For both motors the grains were used as cigarette burners. In the ZA5-9 motor, 2 grains were used, inhibited with rubber tape. In ZAS5-10 one single grain was used, coated with polyester. The void between grain and nozzle was in both cases filled up with zinc-sulfur powder 3/1.

Although the same propellant composition was used (Zn: 70%, S: 25.5%, Al: 4.5%) the difference in propellant grain density in both motors is remarkable. The theoretical density is 4.2. This means that with ZAS5-10 were are at about 95% of the maximum density.

ZAS5-9 and ZAS5-10 (see drawing below) are both zinc-sulfur-aluminum rocket motors. The main characteristics are given in the following table:

 
As can be seen from the table, the SS304 nozzle was severely damaged, while the graphite insert in ZAS5-10 is completely intact. This indicates that the damage is merely caused by high temperature and not by the erosive action of the solid particles.

The Isp value in both tests only differs by 2%. The Isp is calculated based on the total amount of propellant: powder and solid grains. From the powder we know that in this type of nozzles the specific impuls is about 40 s. If this holds for this type of motors than the Isp of the grains ranges around 54 s.