Here are the different combinations to make an airplane in Alchemy 2.

bat + machine
bat + metal
bat + steel

bird + boat
bird + car
bird + machine
bird + metal
bird + sailboat
bird + steam engine
bird + steamboat
bird + steel
bird + train
container + pilot
crow + machine
crow + metal
crow + steel
duck + machine
duck + metal
duck + steel

eagle + machine
eagle + metal
eagle + steel
hummingbird + machine
hummingbird + metal
hummingbird + steel
machine + owl
machine + pigeon
machine + seagull
machine + vulture
metal + owl
metal + pigeon
metal + seagull
metal + vulture
owl + steam engine
owl + steel
pigeon + steel
seagull + steel
steel + vulture