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T-REX 500 › heli drifting inverted
04-07-2010 12:19 AM  8 years agoPost 1
Turner0022

rrApprentice

Old Hickory Tn

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my 500 is trimmed perfect at hover in idle up but when i flip it inverted it drifts ? why would it not hover the same inverted as upright?

I am unstable and have no safe mode

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04-07-2010 12:40 AM  8 years agoPost 2
michael88997

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Lewisville,Tx

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if you use trim it will affect it inverted... what you need to do is trim it so it hovers well then go back and subtrim to get to the same value cause subtrim fixes the center so it doesnt affect it, trim makes a input in that direction which messes it up somehow lol

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04-07-2010 01:09 AM  8 years agoPost 3
Melnic

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Columbia, MD,USA

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How picky are you on the trim?
I do the trueblood swash leveling procedure.
Head is set up as close to perfectly symeterical. Flybar cage and mixing arms are parallel at zero pitch. Servo arms are at 90 degrees at zero pitch. My zero Positive and negative swash points are level using the leveling device.

As long as my CG is correct (is your CG good?) my inverted hover is as close to trimmed as my upright. Anything less than a click or two of trim needed and I just let it be. Wind can always turn it over so check it tail in as well as nose in. If no matter what direction you need the same trim, then it's your swash that is not level or CG.

If it's always tilting towards the tail either upright or inverted, look at your cG (Of course, you should check that already right?).

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04-07-2010 01:24 AM  8 years agoPost 4
Turner0022

rrApprentice

Old Hickory Tn

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thanks for the reply s and info ..for one ,,, i think my expo is way to sensitive , so i need to adjust that ... whats strange is the cg must be right cause at upright hover its trimed at 0 on all and hovers pretty much hands off ... but flip it over and it is not as stable ...my other helis dont do this im a little confused ..cheap carbon blades or head speed may be a factor ? how do you sub trim for inverted without changing upright hover lol ...should be the same both ways ... just when ya think your no longer a newby after 4 years of trial and error reality sets in ... i have a ways to go

I am unstable and have no safe mode

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04-07-2010 01:40 AM  8 years agoPost 5
michael88997

rrElite Veteran

Lewisville,Tx

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lol well you would subtrim to get your servos leveled at zero stick... ya i would check your cg cause if it flies that well its most likely something with your cg

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04-07-2010 01:53 AM  8 years agoPost 6
Melnic

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Columbia, MD,USA

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I've used endpoint adjust to tweek it before (one side of endpoint adjusts upright and the other side adjusts inverted. but Don't understand how subtrim would work for inverted only. Typically if I level the swash and get the CG right, i"m close enough that it won't bother me. Some people use a programmable mix to add in aileron or elevator when negative. Swash leveling is to me easier cause you don't have to do a bunch of tweeking and you can do it on the bench at home before you fly.

http://www.truebloodengineering.com...showpage&pid=10

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04-07-2010 02:45 AM  8 years agoPost 7
knightofcarnage

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chicago

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Sounds like ccpm interaction.

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04-08-2010 04:47 AM  8 years agoPost 8
drdot

rrElite Veteran

So. California, Orange County.

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fwiw..

I'd be sure of the cg...should balance level when held up by the flybar at 90 degrees to the boom...
EPA has an effect on upright and inverted....Punch out upright, see if the heli drifts left/ right or fore/ aft...Do the same test inverted...EPA can be used to trim this out as needed...EPA on a CCPM heli is very seldom 100 % both directions on all three servos....

John.

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04-08-2010 12:18 PM  8 years agoPost 9
Turner0022

rrApprentice

Old Hickory Tn

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now that makes scenes , what was happening was when i gave collective pos or neg the swash wasnt moving evenly , so when mid stick at hover it was even but inverted took some down stick witch would cause the uneven movement of the swash . pure genus !! thanks

I am unstable and have no safe mode

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