固体燃料引擎比较简单，也比较便宜，其猛烈的推力来自于燃烧预先混合好的燃料和氧化剂颗粒，它们像磨好的咖啡粉一样，装在圆筒状的容器中。

• Simpler and cheaper are solid-fuel engines; their fiery impetus comes from burning premixed fuel and oxidizer grains that are packed like coffee grounds into a cylindrical casing.