 Beginning in January 1944 , training exercises were conducted carrying the Tetrarchs and their crews inside Hamilcar gliders . These exercises were successful ; during the training by ' C ' Squadron of the Glider Pilot Regiment , which specialised in flying the Hamilcars , over 2 @,@ 800 lifts were made with an average of 50 lifts per crew . Only three incidents resulted in fatalities or injuries , with seven pilots killed during the training . When the Tetrarch was re @-@ designated as an airborne tank , several changes were made to its design . A number of tanks had their 2 pounder guns replaced with a 76 @.@ 2 @-@ millimetre ( 3 @.@ 00 in ) infantry support howitzer ; these tanks were then designated as Tetrarch 1 CS ( Close Support ) . Additionally , Littlejohn adaptors were added to those Tetrarchs which still possessed their 2 pounders to increase their muzzle velocity and armour penetration . 
