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Old Jan 24, 2013, 04:29 AM
Rotor Controller
CaptJac's Avatar
Aachen Germany
Joined Dec 2007
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Careful!
Tail WAG of the mCPx - Brushless

The rumor mill is working over time with the brushless version about to make its debut - in some parts of the world it already has. Just as there were rumors flying around with the first version of the mCPx (the rumors weren't the only thing flying around with the blade holders letting loose) - no doubt there will be raves and rants and moans and groans with the brushless version. The purpose of this thread is to collect factual information from the initial flight tests so others can benefit and decide if it is better - worse - the same - than the mCPx V2.

My interest in the mCPx BL may very well be outside the realm of expectation or requirement of others. I am NOT interested in 3D performance. I am not interested in extreme performance. My particular interest is indoor scale flying with emphasis in duplicating the flight characteristics of a full size helicopter. Specifically - precision take-off and landings, hovering, slow flight, basic circuits. The base line for my comparison is 2 mCPx's which are used for indoor training and have been flown well over a 100 batteries. I fly them when I am unable to fly my Trex-450 and 550 outdoors.

My initial findings with the mCPx BL in comparison with the mCPx NBL was somewhat disappointing. There was considerable tail-wag. I tried adjusting the gyro gain as there was a non-confirmed rumor the gyro could be adjusted on ch-5 of the transmitter. NOTHING helped. I spoke with HorizonHobby tech support on the phone - they were NOT aware of any gyro adjustment. Per their suggestion I contacted HorizonHobby tech support in Germany - where the BL version had been released. They didn't answer their phone. I tried two different days - no answer. Could it be the left hand doesn't know what the right hand is doing? Going past the tail-wag - other flight characteristics were good. Cyclic and rudder extremely responsive - motor had a noticeable increase of power. The battery is 2s (7.4v) instead of 1s (3.7v) - which uncovered another disappointment. The charger that comes with it, I found to be sadly lacking. There was NO separate balance connector which means you can't use your own charger. Since the battery is 2 cells, the cells have to be balanced. I gave up with their charger - the red-green LED's blinked for 6 hours without a clue of their state of charge or balance. I finally made an adapter for my own charger - it took 45 minutes for the cells to balance after being on their charger for the 6 hours.

Conclusion: After approx 10 batteries of flight time - I can't say with any certainty if the tail-wag syndrome is unique on my heli, or some helis, or all helis, or if it will get better, worse, or stay the same. I'm optimistic someone will eventually come up with a solution. Same game for the charger. If mine is any indication, there is going to a lonnng line of disappointment and discontentment.

captJac
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Last edited by CaptJac; Feb 05, 2013 at 05:06 PM.
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Old Jan 24, 2013, 07:15 AM
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Rich Knapp's Avatar
United States, WI, Appleton
Joined Jul 2012
241 Posts
Per James in Horizon Hobby Product Development

Quote:
Hi Guys,

The gyro gain is adjustable for the tail.

It uses channel 5 (gear channel).

For DX7s, DX8, and DX18 radios
Gyro menu off = 0% gain on channel 5. This is the stock gain and the helicopter will fly just fine here.

Gyro menu on
0% = stock gain.
Increasing the number will increase the gyro gain. Range: 0% to 100%
Decreasing the number decreases the gain. Range: -100% to 0%

For DX6i and DX7/SE radios
The neutral gain point changes from 0% to 50%

Gyro menu off = 50% gain on channel 5. This is the stock gain and the helicopter will fly just fine here.

Gyro menu on
50% = stock gain.
Increasing the number will increase the gyro gain. Range: 50% to 100%
Decreasing the number decreases the gain. Range: 0% to 50%

I hope this clarifies this for you guys.
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Old Jan 24, 2013, 07:32 AM
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United States, UT, Farmington
Joined Aug 2011
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There are great balance adapters for these batteries available from a few vendors. Common sense RC, I believe, has a few models. I regularly charge my eflite UMX batteries on both of my 'big' chargers. The newer UMX batteries can handle 3C charge rates. Not sure what the max rate for the battery with the MCPX BL would be.
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Old Jan 24, 2013, 07:47 AM
Rotor Controller
CaptJac's Avatar
Aachen Germany
Joined Dec 2007
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Please advise James - there was NO change in the tail-wag over the full range of the gear channel. Also advise James - I am NOT the only one who tested those settings. The same thing was observed - NO discernible change in the tail-wag.
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Last edited by CaptJac; Jan 24, 2013 at 10:41 AM.
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Old Jan 24, 2013, 11:02 AM
Rotor Controller
CaptJac's Avatar
Aachen Germany
Joined Dec 2007
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Furthering my concern - when I spoke to the Horizon tech rep, he put me on hold so he could ask my question to others in their department. After 10 minutes wait time he came back on the line and assured me NOBODY knew about or heard about any kind of gyro adjustment. He suggested there "might" be a German version - which made NO sense to me. What I don't get - and what raises my caution flag - why are we hearing about a gyro adjustment that nobody has heard of except James? The tail-wag is obvious. Did someone concoct a gyro adjust to cover up a design problem? I'm not accusing - I'm not pointing fingers - I just want to know - and I think others will want to know as well. Hello Horizon ? Might be time to get this mystery unraveled instead of raveled.

------------------------------Please help keep this thread from sinking below the radar and post your comments.
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Old Jan 24, 2013, 11:02 AM
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It seems to me that just about any non-collective pitch, self-powered tail rotor is going to suffer SOME wag, simply due to the lag time required for the tail motor to spool up or wind down to control yaw.
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Old Jan 24, 2013, 11:11 AM
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CaptJac's Avatar
Aachen Germany
Joined Dec 2007
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Quote:
Originally Posted by AirDOGGe View Post
It seems to me that just about any non-collective pitch, self-powered tail rotor is going to suffer SOME wag, simply due to the lag time required for the tail motor to spool up or wind down to control yaw.
Agreed on the lag time for the tail motor if spooling up or winding down causes the tag-wag. But when the tail wags independent of rudder input or Yaw - lag time is factored out of the equation. The tail still wags when there is NO rudder input and NO yaw. Incidentally - the mCPx is collective-pitch.
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Old Jan 24, 2013, 11:16 AM
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Your best bet would be to return the heli if possible. I have no idea about what kind and how good HH support is in Germany, but it seems in the USA HH and particularly Blade brand gets away with many half-assed products, just because they have great CS.

Good luck.
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Old Jan 24, 2013, 12:49 PM
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CaptJac's Avatar
Aachen Germany
Joined Dec 2007
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The purpose of this thread is not to get my money back or whine - it's to bring attention to what I believe may be a design glitch and collect data from other mCPx BL owners to determine if this is one-in-a-thousand problem or a thousand helis with the same problem. Time will tell. The time stamp on this post will document my hypothesis.
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Old Jan 24, 2013, 02:08 PM
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I've had my Mcpx bl for nearly a week now. Not flown it for a few days due to work!
I had seen a tiny bit of tail wag when returning to a hover but it lasted 2-3 seconds before it settled! sometimes it will twitch a tiny bit when in normal mode but is solid as a rock in idle up.
I've got a dx8 set up with 80% flat curve in IU1 and 100% in IU2.
I bought this heli to do some harder 3d outdoors which it does faultlessly, inverted climbouts and huge rainbows are awesome! this heli flys just as big as my 130x
I am interested to see if anyone gets the tail gyro gain adjusted but don't feel the need to adjust mine
Another user said to rebind the heli after activating ch5. See if that helps you adjust the gain?
Cheers
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Old Jan 25, 2013, 12:22 AM
Still a N00B
lebaez's Avatar
United States, TX, Odessa
Joined Mar 2012
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Quote:
Originally Posted by mygeneration View Post
I've had my Mcpx bl for nearly a week now. Not flown it for a few days due to work!
I had seen a tiny bit of tail wag when returning to a hover but it lasted 2-3 seconds before it settled! sometimes it will twitch a tiny bit when in normal mode but is solid as a rock in idle up.
That wag was probably because he was happy to see you after a few days grounded.
It's too bad this may be an issue, I'd like one, but I prefer to steer clear of these things until it gets fixed. MCPX BL V2.
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Old Jan 25, 2013, 12:25 AM
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United States, TX, Odessa
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Has anybody made adjustments and saw a difference yet? Let us know please. I'd like to see some more videos.

Luis
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Old Jan 25, 2013, 07:18 AM
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Joined Jan 2012
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I just wonder if any of you read the helifreak forum?
Take a look at this http://www.helifreak.com/showthread.php?t=492494
Lot of usefull info for specific transmitters.
See if this helps
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Old Jan 25, 2013, 11:53 AM
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Capt Jac, if you read the manual the charger does balance, if you notic the plug has three wires, discharge and balance in one.
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Old Jan 25, 2013, 12:46 PM
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Quote:
Originally Posted by CaptJac View Post
... Incidentally - the mCPx is collective-pitch.
Thx for replying. By non-collective pitch, I was referring to the fixed-pitch nature of the MCPx tail rotor. Of course that heli series have collective main rotor heads. My bad there with terminology.


But back to the tail, We are speaking of what is basically a slightly enlarged MCPx helicopter with a significantly more powerful main motor and a larger diameter rotor, yet we are still dealing with a motorized tail rotor trying to keep it all steady.

Brushless tail motor or not, this is a fixed-pitch tail rotor system trying to counter even greater yaw forces from the main rotor system and more inertia from the tail's own greater mass, relative to the older MCPx versions.

The new BL seems to have the same wag issue that owners of larger Blade SR's suffer from...too much main rotor for a fixed-pitch tail to deal with smoothly. I've seen fixes for the latter that reduced, but never fully eliminated wag, so I haven't much hope for it going away entirely.

Hope someone finds a solution for the new BL that doesn't send the price up into the 130x region. I'm gonna wait this one out and see where it goes. Will I upgrade from my Nano to an MCPxBL, or save $50 more for the 130x and get a real tail rotor system? Time will tell.
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