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T-REX 500 › Align 500ESP Shake
12-27-2010 04:19 PM  7 years agoPost 1
Bking1340

rrNovice

South Africa

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Good day all. Im a newbie in helis so I can only do hovering in any direction and some slow figure 8`s.
I bought myself a Align trex 250 and 500 - I have some problem on my 500.
When hovering from a milimetre to 1metre from the ground, the trex have a tendency to do a slow shake left/right when I apply aileron or elevator, which is maybe 2 to 5 shakes, but not vigorously, just minor, but its noticeable. When this happen the 500 don`t change direction from the shake so its actually very stable and my tail holds perfectly. There is not a abnormal vibration on the heli, just the left/right shake.
When I give pitch to say 6metres, its shaking less.
This shaking happens about 50% of the time and you can actually just see it on the skids.
I have increased my throttle and then it happens a lot less (50-100-100-100-100).
I did a re-bind on receiver and checked the smoothness of all links. Blade tracking looks good. The 500 have all the standard stuff that came with it(esc, servo`s and gp780). The 500 hovers sometimes 5 seconds hands off and then there is no shaking.
Im thinking that maybe my 2 3cell 2200mah 25C lipos are not up for the job. Dont know what the head rpm is. Some help please.
Thanks all.
PS: this is on the swash axis

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12-27-2010 05:39 PM  7 years agoPost 2
Vella

rrNovice

Shrewsbury Shropshire England

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I had a similar oscilation in pitch with my T-REX500. Maybe an increase in Head Speed and a change of Dampers might help. For general flying I run a HS of 2350 and run on the Align Grey Dampers.

TREX 500

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12-27-2010 06:41 PM  7 years agoPost 3
dkshema

rrMaster

Cedar Rapids, IA

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Your main rotor RPM is too slow. You'll want to speed it up. You didn't say what your throttle setup (curve) and pitch curve setup is, but that is where you will end up fixing things.

I assume you have the stock motor (500M) and 13 tooth pinion installed, and are running a 6S LiPo for power as that is a common configuration.

Two other things....

First, make sure when you built the heli that you put a light coat of grease on the feathering spindle to lube the rubber head dampers a bit. Dry dampers can cause weird wobbles.

Second, make sure that when you programmed your ESC that you did NOT accidentally program it it operate in Governor mode. You would have much better luck with the ESC in normal throttle mode, running an idle-up 1 curve -- flat line about 85% or so, idle-up 2 flat line curve of 95+% (or more). You'd probably want your normal mode throttle curve to be something on the order of 0 - 70 - 80 - 90 - 100 as well. Get the motor running up in its efficient RPM as soon as possible and keep it there.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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12-28-2010 03:52 AM  7 years agoPost 4
Bking1340

rrNovice

South Africa

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I am running the stock throttle curve - 0 - 40 - 70 - 85 - 100.
Yes 13 pinion with stock motor, esc re-programed - everything stock.
Think I must get myself a tach.

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12-28-2010 04:39 AM  7 years agoPost 5
dkshema

rrMaster

Cedar Rapids, IA

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Bump the 2nd, 3rd, and 4th points of your throttle curve way up. You need head speed to make the wobbles go away.

And make sure that you have balanced the tail rotor assembly well.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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12-28-2010 09:24 AM  7 years agoPost 6
Vella

rrNovice

Shrewsbury Shropshire England

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If you set up 2300 to 2400 HS on your tacho this represents 5 deg Pitch in the hover with your standard setup. Bump up your throttle curve to Hover at mid stick position for general flying at this stage.
If you still have any wobbbles look at the dampers.

TREX 500

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12-28-2010 08:44 PM  7 years agoPost 7
Noobyflyer

rrVeteran

Clearwater, FL

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Just wanted to chime in here: I have had quite a few Trex 500's in several different versions. The head shake is common, unfortunatley.

The obvious: your throttle curve. I like 0, 60, 80, 80, 80 in normal and 85, 85, 85, 85, 85 in Idle Up. Pitch Curve of 40, 45, 50, 75, 100 in normal and 0, 25, 50, 75, 100 in Idle Up.

Also, check your gyro. I like foam, metal plate, foam, gyro for padding. I set the GP 780 Gyro with a Futaba Tx at 30%.

Last, the dampeners. Might want to take the shaft out and regrease the thrust bearings as well as replacing the dampeners. I like the soft black but many prefer the grey dampeners.

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12-29-2010 04:13 AM  7 years agoPost 8
Bking1340

rrNovice

South Africa

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How much grease must I use on the feathering shaft and dampers and is it the see thru grease that came with the kit?

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12-29-2010 07:00 AM  7 years agoPost 9
Noobyflyer

rrVeteran

Clearwater, FL

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Yup, the clear grease in the kit is great. Just remove the dampeners and grease the outside and inside...you can use a small rod to get it in there. Just coat the surface and apply some grease to the feathering shaft as well.

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12-29-2010 06:48 PM  7 years agoPost 10
Bking1340

rrNovice

South Africa

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Just opened up the head. The 1 screw that secure the blade holder to the feathering shaft was very loose, but I have changed to the black dampers and greased everything up. Now its dark outside so I will try it tomorrow after work. Will let you guys know what happened - hopefully it will be right. One thing I noticed when I secured the holders to the feathering shaft is that 1 holder is a little bit stiffer than the other(not much) - they are very smooth.
Thanks for all the replys

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12-30-2010 06:16 PM  7 years agoPost 11
Bking1340

rrNovice

South Africa

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I just tested my 500 with the new black hard align dampers. I must say, I like the aggressive feel better. The shaking/wobble is half of what it was before(almost no shaking/wobble now). My throttle curve is as the align manual 0-40-75-85-100, when I change it to 0-45-80-90-100 which gives me 5% more throttle at half stick when the heli starts lifting, there are no more problems. Getting my optical tach tomorrow - will let you know what my headspeed is. What are your rpm suggestions on normal mode and idle up?

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