1lb of c4, regardless of what material it hits, has the same explosive impact against all targets. Its how that target responds that changes. Unfortunately, even a scifi setting such as dust, physics still apply. The same explosion will cause the same amount of damage to a target regardless of its materials, and its a general physical limitation, that, since they fly, helicopters planes etc have less armor then a tank.

This also applies to derpships, seeing as though we might have hover capabilities in dust, the behicle in question would still require a generator of sufficient size to enable lift. This coupled with armor would greatly inhibit a vehicles mobility. So much like modern day, a balance must be achieved between the two. It would of course be possible to create a vehicle with as much armor as a tank, capable of flight, but this vehicle would be far far less maneuvaurable then a tank, as tanks only have to generate enough energy to propel them forward and backwards, while am airborne vehicle of similar weight and armor, would have to sacrifice the majority of its maneuvaurability to maintain VERTICLE lift, its horizontal movemt would be very slow\and or rather clunky and hard to handle. So, asking for one weapon to do less damage, is not only physics wise iimpossible, but also incapable of being argued that an airborne vehicle with the maneuvarability characteristics of a dropship, is better able to resist damage then a tank.

Second, In modern military vehicles explosive resistance comes from reactive armor whihc is desighned to take a hit, and project the blast away from the vehicle as best it can. This usually takes the form of plates that fall off on impact, much like modern cars crumple zones that are used to guide the explosive impact into.a non deadly form. The majority of. These systems are one time use plating. In dust shields and hardners perform along a similar principle, deflecting the blast away as best it can within limits, and are then used up till restocked\recharged.

Your a dropship, your ability to shrug off damage is much like a scouts; its not the ability to soak damage, but the ability to avoid damage, that gives you an edge. You already have an elevated position, stronger weapons and armor then any infantry, and are more maneuvaurable in all axises then anything else on the battlefield.

If we really want a realistic damage profile, let's take the AT4 anti tank weapon used by the us military. It can one shot even our own Abrams. Then there is the javelin missle launcher, capable of targeting both ground and airborne targets, has homing capabilities, and also one shots anything on the modern battlefield. Even classic rpgs can one shot most tanks, and disable all know vehicles. The only difference is that most of the vehicle their used against are desighned to insure their passengers and pilots survival, the vehicle is almost always knocked out of commision by a single strike. Its to bad your derpships arnt desighned that way. Oh wait, nm; you guys always survive your dropship being destroyed unless we hunt you down on the ground.