MASJO

I came across this thread http://www.rcgroups.com/forums/showthread.php?t=852288 where brushless tail motor/ESC on a HBK2 and Belt CP have been run in parallel to the main brushless motor/ESC via a “Y” cable connected to channel 3 and using an already gyro/servo controlled adjustable blade pitch.

This question was asked in the thread:
Any thoughts on how this kind of tail system could be achieved on a 4 channel fixed pitch heli? Tail ESC in parallel with the main motor ESC?

So I went along with it. Well this is where I stand:
My WDF4 has been modified to a brushless conversion using a Powerzone chip. Link here http://tnim.bravehost.com/wdf4blug_stage1.html I also started this thread My WDF4 conversion has gone brushless http://www.rcuniverse.com/forum/m_7964933/tm.htm I have been running this set up since September 2008. Tail has been generally ok but unreliable. I have tried the dual tail mod that seemed to be reasonably ok but not perfect. I have not yet tried the DD tail drive.

Separates can not be done with a stock WDF4 RX. Since coming across the thread on connecting parallels I thought I would try this on my WDF4. I have a 3400KV Orca/25A ESC and Powerzone chip. RX and TX are stock. Since the Powerzone is connected to the channel 3 RX signal output, I would need to run a “Y” cable from the Powerzone to parallel a second (tail) ESC.

I really needed to use around a 1000-1200KV/10A ESC for the tail, but to just test this theory, using “jumpers” I hooked up the HBK2 in parallel, which also has a 3400KV Orca/25A ESC. The HBK2 in this test will simulate the tail. Because both ESCs are also BECs you would need to disconnect the positive (+ red) wire of the tail ESC. Static test was successful!

Now! I have a problem?
The WDF4 gyro is internal which increases and decreases the speed of the tail motor to achieve rudder direction. The tail motor being disconnected is of no use so therefore there is no control over the left and right yaw (rudder). With separates a gyro can be added, this cannot be done with the WDF4 stock RX so there is nowhere to add a gyro.

So again I “paralleled” the rudder servo with the aileron (fly bar paddle ch2) servo with a “Y” cable. Therefore when applying right aileron I would assume I will also be achieving right rudder input and when applying left aileron I would assume I would be achieving left rudder input Again static test was a success.

To complete my setup and do final testing I ordered the following from http://hobbycity.com. 1 x HexTronik 24g 1300KV, 1 x HexTronik 24g 3000KV, 2 x HXM2730-Mounts, Turnigy 10A ESC and 6 x HexTronik HXT900 servos. I've ordered 2 size kv motors to work with and compare. May consider a parallel tail ESC on my HBK2 as well.

I have no idea how the heli will perform. My guess is to get this little bird in the air and straight into forward flight. With parts on the way, and no gyro installed let me complete this mod and see what results.

For more info and pics link to my personal RC website here http://tnim.bravehost.com/wdf4_tail_esc.html

My WDF4 is already setup to receive its new parts. I will be back to update this thread when I receive my parts and complete the modification.

Pic attached is the WDF4 brushless circuit.

HansV

Interesting project! But, no. You can not run the aleron and tail servos on the same channel. That will make your heli yaw when you use the aleron and vice versa. I guess it is just for testing.

You need to replace the RX with a true 4 channel and add an external gyro. Alternative is to find the gyro output to the tail motor ESC on the PCB and wire it to the tail servo. I am not sure if it can be done.

Replacing the RX and adding a gyro will make the electronics a piece of cake:
Throttle channel: Main and tail ESC in parallel. Main is acting as BEC.
Aleron/elevator channel: As now.
Rudder channel: To gyro and from gyro to tail servo.

I dont understand your comment:
Both have belt driven tails so there are no tail motors. I hope you mean that you want the same tail system on your DF4 as the HBK2 and Belt CP. Maybe I would actualy start to fly my DF4 if it had a good tail like that and didn't get the vibrations the first time I do something else than hover.

/Hans.

MASJO

Ok parts arrived and the heli has been transformed. I used the HexTronik 1300kv on the tail and installed the Turnigy 10A ESC. Replaced both stock servos with HXT900 servos and one for the tail. All prelim tests again work fine. Will be back with flight tests once my hand heals in a few days.

For more info and pics link to my personal RC website here http://tnim.bravehost.com/wdf4_tail_esc.html

MASJO

Well test flight did not get of the ground. Too tail heavy. Need to go seperates with new receiver etc. So have returned the heli back to its stock tail.