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Home✈️Aircraft🚁Helicoptere-AlignT-REX 450 › "Sticky" feeling on pitch and cyclics
08-04-2007 02:19 PM  13 years ago
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pmcenery

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Wales, UK

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"Sticky" feeling on pitch and cyclics
I am going to try my best to describe the problem that I am having with my TREX-450. Essentially, I have built it as close as possible to Jason Krause's spec with the exception of Motor and Speed Controller. Here is the hardware list:

It's a v2 SE with carbon frames etc:

Futaba 14MZ radio (running JK's model setup downloaded from his site)
Servos are 3 x Hitec HS-56HB's (on cyclics)
2150 MAh Flightpower packs
GY-401/ Futaba S9650

Motor is still the stock 430L - Align
Speed Controller is the stock one (RCE-BL25G/35G)

Initially I had trouble with the gyro setup but fixed this by moving the ESC further away from the gyro. The tail now performs well and holds like a rock (35% Gain).

The problem that I am now having is that when you give it some pitch so that it climbs rapidly, it takes moving the stick back to about 1/4 stick before it stops climbing. At this point its now got about 6 degrees of negative pitch. When its direction eventually changes it then come screaming towards the ground and takes the equivalent amount of pitch to stop it. This problem is even worse when you put it into Idle up. it almost feels like the motor is using so much power that there is not enough left to power the servos.

Even in normal mode flying slow figure of eights, it sometimes takes a real jerk of the stick to keep the nose up. It just feels like the cyclics and pitch are really sluggish (power problem). It almost feels like I need to put a damn 15KG servo in there to get it to respond!

I have checked the movement of the servos and pushrods and they are silky smooth, the servos even sound like they are having no trouble moving across the full range.

Has anyone else seen anything like this? Is the speed controller delivering only 4.8v possibly?

Any assistance would be much appreciated.
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08-04-2007 05:05 PM  13 years ago
pmcenery

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Wales, UK

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My pitch curve is linear at the moment. Middle stick is 0 full up is about +10 degrees and full down is about -10 degrees.

I checked the voltage output from the BEC and it's exactly 5.0 v. I take it that should be sufficient.

One factor that I have just thought could play a part certainly in the sluggish cyclics; I had the weights on the flybar (right out at the paddles). I will get rid of those next time I go out to the field. I wouldn't have thought they would affect the pitch though.

Any other ideas?
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08-04-2007 07:40 PM  13 years ago
MikeInMobile

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Mobile, Alabama

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Sounds like your ball links are tight. This will make all of the cyclic and pitch controls "stickt", and will reduce your flight times since the servo has to overcome the resistance of the ball links.
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08-06-2007 01:39 PM  13 years ago
pmcenery

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Wales, UK

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Thanks to everyone for responding.

I rebuilt the head over the weekend and found a couple of tight joints. I have since replaced these and its all nice and loose now. Haven't managed to take it for a flight yet, but will report back.

It looks like tight links were the cause.
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08-06-2007 05:33 PM  13 years ago
bigdog714

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Rochester, MN U.S.A.

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On my 450SA with Hitec servos Align recomends CP6 at 80%, for JR and Futaba they suggest 65%, these settings are for the 120 degree swashplate, I dont know the settings for the 90 degree swashplate.MD 800
Logo 600SE
Logo 14/500 Carbon
Ballistic 700
HD 500V2
Hirobo 50E
Avant 90E
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08-07-2007 09:00 PM  13 years ago
helimatt

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Lafayette, IN

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SEV2 has thrust bearings in the main grips- you may have the inner and outer washers reversed, so under load (blades spun up pulling out on the bearing) it is really draggy- would give you the symptoms you describe.. Having tight ball links would not give such extreme "stickyness" you are having, just make it not want to center up so nicely in hover etc, but not so badly.

Check the build up of the main grips.
Never, ever, ever, ever give up.
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08-15-2007 11:33 AM  13 years ago
pmcenery

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Wales, UK

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I managed to get out to the field this past weekend and things didn't go well! I managed to crash it within about 30 seconds.

This appears to be more of a radio problem than anything else. After rebuilding it AGAIN, I decided that I am going to hold the heli while applying some pitch (I know this can be dangerous, but I did it carefully - if thats any consolation).

It definitely appeaars to be a problem with the ESC and the delivery of sufficient power to the receiver to power everything. When there is sufficient load on the motor (about 6 degrees of pitch), the servos (all 3) simply stop moving as if they were powered for almost a second.

I have had trouble with the ESC interfering with the Gyro, so I decided to move it as far away as I can and perform the test again. Still, the servo's just stop responding when the motor is doing some work.

The radio and receiver are Futaba 14MZ/whatever 14 channel receiver they sell with it.

My conclusion at this point is that I need to try a separate 6V BEC. In addition, I decided to go the whole hog and upgrade to the same spec that Jason Krause has (Quark 33A / 6V Medusa BEC). I also bought a Hacker 12L, but will only bother with it once the power/glitching/radio issues are sorted out.

Until the servos respond as expected while I am holding the heli, I will not bother breaking another set of gears, blades, flybar, etc.

Thanks for all the replies! They are much appreciated.
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08-28-2007 02:06 PM  13 years ago
pmcenery

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Wales, UK

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Problem solved!!!

The Quark 33A / Medusa 6V BEC combination seem to have done wonders. That said, I also changed the motor to a Hacker and its an absolute dream to fly now.

This is the first time that I have been home from the field having not destroyed the usual kit (blades/main shaft, etc, all servo gears, etc). This does not mean that I was taking it easy either. I managed a good few, flips, rolls and inverted flight.

I know that most folks could not just afford to replace half the kit in their heli, but I am just going to put this one down to an incomparability between some of the other components (such as the 14mz 14 channel receiver and the stock align motor and ESC.) If I had time, I would probably try the align ESC and motor with the Medusa 6V BEC. Unfortunately, time will not allow this.

Many thanks for all your input. Here are a few pics of the final product:

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