Master CP with Tarot ZYX - RC Groups
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Feb 28, 2013, 12:31 AM
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Master CP with Tarot ZYX

So I decided I hated the existing gyro in the Master CP.

Background is that I more or less learnt to fly on a V120D02s. The idea behind the master was to get something bigger with a bit more grunt. It achieves that - pity it flies in turns like a sack of unstable potatoes.

So, thinks I to myself. What to do. Hmm. What. Exactly. To Do.

Meanwhile, my wife buys me (with my prompting a Gaui X2 with BeastX. I spend hours putting it together and freak myself out with my first flights. Hey. What do you know, a heli *can* feel like those things we fly in Phoenix. Stunning.

But the master sits there. Cool thing about the master? You can pile drive it into the ground, snap the frame, break almost everything on it, and fix it for about $30.

So I'm thinking I'm going to pull the pin and get a Tarot ZYX and see if I can make it work. Before I continue, yes I'm aware this is probably a complete waste of money. But heck, it has to be done. I just *have* to know.

So, here's the bag of parts I intend to see if I can make fly:

1 x Master CP
1 x Phoenix CC 20a - intended for X2 but wanted logging to used an alternate CC on the X2 in the meantime. Look! Spare ESC!
3 x Hitec servocs (metal gear)
1 x eBay brushless tail kit with 10a turnigy ESC.
1 x RX802 replacement receiver.
1 x Turnigy 3800kv main motor.

Ain't gonna be much left of the master. I will take *particular* joy in using a trebuchet to launch the old Gyro into the inlet across the road from us. The trebuchet will be a project for another day. Enough babbling, SHOW ME THE HELI.
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Feb 28, 2013, 12:37 AM
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OK, here's the initial "development mule".

Not sure if the location of the gyro (close to engine, side of a servo) is going to work long term, but it hasn't crashed into the side of the kitchen yet.

Wiring can certainly be tidied and shortened, but at the moment I want to see if it can fly properly before I rebuild it!
Feb 28, 2013, 12:39 AM
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Current progress:

Upped the gain in increments of 5, from 10 -> 45.
Gyro %age on the transmitted up from 72 -> 90. Currently I'm playing with values in the 75%+ range.

First goal is to get the heli stable in a hover and able to do pitch pumps as good as or better than the original. Only problem is I can't remember how good the original was now! haha. I'll have to borrow a mates and see.

I might even go and post a video of where things are up to.

Here we go (uploading from NZ, so give it an hr or so):
Pitch pumps at Tail Gain 50 (0 min 0 sec)
Last edited by scornflake; Feb 28, 2013 at 12:54 AM. Reason: Updating with a video
Feb 28, 2013, 12:46 AM
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Sorry for my extremely noobish question, but isin't onlyTarot ZYX gyro used in belt or shaft driven tail models. Master CP has a tail motor driven tail right?
Feb 28, 2013, 12:58 AM
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You are 100% correct. There is an additional 10a ESC driving a brushless motor. The Tarot is driving that ESC as if it were a 1520us servo. The setup within the tarot programming s/ware becomes a little different (end points and offset change), but I'll post detail on that when I've got it nailed a bit more, or if I fail completely
Feb 28, 2013, 01:05 AM
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I see. Looks like the heli is having loads of power.
How does the tail hold during pitch pumps?
Feb 28, 2013, 01:17 AM
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See the video above, when it loads. These are inside only at the moment. I need to get outside soon as the stuff I want to try requires more space now.
Feb 28, 2013, 03:57 AM
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Anyway you could check if the original tail/esc can be used? Just check if it compensates correctly on the bench.
Feb 28, 2013, 05:20 AM
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Hmm. Do you mean connect the rudder output of the Tarot, to the old ESC, and see if it'll drive a standard tail motor?

Do you happen to know if the input expected by that ESC is the standard 1560us, 1/2ms pulse that is fed to other ESCs (cos I reckon it aint). I'll see what I can do...

If it's sunny tomorrow, I'll do some outdoor flight and see if I can tone down the right rudder hard stop bounces I'm seeing. Once I've got that, I can see how it responds to simple circuits - which is something the original M.CP struggled with imho.

THEN we can engage stunt mode and see if it spins itself out of the park
Last edited by scornflake; Feb 28, 2013 at 05:26 AM.
Feb 28, 2013, 04:48 PM
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I've now tuned out the bounces while retaining reasonable tail control doing pitch pumps. Here are the current settings.

Note my goal here is not to replicate a Gaui X2 (or similar). I don't believe it's possible to get it to stop THAT well with a motor tail.

It's now ready for a larger FF outdoor circuit (my kitchen isn't large enough .
Feb 28, 2013, 04:50 PM
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Quick vid showing "soft" stops after tuning Yaw P and Accel/Decel L/R values.

No bounces on stops (0 min 0 sec)
Feb 28, 2013, 06:01 PM
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I am pleased to report a successful maiden flight. I am not the owner of a bag of heli parts.
  1. I didn't crash
  2. The heli handles MUCH better than the original Gyro. All the 'weirdness' when doing circuits and loops is gone gone gone. Hello consistency.

Things to work on now include better left roll behavior - it's very slow. Slow enough that even two-mistakes-high I had to abort a left roll because it wasn't going to make it. I'm conscious however that I didn't really pay THAT much attention to mechanical setup when I installed the tarot. Maybe I overly limited aileron (although I'd expect right stick input to behave same as left).

Right rolls were good. Very little tendancy for the heli to be tilted back by the time the roll is completed (and that might be me). None of the original "Hey; I just got 80% through the roll, I think I'll speed up now" behavior that I saw on the old gyro.

The primary goal - a heli I can practice inverted circuits on, that feels consistent and even (given it's constraints), I think, has been reached. More tuning to do, but the concept works and it's far, far far better than the brushless conversion kit, which I couldnt' even make hover, let alone fly.

I've done a vid trying to show initial flight. Sorry the heli is kinda tiny even though I have zoomed in a little. It's really to show how it handles basic stuff.

Possibly of interest:
  • 00:26 - first flip
  • 00:47 - pitch pumps (but a kinda low battery), one at full collective. tee hee.
  • 01:11 - inverted circuit (kind of - my skills are only average)
  • 01:37 - playing with piro. just seeing how it is.

So for me, the tarot has transformed it into something that I now want to fly. Before that, it had become "well yeh, it's larger, but it's weird as heck in turns ... and ... do I really want to learn anything on it?". So, success!

MonsterCP Maiden Flight (Tarot ZYX) (0 min 0 sec)
Last edited by scornflake; Feb 28, 2013 at 06:01 PM. Reason: Adding link to video
Mar 01, 2013, 05:01 AM
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Though, for the cost of a brushless tail motor + esc you could have gotten a 250 kit

Thats what i decided to do, would be nice to know though if the zyx even has a chanse of controlling the original tail motor.
Would make for a very decent practice heli if i could swap in the zyx intended for my copterx without having to go for a brushless tail.
Mar 01, 2013, 05:50 AM
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Yep, for sure. Which is why I mentioned at the top that it was prob a waste of money. I guess it is, and it isn't (well, for me anyway).

On one hand it's expensive. I live in NZ. I have to import all parts. Freight adds up.
Servos, motors, controllers, receivers, spares etc - I've prob spent close to $300 just on extras for this project. On the other hand there's the experience gained and really lots of this can/could be reused later on other projects - and if I want to fly something "classy" I've the X2 sitting on the desk

For me this was more of a "is it possible? wonder what it's like?" kind of experiment. Turns out I get to play with another Gyro as well, so that's nice (only setup a beastx before this).

Xermalk: It was actually your original post on some other forum that got me thinking it was possible in the first place, so ta It's actually been lots of fun getting it going!

Re the brushless tail - those parts are I think from memory only about $40. Actually, if you get the ESC (10a Turnigy) and motor (2000kv) separately, they are likely even less. Prob $20 if you're in the USA. I haven't connected up the Tarot -> old ESC yet to see if it can drive it yet. I had intended to stick it on a scope, except I don't have one :| I was curious to see in reality if the MastCP receiver (thus input to the original ESC) was outputting something different from it's rudder port than a 'normal' receiver.
Last edited by scornflake; Mar 01, 2013 at 06:16 AM. Reason: Commenting on brushless tail
Mar 01, 2013, 06:25 AM
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heh, np.
I would have done the same just for fun. But i have a very limited budget for my rc stuff as im currently studding.

Atleast repairs will be cheaper for the monster cp

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