Engineering Tech Tree

Do the Kerbals discover rocketry before winged flight? You decide. Both winged flight first and rockets first options.

Scope
A tech tree based on engineering/scientific principles that is challenging to unlock yet fun to play through.

Goals & Requirements
1. Branches of the tech tree based on engineering disciplines.
2. The Kerbals discover rocket powered flight before they figure out winged flight (or vice-versa).
3. Unlocking the entire tech tree is not required but must involve flights to nearby planets.
4. Parts that generate science are spread throughout the disciplines and are not based on which branch you focus on (e.g. Flight, Liquid fueled, Solid, Exotic).
5. The player may unlock just the branches that they are interested in.

Highly Recommended for FLIGHT FIRST option:
Firespitter, KAX, and/or SXT

Highly Recommended for ROCKETS first:
Interstellar, KW Rocketry, MRS, and/or SpaceY

Recommended for the tree overall:
DMagic Orbital Science to boost your science output.
Kerbal Engineer or MechJeb for delta V calculations.