Hi Sixgun
First off - look behind you !
I had what I thought was the same problem the first time that i tried it too - trust me, the smoke IS dropping, it just takes a few seconds to start "billowing". If you go to "Command" view and zoom around so that you're looking behind yourself you will see the smoke spewing out all over the ground.
The problem I think is the limitation of the "drop" command - the actual effect is created by only a few small particles which look dense only when they're all together. When the shell is falling the "trail" consists of only a few particles at any point in the line. Of course, once the shell hits the ground it starts to billow nicely !
I combined my little marking runs with Manual Fire and a follow up rocket attack - lots of fun ! I've mapped my Look Around and Command views to convenient keys (for me at least) - after I drop smoke i jump in and out of Command vew to check my aim, then turn around for the follow up attack.
BTW - after I threw the script together I thought about how much fun it would be with a custom sound effect (hiss and fizz in the cockpit as the grenade is primed and dropped), a "hit" event handler to create much louder pinks and banging noise when the ground fire hits you and some sort of extra routine attached to the smoke script to direct your gunship buds to drop down and service the target !
If you ask nice maybe Santa will come early this year !
Cheers
Roni