Originally Posted by mwtoelle

About the only places that I have seen the BT-52 used as an external tube are the Thor-Agena B (K-28), the Semi-Scale Saturn V (K-39/1239), and the Colonial Viper (1310) kits. BT-52 was more often used as a sleeve over the BT-50 motor tubes in several 'D'-powered kits. John Brohm's Estes tube reference goes into a bit more detail about which kits used the BT-52 as a sleeve. An interesting note is that the BT-52 used on the K-39 is actually a bit too small for the correct scale (1.014" as opposed to 1.081"). I suspect that Estes just used the closest available tube for that kit to save money.