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Old Jun 20, 2012, 03:39 PM
rldeveer's Avatar
Big Island of Hawaii
Joined Jan 2011
247 Posts
Quote:
Originally Posted by zadaw View Post
I had a bad time trying to learn 3D with the Genius because the motor got bogged down all the time. I was surprised that this didn't happen with the same motor in the Mini CP. Perhaps the Mini CP board is able to provide more power to the Genius motor. Anyway, I will see whether I could fix my Genius and make a comparison. If you are worried about the battery life of the Mini CP, you can definitely consider using the Genius CP motor.
I converted my 2801 GCPs to MiniGCPs and use the GCP stock motor with the Mini Main Gear. Get 5 min using Hyp 240 Mah batts. sport flying. (No 3D) I think the Mini's stiffer frame and smaller gear give the Genius motor better performance. It seems to last longer as well.

I think the smaller main gear creates higher head speed.

RD
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Old Jun 20, 2012, 05:31 PM
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Originally Posted by rldeveer View Post
Ty Wrap as replacement Tail Fin

RD
Great idea. So we can conclude that there are no aerodynamics purpose for the tail fin, just keeping the tail rotor safe.
Is that a V911 canopy you put on? I have a few at home a measured it a couple of hours ago. Did you cut the upper and lower parts to get it fit?
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Old Jun 20, 2012, 07:55 PM
rldeveer's Avatar
Big Island of Hawaii
Joined Jan 2011
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Originally Posted by eagle75 View Post
Great idea. So we can conclude that there are no aerodynamics purpose for the tail fin, just keeping the tail rotor safe.
Is that a V911 canopy you put on? I have a few at home a measured it a couple of hours ago. Did you cut the upper and lower parts to get it fit?
The canopy is a hard shell for a 9958 (P/N SANLIANHUAN 0021) that I got from Focalprice.com for $1.95 ea or $1.49 ea if you buy 3+. Free Shipping! Vertualy indistructable and <0.5g additional weight. Don't know if it will work with the vert RX on a real Mini but it is perfect for a MiniGCP. Single hole punch used to make holes for the legs to go through and new pin holes for the supports. It should last for ever.

RD
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Old Jun 20, 2012, 08:12 PM
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United States, TN, Memphis
Joined Dec 2011
862 Posts
The only broken Mini Cp canopies I've seen are from the landing gear splitting them. I cut away some canopy where the landing gear fits into it and added a carbon rod and a pair of canopy grommets to support the canopy instead. As a bonus the rx is also now better protected.
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Old Jun 20, 2012, 10:03 PM
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United States, TN, Memphis
Joined Dec 2011
862 Posts
What a beautiful sight, 30 minutes of intense flying with 17 min charge times:


Got most of my 2s components ordered and just have to decide on and assemble some battery packs. Here's a 2s mcpx to give an example:
Blade mCP X - 2 cells powered: HP08s/2S + XP-12A (3 min 48 sec)
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Old Jun 21, 2012, 10:53 AM
Hong Kong
Joined Jan 2010
6,167 Posts
Receiver FET blown again - now I am really fed up!

I posted earlier than a receiver was repaired by Walkera a couple of days ago. I found that the technician had put on the motor sockets the wrong way round. Still I am grateful that it was repaired.

To my horror, the tail fet blown suddenly today while I was flying it. I have only had 16 flights with this repaired receiver. I was probably at some fault here because it was slightly raining and the wires were wrapped round a 2.5mm CF rod. It was possible that the wires had been damaged by a blade strike or that the rain water shorted the tail motor.

My vendor told me the incidence of blown tail fets is very high with the Mini CP, so much so that many are now scared of flying it. Instead, they are switching to the V120D02S even though that is much less durable. He recommends that I buy a complete tail assembly each time rather than to wrap the tail motor wires around a solid CF boom.

So now, I have got 4 receivers with blown tail gets sent back to Walkera for repairs. I will update you once I get them back. I am really getting fed up with it. I have had 163 flights and a receiver had been damaged 6 times. A truly exceptional heli has been ruined by all this. I am surprised this isn't mentioned more often here. Perhaps modelers here are much more experienced and technically minded than those in Hong Kong. For a start, Walkera helis are sold at LHS so we can get good support. Also, there is a culture of dependency over here so that people rarely buy DIY furniture or know how to fix their cars.
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Old Jun 21, 2012, 05:34 PM
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United States, GA
Joined Dec 2011
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Quote:
I am really getting fed up with it.
I'm right there with ya. I have 4 bad also that I sent to another member to try and fix. They aren't all the tail fets tho, some just quit working after crashes. The board should not be at the front of the heli with very little protection where it takes a beating. I'm probably done with the Mini as I am as disgusted as you are.

Rant over.
Moto
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Old Jun 21, 2012, 07:25 PM
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i812's Avatar
Joined Aug 2009
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Quote:
Originally Posted by zadaw View Post
I posted earlier than a receiver was repaired by Walkera a couple of days ago. I found that the technician had put on the motor sockets the wrong way round. Still I am grateful that it was repaired.

To my horror, the tail fet blown suddenly today while I was flying it. I have only had 16 flights with this repaired receiver. I was probably at some fault here because it was slightly raining and the wires were wrapped round a 2.5mm CF rod. It was possible that the wires had been damaged by a blade strike or that the rain water shorted the tail motor.

My vendor told me the incidence of blown tail fets is very high with the Mini CP, so much so that many are now scared of flying it. Instead, they are switching to the V120D02S even though that is much less durable. He recommends that I buy a complete tail assembly each time rather than to wrap the tail motor wires around a solid CF boom.

So now, I have got 4 receivers with blown tail gets sent back to Walkera for repairs. I will update you once I get them back. I am really getting fed up with it. I have had 163 flights and a receiver had been damaged 6 times. A truly exceptional heli has been ruined by all this. I am surprised this isn't mentioned more often here. Perhaps modelers here are much more experienced and technically minded than those in Hong Kong. For a start, Walkera helis are sold at LHS so we can get good support. Also, there is a culture of dependency over here so that people rarely buy DIY furniture or know how to fix their cars.
I doubt exposing any of the electronics to rain is the problem, because many people have reported not having problems when their heli's get wet. In fact, some people intentionally clean their Motors by running them in water.

Here are some quotes from a discussion last year in a different thread:

Quote:
Originally Posted by fishfiend View Post
At last I'm having a blast with my Genius! I just changed the main motor, and now it's fun, I can go inverted without hitting the ground whilst bogging the motor a LOT more power with this one. It's my fourth motor and the only thing i've done differently is NOT putting Triflow in the can before flying it. I thought if I used some oil in it it would prolong the life of the motor I guess i was wrong. The other motors were oiled before use and never seemed to have the power of this one, and they got HOT too, whilst the latest stays warm.. So if you're suffering from a weak motor and have been oiling them try it dry...!
A few other people in different threads have reported loosing power after getting oil on their Motor's brushes. Here's another example:

Quote:
Originally Posted by tracknoob View Post
...
So, I went ahead and did a 'no parts rebuild' -- rather than throw more money at it, I took the two motors and dunked each of them into their own glass of water with a 1.5V battery to see if anything would come out. The old motor came out clean, not even any brush debris, but the current motor sure enough was spiting out oily debris, and some sort of strandy stuff... it did not turn the water black from carbon dust like burning in a new motor does, but it was definitely contaminating the water.
...
Quote:
Originally Posted by tracknoob View Post


I don''t break in all brushed motors in water, but for the 120Sr and the mcpx I have done it and even (As described in the post you are concerned about) used it after the fact to clean a suspect motor.

When used on a new motor, the slower speed, cooling and lubrication of the water, etc is supposed to allow the brushes to more perfectly form to conduct well and thereby have max contact area, and work efficiently and last longer. I cannot say that I have scientifically verified all claims, but the technique is almost as old as brushed motors themselves.* Some people recommend alcohol, but the old salts say it is not as good as water. People just hearing about it often express concerns about conductivity and rusting. I assure you that with soft water (or DI or distilled if you are a real nervous norvous) and then a blow out with air, followed by putting it back in use, you needn't worry about rust.

I'm not here to make crazy claims about super performance using this awesome technique that EVERYONE ought to do right away.... I'm just sharing what I did to restore my own balky mcpx, for free.


This is what a brand new 120SR motor looks like after 20 minutes of run in:




*there are many 'guides' and 'how-tos' around -- here is a link to just one typical one:
http://www.rcuniverse.com/forum/m_5628228/tm.htm
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Old Jun 21, 2012, 08:37 PM
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Quote:
Originally Posted by zadaw View Post
I posted earlier than a receiver was repaired by Walkera a couple of days ago. I found that the technician had put on the motor sockets the wrong way round. Still I am grateful that it was repaired.

To my horror, the tail fet blown suddenly today while I was flying it. I have only had 16 flights with this repaired receiver. I was probably at some fault here because it was slightly raining and the wires were wrapped round a 2.5mm CF rod. It was possible that the wires had been damaged by a blade strike or that the rain water shorted the tail motor.

My vendor told me the incidence of blown tail fets is very high with the Mini CP, so much so that many are now scared of flying it. Instead, they are switching to the V120D02S even though that is much less durable. He recommends that I buy a complete tail assembly each time rather than to wrap the tail motor wires around a solid CF boom.
IMO, this above paragraph is a red flag!! The fact that your Vendor's repair person thinks it is common for Mini's to have this problem, makes me think he may have a bad habit of introducing problems when trying to "repair" Tails on the Mini! I think you either need to let him read my below post, or find a better repair person. A good electrical repair person would already know to look for a short when something smokes. Since most people in the thread are not reporting problems with smoking FETs, there is a very good likelyhood that the FET ciruitry is adequately designed, and will not cause the FETs to smoke when used as designed. The fact that the repair person recommended replacing the entire Tail Assy everytime you smoke a FET, is an indication that the repair person knows the real reason why the FETs are being smoked is because there is most likely somethng wrong (a short) with the Tail! Shorts are one of the easiest electrical problems to find (most of the time an eye ball is all that is required) and to fix (most of the time shorts can be fixed almost for free in less than a few minutes).

Quote:
Originally Posted by zadaw View Post
So now, I have got 4 receivers with blown tail gets sent back to Walkera for repairs. I will update you once I get them back. I am really getting fed up with it. I have had 163 flights and a receiver had been damaged 6 times. A truly exceptional heli has been ruined by all this. I am surprised this isn't mentioned more often here. Perhaps modelers here are much more experienced and technically minded than those in Hong Kong. For a start, Walkera helis are sold at LHS so we can get good support. Also, there is a culture of dependency over here so that people rarely buy DIY furniture or know how to fix their cars.
The most likely reason for smoking anything electrical is because its output was shorted; therefore, if, and every time you get done smoking a FET, afterwards the repair person should always look for and repair a short before replacing the FET. Otherwise, as you have learned from experience, simply only replacing a smoked FET will probably not be a long term fix, and the owner will probably be smoking another FET shortly again.

I suspect the reason why some people are smoking more FETs than others may have something to do with the difference in handling. IMO, the easiest place and therefore the greatest opportunity to mis-handle the Tail circuitry would be the Tail Motor wires because their insulation is so thin, and they also have the most exposure to mis-handling. The fact that the smoked FET can be replaced, and it doesn't get smoked again until after 16 successful flights, provides more probability that the Tail Motor Wires might be intermittently shorting with each other depending on how the user re-positions the wires each time the heli is handled.

I'd look closely all around the entire length of the Tail Motor Wires for signs that their insulations have been compromised allowing the wires to be exposed and the opportunity for them to electrically touch each other. I would pay careful attention to these areas:
  • Heatshrink not positioned properly over both Tail Motor Wire-to-Tail Motor solder joints

  • Heatshrink not positioned properly over both Tail Motor Wire-to-RX Motor Connector Wire solder joints

  • RX Motor Connector Wire not properly installed in RX Motor Connector (i.e. wire insulation isn't going ALL THE WAY inside the connector, and therefore allowing wires to short each other at the Connector)

  • Missing insulation at same place on both Tail Motor Wires. IMO, insulation missing only on one wire is no problem, a short only occurs when both wires are exposed at same spot and electrically contact each other. IMO, the most likely occurrence of both wires having insulation missing at same spot would be places where they are both sharply kinked/bent:

    • two "J" hooks on the Main Frame

    • (if routing wire's inside the Tail Boom: where they enter and exit the back end of the Main Frame where the Tail Boom inserts - even if you're not routing Tail Motor Wires inside the Tail Boom, inspect that location along the wires where they used to go into the Main Frame because it my have been kinked/damaged by the assembler at the factory)

    • Edge of Tail Motor, especially if using a "protective" Cover on the end of the Tail Motor. If not carefully installed, the Tail Motor Cover will squish the thin Tail Motor Wires against the sharp edge of the Tail Motor, and over time the pressure from the Cover may cause the Tail Motor Wire insulation to "flow" away from the pressure point and allow the wire(s) to electrically contact each other and/or the Tail Motor Case. I like the idea of using a Cover to protect the Tail Motor wires from being damaged from Tail strikes; however, I position the Tail Motor Wires so their solder joints/heatshrinks are both over the Tail Motor edge, to take advantage of the thicker HeatShrink insulation.

Also, I carefully wind my Tail Motor wires loosely wrapped around the Tail Boom, and afterwards try using the least amount of handling/force when touching the wires around the Tail Boom. Any time and place thin wires with thin insulation are kinked there is greater opportunity for causing a short or a break at that location.

Whenever I work on electronics, I pay special attention trying to avoid the possibility of exposed metal from touching each other, and position and handle things to avoid kinks and pressure points.

In the short term, replacing the entire Tail Assy maybe the quickest and easiest "no-brainer" solution; however, I think in the long term it might be faster, better, and cheaper to actually find the real problem. Spending extra time up front, learning exactly where and why the problem occurred, in the long run may be the most efficient solution, because it may help the repair person find a better solution which may help prevent the problem from happening again.
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Last edited by i812; Jun 21, 2012 at 09:50 PM. Reason: added "red-flag" Vendor comment
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Old Jun 22, 2012, 03:10 AM
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Joined Nov 2007
44 Posts
Every time when change the tail boom, we need to pull the copper wires out from it. The split carbon fiber just like a paring knife which easy to removed the coating on the copper wires if pull out too quickly, that may be a reason why the FET will blown.
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Old Jun 22, 2012, 08:15 AM
Hong Kong
Joined Jan 2010
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Thanks for your input. The repair is actually carried out by Walkera itself at their factory in China. It is usually done for free except that you have to pay for return shipping. That usually comes out to be around $3.3 back to Hong Kong. The turnover time was 4 weeks but has been longer lately because they have a new technician. The problem with repaired receivers is that sometimes they do not fly as well as before. I have now got 4 receivers with Walkera and I will update you once I got them back.

My vendor was speaking from his personal experience and also that of his customers. I think there are two issues here; problems that are specific to the Mini CP and those that are common for all 100 sized brushed helis. I think the problem with the coil and also the risk of damaging sockets at the front is specific to the Mini CP. The board of the MCPx is at the front but does not have this problem. A problem that is common to all 100 sized CPs is the propensity for the battery wire to be pulled off. This had happened to my MCPx, Genius CP and MIni CP. Finally blown tail fets is common to all 100 sized brushed CPs as well. Again, this had happened to my MCPx, Genius CP and Mini CP.

At least in the case of the MCPx, the blown fet occurred after a crash when the blades were likely to have struck the exposed wires on the boom. However with the MIni CP, the fets were blown when I was hovering or flying the heli. The question would be whether the Mini CP is more susceptible than the MCPx because of the type of wire or motor used.
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Old Jun 23, 2012, 09:48 PM
ladybird, miniCP, msrx, 4F180
Joined Jan 2012
515 Posts
http://www.ebay.com/itm/170865817914...#ht_552wt_1267

I have my MiniCP and LB together on ebay for 175.00. With Devo 7 and extra's if anyone doesnt want to wait for china or just wants to save money.
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Old Jun 24, 2012, 10:50 AM
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United Kingdom, Warks
Joined Jun 2012
214 Posts
Hi,

It's a long shot but, before I shell out for a new one...

Does anyone have a Devo compatible Genius CP receiver that they want to sell or trade for the WK version?

I not, does anyone want to buy a WK receiver?

I'm in the UK but will mail outside if required.

Cheers.
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Old Jun 24, 2012, 01:37 PM
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United Kingdom, England, London
Joined Jun 2012
57 Posts
is the genius motor better with stock mini main gear? or with the genius main gear? i got a load of nano-tech 300mah batterys, just wanted to know what combination is better
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Old Jun 24, 2012, 02:16 PM
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United States, ND, Bismarck
Joined Mar 2012
297 Posts
i just thought i would share my ladybird motor/double tail rotor mod with you all as i haven't see anyone doing it yet. i have a hp05s main motor with 7t pinion and genius main gear in this and the tail holds great during pitch pumps with a flat 100% throttle curve, 55% pitch. it does kick out 1/8th of a turn if i go to 60% pitch with hard pitch pumps. the ladybird motor weighs 3.17g bare so it is marginally lighter than the double stock motor setup (stock tail motors weigh 1.71g bare).

I do think the ladybird motor is just a standard 7mm motor so any 7mm motor should work as long as it spins the right way. i just had some ccw ladybird motors laying around (because for some reason only cw motors go out on my ladybird ).
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