This is a special 
and rare picture
of the first prototype.
The X51 antigravity
rotorless helicopter,
landing on a top secret 
military area.

Why an expensive 
turbine engine 
could be replaced
with a new one,
experimental and
a bit hazardous?

Because we simply
have seen that the 
turbine engine is too 
expensive, too complex, 
too fragile and 
basically without 
a good safety to 
carry out the human 
life in the sky.