"The back of the envelop calculation gives indeed around 100w ( mechanical ) for a level flight at 10Km in a stable air. One of the challenge is to be able to have enough mechanical power left at that altitude, because you will need a propeller…"

"@patrick, your softwares are excellent ( I have a multi element airfoil licence that I acquired when the price was lower!) but they are beyond what an individual can afford. I understand you try to protect your revenue stream, but it would be great…"

"@zhanggi
with a small piece of paper, high school math and physics and a pocket calculator you can compute approximates for a lot of physical data!
my comment on flexibility was that your current system is about 2KW so, on one end, if the need is,…"

"with a back of the envelope calculation, it should use around 2 liters of gas per hour, which means that durations above 15' benefit from that approach for that configuration. the main drawback is that there is little flexibility in the power…"

"@Gary. is that the "wing" project you are talking about? I read some rumor but from people directly working there it is business as usual..."

"interesting study!
I have approached the efficiency problem from the fixed wing point of view.
first I came to the conclusion that the range is not the factor to optimize I prefer the range x speed. you want to fly far and fast. optimizing is always…"

"never is a long time, especially close to the end...;-)"

"@Andrew Rabbitt. I would be interested too to see your approach of the climb and glide.it seems you consider the gain comes from the better efficiency of the propeller in climb vs cruise. why would that be?"

"I answer to myself on flying in circle. from the picture of your flying site I see that the radius is about 600m, which means that at that speed it is about 2N centrifugal force. the average banking is then 2 degree which result in a difference in…"

"impressive, congratulations!! I wonder if you have compared flying in circle with a rectangular path. in theory flying in circle is a little bit less efficient as to generate the lift to offset the weight you have to either fly faster or with a…"

"@Damian, I do not understand. you say that the plane would fly faster that the pitchxrpm speed. I thought it was never the case and that the propeller <100% efficiency was coming from the fact that it was "slipping" and so the pitchxRPM was always…"

"as for the 3S vs 6S, I think the only real advantage is to lower resistive loss. very rough evaluation:  if during cruise you are @ 100w and your total resistive path ( batteries, contacts, cables, on resistance of the Fets, motor ) is 0.1 Ohm…"

"@ Damian, I am curious. where does the 70W come from?with 20AH and 3S you have around 800KJ. the flight being 100min that's about 130W average power? if your assumption is true on the L/D ratio the mechanical power needed is DxV so around 33W the…"

"why not?
more complex
more expensive 
heavier
less reliable
less energy efficient
drive system from a central engine = lots of destructive vibrations
...


in fact one could claim that the only multicopter advantage is mechanical simplicity thanks…"

"does it mean that normal RC airplanes will be now limited <50m altitude? that would be the end on the hobby. try to do a loop with a 2.5m wingspan airplane and stay under 50m or fly a sailplane under 50m...nonsense... if the next slice (50->150m) is…"

"looking at the spreadsheet the overall drag is just the zero lift drag ( considering that it is a coefficient for the full airframe with the wing area as a reference area?? ) plus the induced drag. I do not know how the zero lift coefficient is…"