As a student in aerospace, this is an awesome game. Some things I really liked:
-Variable environments
-Variable gravity (seemed like it)
-Interesting missons, especially cargo
A few things that could add to the game:
-While your stats list was good, some of the items were not shown (ie head fuel/power/etc)
-Add a weight fraction, not just weight: ie, right now, it was usually best to stick with default fins and head, since they had lowest total mass, and did not affect streamlining. A good way would be to have higher end components to have a lower mass than default, but with same attributes.
-Aerodynamics: Yes, that sounds about right.
-Fuel: Do your gravity/excess power/vertical acceleration equations take into consideration the expended mass of fuel? I understand this may cause problem with all the "fuel +1/+2/+30" bonuses. A way around this would be to assign a specific propellant power per weight to fuel, the bonus would be to increase the power to weight of the fuel.
-Clutter: Well, those are cluttered skies! Maybe just a tad bit less cluttered? Using boosters becomes completely useless when you hit everything. Having a debris-clearing gun/shield would be nice...
-Velocity: While the Vertical Speed Indicator and "normal" arrows were useful, a greater range would be good (negative VSI range). Also, the 1200 mph speed achievement could not be attained, even using all best power-to-weight and simple max-power components.