 Rockets described in the "Huolongjing" were not all in the shape of standard fire arrows and some had artificial wings attached.An illustration shows that fins were used to increase aerodynamic stability for the flight path of the rocket, which according to Jiao Yu could rise hundreds of feet before landing at the designated enemy target.The "Huolongjing" also describes and illustrates the oldest known multistage rocket; this was the "fire-dragon issuing from the water" (huo long chu shui), which was known to be used by the Chinese navy.