" . . . to be able to drop a tank into a battle with troop transporter would be great . . ."
Hoho, the Hamilcar was intended to be able to carry a small tank into action. A light tank weighing about five tons was developed for it; first test-flight, the tank fell straight through the bottom from a few hundred feet up. Wheeeeeeeeeeee . . . . . !
I was present when the RAF and Army got their heads together in 1970 and came up with the idea of dropping heavy loads by deploying parachutes at ultra-low level to drag the load straight out of the back. First load they strapped onto the pontoon was a Land Rover, and away went the H.S. Andover to try it out. The aircraft roared low across Old Sarum airfield, down went the ramp, out came the load - and it dug nose-in, somersaulted once and then slid upside-down what seemed to be half the length of the airfield. Took the JATE boys a couple of hours to drag away the mess (the Land Rover was about two feet high when they got the pontoon upright) and rather longer to fill in the trench so we could continue flying.
The Boss' comment as the mud, grass and bits of Land Rover flew through the air was priceless: 'Hmmmm, doesn't work. And just look what they've done to my lawn.'