Lilium and the thirty-six ducted electric jets that went bankrupt before they could prove the physics
Lilium bet everything on 36 ducted electric jets, went bankrupt, and is now attempting a comeback under new ownership.
Vectoraerospace startup
Hermeus and the Mach five reusable aircraft that wants to make hypersonic flight routine
Hermeus is building a Mach 5 reusable aircraft using combined-cycle propulsion, with military contracts funding the path to eventual commercial hypersonic flight.
Vector