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HomeAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › CSM 420 Tail drift
11-07-2004 04:14 PM  13 years agoPost 1
flyingace

rrNovice

Bristol, Uk

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Hi.
I have a raptor 50 fitted with OS 50, futaba receiver, csm 420 gyro with a futaba 9451 tail servo and 6 volt battery pack. The transmitter im using is a Futaba FF9.

The problem im having is tail drift to the right hand side, I have tried increasing the gain, decreasing the gain, mounting the gyro on thicker foam and altering the length of the tail push rod. All this has had no effect over the problem.

Please help this is driving me mad.

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11-07-2004 06:08 PM  13 years agoPost 2
G.Man

rrProfessor

Bristol

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Flyingace

there are 2 main reasons for the drift on a 420..

1st is poor mechanical setup, which I doubt is the case with yours as it sounds like you would have checked for that..

2nd is engine tuning, and just your statement about using an OS50, which is renowned for having a rich spot at the hover throttle setting resulting in a 4-stroking vibey motor leads me to believe its probably this...

Things to listen for are a rough engine note in the hover and indication the engine is not firing on every stroke (most OS50's I have heard sound like that)..

This will cause enough vibration and moreover an inconsistent tail speed that leads to drift...

The 601 is more tolerant of this situation but I had it bad enough with the 601 and my bergen to get drift as well..

Consider changing the carb on the OS50 for a supertigre carb or an OS 60B carb (you can often pickup a cheap thrashed worn out OS61WC with this carb on ebay or from people at your club)

The extra needle allows you to lean the midrange and get the engine cleaner running combatting the drift...

The other alternative is the OS50 Dossifier mod

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11-07-2004 07:16 PM  13 years agoPost 3
Fifer

rrApprentice

Fife Scotland

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60B is a great carb I fitted one 3 weeks ago and never looked back it`s like a more powerful engine and very smooth right through the throttle range...........

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11-07-2004 09:31 PM  13 years agoPost 4
flyingace

rrNovice

Bristol, Uk

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Thanks for your input the os does sound lumpy around the hover, looks like im in the market for a new carb.

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11-08-2004 12:32 AM  13 years agoPost 5
TMoore

rrMaster

Cookeville, TN

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I just spent the afternoon at the flying field with my 560-V3 and a PC. I had the same problem as you described. As a preface, I'm not using the CSM tape but I am using two layers of the 3M 1/8" thick foam tape mounted on each end of the gyro with air in between. This is on a Freya with a C-Spec and plastic tail blades. The problem that I was having was that the quick trim offset exceeded +/- 30%.

There is no way to find out what this is on a 420 but when I went back through and re-set my linkage, did the quick setup and then went out and flew, the drift was gone.

Try going through and setting everything back to book specs and see what happens. Your motor would have to be running really rough to make the gyro drift.

I was out test flying a new Rap 50 with a TT50 and MP2, 500T gyro and 9253 servo and the engine was changing from a 4 stroke to a 2 stroke because it was rich and the gyro would pulse the tail but it didn't drift once it was adjusted correctly.

TM

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11-08-2004 07:58 AM  13 years agoPost 6
G.Man

rrProfessor

Bristol

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The 500T uses the EXACT same sensor as the 601 and 401 and is more vibration tolerant than the current 560...

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11-08-2004 03:18 PM  13 years agoPost 7
TMoore

rrMaster

Cookeville, TN

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The 500T uses the EXACT same sensor as the 601 and 401 and is more vibration tolerant than the current 560...
The point of my post was the quick trim offset. The 500T was just offered up as an example on drift. I would hate to see flyinace go out and spend money on a carb he may not need and still have the same problem at the end of the day. An experienced pilot and can see when an engine is causing drift due to to tuning.

Terry

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