I calculated an 0.6:1 thrust-to-weight ratio to choose the motors (cruise). So for a weight of 6 kg, I estimate a 3600 gf divided by 3 motors = 1250 gf per motor. According to the table above, I will have a current draw of 7.8 A and 174 W per motor (23.4A 522W total).
But on the other hand, I read a rule of thumb of 100W per 1 pound (13 pounds = 1300 W), so I am a little bit lost.
I would appreciate your help to understand the current draw and power consumption in order to choose the correct battery for the target flight time (6S).
Hi Fede, I have the Ranger2000 and my MTOW is 2.5kg. I do not think it will fly very well at 6kg if it would fly at all!
On the other hand, when you size your motors for a vtol, take into consideration that you need to lift that vertically, so you need a power system able to lift at least 10kg for a MTOW of 6kg. The closer you are to 2:1 thrust the better your chances to make it work!
That is not true that it will not fly well at 6 kg. Any plane will fly well if it is brought to a good speed above stall. However, if the plane is “bulky” with a lot of drag, it will require much more power to be brought to that speed. Volantex is intermediate in this sense.
However, you will have several problems with a plane at 6 kg versus 2.5 kg.
First, the spars may suffer… (wings could fold)
Second, the overall speeds will be about 50 % faster, so stall speed and transition speed would be 50 % higher. Any mistakes in transition setup which would lead to a sloppy transition at 2.5 kg will lead to a fatal transition at 6 kg. And flying 50 % faster means that you have to be much better at controlling planes.
If it is your first project, 6 kg will never pardon your smallest mistake (and you will have them guaranteed!), so maybe it is not such a good idea…
