brushless tail revisit

[Helipsyko]

Originally Posted by Roffey

Been battling on, trying to get the HP06 16Kv motor running in the heli. Got there in the end by using a walkera 2S pwm unit. Modified it to work on 1S. At least I can get something flying. Support from mgm on the 'expert' expensive esc is that it might not work on all motors! Hmmm. which ones then? Don't see a list. ( I actually measured the Kv to be closer to 18000 on the scope for a 1V rms output, shame there is never any decent data available)

Couldn't get a better esc around here so I have to make do. It works though and certainly does the job. I had to modify the software a bit, but no matter.

Had to use a 1.5mm drill shank for the shaft, ( arrived bent) so I ground it down for a stock 8 tooth.
Had to make a few curve changes, but got there in the end.

The motor is current hungry, and does cut cause cutouts, so I need better batteries. The point was to see how the tail held though. Pumping holds with no problems. That bit's fine. Hovering with the higher headspeed has introduced a new set of vibrations, and it is imperative that dynamic balancing is done. Bit of tape here and there sorts that out.

I've got a few tricks left in the bag to shove in the software, so once that is done, I should be close to having it sorted.

A few photos to show how I'm getting along. One day it will be tidy! Just a shame it's taking so long.

Nice job!!

Maybe you can help me with a question regarding BL tail. I have a 3-1 board with a burned component(?) see pic, had a short in the extended tail. I wonder if the signal to the tail motor is taken before the burned component or not? I will use the 3-1 for a full BL setup if it can.
Thanks

[Roffey]

Originally Posted by Helipsyko

Nice job!!

Maybe you can help me with a question regarding BL tail. I have a 3-1 board with a burned component(?) see pic, had a short in the extended tail. I wonder if the signal to the tail motor is taken before the burned component or not? I will use the 3-1 for a full BL setup if it can.
Thanks

Yes, the signal on my development comes from the 'gate' connection to that mosfet, so that actual component is not required. If a different tail BL converter is used it will come from the back of the board anyway, so the 3in1 is worth keeping for the future. Let's hope it's soon

[Helipsyko]

Originally Posted by Roffey

Yes, the signal on my development comes from the 'gate' connection to that mosfet, so that actual component is not required. If a different tail BL converter is used it will come from the back of the board anyway, so the 3in1 is worth keeping for the future. Let's hope it's soon

Thanks!
It will be soon, can't sit still too long you know. Besides a spare Mcpx is allways needed.
May I ask for a close up pic of the connection point?

[Roffey]

Thought I'd give a short update. Still waiting for the frame and bits to come. I have managed to 'fudge' it together to see how the HP06 goes. With a 6 turn wind and 8 tooth pinion the thrust is up to 180gms! Yup, it is an animal! It can take up to a good 8 -10 amps, so I'm using a separate 160mAh for the board and the tail. AUW is about 60gms. Motor seems quite happy. A bit shaky after the first couple of tests, me that is, not the heli!

The XP12A esc does well and doesn't get hot, so I'm pleased with that.

With the higher headspeed, characteristics have changed again as far as hover stability is concerned, so I'm looking into that. As far as hold on pitch pumps is concerned, it is surprisingly actually solid without a hint of straying out.

Vibration pickup is a real pain, with the chips solid on the board, so it's back to software again. Probably going to separate the gyro signal as I did on the variable pitch tail, then add it back again, have to see.

Hope to have more news n vid soon.

[liftbag]

@Roffey

For some time I did not read this interesting thread.

I have read of the attempts made to use the HP06S.
I used this motor about a month ago with the XP-12A and 9T pinion with no problems.
I confirm the motor is a very hungry.

I used it for a week, then I replaced with the Turbo Ace 713 13000kv with 10T pinion.
Best performance, but even more hungry.

On another mCP X I have mounted the Turbo Ace 915 16200 kv with 9T pinion and XP-12A. It's the most powerful of all my helicopters, and seems less hungry of 713.

However with these motors, I can not fly for more than 3 minutes with Thunder Power 325 mAh or 3' 30" and with the wowhobbies linear 400 lipos.

I am also in the finals for my 2S model.
I was able to reduce weight through Murata Power Solution switching step-down set to 4,44 Volts (if I remember correctly, you had advised me), have a powerful motor (Spin 8800kv 2S) and I'm waiting for the Phoenix 10, hoping to use it.

For now I'm flying with the XP-7A and the power expressed using two Hyperion 160 lipos connected in series is awesome.
The flight time reaches about 3' 30". I will probably opt for a 180 mAh 2S lipo.

The beauty of this model is that the dual coreless tail is stronger than 1S models (due to the 4,44 volts at the board) and the tail thrust remains constant throughout the full time of flight.

[Roffey]

Originally Posted by liftbag

@Roffey

For some time I did not read this interesting thread.

I have read of the attempts made to use the HP06S.
I used this motor about a month ago with the XP-12A and 9T pinion with no problems.
I confirm the motor is a very hungry.

I used it for a week, then I replaced with the Turbo Ace 713 13000kv with 10T pinion.
Best performance, but even more hungry.

On another mCP X I have mounted the Turbo Ace 915 16200 kv with 9T pinion and XP-12A. It's the most powerful of all my helicopters, and seems less hungry of 713.

However with these motors, I can not fly for more than 3 minutes with Thunder Power 325 mAh or 3' 30" and with the wowhobbies linear 400 lipos.

I am also in the finals for my 2S model.
I was able to reduce weight through Murata Power Solution switching step-down set to 4,44 Volts (if I remember correctly, you had advised me), have a powerful motor (Spin 8800kv 2S) and I'm waiting for the Phoenix 10, hoping to use it.

For now I'm flying with the XP-7A and the power expressed using two Hyperion 160 lipos connected in series is awesome.
The flight time reaches about 3' 30". I will probably opt for a 180 mAh 2S lipo.

The beauty of this model is that the dual coreless tail is stronger than 1S models (due to the 4,44 volts at the board) and the tail thrust remains constant throughout the full time of flight.

I must say I admire your work Lift, and your set of helis you must be having fun!

I would have stuck with the 2S myself for the same reasons, I don't really like the high currents these 1S motors chew up. But, I must say, having rewound the 06, and using separate cells for the main and tail, it seems to be pretty good so far. I may have struck lucky with the wind count, I'll have to wait and see. Had a couple of cells looking like angry puffa fish at first though! Good learning curve for me as well.
I've got some nano techs coming in which I will strip and wire in parallel to see if the 25-40C rating is as good as they say.


I have gone back to 1S only to get this bl tail converter sorted, as it is typically what is being used. I've managed to separate the gyro from the tailmix now, so I have external control of the gain (decreasing it) on the converter, which I'm hoping is close to being a final step.

On my 2S I used bare Hyperion 160 cells wired in series, and they were not only cheap, but good. I was impressed with those.

All good fun.

[Roffey]

Originally Posted by liftbag

@Roffey

For some time I did not read this interesting thread.

I have read of the attempts made to use the HP06S.
I used this motor about a month ago with the XP-12A and 9T pinion with no problems.
I confirm the motor is a very hungry.

I used it for a week, then I replaced with the Turbo Ace 713 13000kv with 10T pinion.
Best performance, but even more hungry.

On another mCP X I have mounted the Turbo Ace 915 16200 kv with 9T pinion and XP-12A. It's the most powerful of all my helicopters, and seems less hungry of 713.

However with these motors, I can not fly for more than 3 minutes with Thunder Power 325 mAh or 3' 30" and with the wowhobbies linear 400 lipos.

I am also in the finals for my 2S model.
I was able to reduce weight through Murata Power Solution switching step-down set to 4,44 Volts (if I remember correctly, you had advised me), have a powerful motor (Spin 8800kv 2S) and I'm waiting for the Phoenix 10, hoping to use it.

For now I'm flying with the XP-7A and the power expressed using two Hyperion 160 lipos connected in series is awesome.
The flight time reaches about 3' 30". I will probably opt for a 180 mAh 2S lipo.

The beauty of this model is that the dual coreless tail is stronger than 1S models (due to the 4,44 volts at the board) and the tail thrust remains constant throughout the full time of flight.

I must say I admire your work Lift, and your set of helis you must be having fun!

I would have stuck with the 2S myself for the same reasons, I don't really like the high currents these 1S motors chew up. But, I must say, having rewound the 06, and using separate cells for the main and tail, it seems to be pretty good so far. I may have struck lucky with the wind count, I'll have to wait and see. Had a couple of cells looking like angry puffa fish at first though! Good learning curve for me as well.
I've got some nano techs coming in which I will strip and wire in parallel to see if the 25-40C rating is as good as they say.


I have gone back to 1S only to get this bl tail converter sorted, as it is typically what is being used. I've managed to separate the gyro from the tailmix now, so I have external control of the gain (decreasing it) on the converter, which I'm hoping is close to being a final step.

All good fun.

[Pigs dont fly]

Originally Posted by Roffey

With a 6 turn wind and 8 tooth pinion the thrust is up to 180gms!

I imagine its gong to be hard not to bury it into your lounge ceiling 180g of thrust!

Keep up the good work I cant wait to see the finished item.

[Roffey]

Originally Posted by Pigs dont fly

I imagine its gong to be hard not to bury it into your lounge ceiling 180g of thrust!

Keep up the good work I cant wait to see the finished item.

Yup, it can definitely give it's own unique look to any ceiling! I kind off like that new swirl look Wife not sure at the moment! Headspeed a constant 5300 with full stock blades max pitch!
This motor thing opens up new challenges for sure, and certainly exposes the lack of accurate motor data.
Be interesting to see Liftbag's findings. I don't really want to get too diverted at the moment.

The limitation of dealing with data output just from the main and already mixed tail/gyro is certainly a challenge. I'm trying to complete the next phase, but it is a bit slow, due to these old sluggish brain cells.
Main/tail mix is now variable as is gyro gain (up/down), although gyro gain affects rudder gain ( as it is derived from the mix sent from the mcpx tail). Just a bit more reaction speed and that will be as much as the software can do.

Oh well, roll on free time!

[Roffey]

Just a short update. I haven't had much time recently, and I have felt the need for more understanding and research.
Now I am dealing with the rewound HP06, it highlights the need for a much more reactive brushless tail motor, which will also spill down to lower power setups. The AP(HP)03 with a suitable prop really doesn't do it, even with a rewind. Sure, dealing with pumps is less of a problem, but as for piro stops it is far less than desirable.
In order to get the reaction speed and reduce time constants, more power is needed, along with low mass.
That's why the multiple coreless setups do so well. There are still issues relating to wag and bounce with those, but they show what is actually required with a brushless tail.

I've just rewound a 5gm 'pole/stator' bl which is looking really good, has the right characteristics, and with a lighter prop has cut out the piro stop bounce due to the higher main bl torque. I also have a 5gm inrunner coming which will be interesting.
This setup will hopefully allow me to automatically change the gyro gain in response to control variation, which will iron out vibration wag and glitches that can cause issues.

So, still plodding away not beaten yet! Then it's back to the vari pitch tail, which I miss.

I note with interest the dual esc unit. Looks very neat, although it is a compromise design. What is really needed is a purpose designed bl tail motor. Who knows, maybe that's to come.

[Roffey]

Oh well, more annoying holdups. Gyro vibration pickup even though attention to fine balancing of the tail and main mechanisms. Can hardly feel any though. It turns out to be the motor bearings. New to me is the need to balance the bell on these motors, but research is pretty clear that it is needed. On order!

I thought I would see just how sensitive the gyros were, so I put a small piezo disc on the tail chip, and took it through 1 to 30Khz. It is very easy to see where problems can arise. Tiny vibrations at the 'wrong' frequencies can send it into a world of its own. Unfortunately these frequencies can be generated quite easily by the tail, main and combination of both. Quite common is the tight gear mesh twitch.
Another wake up call here.

I did manage to get some idea of the response time of the brushless tail motor rewind. It's about 50mS for low to max rpm and about 80mS for the reverse. That compares reasonably with fast servo 60 degree swings. That's using the walkera tail esc. Interestingly that will work a 8Khz, which is what I am driving it with.

With less powerful setups, there may not be as many issues............. time will tell. Not giving up yet....

[Pigs dont fly]

Good job Dave, have you tried stiffening up the head dampening (adding a couple of extra washers to the feathering shaft)?..it may help get rid of some of your low frequency vibrations.
Even if it doesn't, the heli fly's a lot nicer at high rpm with the head stiffened up.

[Naito]

Question.....TheSteve converter really just outputs a servo signal doesn't it? Could it be used on the tail signal solder point with a micro linear servo to make a CP tail? Then you can use your brushless motor to just drive the tail at full speed and control it just with the pitch like a big heli.

I don't have the skills to do any of that, but wouldn't it work?

[Roffey]

You mean like this?

https://www.helifreak.com/showthread.php?t=330337

The steves converter is just that, a converter. The micro I uses here, separates the gyro signal from the tail motor drive, then sends the required ppm to the tail servo.

This was experimental and as such, unfinished, but I shall be returning to it.

[Roffey]

Well, I have just finished for the night, the heli has been the closest to being crushed as it's ever been.
When shifting up in power etc, vibration is the killer, and the solid board just won't hack it. No gyro ever could work under those conditions, and there is no substitute for removing it from the actual sensor.

Filtering, dynamic gain, various trick routines just wont get it right.

Mind you, I have done it. But..... it's not an easy mod.
Right now, I have gone back to the inrunner Medusa 4000Kv with an 8 tooth. Running at 3S mind you, so it's not without it's power. Got fed up with the coggy, unbalanced, vibration inducing rewound 06.
The tail is a rewound (to 7Kv) 5gm, 12 spoke, 16 magnet 20W capable outrunner, with a response fast enough to deal with pumps and piro stops.
Not a twitch in sight.
The bad news .......... The gyro is now on the tail shaft. Same chip type. I pulled one off a spare board. Could have got one online for $5, but with a $50 p&p the former seemed a better deal!

I'll give it a little tidy, and put some pics and vid up tomorrow.. Obviously more work to do....

[Pigs dont fly]

A gyro on the tail..you have been busy.
Would a carbon frame and a soft mounted pcb, make any difference to the vibration issue?

[Roffey]

Originally Posted by Pigs dont fly

A gyro on the tail..you have been busy.
Would a carbon frame and a soft mounted pcb, make any difference to the vibration issue?

I tried everything I could with soft mounts and frame stiffening, but just maybe there is a way.
The pcb has no mass as such, so no dampening factor there. Isolate it, and grip it firmly , dampening it with the hand, just about does it, so something pretty effective has to be designed. Probably along with a purpose designed frame, with vibration as the focus. All that has to be combined with considerable effort in minimising all sources of vibration. Motors, gearing, both main / tail blades etc etc.

The frequencies are the fundamental and harmonics, so starting from around 60Hz up for 4K and higher. The gyro is extremely sensitive to those frequencies, and being hard mounted is on a lovely pick up plate. It's an ideal vibration sensor, if you were going to design one. The way the pcb is fixed etc.

I still have tracking digital filtering to play with, but that is not ideal. I really needed to get the thing flying again, and double brushless working to give me inspiration to carry on. At least I can work backwards from something that actually works!

[Pigs dont fly]

Perhaps with a metal plate sandwich mount, like the ones that come with a mems tail gyro...?

[Roffey]

Originally Posted by Pigs dont fly

Perhaps with a metal plate sandwich mount, like the ones that come with a mems tail gyro...?

That's a possibility, it needs some damping weights for sure.
In the meantime, here's a vid and some pics.

Dumped it at the end, but only popped some links. Happy that it worked more than anything else. I haven't played with the gyro gain or tail rpm mix, but I think I ought to fly a bit first!!!!

[ame]http://www.youtube.com/watch?v=9QZvOajtQGo[/ame]

[wadders248]

Wow, that's a lot of work there...