RunRyder - weird gyro/tail rotor behaviour on Eco 8...

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e-Electric General Discussion > weird gyro/tail rotor behaviour on Eco 8...

nickybee
Heliman
Location: Vancouver

Ok. I am a (very - as in 10 minutes) low time RC pilot (though I fly full size helis)

I have an Eco 8 with a jeti brushless setup 30/3 and an Ikarus Micro Gyro.
The Tx/Rx/servos are all hitec (eclipse 7 radio, hs 81 servos).
I am running 10 cells.

The swash is the standard plastic one.
Blades are balanced (both static and dynamically as far as I could manage).

on the table with the motor not connected everything looked good - the swash moved like it should and the pitch range (According to the ikarus clip-on gauge was -6 to +12 so I left it at that.

I had a friend test fly it to help me trim it out and other than tweaking the rates quite a lot on the cyclic (cause it was waaay to twitchy for a beginner) he said it was pretty much fine.

except for the gyro/tail rotor.
he seemed to be able to fly it more or less ok but we kept turning the gyro gain up and up and that was causing him to keep trimming the tail rotor in the radio.
I discovered when I got home that the reason this happens is that on this particular gyro when you change the gyro gain (which is done by turning a small screw on its side) the servo arm moves too - which throws your zero position totally - there is another screw which you can move to change the zero position back...(which we didn't do in the field).

The problem was today when I went to fly it on my own (and btw though I'm a beginner I'm quite comfortable flying tail-in nose-in and doing loops and rolls in Realflight G2 so I have a vague idea of how it's supposed to be).

I powered it up and it lifted off and suddenly yawed hard left - REALLY hard - almost 180 degrees before I brought it back down - tried it again and tried to hold the spin with right rudder...slowed the spin down but it still went quite far over.

Note I have made NO changes to the setup since he flew it...

I tried a few more "hops" (can't really call them hovers) and when I nudged it into slight forward flight it would become slightly more stable but it would still yaw like a bastard when I slowed down.

so - my question is this

1. Is the gyro upside down ?
In my simple understanding of gyros this would seem to be a possibility - although I wonder why his flying wouldn't seem to be affected by this...

2. Am I just a crap pilot and everybody deals with this ? I ask this because when learning to fly a real heli the difficulty in control with precision hovering is almost always cyclic above everyhing else - here the cyclic was almost a non issue.

3. Is the gyro busted ? or as an alternative - is there something wrong with the tail rotor and/or Tx ?
I ask this last one because of another weird idiosyncracy...

I have some revolution mixing setup - and the UP stick number is slightly higher than the DOWN stick number - which is fine - and I notice a very slight "click" in the tail rotor as I move the stick back and forth (just through the halfway point it clicks in as the rev mixing rate changes.)
but - at about 1/4 stick (in fact 7 ratchet clicks in from the bottom - there are 33 ratchet clicks from collective full down to full up) there is a BIG click in the tail rotor servo and it the servo arm moves by almost 10 degrees.
this happens regardless of how fast I move the collective stick up and down - and in fact if I try and hold the stick "mid" ratchet click the tail rotor servo can get "caught" and madly skip back and forth of its own accord...

if anyone could shed any light on this it would be much appreciated.

nick

01-12-2003 Over year old.

HOMEPAGE

meltr
Senior Heliman
Location: London, UK

I havn't used a Ikarus gyro but I have seen this on other gyros.

You turn the gain and the servo moves. This can be because
the zero offset (trim) is not really zero. A setup error which should
be corrected.

Some gyros have a pot on the gyro to adjust the zero offset. The
easiest way to adjust this accurately this is to adjust the zero offset
pot until moving the gain pot over it's full movement no longer moves the tail servo.

The reason is that if there is an offset that is not zero the gain
pot amplifies this value and thus moves the tail servo. When
the offset is truley zero the gain cant affect the servo since
anything multiplied by zero is still zero.

Once the zero offset pot is set up then dial in 50% of gain to
start with. Fly the model and adjust the tail linkage so that the
heli does not rotate (much

) by itself.

Unfortunatly the zero offset will drift over time on that type of
gyro due to mechanical and tempreture variations so you
need to perform this setup once in a while.

Some other gyros have a better method for adjusting the zero,
there is a bi-colored LED. You turn the zero offset until both
colors are on.

Mel.

01-12-2003 Over year old.

meltr
Senior Heliman
Location: London, UK

Remember that until the heli has revved up to a high enough
speed the tail won't be effective. You'd normally have to hold
a bit of rudder in while it's spooling up because of this.

I read about your 'revo' thing too. Not sure what that is. To
be honest it's not really possible to setup revo properly until
you can fly moderate climbouts and decents. Also you cannot
set a revo setup correctly until the other problems you talked
about are sorted.

I would take the revo out for now, and sort out the other problems.

Make sure you don't get that funny 10 degree jump or the funny
back and forth at center stick. This could possiblly be because
you have stripped a gear in the servo, or the servo or gyro
electronics are broken.

Try this plan 1) Take out revo settings 2) Adjust the zero offset
like in my last post 3) Connect a different servo that you know is
good and make sure you don't get the jump or mad skipping
when both throttle and rudder are moved.

Mel.

01-12-2003 Over year old.

Eco8gator
Key Veteran
Location: Palm Beach Gardens, FL

Hello

I have not used that gyro before so Ill let someone who has make a suggestion on how to fix the problem you are haveing.

What I suggest, and I guarentee all your gyro problems will go away, is to get your self a Futaba GY240, plug it in(still in standard mode), center all your trims and remove any off sets, turn off your revo mix, center your tail pitch and your tail servo horn, and after everthing is centered put your gyro in AVCS mode and you will never have a problem again. Oh and be sure your gyro is correcting in the correct direction(if it is correcting in the wrong direction then flip the direction switch on the gyro).

Carlo

01-12-2003 Over year old.

nickybee
Heliman
Location: Vancouver

ok will try and report back.

it's raining outside now so I don't want to try and lift it indoors...

but as soon as I can I will try the stuff about the servo zero setting - and turn off the revo mixing to see if it makes a difference.

I'll post back what happens.

thanks

nick

01-12-2003 Over year old.

HOMEPAGE

nickybee
Heliman
Location: Vancouver

ok some initial reports.

thanks to everyone for posting - I think I'll try to fix it with the existing gyro and if it fails to work adequately I will give hobby lobby some **** for recommending it.
and then get the futaba.

however in the meantime here's an additional comment (re the 10 degree skipping stuff)

1. it is definitely not the servo - when I try other servos that I know are good the same skipping happens.

2. the skipping is also not caused by the gyro - when I try to bypass the gyro I still get the skipping.

3. I can prevent the skipping by putting the rev mixing to 0% stick up 0% stick down.
once I realised that I tried putting it 50% stick up 50% stick down - at this point there wasn't even a slight click at half stick (as expected because the rates are the same) but the 1/4 stick sharp click was still there.
weird eh ?

I wonder if this means that there is some kind of weird problem in the Tx itself ?

anyways - more on the servo settings later

thanks

nick

01-12-2003 Over year old.

HOMEPAGE

R-Rocks
Heliman
Location: Porterville Utah

ECO 8

I wonder if you got enough head speed, next to changing the pinion you can back off on the pitch just a bit.

01-13-2003 Over year old.

nickybee
Heliman
Location: Vancouver

hmm - head speed ?

I'm curious as to why that would make a difference...
I have a feeling if anything it could be a little too fast (I've read elsewhere that people with this setup and this motor have to lower their throttle curves cause max speed is too fast)

nick

01-13-2003 Over year old.

HOMEPAGE

nickybee
Heliman
Location: Vancouver

ok news on this setup

didn't test fly today but will tomorrow.
tried the (move the zero gauge then the gain gauge trick described above for the gyro) but no matter what zero gauge position I try I cannot get the servo arm NOT to move when I through the full range of gain.

I have settled on extreme left on the zero gauge - because now the servo arm only moves through maybe the first 1/3 of gain gauge movement - through the rest it is stationary...

have zeroed all the tail rotor servo arms at centre stick and will try to take off with no rev mixing at all.

(btw I discovered that what I called the dreaded 1/4 stick flicker is actually happening at 50% throttle setting)

My friend who test flew the chopper adjusted the throttle curve to be

0 70 77 85 92

to check my hypothesis I changed it to 0 25 50 75 100
and lo and behold the weird clicking was on 1/2 stick.

anyways - will be calling hitec/hobby lobby tomorrow see what they say.
will report back

nick

01-13-2003 Over year old.

HOMEPAGE

R-Rocks
Heliman
Location: Porterville Utah

ECO 8

With out the head speed your tail wont be turning as fast to counteract the tork of the main roter blades, I had this same problem, I even went as far as changing the gear ratio on the tailrotor to a 35t gear from the 40t that came with it , this took care of it but when I figured out my problem I went back to the stock 40. My throttle curve is 0/70/100/100/100. I run a mega brushless, 17t pinion with 8 cells 2000 mah's. With this set up I get around 8 or 9 minutes flight time.

01-13-2003 Over year old.

meltr
Senior Heliman
Location: London, UK

The extreme left is very probablly not good.

It probablly doesn't move in the 2/3rds because it's maxed
out is bad.

Try this

1) Put zero pot at 50% (the middle of that pot is zero)
2) Put the gain pot at 0%
3) Remember the servo position
4) Put the gain pot to 100%
5) Move the zero pot until the servo moved to the position remembered
6) Repeat from step 2 until the servo doesn't move much when
the gain pot is twiddled.

Also here is a procedure which can tell you if the radio trim is
out of range.

1) Put the zero pot at X% and the gain pot at 0%
2) Remeber the servo position
3) Put the gain pot to 100% and note the direction the servo moved in

Repeat steps 1 to 3 using three different values for X% Do 10%, 50% and 90%. If the servo moves in the same direction each time then
the radio's rudder trim is out of range.

The setting of the zero offset is not as critical as getting your
funny 10 degree click and wobbles out as this will certainly show
up in flight. Make sure all your other mixers are off.

Mel.

01-13-2003 Over year old.

MJA
Key Veteran
Location: Cumbria-UK

Are you using Ikarus's own mechanical CCPM mixer with mechanical tail compensation mixer.If you are and your radio supports Electronic CCPM for the swashplate servo's i'd suggest doing away with the Ikarus mech unit.It ends up either too tight or has ton's of slop in it . That way you only have the electronic tail mixer from the radio to worry about rather than two lots of tail compensation going on.It should be more accurate also.

Martin

01-13-2003 Over year old.

Brian Bennett
Key Veteran
Location: Dugway/Tooele UT, USA

What Gyro is it exactly? I have been running a Profi on my eco with 8 and 10 cells since 1998 without the symptoms you are describing. Would you please list all of the criticals; Cells, gearing ect.

01-13-2003 Over year old.

HOMEPAGE

falcon9
Heliman
Location: Bellmore, New York

Nick,
I have one simple question to ask, are you sure that you don't have anything reversed in the TR assembly? Often times first time builders of the Eco8, myself included, reverse the belt direction and then the gyro has a tough time keeping the tail in line. I flew my first Eco with an Ikarus gyro and had no trouble at all. If you are not sure check out this site that a couple of the guys are building just for the Eco8 http://www.dream-models.com/h/

Look under Setup and there you will find an article I contributed on the proper setup of the tail rotor. It might help you to be sure that mechanically everything is right before blaming the gyro. I now use the GY240's on my Eco's.

Mike

01-13-2003 Over year old.

nickybee
Heliman
Location: Vancouver

ok setup detail..

Tail rotor pinion 40t
Main rotor pinion 24t

motor Jeti brushless 30-3
ESC jeti 40-3P
Gyro Ikarus MICRO gyro
Servos/Tx/Rx all hitec

It's a 10 cell setup and I'm using Electronic CCPM through the Eclipse 7.
The mixing setup is odd (in so far as I'm using the 180 degree swashplate mix and then slaving the elevator to the aileron channels with one of the programmable mixes) - that's what I was told to do - and that does not seem to be a problem - swash movement is fine

(tail rotor servo mounted on frame as per manual - not on the tail...yet)

the rest is stock plastic - no upgrades (other than auto hub)

in answer to a few recent posts.

1. No the tail rotor is not reversed (though it was a while back

)
nice site for beginners though this dream-models one

2. thanks meltr for the gyro instructions - will try...and let you know
currently have left voicemails with Ikarus, Hobby-Lobby and Hitec - and awaiting their response...

01-13-2003 Over year old.

HOMEPAGE

nickybee
Heliman
Location: Vancouver

gyro seems sorted out...still nothing on clicking

ok so the gyro tips (about repeatedly rotating the zero and gain pots till movement is minimised) were quite useful.

now I've got it almost completely steady throughout all of the gain pots movement.

thanks for that.

last thing remaining is the dreaded clicking rev-mix issue.

spoke to hobby-lobby and the heli guy there (dave) said he'd never heard of anything like it.
hitec have still to come back to me.

I'm suspicious of a bug in the rev mixing in the Tx.

To give you an idea of the magnitude of the jump - when I set rev mixing to say 80% up and 0% down - to deliberately make a big difference there is a discernible shift in the servo at 1/2 stick (as you're moving the stick up to down) - as I would expect their to be because the rates are so different...

however when I set the rev mixing to be say 50% up 50% down then a similar size shift (or as I called it - click) occurs at 1/4 stick (or as I described in a previous email at the 50% throttle point)

any other takers on this ?

I mean I know I could just try it with no rev mixing but it seems a bit lame to have this kind of problem in hitecs highest end radio

nick

01-13-2003 Over year old.

HOMEPAGE

meltr
Senior Heliman
Location: London, UK

I have only a vague idea of the sort of clicking you are having
only that I can tell something is not right.

I would reccomend that you switch to another model memory,
and reset it completely. Put the model memory into heli mode
and touch nothing else. Then check the clicking problem out.

Hopefully there is no clicking to be seen. If there still is then
I'm completely stumped.

If the clicking is gone then set things up one step at a time,
at each step making sure the clicking is not there.

I would reccomend that you don't touch the revo mix until
the heli is at least hovering cleanly. It really isn't possible to
set a revo mix until then.

Mel.

01-13-2003 Over year old.

nickybee
Heliman
Location: Vancouver

thanks...

that's exactly what my friend (a guy called Russ Tront who flies in Vancouver) recommended and I did exactly that and I got the same thing.

the clicking seems to follow the 50% throttle curve even in a totally new (RESET) model memory...

as I said - if and only if the mixing is turned on...with no mixing it is not there at all...

chasing info from hitec but nothing yet

nick

01-13-2003 Over year old.

HOMEPAGE

nickybee
Heliman
Location: Vancouver

will post in radio forum

I just noticed there was a radio forum too - and since the gyro has been more or less tamed there's just the eclipse 7 issue - hitec still looking into it.

granted I could just get a heading hold gyro and forget about it all - but I will crosspost a summary into the radio forum. (which I only just noticed existed.

apologies for anyone who reads both.

thanks.

nick

01-14-2003 Over year old.

HOMEPAGE

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e-Electric General Discussion > weird gyro/tail rotor behaviour on Eco 8...

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