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T-REX 450
Trex 450 SE slow tail drift...
kc7328

Senior Heliman

Kansas City

Probably been covered before.. but i am having a hard time getting to a fix...
Problem is.. heli is flying well.. but i just have a very slow drift clockwise.. running a DX7 tx and gain is on gear channel set at 72..
When i say slow.. i mean probably every 20 seconds or so i need to give it a little tap back to the left...

Set up:
450 SE stock
stock motor and esc
401
3400g tail servo
DS285 on swash
align carbons

running 0 50 80 90 100 on TC


Any ideas...

Alimony is like buying hay for a dead horse !!!

10-07-2008 Over year old.
Waco

Senior Heliman

Bernalillo, New Mexico USA

Can we assume that you are flying in the HH mode?

10-08-2008 Over year old.
Dale M

Senior Heliman

Lakewood Ca USA

If it is in HH, 72 on gear channel seems too high.. I've found that the magic number on gear channel to be around 38

10-08-2008 Over year old.
kc7328

Senior Heliman

Kansas City

Yes I am in HH mode.. nice steady light on the 401

From all the documentation.. and the finless vids, 72 is the sweet spot on the DX7.

Alimony is like buying hay for a dead horse !!!

10-08-2008 Over year old.
nmrs

Senior Heliman

Austin, TX

72 is the sweet spot IF using gyro sense.

When using gyro sense, gain = (displayedGain - 50) * 1.44

(the 50 is because anything above 50 is HH, anything below is rate)

so 72 in gyro sense ~= 32 gain (actually 31.68)

if using gear menu displayed gain is actual gain.

I run 47 on gear menu.

450 se v2

10-08-2008 Over year old.
kc7328

Senior Heliman

Kansas City

Right you are..
I am using the gear channel in gyro gain mode for at the 72 setting.

and another thing.. i double checked all of my trims and sub trims.. they are all centered on the rudder channel...

Alimony is like buying hay for a dead horse !!!

10-08-2008 Over year old.
nmrs

Senior Heliman

Austin, TX

I had a pretty long thread about my tail issues on my 450. I'm still a beginner, but I learned a lot going through this:

http://www.runryder.com/helicopter/t434917p1/

Few things I learned.

1) This is probably not it, but I'll still throw it out there: Make sure your headspeed is high enough. Originally I had too low of a normal throttle curve (0, 50, 85, 92.5, 100) and horrible collective management skills, so I would drop the stick too low, headspeed would decrease, tail would drift...

2) Gain could be too low. Keep raising your gain until it wags and then back it off. 72 is just a recommended starting point. Required gain will be influenced by a lot of factors: mechanical gain (i.e. how far out from center the ball is mounted on the tail servo), head speed, battery power, vibrations, and on and on. Just raise the gain by about 5 points at a time until it wags, and then back it off. If you can't get it to wag no matter how high you go, increase mechanical gain (i.e move the ball farther out on the servo horn), bring gain back down to 72, and start again, slowly increasing gain until it wags and bring it back down.

3) Could be interference from esc or motor. Make sure your gyro wires don't get near these.

4) Could be vibrations. Is your tracking right? Do you see any vibrations when hovering?

There are probably loads more things that could cause tail drift, but those are what I can think of off the top of my head...

450 se v2

10-08-2008 Over year old.
steffgiguere

rrProfessor

St-Eustache, Quebec, Canada

Was your tail set up right in normal mode before switching to HH? It should hold centre in normal before switching to HH. Also check to make you have no trim.

Team Synergy, Canada: Team Scorpion

10-08-2008 Over year old.
HOMEPAGE  
kc7328

Senior Heliman

Kansas City

Thanks for all the suggestions everyone..
NMRS.. i went through that post you linked.. lots of good info there...

I think I will go through a few things this evening.. namely in order

1. rebind
2. double check my setup .. i think i will change the gear channel to use gear=gear instead of a gyro setting and try the 53 as my approach..
3. drop back down to rate mode and realign everything...
4. check tracking on blades and look at mechanical gain
5. crank up headspeed a little..


aint this fun..

Alimony is like buying hay for a dead horse !!!

10-08-2008 Over year old.
jetnc

Heliman

charlotte, nc

Also.....

1. Check belt tightness
2. Replace Gyro adhesive mount

10-16-2008 Over year old.
baby uh1

Veteran

St. James, Mo.

Neat trick with the 401. Fly heli, add trim until no drift, land and then flip HH switch on off three times rapidly. This resets the gyro's midpoint to the new setting. Gyro light will go to solid red and you should be good to go!
I tried this on my 30 nitro and it worked perfectly.

Anything is possible if you don't know what you are talking about!

10-16-2008 Over year old.
Swoop

Elite Veteran

Newark, DE USA

Every time I've seen a drift, it turned out to be a vibration. Check your tailshaft and make sure both tailblade grips are still completely seated against the tail hub. It goes without saying, balance the main blades.

Also check that the tail hub or tail pulley is not slipping on the tail shaft.

Usually gain related drift only shows up during collective changes, ie... the tail kicks then stops (not constant clocking)

Also if your using a tie down strap over the gyro, make sure its not too tight.

10-16-2008 Over year old.
nmrs

Senior Heliman

Austin, TX

Usually gain related drift only shows up during collective changes, ie... the tail kicks then stops (not constant clocking)
I see this a bit on my 450 w/ 401 and s9257. To correct it do you increase or reduce gain?

450 se v2

10-16-2008 Over year old.
Swoop

Elite Veteran

Newark, DE USA

As long as you have enough headspeed and all other variables are correct, then you should increase the gain. With the gyro and tail servo you are using, that tail should be rock solid even under the stiffest 3d flight if it is setup right.

10-17-2008 Over year old.
TomRex

Elite Veteran

West Palm Beach Join Date: 12-28-2005

Try a straight throttle curve non linear like a 0-75-75-75-75 in norm, higher for I1 or I2 makes life easier to get things right.
You can always go to a V' curve later.

Ignorance is the absence of facts.Stupid is lacking the intellectual capacity to comprehend the fact

10-17-2008 Over year old.
HOMEPAGE  
kc7328

Senior Heliman

Kansas City

Great advice everyone.. still working on getting it right..
Havent had the time i would like to experiment.. With the financial meltdown occurring.. i have been sent all over freakin creation putting out fires at work..

I was able to try a few things before heading out to China and Glasgow though..
Heli is mechanically set up correctly.. no trim any on rudder..
Tried to alte the HS... bumped it up to a flat 90 across the board in Id1 and then to 100 in ID2.. still experiencing the problem.. however it slowed down some.. turned to a very slow creep on the tail..

checked components in the head.. all is good.. starting to think my tail might have some vibration.. will check the output shaft this weekenend.. maybe do a full rebuild on the tail..


another question..
What is the heaviest batt anyone has used on a 450? No 3d stuff.. just basic sport flying for now.. Didnt know if anyone has used a pack in the 200-220g range?

Alimony is like buying hay for a dead horse !!!

10-17-2008 Over year old.
Swoop

Elite Veteran

Newark, DE USA

If I remember correctly my Kong Powers are about 220 grams. They are pretty hefty but I can still toss it around without much effort.

10-18-2008 Over year old.
Swoop

Elite Veteran

Newark, DE USA

edit: My kong power is 209grams

10-20-2008 Over year old.
Ken4

Senior Heliman

Singapore

Took me a long time to figure out why I was having a slow clockwise drift on my Trex 450seV2. I changed the mounting pad of my GY401, new tail CF blades, new CF main blades, new counter gear & bearings, new autorotation gear, new one-way shaft, new one-way, new main gear, rewired and insulated the gyro wires......nothing worked. Then I noticed my Trex was having a nasty vibration on the tail on spool up. I suspected vibration was the culprit. In desperation I held up my Trex with one hand on the skids, and started her up at low rpm, maybe 2000rpm, I could feel the intense vibrations! I took out the main blades and spooled her up with only the fly bar, and still had vibrations. To cut a long story short, I changed the flybar paddles, adjusted them, until I felt no vibrations. Also changed new dampers, new damper spacer, new 4x7x2.5mm bearings on the main blade grips.....and viola......vibrations gone! Now my tail locks on with no drift! Woohoo!

11-30-2008 Over year old.
Swoop

Elite Veteran

Newark, DE USA

To cut a long story short, I changed the flybar paddles, adjusted them, until I felt no vibrations.
Did you by chance weigh the paddles to determine if one of them was substantially heavier or lighter than the other, or was it the case of the distance from the seasaw to paddle different between the two sides?

11-30-2008 Over year old.
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T-REX 450
Trex 450 SE slow tail drift...
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