This early success convinced the Japanese commanders to continue the "kamikaze" attacks. Many more pilots were recruited to act as "kamikaze". Over the next few months, more than 2,000 planes made such attacks. When the Japanese stock of airplanes began to run low, new models of low quality were built for these missions. Some of them, like the Nakajima Ki-115 "Tsurugi", were made mostly of wood and used stocks of older engines. The plane's landing gear was usually dropped by the pilot after takeoff so it could be used by other aircraft, because he would not be landing again. Similar suicide attack programs were planned, including rocket bombs with pilots (called "Ohka") and submarine torpedoes ("Kaiten").