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Author Topic: Stuttering Rudder  (Read 2266 times)

Tug-Kenny

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Stuttering Rudder
« on: April 15, 2008, 09:46:48 pm »


I have just wired up my Boston Typhoon and am experiencing a weird effect during bench testing.

When going forward I can rotate the rudder OK. When in reverse and just starting to revolve the prop, the rudder flickers and vibrates by itself. When reverse speed is increased the effect goes away and I can control the rudder OK.

I'm using the Robbe 1000 motor and Futaba 3002 servo, and have the Mtronics speed controller in a plastic box with the R/X  on the outside wall. Could I be picking up some interference,  do you think, or might it be faulty gear ? Anyone seen this effect before ?

Ken


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DickyD

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Re: Stuttering Rudder
« Reply #1 on: April 15, 2008, 09:57:47 pm »

I had this Ken. In my case I was picking up interference from my desktop hobby light.
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Tug-Kenny

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Re: Stuttering Rudder
« Reply #2 on: April 15, 2008, 10:01:19 pm »


I never thought of external interference. Thanks for the idea. I'll take her outside and have a go

Cheers..Ken
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Bunkerbarge

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Re: Stuttering Rudder
« Reply #3 on: April 15, 2008, 10:07:06 pm »

Maybe check crystal compatability, if they didn't come with the set. Conversion 1 or 2, AM, FM, etc..etc..
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malcolmfrary

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Re: Stuttering Rudder
« Reply #4 on: April 15, 2008, 10:16:33 pm »

Indoors, there is the effect of everything mains driven.  Mains is 50Hz, our RC works at 50 frames/second.  Any signal turning up 50 times a second will upset the timing signals by fooling the RX into starting its frame at the wrong point.
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Tug-Kenny

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Re: Stuttering Rudder
« Reply #5 on: April 15, 2008, 10:29:32 pm »


Looks good from the general concensus.  I'll check back tomorrow.

Whilst on the subject of rudders, I noticed another funny effect.

I had centred up the rudder to mid point on the servo but, when switched on, the servo moved it out of line a fraction. I then readjusted the rudder to centre at this point. Of course, when I switched off, the rudder assumed an 'out of line position'. Is this normal ?  (My servo has a mind of it's own  ;))

Ken
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wombat

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Re: Stuttering Rudder
« Reply #6 on: April 15, 2008, 10:47:03 pm »

"Doctor, doctor, it hurts when I do this"
"So, don't do it!"

Servo glitcihng when the power goes off - you will probably get a number of flasle pulses as everything shuts down - just enough to glitch the servo a bit.

If the servo is vibrating in reverse, could be the power dipping as the commutator switches - I have motors where this is worse in one direction. I think something like this is more likely than external because you only see it in one direction. Probably the effect does not go away as the speed goes up  -just that the mechanics of the servo are not fast enough to respond. The frequency will increase with the speed fo the motor

Wom

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malcolmfrary

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Re: Stuttering Rudder
« Reply #7 on: April 16, 2008, 11:13:42 am »

As long as the rudder faces the way intended with the transmitter switched on, no problems. 
With the TX off, the receiver will do its best to resolve some sort of signal from whatever it can pick up.  Sometimes it will succeed, sometimes not.  When it does resolve something, it will probably be something unexpected.
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Bunkerbarge

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Re: Stuttering Rudder
« Reply #8 on: April 16, 2008, 11:38:13 am »

If you switch the reciever off first anyway you should find that it remains in the central position.
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Tug-Kenny

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Re: Stuttering Rudder
« Reply #9 on: April 16, 2008, 08:32:32 pm »


I have it now centred when it's switched on so that should be OK. It does move a bit sideways when off, but it doesn't really matter then.

The stuttering on reverse is only noticeable at first push of the throttle and goes when the revs increase, so should be OK in the water.

I've now noticed faster revs in reverse than forwards on the transmitter, so I reversed the motor wires. Unfortunately it's a LH prop which doesn't help as it goes backwards when told to go forwards  (70mm new brass un from Westbourne Models).  I suppose I need a RH prop now ?  :(

Ho Hum

Ken
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John W E

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Re: Stuttering Rudder
« Reply #10 on: April 16, 2008, 08:46:27 pm »

hi there Kenny, does your transmitter have a servo reversing switch on the back somewhere??? instead of swapping the wires on the motors around, could you not just flick the reversing switch if it was one??

Also, was your throttle stick trim tab set in the centre position when you set the MTroniks speed controller up?

Food for thought, when you are at full bore with your throttle on the transmitter, and, if you move your trim tab for your throttle fully up position, does this no increase the revs on your speed controller  O0  cos on one or two of mine (speed controllers) this is generally the case.   I leave it set that way knowing I have that bit extra speed on the trim tab when I need it.

aye
john e
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Tug-Kenny

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Re: Stuttering Rudder
« Reply #11 on: April 16, 2008, 09:13:04 pm »


Gosh, your a clever man John.  I just ran down to the workshop to have a look.

The Bl***y reverse switch was down on T/X.

Who's got that little cartoon of a man bashing his head with a mallet.  :embarrassed:

Cheers...Ken
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DickyD

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Re: Stuttering Rudder
« Reply #12 on: April 16, 2008, 10:03:13 pm »

Not bashing his head with a mallet Ken but.

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Tug-Kenny

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Re: Stuttering Rudder
« Reply #13 on: April 17, 2008, 08:56:21 pm »


I knew I'd seen one on here.

Yes, that's me again. Still messing things up. What a learning curve this glorious hobby is.  ;)

Had another play with the controls today. Isn't it nice when you're ready for the water.

Cheers...Ken
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DickyD

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Re: Stuttering Rudder
« Reply #14 on: April 17, 2008, 09:07:36 pm »

I know what you mean Ken, I have been charging batteries all day. ;)
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