In article ,
says...

There is quite a possibility that the Flapper would also take off
without its wings flapping. In that scenario the flapping can hardly be
described as sustained flight.

The Wright Flyer needed a run down a hill. Was that not sustained flight?

If you fire a Super Hornet off an aircraft carrier to get it up to
speed, does that mean that it's not sustained flight when it maintains
airspeed and altitude on its own?


Sustained flight as an aircraft =/= sustained flight as an ornithopter

The Wright Flyer is not an ornithopter but an airplane/glider.

The Flapper (jet powered or propellor pushed) was claimed to maintain
flight / propulsion by the sole use of flapping wings.

It is not certain that it achieved that because it is quite likely that
the lift originated from the small wing combined with the flapping wing
wether the big wing was flapping or not. So it is not certain that the
flapping did contribute to lift generation.

Otherwise building an ornithopter would be quite ease: take a glider and
when in flight open the canopy and flap your arms. The glider won't fall
(immédiately) out the sky but I suspect that the armflapping will add
nothing but drag.

In fact the first claims for ornithopter were following this method by
iirc the same German engineer who develloped the Messcherschmidt Comet.
He added clapping paddles to a glider.

Tom De Moor