Could a combustion engine powered auxiliary power unit (APU) be installed on a quad rotor aircraft that is light and powerful enough to maintain a charge of the main battery that is used to power the motors and avionics? In other words, could a small engine powering a generator keep up with the electrical demands of the aircraft that would have to carry it and the fuel?
Here is a link to a company that produces generators for conventional RC aircraft:
Food for thought at least.
Replies
Very interesting concept however!
That is exactly right Justin. I can't see how it's possibly conceivable to build a gas-powered quadcopter that is simpler and more reliable than a gas powered helicopter. It really is a solution looking for a problem.
IMO, it's just an example of how quadcopters are in fashion right now, and everybody is trying to fit a square peg into a round hole.
A gas powered quadcopter is going to be heavier, have less disk area, and have 3 times more failure points than a gas powered helicopter. And it will probably also fly worse.
Electric fixed pitch multirotors are great. But if they don't meet your performance requirements, then there are other platforms that will.
Oh I agree the gas powered Heli wins hands down.
I am however very very good at tuning gas motors and I wouldn't use nitro. You could keep the copter afloat by using just timing advance and retard on a conventional 2 stroke and use a lot less throttle for control.
Oh heck perhaps I will give it a shot just for fun!
Doooo It!!! ;)
That would have a major cool factor. Unpractical, but seriously cool.
I couldn't agree more.
Multi's are easy....Well, they are supposed to be. No matter what you do, there is immense complexity in any thing that can take off vertically or hover.
I think the major craze with multi's is the fact that most people would prefer to tune electronics than they would a mechanical set up. However, I think many people fail to realize that they often have more incidents due to a bug, new firmware, a faulty esc, a faulty bullet connector, a fault motor, etc....
I think if more users had experience with conventional heli's they would realize that they really aren't at all more complicated, simply a DIFFERENT type of complicated.
As I responded below, simplicity goes right out the window when you add a gas motor. It makes me wonder how many people have tuned a gas motor, or had trouble starting a nitro or gas engine on a cold day (or even the same day, after flying in the morning and then trying to fly in the afternoon). Once that gas motor is on the multi, all simplicity is gone, whether it is 4 gas engines, 1 gas engine driving 4 props, or a hybrid.
I've been flying rc planes for years and sometimes in cold conditions and your right they can be a pain in cold weather. HoweverI found that adding a small amount of regular gas in the nitro full alleviated cold start problems. I recently got a 4 stroke Saito and that things starts instantly every time with little or no adjustments unlike the 2 strokes. Not sure if a 4 stroke could be used on a conventional help though? Lots of torque.
That was my recommendation a while back during a lengthy discussion on the potential for fuel cell power supply. Gas/electric has been around a long time powering trains (diesel/electric) and hybrid cars. I think it's the way to go for long-duration multirotor flights. I imagine it all boils down to weight.
Given modern battery technology and the innovations in brushless motors, gas hybrids are still the elephants in this hobby.
LOL. Maybe in another 25 years electric systems will hold a candle to IC.
Right now the energy density of batteries is around 1/100th that of gas.
We've discussed the whole hybrid multicopter idea before. The calculations seem to show that you could *probably* get one to fly. It would have to be around the size of a golf cart, cost several hundred thousand dollars, would fly terribly, and be horribly inefficient.
It would still be four motors powered directly by a battery. It would just be carrying a payload consisting of the APU and it's fuel. Yes the generator would have to provide enough juice to keep up with the constant demand but would not have to produce "full throttle" demands. The battery could absorb a few minutes of that. I just wonder, as you scale up in size, would it eventually be possible and effective to trade a majority of the battery weight for an IC powered APU and fuel? I'm not trying to get a "free lunch" since all things comes at a price and it would eventually run out of fuel.
Now, to me a variable pitch IC quad sounds like that would take most of the advantages of an electric powered quad out of the equation. My initial thoughts are that the drivetrain and pitch control adds so much weight and complexity that you might as well go with a conventional helo design. It would be neat to see though.
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