Flapping Flight

Although significant amounts of funding have been expended to understand and replicate natural fliers,
I believe the problem will not be solved until
we have the patience to understand it on a fundamental level.

Flapping-flight locomotion will most likely be solved by man in the same order it was solved by nature.

That is, it must be solved in water first.

1: Start Underwater

We must begin at high Reynolds numbers and low flapping frequencies.

Here we work out the problem in a naturally buoyant state, where failure is not catastrophic.

In this regime we understand the hydrodynamics, the unsteady effects are minimal, and we can focus on optimizing propulsion and control.

We bring together the complex systems required so that hydrodynamics, structures, and other systems work in concert.

2: Repeat In the Air

We must then repeat what we have learned in a non-buoyant medium such as air.

We remain at high Reynolds numbers and low flapping frequencies, but optimize propulsion and control in the air, where failure can be catastrophic.

This is similar to the behavior of an albatross: high Reynolds number and low flapping frequency.

3: Eagles and Hawks

Move to a lower Reynolds number and higher flapping frequencies, somewhat akin to Eagles and Hawks.

Study and understand the problem at this level.

This will stretch the fluids and dynamics, but can be understood as an incremental step from the previous solution.

4: Pigeons and Doves

Increase the flapping frequency and lower the Reynolds number again.

Build on the experience of the previous steps and stretch the tools and analysis to a new level.

5: Hummingbirds

Once again, increase the flapping frequency and lower the Reynolds number.

Learn to hover.

6: Dragonflies

We're now ready to enter the world of insects. Again, start at the highest Reynolds number and lowest flapping frequencies possible, and move down the chain.

7: Smaller Insects

At each of the forgoing steps, the tools and analyses will improve and expand until the most challenging problems of low Reynolds number and high-frequency flapping flight can be solved.

We cannot hope to solve these in the reverse order.
Doing so combines some of the most challenging problems of fluids and systems,
and attempts to solve them all simultaneously.
Such an approach has never worked in the past,
and won't work now or in the future.

The process for fundamentally understanding the aerodynamics, mechanics, systems, and structures of flight will require years of patience and persistence, and a methodical approach.