Random Worldbuilding Questions (Biology, Geography, Society, etc.)

[Bryn]

Early airplanes almost universally used wood frames and cloth covering, with the notable addition of dope, which is an unpleasantly noxious and highly flammable chemical compound that shrinks the cloth tightly for higher strength and lower drag. Not sure how easy it is to synthesize at a low tech level, but it's probably not strictly required.

Thanks, I didn't know about dope! Synthesising nitrocellulose or cellulose acetate seems to involve quite a lot of steps, so that's out. Wikipedia says that before nitrocellulose etc. were used, people tried sago starch and rubberised fabric, and this wasn't very good. Since I can't find anything on how easy it is to make rubberized fabric, I guess I'll go with sago, and maybe mention that the aircraft need to be re-starched frequently.

Well, ornithopters are tempting, but highly impractical without stupidly advanced materials and a lot of in-depth knowledge. So if the birds understand aerodynamics well enough, they would probably just skip to the simplified gliders that just use the basic idea of lift.

Right, I wasn't thinking of ornithopters! Just that knowledge of aerodynamics sufficient to build functional aircraft could be obtained on a timescale less than several hundred years, by discussion with the birds and the wind.