Gasoline engines for homemade "copters" and helicopters

Question

Do it yourself

When reading DIY, I often see how people build quadcopters. Everyone has a problem with battery life. Why are internal combustion engines not used? Do Khabarovsk residents have experience in assembling helicopter-like things with non-electric engines?

I'm interested because I want to assemble a small helicopter with a long flight time from one refueling (40 minutes).

Answer 1

40 minutes is quite realistic to reach on an electric quadric. Take 4S batteries, something like 8000-10000 mAh (two batteries can be paralleled) with a low C-rating (you don't need a lot of current, minimum weight is important), disk motors under 300-400kv, and carbon propellers about 17-18". All this on the lightest possible frame (two 12mm carbon tubes glued with a minimally sized central plate), with small regulators (10-12A is enough), well, whatever controller you want on top - the same MultiWii, APM, Naza, there are many options. such a frisky copter will not work, but it will fly long and persistently.On
our forum (fpv-community.de), a local craftsman flies for 96 minutes on a single charge - however, he generally collected his own battery from separate Philips AA cells (video: vimeo .com/67425568). With a standard 4S battery and FPV equipment (camera, transmitter), he flew for almost an hour, and he flew, and did not hang in one place (video: vimeo.com/66010657 ).

Answer 2

I am not a pro, the same in fact interested, but at one time I got the pros with similar questions.
I will share what I know on the topic, although in some places I may be mistaken / mistaken.
There are two main types of internal combustion engines - gasoline and "nitromethane" (a fuel mixture that includes oil).
The former are usually large and heavy, the latter are an order of magnitude lighter, almost comparable to electric ones.
Helicopters for both of them are mass-produced. There is no special point in collective farming your own, because. to surpass good serial numbers in terms of performance characteristics, if with direct hands it will be possible, then not by much. However, helicopters have such a feature - the engines operate mainly at certain "cruising" constant speeds, and the flight is controlled by a swashplate and changing the angle of attack of the blades (the tail rotor also changes the angle of attack, if we are not talking about "room" models).
With copters, the situation is different - they are not made on ICE (maybe someone does, but these are rather exceptions to the rules, or large models).
The reasons for this are many. So, offhand, there are two options for using it:
1. It makes no sense to put an engine on each beam, because it is necessary to constantly steer the speed, and the internal combustion engine has an unstable and slow response time to the “gazulka”.
2. One engine, distribution of torque to the beams and variable pitch on the blades - expensive in terms of efficiency, because the transmission, CV joints or angular gears, plus angle of attack control - too much mechanics. Expensive, noise/vibration, wear and tear, amount of damage even in minor incidents, etc.
Among other things, firstly, other commentators have already pointed out that too much fuel needs to be taken on board in relation to the total weight / volume for the same 40 minutes of flight. And secondly, if you want to do something long-term, you will have to do it on a gasoline engine, and at the same time the model will be very large and heavy - in the event of an incident, you can demolish someone's house. Here you can kill with a small electric model if the pilot is a beginner ...
In conventional designs of copters, they put an electric motor on each beam, the engines have a rather quick response to changes in speed, the efficiency of the engines themselves is also quite good.
Something like that.

Answer 3

In my opinion, if you really do it on gasoline, then it’s not a quadrocopter, but a hybrid - a main rotor on gasoline (better, of course, two coaxially), but to steer with electric ones like a regular quadrocopter.
I would start the calculations from the minimum power - with an attempt to provide such a design with a safe landing on each of the systems - i.e. if the petrol one cuts out, the electric ones should be enough for a soft landing and vice versa.

Answer 4

Big vibrations.
The complexity of the design.
From one refueling 40 minutes is unlikely to succeed, most likely it will be closer to the same 20 minutes.

Answer 5

If you figure it out like that, then I think the engine from a 750 watt lawn mower will work.

Answer 6

As I understand it, the point of a multicopter, compared to a helicopter, is to avoid the use of swashplate and other mechanical control of the propeller pitch and achieve the same effect, in terms of controllability, by using several engines and separately controlling the thrust of each engine by controlling it turnovers. Electric motors are needed here - they have the simplest dependence of thrust on the control input and zero delay in response to the control input. An additional "bun" of using a normal "non-mechanized" propeller should be a little more thrust , compared with a helicopter propeller of the same area at the same speed, and a slightly greater efficiency.
So there is no point in building a multicopter on gasoline engines.

Answer 7

Just a thought to control instead of changing the angle of the blades:
Use viscous couplings to transfer torque from the motor to the propellers. To change the speed, brake the desired screw with an electromagnet and some kind of loop over the screw shaft., You can pulse.

Answer 8

Is it possible to put a gasoline engine with a generator for make-up in parallel with the batteries?

Answer 9

And if you put the main carrier gasoline engine in the middle, and on the sides there are 4 controlled propellers from an electric generator? Why not make helicopters this way? By the way, similar helicopters were in "Avatar"

Answer 10

there are projects of hybrid copters, where the internal combustion engine turns the generator, and the electric motors of the propellers are powered from it

Answer 11

There is a non-hybrid bicopter with an internal combustion engine. Control is being worked out and the controller is being adjusted