General Question about twin engine electrics

zenmetsu

Member
I haven't found too much information online about how twin-engine electrics are wired. I have a scratch built plane that I have been wanting to build for years and I decided to get off my butt and do it.

Do you use one large LiPo, power your receiver from one of the speed controller's BECs, and run both ESCs from this battery and their own channels on the receiver?

If anyone could provide a simple schematic, it would help me immensely in my planning.
 

zenmetsu

Member
OK, not 100% sure that this is the right way, but it works...

I have one 3S battery and I split the power leads to attach to both ESCs. I then hacked up some computer cables to make a "Y-splitter" to connect both ESCs to the throttle channel of the receiver.

This thing has a 68 inch wingspan, so I'll likely need bigger motors, but at least I believe that I have the electronics figured out.

- - - Updated - - -

Removed power (red) wire from one of the ESC's so that it is just connected to data and ground on the throttle channel just in case. I don't want the ESC to get flipped from 6V to 5V and run into issues with the other.
 

RCD

Glencairn Drone
It also helps if the motors are spinning different dirrections so that your plane doesnt torque roll with throttle
 

zenmetsu

Member
True. This is an asymmetric model though, so the torques will cancel out due to COG offset. I'll get photos up once I get the full size model underway. The little model glides well, and I am tempted to put small motors on it for giggles.
 

Lee

Well-Known Member
You have the right idea with the set up. Lets see this monster then.
 

zenmetsu

Member
Thanks for the confirmation Lee.

The main wing will be constructed of a 26" segment and a 42" segment, with the dihedral angle of about 8º formed at the intersection above the main fuselage. The auxiliary fuselage will house the camera and will be located more towards the middle of the main wing.

Ultimately I want to use this plane for photography and will want to experiment with FPV eventually. Since I am in the process of scaling up the model to full size, I am looking into materials. Everyone seems to use foam for the wings so I will probably go that route. The fuselage will probably be really simplified, but the tail booms will probably need to be fairly rigid. I am looking at carbon fiber tubing, but my experience is that these tend to not have very much torsional rigidity.

I'll see if I can get a photo of the miniature model while it is gliding.
 

Tony

Staff member
There are two ways you can do it. YOu can run dual batteries/ESC's/Motor's and use a Y to connect the two ESC's to the Rx. However, because the batteries are independent of each other, you can end up losing a motor in flight.

The second way is like you stated, one battery, Y to the battery wires on the ESC's, dual motors and a Y to the Rx. However, you need to keep draw in mind. Two motors are going to draw double the power. If you want to know what this looks like, watch the video below lmao.

The way I would do it is dual batteries (each enough to support both motors, so you have double the C you need just in case), Y the batteries together, then Y the connector to teh ESC's. This will give you double the run time AND will equal out the batteries so they are at the same voltage and have the exact same draw.

Rc Foam Fighters FF-22 Maiden Flight - YouTube
 

zenmetsu

Member
Thanks Tony.

I am not so worried about losing a motor. Asymmetry will increase stability with a lost motor. Instead of applying rudder and yaw to make the model fly straight, a little rudder is used and the model will fly in a slight crosswind sort of orientation.

Been toying with this design for a long time and have built it in simulators and fine tuned it. Making it a reality is one of my highest priorities now. I also am looking into FPV setups. I have my amateur radio license and can get a pretty decent video transmitter, but I am thinking I might have to drop down to 50MHz and get away from the Spektrum transmitter/receivers if I want any sort of range for flight control.

It's been a long time since I have done planes, so I will need to get a feel for matching motors to the airframe and finding what sort of flight times I can get away with.
 
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