Ive gathered and organized various parts to be easily tested for durability. simply drag and drop the weapon and target(s) of your choice, be sure to enable "show damage" and fire away.

Controls (yes this has controls):
gear 8: guns, cannons, and rockets enabled
gear 1: deploy parachute
gears 2, 3, and 4: missile launch
gear 7: target weapons (dont press this unless you want a prolonged self destruct)

analysis:
tl;dr theres not a lot of ways to effectively reduce damage or improve your crafts durability without xml editing. explosives are pretty much instant death, and guns can chew through your aircraft fast. that being said, i dont have direct access to code, and the results here are based on limited testing.
-out of all the parts, blocks (floating, normal, straight, etc) can seemingly take the most damage.
-gun damage appears to be very, very random.
-parts with fuel wont explode but seem to break down faster.
-parts with dead weight do not seem to block significantly more damage than normal.
-parachutes, when deployed, will fall off when damaged.
-when a part is destroyed, surrounding parts are also likely to be destroyed or otherwise disappear.
-weapons and bombs when destroyed wont reliably explode, unless damaged by other explosives.
-explosive cannon fire will always deal critical damage and destroy the craft.