ANCP Ammonium Nitrate Composite Rocket Propellant
ANCP is a powerful rocket propellant that primarily consists of ammonium nitrate and magnesium powder roughly 60/20. Although not usually necessary for amateur motors, the pure ammonium nitrate is stabilized by adding 3% zinc oxide while the ammonium nitrate is in liquid form.1 This Phase Stabilized Ammonium Nitrate (PSAN-I™) was developed in order to stabilize the propellant over temperature cycling, as ammonium nitrate tends to expand each time it is frozen.2 For a long time, ANCP was known as a cheaper, slower burning alternative to the well known APCP propellant. Historically, ammonium nitrate was used as fertilizer extensively in the US and was easy to purchase at low prices. APCP propellant on the other hand, had been considered explosive by the BATFE. Recently however, APCP is no longer considered an explosive by the BATFE, while ammonium nitrate has been almost completely pulled off of the fertilizer market due to its unfortunate role in terrorism.
Typical Ratio:
ammonium nitrate ............................................60%
magnesium powder ..........................................20%
Advantages:
- Good performance, fast burn rate possible
- Steady, reliable burn rate
Disadvantages:
- More expensive compared to sugar propellant
- Harder to get than candy/sugar propellant
- Magnesium more expensive than aluminum powder
- Limited information available
- Harder to ignite
- Slower burning than APCP
Cautions:
Mixes with fast burn rates can rupture the motor in an explosive manner if the casing strength is insufficient or the pressure and rate are incorrectly calculated.
Interesting Facts:
There are a number of additives, binders and techniques that greatly enhance the performance of ANCP powered in mid sized rockets. Some of these include: using a very fine mesh magnesium (1000mesh) and adding a small amount of ammonium perchlorate. Particle size of the oxidizer and fuel should be quite small to get a burn rate comparable to APCP.
1. Adolf Oberth, US Patent 5071630 (http://www.freepatentsonline.com/5071630.html)
2. Wickman Spacecraft & Propulsion Co. (http://www.wickmanspacecraft.com/psan-i.html)
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