I hope I don't step on any toes here since I am a newbie to the forum.
I have searched the forums and have read a few different discussions regarding this topic so of course I know the idea is not a new one.
There was clearly some good information but it does not sound like anyone has yet succeeded in building a power plant that would work for the purpose.
I believe I have found the components that would be capable of doing the job. At least as far as a producing the raw power for the job.
My goal is to keep the generator package under 10Kg while producing 180 amps@18V continuous and a peak of more than 300 amps. All of this while carrying enough fuel to run for an hour+.
The problems I am running into are more to do with the electronics than the actual power plant.
I believe I have found the required alternator and engine combination to do the job.
But for this to actually work the gross power needs to be rectified and regulated into a form that is usable by the flight control system and the ESC's.
After that there is a motor control circuit required to actually run the generator engine to control the output in relation to load requirements. This system would have to monitor the capacity and charging status of the batteries and the amperage consumed by the drive motors allowing it to determine how much throttle to give the generator.
Finally the flight control module is going to have to know when the generator runs out of fuel to be able to use the batteries for a controlled safe landing.
The assumption is that with a generator on the rig batteries would be required but the amount of batteries required could be reduced by 50 to 75%.
The information I am missing is real world data on how much power is being consumed by a rig that can carry over 10Kg under different flight conditions. For instance I know of a 700mm class rig than can lift in excess of 15Kg running on 4 Turnigy nano-tech 5000mah 6S 65~130C Lipo Packs and 8 Turnigy G60 Brushless Outrunner 500kv motors. what I don't know is what the actual power consumption is for this rig when it is carrying a load while hovering and maneuvering.
I can run the theoretical math of what it could use as a maximum but the goal is not to provide the maximum power but instead to provide something that has a continuous power supply that can hover the rig and a peak that meets the majority of the requirements for maneuvers.
I appreciate any comments or input everyone may have.
I am new to this forum, but I am working on a similar concept. The system I am working on is less ambitious, but I hope will prove practical. I am using a Honda 35cc four stroke engine driving a Turnigy 160Kv brushless motor. The 3 phase output is rectified, smoothed and sent into a stripped, DC input 6s dual channel battery charger. The charger compensates for the wandering DC voltage output and so the motor is unregulated and operates with a fixed throttle setting. The charger provides the input to a pair of limited capacity batteries. The entire module will be exchangeable for the existing 4 x 10,000mAhr x 6s batteries. I am aiming at 6 Kg for the module.