Zinc-Sulfur motors

General : zinc-sulphur powder motors

THE
OPTIMAL RATIO OF THROAT AREA TO OUTLET AREA FOR

ZINC SULFUR POWDER ROCKET MOTORS

   Antoon Vyverman VRO 02/09/2005

Zinc sulfur powder rocket motors yield a higher diversity of specific impulses than for instance KNO3-sugar motors. With the
same propellant composition the specific impulse may range from 25s to 50s. The reasons for the large spread of measured results have been attributed to several factors as powder density, particle seize, shape of the nozzle, the ratio between the inside motor area (or propellant burning area if considered as a cigarette burner) to the throat area, isolation material, etc... It was however unclear which parameter was responsible for which impact. So for instance, tests from GEA (Belgium) showed that small inlet angles of the nozzle had no
influence on the specific impulse, while on the other hand NER0 (The Netherlands) advocated strongly this type of nozzles because of better
performance.

In search for data I found a diagram I made in the early eighties. In this diagram the specific impulse was put as a function of  Ae/At. Because of a lack of data at that time no conclusions could be drawn from it. So I started looking for new data.  Especially the results
from zinc-sulfur powder 3/1 were interesting because I could dispose of much data essentially from NERO, but important information also came from our own tests of 2 large zinc-sulfur powder motors (ZAS9-1 en 2). In these motors we used an Ae/At ratio of 33.

The “reliable” data is depicted in the diagram. The Isp is calculated without taking into account the remains. The diagram clearly shows that an optimum is reached for values of Ae/At between 16 and 18. Between Ae/At values ranging from 0 to 16 the slope of the curve is quite large. After a Ae/At value of 18 the specific impulse goes down slowly.


 

The full story: optimal%20Ae_At%20for%20powder%20Zn%20S.pdf

General : zinc-sulphur cast motors

 

 

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Potassiumnitrate-Sorbitol motors

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Test report on the static test firing of Zinc-Sulfur cigarette burning motor ZAS5. More…