New 600N and getting desperate.

[Chief heli]

Hello Helifreakers!

Ok I’m getting desperate.
I completed my build on the Trex 600N sport last sunday!
So it was time to take it out for his maiden! But I ran into some shaking problems :(
Please help out with this one.

Here is the story:

My last heli was a Gohbee stinger 50 Deluxe. I crashed it cause of a broken Jesusbolt while flipping it upside down. After that I never got it back into the air without vibrations. I replaced all damaged parts, mainshaft, spindle, tailshaft, flybarrod, mainblades (Things that can cause vibrations) But still vibrations! Experimented with other blades but didn’t work either.

I had enough of the gohbee so I decided to buy the trex 600N sport.
So I got it! This my (all new) setup:

Align Trex 600N sport
- OS 50 Hyper / Hatori 522 (OS50 Hyper taken out the gohbee)
- Futaba FF7 / 149 DP (soon a JR 9303 2.4)
- JR 8455 x3
- JR 820G / RevMax
- JR 770t / 8900G
- Fromeco Arizona regulator
- Fromeco Relions 2600 mAh
- Align metal fan
- SAB 600
- SAB 20gr paddels

I spent a lot of money on this setup and thought the only problems I could have are my flying abilities. But the plan didn’t work out that well.

First take-off was shaky as hell! I had to reduce the gyro gain (770t) from 35% in HH mode to 4% to make it flyable (is this normal with this JR gyro and futaba transmitter system?). But it kept shaking, so I decided to change the blades and after that it flew nice and stable. After hovering a while en some figure of 8’s I pumped it up to Idle 1 with some more headspeed. (revmax off) and did some flips and rolls and a inverted hover. Brought it back down and saw it was shaking again (tail fin side to side). So lower headspeeds are no problem, but for 3D it starts shaking real bad.

Today I tried it again, got a good set of balanced blades but still shakes when idle1.

What do I think is the problem?
-The 770t/8900G combo is very sensitive and when it starts shaking somewhere, this thing makes it even worse. (I think) But where does the shake come from?
-Maybe the engine from the gohbee has a bend shaft? The coolinghead is damaged from the gohbee crash but it runs just fine. It’s the only “old” part from the gohbee.

I don’t have any expert help in my area that can help me out with this one.

Sorry for the long story. Thanks for reading and I hope someone can help me out!

Greetings,
Chief

[creightoncarr]

Could easily be a bent crankshaft in the engine from the original crash. If the head on the engine is damaged from the crash the engine took a hit. I'd change the crank and the bearings.

[mporlier]

Look at the head button on the shaft when you spool down. Observe it until full stop. This is a good indication of imbalance in the head/blade setup. Since the engine is disengaged you can isolate the problem. Could be paddle, fly bar not symmetrical, etc...

Can you main shaft slide down the 3 bearings easily? Maybe your bearing bloks are not strait. When you thighten them they can warp the frame.

With an electric you can also spool up a bit without the main blades, this shows me if I have a problem with the tail rotor. With a nitro I don't know if you can do this.

Are you engine mount screws tight?

[ClayK]

What's shaking exactly? Tail? Helicopter? I'm confused....

[Azlum]

I'm confused as well.... from reading your description it sounds like your tail is wagging?

Please clarify... are you having a vibration? or do you mean the tail is wagging back and forth?

[captcasper7]

Where is your ball link on your tail servo any more than 11mm from centre and you will have issues with the 770 gyro, it states in the manual 11mm.

Loosen up the screws on your bearing blocks and make sure your main mast just drops into place with no force from you. Once that is OK leave the mast in place and tighten up the screws on the bearing blocks.

Check your tail slider and pitch arms make sure they are very very free with not binding. and the set-up is as per thr manual 90 on the servo horn and tail link and your tail slider is at centre travel when everthing is at 90.

Mike

[joco]

Could easily be a bent crankshaft in the engine from the original crash. If the head on the engine is damaged from the crash the engine took a hit. I'd change the crank and the bearings.
I agree... two helicopter both with a vibration problem.... sure seems to me it has to be the ONLY Part you had on both.

[Chief heli]

Thank you all for the replys! Really appreciate them!

Could easily be a bent crankshaft in the engine from the original crash. If the head on the engine is damaged from the crash the engine took a hit. I'd change the crank and the bearings.
But how can it be with the lower headspeeds there is no problem?
I think when the shaft is bend it rotates a bit ruff, or not at all.
What can I do to check this?

Look at the head button on the shaft when you spool down. Observe it until full stop. This is a good indication of imbalance in the head/blade setup. Since the engine is disengaged you can isolate the problem. Could be paddle, fly bar not symmetrical, etc...

Can you main shaft slide down the 3 bearings easily? Maybe your bearing bloks are not strait. When you thighten them they can warp the frame.

With an electric you can also spool up a bit without the main blades, this shows me if I have a problem with the tail rotor. With a nitro I don't know if you can do this.

Are you engine mount screws tight?
I will check the head tomorrow!
Paddles and flybar are both at centre of the head. So that can't be a problem either. Took extra care on that one!
My mainshaft drops in like a glove..
What do you mean with tight screws? Well I think so... Yes they are tight.

What's shaking exactly? Tail? Helicopter? I'm confused....
It's hard to say, I'm getting a bit scared when it starts to vibrate so I focus more on my flying then on watching wat vibrates on the helicopter.
Hope to do some testing tomorrow. I'll ask someone to come and watch with me. But what I can remember, the tail-fin goes left to right and the header tank vibrates.

Where is your ball link on your tail servo any more than 11mm from centre and you will have issues with the 770 gyro, it states in the manual 11mm.

Loosen up the screws on your bearing blocks and make sure your main mast just drops into place with no force from you. Once that is OK leave the mast in place and tighten up the screws on the bearing blocks.

Check your tail slider and pitch arms make sure they are very very free with not binding. and the set-up is as per thr manual 90 on the servo horn and tail link and your tail slider is at centre travel when everthing is at 90.

Mike

OK we might found a fix here! My ball is located 15mm from centre.
My tail linkage is OK! Put extra work on that to make it as smooth as possible. Also tried my best on all the linkage all over the heli.

Thanks again for the help!
You guys ROCK!

[rototiller]

Too funny, I started with the gobee also. Got sick of chasing the vibration. LOL.

I now have the 600N sport also.

Not sure what vib your chasing but I will give it a shot. First, if its the motor you will see your fuel sloshing around in the tank or even foaming up. That might show up in the tail fin also but, mostly that would be from the head. You stated that when you bumped up the head speed it would shake more. My gobee did the same thing and it turned out to be bad paddles. I see you dont have the stock paddles on. Put the stock paddles back on and balance your head with out the blades. If you dont have a balancer then measure the flybar in the head and get it as close as you can. Then make sure you screw the paddles on evenly.

There were a few reports on here about the tail wagging. It turned out to be screws to tight in the tail assembly.Check your tail over really good to make sure there is no binding.

Hope this helps.
DK

[Chief heli]

Too funny, I started with the gobee also. Got sick of chasing the vibration. LOL.

I now have the 600N sport also.

Not sure what vib your chasing but I will give it a shot. First, if its the motor you will see your fuel sloshing around in the tank or even foaming up. (thought this was a sign of vibrations in the engine area? what might be possible with the crashed engine) That might show up in the tail fin also but, mostly that would be from the head. You stated that when you bumped up the head speed it would shake more. My gobee did the same thing and it turned out to be bad paddles. I see you dont have the stock paddles on. Put the stock paddles back on and balance your head with out the blades. If you dont have a balancer then measure the flybar in the head and get it as close as you can. Then make sure you screw the paddles on evenly. (I really did my best on placing the rod in the middle of the head and the paddles the same distance from the flybar so this must be correct! These are new paddles so I don't think anything could be wrong with them... Ohh well I'll try tomorrow with the stock paddles)

There were a few reports on here about the tail wagging. It turned out to be screws to tight in the tail assembly.Check your tail over really good to make sure there is no binding.
(never read anything about this, exactely what screws do you mean?)

Hope this helps. (offcourse it helps! Thanks!)
DK

Chief

[rototiller]

The paddles that gave me problems were brand new. It happens.

The screws that go threw the pitch slider into the blade grips are easy to over tighten. Very easy to over look also.

DK

[scooby61]

i had the same problem, first few tanks no problem at all just hovering. brand new everything even the motor. then when i started ramping up the headspeed the vertical stabilizer on the tail would just start whipping back and fourth violently just as i was getting airborne. turned out it was several problems. my head speed was way too high ( should be about N 1750-1800 I1 1950 I2 2100) and i had too much gyro gain. (using a 401 seems best about40 don't know about the jr) and last but not least had my motor too rich which seems to cause some stuttering preignition sort of vibration. I finally got it all sorted out and she flies awesome. (Thanks to ClayK's assistance at my local feild and some perseverance of my own).
don't know if any of this helps but more info is better than none. good luck you'll love the bird once she's flying right!

[Dré]

Hello Chief,

FYI


I also have the 770t giro with the ds8900g servo. on a 600 Nitro

I do use a Jr radio, but I have the Gain at 60%, if you put it that high it will not sit still when the heli is sitting on the ground (it is buzzing all the time), but I asked around and this seems to be normal.
And it works perfect, the tail is stable, and the heli will not shake


Greets


Dré

[Chief heli]

Thank you all for the help! You guys are the greatest!

Ok, I did a test flight today. I started with the shorter distance from the centre of the servo. Now got it at 11mm from the centre. It worked out very well and the vibrations decreased a lot!

Next thing I tried is change the throttle curve.
I went from 70-55-45-55-70 to 65-40-35-40-65 on idle 1
What I concluded was almost no vibrations in the head/frame part of the heli. So I think the head is well balanced! But the tails keeps wagging and shocking up and down. When I reduce the amount of gain the wagging starts to decrease but the tail starts to break-out at a climb out..
Maybe a bend tail shaft? I replace it right away.

BTW I checked the main shaft, it's straight! And no fuel foaming inside the tank! (what I did have on the gohbee)

I really need a tacho, want to know my headspeed, maybe it was just to high!

Thanks again for the help! And if someone has any input, feel free to post!!

Greetz,
Chief

[captcasper7]

My gain on my 770 3d is 30%, any higher and I get a wag when coming out of backward loops and flips.

My throttle curve is 100 65 100 on my JR 9X11 and I use a RevLock 20 Gov, headspeed is at 2100.

[Chief heli]

Hello,

I did some testflying again today!
The tail keeps on shaking ( a little ) It looks like a little wag but it also goes up and down. The rest of the heli is stable!

Ok so let's say the gain is still to high so it starts wagging.
But on climb-out the tail can't keep up! If I start to increase the gain. The shaking increases to! So I think something else is wrong here.
The gain is 8% right now... (futaba transmitter)

I did 3 tanks on the bird, couldn't resist to try her out some more :oops:
Did my first inverted circuits aswell! Stupid I know but she flies so smooth! I love her! She flys like the sim!

Anyway, please help me out. Can't wait to get the max performance out of it.

Greetings,
Chief ;)

[helihelge]

if the screws on the tail pitch slider is overtightened, this may cause tail wag.

[erniefritz]

move the ball on the tail servo closer to the center of the servo. then you can increase the gain. is the tail is bobbing up and down slowly? ir is the heli in a wobble? if it's wobbleing then your headspeed is too low , needs to be 1900 + , if the tail is vibrating up and down fast and sharp , then either your paddles are not aligned correctly or out of balance. as for the tail shaking back and forth , change the ball on the sewrvo like i said and increase the gain , make sure you have it in Heading hold mode and can switch back and forth from rate mode to HH and that your mechanical center is ok , meaning that when you hover in NON heading hold , there is no drift left or right , then put back in HH. Hope this helps.

[Chief heli]

Whohw thanks for the replys!

I would give them a try next weekend! Lots to do!
I'll keep you guys up to date!

Thanks again all!

Chief ;)

[MarkD]

Hello,

I did some testflying again today!
The tail keeps on shaking ( a little ) It looks like a little wag but it also goes up and down. The rest of the heli is stable!

Ok so let's say the gain is still to high so it starts wagging.
But on climb-out the tail can't keep up!

From these two paragraphs - tail bobbing and no tail authority on climouts I would guess your head speed is to low

[Chief heli]

Hello MarkD,

Thanks for the reply. When I increase the headspeed the tail start bobbing more. I'll try to use the stock paddles and the shorter arm on the rudder servo.

Chief ;)

[erniefritz]

Chief, make sure your tail blades are rotating in the correct direction. if looking at the heli from the passenger side (right side) the tail should rotate counter clockwise so the blades rotate up into the main blade downwash. if the tail blades rotate clockwise then the belt is 180 deg off.

[JEFFRO503]

Man , i don't even own this heli yet , and i have already learned so much about the 600 N in this thread it's crazy!! man i love it here.........The freaks rule for sure!


Jeffro

[Chief heli]

Thanks for the replys guys!

OK, what I did today:

- Checked the paddle on weight and profile (perfect match)
- Change servo to 9mm from centre (before:11mm)
- Checked all tail linkago to run as smooth as possible

I wanted to change to stock paddles but the holes for the screws to lock the paddles on the flybar rod were to big! Anyone else had this problem? It says 3mm set screw. But the outside of the hole is also 3mm.. It falls right in.. I tried a 4mm but it was way to big.

Anyway I tested the bird today but still having problems :(
With the low curve no problem, but after pumping up the headspeed it started shaking again. Tailfin from side to side. Something is wrong here.
I'm loosing my patience now.

Think I need someone to look at it with a little more experience.
But if someone has a idea? Please tell me.

Greetings,
Chief

[Dré]

I think there are many experianced people on this side to solve it.
Problem in most cases is to explane what is happaning.

Maybe you cn post a vidoe on what is happaning, with a couple of detail pictures of your bird, and all your settings (transmitter, gyro, enz enz)?

I know its sounds like a lot of work, but trouble shooting without all the info takes a long long time.


Greets


Dré