the engine seemed like it would be a bit of a challenge so I looked into some non liquid oxidizers and found that Sodium Chlorate has a really high solubility in water especially near 100C. According to Wikipedia it's around 220g/100ml of water.
If the mixture was loaded while near 100C do you think the concentration would be great enough to provide sufficient oxygen to the kerosene?

macckone - 26-2-2017 at 10:03

Perchlorate is used in 'rocket candy' which is a solid
rocket engine. Mixing a perchlorate, preferably
ammonia perchlorate with sugar.

Other combustible substance, such as various
polymers are used to create APCP. Note that the
burn rate is limited to 1M/sec to avoid explosive

The next step above that is going to be a hybrid
rocket motor consisting of nitric acid and either
butyl rubber or solid polystyrene (not expanded).
High test hydrogen peroxide is the preferred oxidizer
between nitric acid and liquid oxygen.

Once you have mastered liquid oxidizer hybrids, then
move on to liquid fuel.

If you are going to be experimenting with rocket
motors, I suggest you get involved with a local
rocketry club and earn your HPR cert before
moving on to liquid oxidizer motors. HPR cert
for an O type engine requires a lot of work.
Anything more powerful than an O type requires
FAA clearance and depending on projected
maximum altitude you may need an FAA clearance
with less powerful engines.

Solid rockets are used in ICBMs and launch vehicles.
They are perfectly capable of orbital flight.
Don't dis the solid rockets. Most military rockets
are solid propellant.

yobbo II - 26-2-2017 at 11:45

Sodium perchlorate is even more soluble than chlorate and you get more oxygen.

The interesting one is ammonium nitrate. Crazy soluble at 100 degree C. You have nearly approx. 98% + water at these temperatures.

Archenemy_6 - 26-2-2017 at 12:35

I'm not dissing solids I've just always liked liquids better.
I've seen plenty of resources on how to make homemade solid rocket motors. Seems fairly straight forward.
I'll definitely check out local clubs if there are any around here.
and liquids definitely seem doable on a smaller scale and it just sounds cooler than solids.

as far as picking sodium chlorate it seems reasonably priced and easily obtainable There's some on amazon. Perchlorate doesn't seem as easy and I would feel weary about ordering straight ammonium nitrate.
Sure it's not the best there is but does it sound reasonable?

macckone - 26-2-2017 at 13:02

Go hybrid with nitric acid if you want to go the
liquid oxidizer route. Otherwise nitrous oxide
is used as a lower power oxidizer that is more
appropriate for model rocketry.

If you are doing it for the 'sounds cooler' factor,
just don't. Stick with solid fuel rockets until you
have the basics down.

Liquid fuel and oxidizers get into pumps and
control valves and those are not easy.

*edited for formatting

[Edited on 26-2-2017 by macckone]

Archenemy_6 - 26-2-2017 at 13:30

I appreciate the advice. It's about what I expected.
I will look into.

Dr.Bob - 27-2-2017 at 20:17

Most perchlorates are regulated as components of illegal explosives, so that is why many are hard to get. You can buy a pound a year without issue, more than that, and TLAs show up at your house. But find a rocketry group, they will know the issues and what you can and can't do without problems. Much like fireworks, there are lots of regs, but you can still get things done if you know how to work within the rules.

Liquid fuels and oxidants are pretty exciting to work with, I wish you good luck. If you really want a challenge, try nitrogen trifluoride as the oxidant. You can pretty much use anything as the fuel then: kerosene, paper, wood, rubber, concrete, asbestos or sand are all good fuels...

yobbo II - 28-2-2017 at 07:11

The nitrogen tirflouride is a great idea once you figure out the container.