I'm sure there are other ways. This worked for me.
Save a copy of your database so you can try again. That's what I did till I understood what's going on. I also found that a small number of marine companies is nowhere near enough troops for most ships. My troop transports are in the same task group with the dropship carriers plus assorted escorts. All ships go ~ 3000 km/s. The troopships are also 5 battalions capacity. For practice: Move fleet to near where you are going to launch dropships ie a moon, planet, waypoint etc:
On Task Group window
System Locations Available Actions AvailableWaypoint #1 Move to
Waypoint #1 Load GU into DropModule within Fleet ( this action should be available if you have troops in Task group)
At this point a new box should open up "Select Ground Unit". Highlight a particular Ground Unit and select "Add Move"
Plottted move should show "Combat Load xxx Company or Battalion from within own fleet"
When you move to the next turn, your events should show the Ground Unit has completed orders. You can check your dropships by clicking on them and you'll find the one holding this particular unit on the Individual Unit Details page under Parasites/Cargo/GU.
After several attempts, I had 100% casualties each time. Usually shotdown or splattered on the hull
. I increased dropship speed to 10,000 km/s and had better results. There were a few surprises along the way but I did capture that first ship. A nice one too.
Lessons learned:
I had fun figuring out what to try and not try.
Dropships need to be fast.
Don't leave troops in the dropships too long.
Bring more troops than you think you need.
Don't leave task group too near the target. I want to capture it, not destroy it or be destroyed.