Frankenheli project

[DMfrench]

I got a DX7 radio, and have been able to get most of my models easily programmed into it. All that is, except one, my frankenheli project...

Basically, I want to control a Walkera #4 fixed pitch heli using a spare eflite 4-in-1 I have from a Blade CX2 coaxial, so I can fly it with the DX7. I was able to get the servos are working properly, but I'm having trouble figuring out how to control or program the main motor and tail rotor motor to remove the onboard mixing from the eflite 4 in 1. I have the motors plugged into the two motor plugs on the 4-in-1, but that really doesn't work right because it mixes between the two motors to gain control of the tail. When I give it some rudder input, it speeds up one motor and slows the other just like in the CX2. That's not good on a single main motor setup. To turn, the tail rotor motor speeds up, but that also slows down the main motor.

Does anyone know of any programming tips, or different setups, so that I can get control of the rudder without slowing the main motor? I don't want to spend much money on new electrics. This is just a beater that I'm trying to put together with spare parts. Thanks,
Dave F.

[widower]

I'm not familiar with the 4in1. I presume it has a gyro, mixer, esc, and ???. It's just a guess, but maybe you need to purchase a new esc to drive your rotor, and use just one of the motor outputs on the 4n1 to drive the tail. That way, if there is a gyro, it will help stabilize the tail.

[DMfrench]

Thanks,
The 4 in 1 is a receiver, main motor mixer (because a coax uses two main motors and no tail motor), esc for the motors and a gyro. If I use a separate speed control for the main motor, what would I plug it into on the 4 in 1? It has L and R motor plugs and two spare three prong channel plugs.

I've thought about the separate esc, but just need to figure out how to plug it into the receiver. Plus, I really don't want to throw any money at it, this is really a spare part project. So, I'm not opposed to the idea of splitting open the 4 in 1 case to disable the mixer function. Anybody got ideas on how to do that to the 4 in 1 from a CX2 without affecting the receiver, gyro and escs?

Dave F.

[widower]

So it sounds like you could use one motor connector to drive your tail motor (because of the integrated gyro). One of the motor outputs will probably be reversed so you need to choose the correct one. Then use one of the free channels to an external esc and the output of the esc to your main motor.

I doubt that opening the 4-1 will be helpful because they probably have a uController like a PIC that is implementing the motor driver cct. There's probably 2 pins from uController that drive a 4 transistor bridge that drive the 2 wires on 1 motor. I expect that the bridge will not be anywhere near strong enough to drive your main motor.

[LockMD]

So it sounds like you could use one motor connector to drive your tail motor (because of the integrated gyro). One of the motor outputs will probably be reversed so you need to choose the correct one. Then use one of the free channels to an external esc and the output of the esc to your main motor.

I doubt that opening the 4-1 will be helpful because they probably have a uController like a PIC that is implementing the motor driver cct. There's probably 2 pins from uController that drive a 4 transistor bridge that drive the 2 wires on 1 motor. I expect that the bridge will not be anywhere near strong enough to drive your main motor.


I read over this pretty quick, but I agree it will not work as wanted. You will need to by a single rotor 3-in-1 and a seperate rcvr (ar6100e) for that to work. Well that is what I had to do for my HBFP which had a 4-in1 in it as well.