引用・参考資料等 https://web.archive.org/web/20120408211614/http://www.vectorsite.net/avcobra_1.htmlhttps://www.quora.com/In-attack-helicopters-like-the-AH1-it-appears-that-the-gunner-obstructs-the-view-of-the-pilot-How-does-the-pilot-see-in-front-of-the-helicopter
http://www.nicovideo.jp/watch/sm45015641
