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HelicopterMain Discussion › Inverted Tail Drift.
12-11-2004 03:11 PM  13 years agoPost 1
livez

rrApprentice

Colchester UK

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Hi Guys

I am just getting into inverted.
In normal hovering the tail is rock solid.
But when hovering inverted it tends to drift very slowly anticlockwise.
Any ideas why the difference.

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12-11-2004 03:17 PM  13 years agoPost 2
CWC

rrNovice

Hong Kong

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Have you activated the the head hold gyro in idle mode?

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12-11-2004 03:22 PM  13 years agoPost 3
z11355

rrMaster

New England

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similarly, do you perhaps have a tiny bit of
tail trim in idle-up mode?

hover up right in the same mode as you try
to hover inverted and see if you experience the
same drift.

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12-11-2004 03:49 PM  13 years agoPost 4
airdodger

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Johnston USA

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Are you using a heading hold gyro? Chris

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12-11-2004 04:23 PM  13 years agoPost 5
livez

rrApprentice

Colchester UK

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I'm using GY601 and hovering right way up in same mode there is no drift.

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12-11-2004 05:16 PM  13 years agoPost 6
helicrap

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Atlantic City , NJ.

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Fact of life, has to do with tork reversel. Learn to live with it.
I'm sure someone will explain in detail.

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12-11-2004 05:19 PM  13 years agoPost 7
pip

rrApprentice

Baltimore, MD

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Livez,
I have the same issue with my 500t/8700g setup in my logo. I cannot find the source, the radio is set correctly and the model is balanced to perfection. Like yours is it perfect in all other flight modes. Dave Storey (JR) recently moved to my area of town, I will see if he has any ideas the next time I see him at the field.

Pip


PS My Extreme and Tempest do not have the same issue.

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12-11-2004 05:26 PM  13 years agoPost 8
helicrap

rrApprentice

Atlantic City , NJ.

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Oh I forgot to mention main blade wash over tail blades, changes inverted. There is probably nothing wronge with your gyros or setup.

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12-11-2004 05:50 PM  13 years agoPost 9
JohnC

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East Yorkshire, England

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Most of the solid-state gyros are sensitive to acceleration effects - so if the sensor is upside down, the null may well shift slightly from what it is the right way up.

I wouldn't expect it to be more than a degree/sec or so. Have you tried holding the sensor upside down and seeing what happens?.

JohnC.

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12-11-2004 10:05 PM  13 years agoPost 10
livez

rrApprentice

Colchester UK

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Interesting theories.
I would have thought the GY601 with high gain would handle any attempts to drift the tail.

It is not excessive, probably only equal to 1 revolution per min, so I can live with it, be nice to sort it though.

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12-11-2004 10:13 PM  13 years agoPost 11
TOSH

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UK.Peterborough

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livez
GY601 with high gain
What gain and what tail blades are you running?

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12-11-2004 10:14 PM  13 years agoPost 12
A. Bundy

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Aurora,IL. 30W/SW of Chicago

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I'm running a 601 on a R50.No drift that I recall.

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12-11-2004 10:32 PM  13 years agoPost 13
livez

rrApprentice

Colchester UK

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My favourite theory so far:
It's been suggested to me that the engine may be running leaner inverted causing vibration.
Which in turn can cause the Gy601 to drift.

Although I am only running 85mm tail blades they hold very strong normal ways, so I don't see a difference inverted.

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12-11-2004 10:40 PM  13 years agoPost 14
kthane

rrVeteran

Pensacola

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It's been suggested to me that the engine may be running leaner inverted causing vibration.
That is probably the most sound theory going. If the engine gurgles and kicks the tail repeatedly. The gyro will either over compensate or under compensate for the rapid movements causing the tail to wander off to one side ever so slowly.

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12-11-2004 11:01 PM  13 years agoPost 15
TOSH

rrElite Veteran

UK.Peterborough

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Ummm.
Never known a lean engine to gurgle.So what Gain?

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12-11-2004 11:11 PM  13 years agoPost 16
kthane

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Pensacola

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Rich engine gurgles, lean engine crackles. Doesn't really matter if it's too lean or too rich, if the engine isn't running smooth upside down, it can cause the tail to drift. His gain is probably 37% like everyone one and their grandmother.

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12-11-2004 11:15 PM  13 years agoPost 17
TOSH

rrElite Veteran

UK.Peterborough

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kthane

So why say high gain.

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12-11-2004 11:48 PM  13 years agoPost 18
airdodger

rrElite Veteran

Johnston USA

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My money is with helicrap,the main blade downwash makes the tail blades more effective in upright hovering and a little less in inverted.That said heading hold gyro's are sensing where the hold spot is and should return when trimmed correctly for inverted. But you stated rate mode, rate mode only reacts to stop the rotation ,heading hold senses where it was and return's the tail to it's original position.Which mode are you using? Chris

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12-12-2004 12:26 AM  13 years agoPost 19
helicrap

rrApprentice

Atlantic City , NJ.

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I did forget to mention that 85 mm tail blades are small ( probably to small ) for raptor .60 What heli are you running ?

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12-12-2004 12:40 AM  13 years agoPost 20
helicrap

rrApprentice

Atlantic City , NJ.

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Please ignore my last post as I crossed up two threads I was following.
Would like to know what heli though.

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HelicopterMain Discussion › Inverted Tail Drift.
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