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Old Apr 26, 2014, 11:44 AM
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Malta
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Help!
Syma F3 spinning in circles - damaged tail rotor motor ?

Hi Folks, after just 17 days of flying my brand new 4CH single rotor Syma F3 it started spinning in anti-clockwise circles. Admittedly, it had taken a few knocks in the first 4 to 5 days that I was learning to fly it but today all that happened was a slight scrape of the tail rotor against the wall and after that it started spinning. I suspect a damaged tail rotor motor as this is what I am observing when I hold the heli in my hand, and throttle it up : tail rotor spins sluggishly when the right stick (which I have assigned as the rudder control stick) is in neutral position but spins up fast when stick is pushed to the right. If I touch the rotor as it spins it'll stop and I can get it to spin again if it spin the rotor. When I push the stick from neutral to the left the rotor stops straight away and won't start even if I try to spin it with my finger.

Has the tail rotor motor packed up and needs replacing or can it be fixed ? Could you please offer me your advice.
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Old Apr 26, 2014, 12:10 PM
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The tail motor, gyro and speed control are all common points of failure, in that order. A bad gyro or speed control usually means a new board. Since they fail a lot, they are readily available. If the tail motor will still spin fast, odds are it's the board.
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Old Apr 26, 2014, 12:53 PM
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Thanks, Balr14. It doesn't spin so fast either on further testing: If I sit the heli on the floor and just give enough throttle to spin the heli but not make it take off and apply full right stick it doesn't compensate for the anticlockwise spin of the heli because there isn't enough thrust from the tail rotor motor as it's not spinning all that fast as it used to and so I'm inclined to think it's the motor. Could you please tell me how to check for gyro and speed control failure ? If it's motor failure what goes wrong usually and can they be repaired ? (I'd like to repair it if I could rather than wait a long 3 to 4 weeks minimum to get the motor from China)
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Old Apr 26, 2014, 01:04 PM
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You can't really test the gyro or speed control without a good motor. You can't repair the motor, the brushes are burnt out. A bad speed controller means the motor is always on full or not at all. A bad gyro usually means very erratic tail movement. Buy 3 tail motors and a new board.
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Old Apr 26, 2014, 01:17 PM
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OK but one thing, the motor is brushless. Can't it still not be repaired ? Gyro should be OK in my case then as I have not had any erratic tail movement.
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Old Apr 26, 2014, 09:51 PM
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Unless it was modified, the tail motor is coreless, not brushless.
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Old Jun 04, 2014, 01:08 PM
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Hi, I have the same problem with my Syma F3. After a week, the heli start spinning counterclockwise when lifting off. This also occurred after a crash. There is no physical damage and all servo's are working fine. After analyzing, I think the tail rotor is the problem. The rotor is spinning but has not enough power to compensate the main rotor.
Strangly, this is the second time I have this problem. Shortly after the first time the problem was fixed by itself and the Heli was functioning normally for a week. Now, the spinning returned..
I was wondering if anybody had the same problem and found a solution for this? By replacing parts?
Thanks for the feedback.
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Old Jun 04, 2014, 02:13 PM
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The tail motors wear out on a frequent basis. You will be replacing them often. The blades themselves can get bent or start to slip on the shaft. Sometimes the rotor gets pushed too close to the motor and it's movement is effected.
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Old Jun 05, 2014, 09:32 AM
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United States, WI, Beloit
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Quote:
Originally Posted by pfspeeddemon View Post
If I touch the rotor as it spins it'll stop and I can get it to spin again if it spin the rotor.
Quote:
Originally Posted by dds81 View Post
The rotor is spinning but has not enough power to compensate the main rotor.
Sounds like worn out brushes or a damaged commutator.

An open pole on the armature could also be the culprit.

Try a new tail motor.

As Balr14 mentioned, expect to replace them often.

I would buy in bulk

Among my brushed fixed pitch fleet, I would guess I have installed at least 50 tail motors,
and I have only been in this hobby for a year and some change.

If you really like your Syma F3, a hobby grade brushless CP will give you goosebumps.

They are not even in the same dimension, and I have some heavily modified brushless
belt driven 6Ch FP's (using the same basic head design as the F3).

Wind is the main limitation, yet 6Ch CP's and quads eat a 15 Mph breeze for breakfast.
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Old Mar 28, 2015, 07:05 PM
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Quote:
Originally Posted by Balr14 View Post
You can't really test the gyro or speed control without a good motor. You can't repair the motor, the brushes are burnt out. A bad speed controller means the motor is always on full or not at all. A bad gyro usually means very erratic tail movement. Buy 3 tail motors and a new board.
Hi Folks, I'm on my 2nd tail motor replacement as of today on my Syma F3 and it's only 11 months old (2 of which most probably were non-flying ones as I awaited parts to come from China). These motors are way too fragile.

Here's the latest issue: after fitting the tail-motor I thought I was going to have some fun flying the helo after being grounded for about 3 weeks waiting for parts but to my dismay it immediately started flying erratically in all directions, going to the left and the right, forward and backwards and it just wouldn't hover and I was constantly giving it stick inputs to compensate but it was uncontrollable in a restricted indoor surrounding as it was darting all over the room. I just don't know why it's doing so. It's not spinning so that means it's not the tail motor. I posted Balr14's reply because he said the circuit board's gyro could be a problem...is this uncontrollable/erratic flying a result of a failing gyro ? Any Ideas as to what's gone wrong and what to do to fix the problem ? BTW, there is nothing/broken wrong with any of the moving control parts/flying surfaces...physically, the helo looks in perfect condition.
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Old Mar 29, 2015, 04:26 AM
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United States, WI, Beloit
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If your linkage is too tight it will act like this.

It can also be caused by extremely worn out and loose linkage, or if one of the links
are pushed on too far, and are not sitting on the ball. (Sometimes it's hard to notice
unless you look for it.)

Also, check your servos for smooth operation.

Did you crash back when the tail motor failed?
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Old Mar 29, 2015, 04:54 AM
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Hi Steve,

Thanks for replying ! I had hit the tail rotor a month ago (clipped a wall with the tail rotor and it subsequently fell a height of about 7 feet) and the helo started spinning badly immediately after that and so I was grounded for a month until I received and installed the new tail motor yesterday and got the weird behaviour I have described.

I had already checked the linkages for correct movement and for correct ball joint connections. Servos operate fine too. As I said, nothing seems to be amiss, physically.

This morning I flew it in a large area to see what it would do if I just flew it up vertically and just "let it sit in" the air without giving it any stick inputs and it started to track a circular motion in a counter-clockwise direction without turning its nose...basically for me this is a classic "toilet bowl effect" but is this something which just applies to co-axial helos only and not single rotor, FP ones or am I mistaken ? My SYma F3 is the latter single rotor, FP -type.

I observed/experimented by doing the following this morning: I synch'ed the helo and the transmitter while holding the helo upside down ( to see if I "freak out " the gyro ???). Placed it on the ground and took off and it flew fine for about 30 secs ! I thought I was on to something but after those 30 secs it started misbehaving again, particularly with that" toilet bowl" effect.

Please help if you can...
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Old Mar 29, 2015, 02:47 PM
Crash and learn
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Quote:
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but after those 30 secs it started misbehaving again, particularly with that" toilet bowl" effect.
On my V911's, usually the flybar does not move freely.

Turn the flybar holding screw all the way in, then back it out until the flybar bounces freely when tapping the end.
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Old Mar 29, 2015, 03:22 PM
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Hi Ribble, tx for your input too. I would have done that but just before seeing your tip I read elswhere to lubricate the linkages with silicone spray which I did. Steve was right, I did have some binding in the linkages/ball joints and flybar but after using the silicone spray everything started moving freely and there was a noticeable improvement in the TBE but not 100%. The fix was again as per Steve's advice who said to look for a ball joint that was pushed in too far and sure enough I finally noticed that the ball joint on the servo linkage to the wobbler (Swash plate ?) was pushed in too far and as soon as I pushed this back into the correct position the TBE disappeared and my helo was restored back to flying status ! You really do need to look ultra-closely at these things since they are so minute that such a detail can easily escape your attention and yet have such a large negative effect on your helo...and my eyesight isn't as good as it used to be nowadays !

BTW, Ribble, since we have similar helos (clones I would say) do you notice that when you are hovering and you let the helo drift slight lightly that it sort of shakes/vibrates/wobbles slightly ? Any idea what this is and if it's something we need to fix ? Of course this doesn't manifest itself when you are flying around as the darn thing darts around so fast.

Tx Steve and Ribble for your help.

I hope this thread and its posts help others who are experiencing similar issues.
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Old Mar 29, 2015, 04:47 PM
Crash and learn
United States, PA
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Quote:
Originally Posted by pfspeeddemon View Post
when you are hovering and you let the helo drift slight lightly that it sort of shakes/vibrates/wobbles slightly ?
I fly outdoors and would not notice anything minor.

Try some lubrication where the propellers push onto the main stem. Or a cracked blade.
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