SOLAR PLANE PROTOTYPE

This Solar Plane is a prototype UAV inspired by Solar Impulse 2 (SI2), which flew around the world, setting many endurance and distance records, including some all-out records for any aircraft. Some aspects are taken from SI2, and others from human powered aircraft, but also from personal experience in long endurance UAV design. It was entirely designed in 2D and 3D CAD. All parts are machine cut and printed. It uses Sunpower Maxeon c-60 solar cells and will use Li-Ion batteries for energy storage. As of the time of publishing, the aircraft has not flown, and has been designed in the best way we know how, but we do not have any performance expectations, or projections. So please don't ask, because we don't know.. :) Any suggestions are appreciated, especially on how to deal with solar charging of the batteries in flight as well as power management, electrical system architecture, etc. We would also appreciate any specific Arduplane tuning tips for such large and slow aircraft.
Specs: 4.6+m
70 total solar cells
electrical configuration:
23 cells right wing and part of center wing section
23 cells left wing and part of center wing section
24 cells horizontal stabilizer, rear of fuselage and part of center wing section
so, the solar cells are split into 3 arrays. This was done to keep voltage at reasonable levels, mitigate the inevitable shading from the vertical stab from having too much of a negative effect on the total solar production(to avoid having ALL of the cells in series) and to account for possible damage, or failure of one of the arrays for any reason, and make sure that there is some redundancy in the solar production system.
so the maximum power point for a 23 cell array is 12.65volts DC, the same max charging voltage for a Lithium Ion 3S battery. The hope there is that direct solar charging can be used during the day, and that the battery can be fully charged at the point in the evening when the solar power in no longer generating enough power to keep the aircraft aloft, and the batteries are needed. This is referred to as solar evening.
We are hoping that we can use direct solar charging, however.. We are open to options for MPPT charging. If the aircraft can survive the night aloft, the maximum power point of the cells will not match the battery voltage, which will mean that a boost MPPT converter must be used, or a normal MPPT controller may be used all the time with all of the cells in series, which can be configured by simply changing the central joining harness for the solar cells from a parallel harness to a series harness. Suggestions please...
We have it set up currently with Iflight Xing 28 x 6.5mm motors, 1800kv(obviously we will be tuning the PWM output to the motors much lower to run them at much less than full power, especially because we're using 10x 10 APC thin electric props, which are much larger than the motors were intended to be used with)
We plan on adding two more motors, for a total of 6.
We are currently trying to decide on a landing gear configuration as well, so open to ideas there too for launch and recovery.
the stabilizer is a lifting type, but has a thinner section by percentage of chord to the main wing.
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Also see our video on solar aircraft design if you are interested:
   • How to Design Solar Powered Aircraft for P...  

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