Extending range with petrol engines question

When I was going through a start up program the one guy built a petrol range extender for drones. It business idea didn’t go anywhere but I see some other companies are doing it.

I don’t plan on using this but fun to talk about it.
Has anyone done something like this?
Why don’t the human sized drones use this?
How would it work with the pixhawk?

200W/Kg, (for lifting and cruise)
200kg, 40 Kw needed
A lot of weight to add, so more power needed,…

Long range human drone need wings (for lift).

Petrol is around 9.7 kWh per litre, say per kg.
So having 4 motors run on petrol and 4 run on battery power so that the 4 on battery power does the steering seems like you will be able to go much further.

I agree to have long distance you need to go wing’s but if we talk about a possible future of ‘flying cars’ then you need a compact vehicle.

So combine petrol and batteries I would think is better than just the current battery vehicles.

Here are a bunch of flying vehicles. Some use batteries and some use jet engines. I am thinking if they use batteries + petrol on them they will get best of both worlds

Sure. One configuration is using a Boost Motor which has been supported for quite awhile:
Boost Motor

That is interesting.

From what I read props blowing through Props lose about 20% efficiency so I wonder how much you lose with this kind of configuration.

So you would kind of build a helicopter/quad. I don’t know easy it is to fly a helicopter pixhawk but it might become more efficient then to build a helicopter at that point. Documentation says it has to be centrally located.

What would happen if you have 4 located upwards where the electric motors are on the edges of the arms and have the electric motors face down?

So build an 8 motor drone but 4 petrol and 4 battery.

Quite a few companies now sell standalone generators or drones integrated with a generator, see Foxtech or Harris Aerial or Richen Power. There’s also fuel cells being used as range extenders, see Intelligent Energy.

Ardupilot natively supports telemetry from the RichenPower and Intelligent Energy range extenders mentioned above. See wiki here.

A buddy of mine did his thesis about this topic using a tubojet with a turboprop turbine as the generator.

Very interesting.

I don’t know why the big drones don’t add petrol engines.

Actually the bigger drone they use petrol hybrid. Petrol hybrid is between the area of efficient and inefficient.

Its more efficient than smaller drone and inefficient than any sort of battery operated drone.

But certainly it increases the distance and length of flight by 3-5 times.

Btw hybrid drones are just petrol generators that generate electric for the motors, the combustion does nothing for propulsion.

OK that is different than what the guy in the start up program did. I don’t know if his idea ever worked.

He actually added extra propellers and belts from the petrol engine to turn the propellers. I guess the idea was to spin them up just enough before lift off so that the battery propellers do the control