I know what are empty weight and MTOW, which are data I need for my school project. But the website for Moller Skycar only shows the gross weight and net payload: https://www.moller.com/moller_skycar400.html.

But in the wiki for the same vehicle, it shows that the empty weight is the gross weight and the MTOW is the gross weight + net payload: https://en.wikipedia.org/wiki/Moller_M400_Skycar.

Could you guys please help me figure out what is the correct value for the Moller Skycar 400?

  • 2
    $\begingroup$ Considering that the whole project is basically vaporware, I wouldn't put much stock in ANY number. That said, "gross weight" is basically a "right now" value (the GW of this aircraft right now is ___), while MTOW is a limitation, and empty weight is (generally) a constant. If max payload + empty weight = MTOW, then they're including the weight of the fuel as part of "payload" (ummm, okaaaay...), or else somebody neglected the weight of the fuel. Since it's basically a bankrupt fantasy, who really knows at this point? $\endgroup$
    – Ralph J
    Jan 19, 2021 at 18:06
  • 1
    $\begingroup$ Yep. Vaporware... love that term. It's so perfectly descriptive. $\endgroup$
    – John K
    Jan 19, 2021 at 18:28
  • $\begingroup$ Wikipedia is a joke; it's a shame when questions center on it. $\endgroup$
    – Fattie
    Jan 19, 2021 at 23:50

1 Answer 1


First of all, Wikipedia does not regard itself as a reliable source, and nor should you. It is only as reliable as the last editor, and since it is the encyclopedia that "anyone can edit" (and frequently does, me included :-) ), that is not saying much. In fact the last editor to touch those stats has messed it up and the stats given do not match the sources cited.

An aircraft's gross weight is the weight of the plane and everything on board. Typically the maximum gross weight is also the maximum takeoff weight (MTOW), although a few planes can take on extra fuel when airborne so that their gross weight then exceeds the MTOW.

As stated in another answer, the M400 is just a recurrent daydream and all figures are estimates provided by the daydreamer. But, with that in mind, the daydreamer's own numbers are clearly the definitive daydream. In other words, go with the website.

  • $\begingroup$ Moller managed to get multiple prototypes into hover, the last one being the version with four nacelles and little stubby wings that was to be self-piloting (i.e. operator wouldn't need a pilot's license). His operating mode very strongly resembled the new wave of passenger drones, he just had the misfortune of being fifty years ahead of the technology. $\endgroup$
    – Zeiss Ikon
    Jan 19, 2021 at 19:31
  • 1
    $\begingroup$ He was my manufacturing methods instructor at UC Davis in 1974. His earlier flying car designs were suspended from the ceiling of the fluid dynamics lab where the wind tunnels were located. When not teaching in the ME department he ran a small company called DiscoJet that manufactured spark arrestor mufflers for use on off-road motorcycles. $\endgroup$ Jan 21, 2021 at 7:24

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