T-Rex 450 sport head wobble

hallstu · 09-26-2009, 06:35 AM

Hi to all, i have just purchased & built a trex 450 sport & i'm getting really bad head wobble.
I have balanced the blade.
I have checked main shaft & thats ok.
I have check the flybar & thats ok.
I have weighted the paddles & they are the same.

I was wondering if anyone know what it could be.

michael503 · 09-26-2009, 08:06 AM

We need some more info.
when does it wobble? all the time? just at spool up?
does the nose bob up and down?

??

jonnyk · 09-26-2009, 08:07 AM

That leaves either the feathering shaft or headblock. If it is a vibration and not a wobble there are a million more possibilities including bearings, motor, belt, tail.

Buffaloirish · 09-26-2009, 08:54 AM

After my most recent 450 pro/street in front of my house conference I replaced feathering shaft, flybar, blades, boom, TT, TT gears front/back, tail rotor shaft, and main rotor shaft. Balanced everything out and got her up only se see a tail vibration and a head wobble. My two main gears had that goofy Align wobble from day one so I didn't think anything of it but I had some fresh ones in the tool box so I swapped them and tail vibe was gone as well as a reduced head wobble but it was still there. Upon further investigation I found a bent/dented lower bearing in the main shaft/servo block trying to hide on me. That was the head wobble. Inspect those things good.

Finless · 09-26-2009, 12:02 PM

Probably too low a head speed. The 450 Pro really likes higher head speed. What is your throttle curve? If you left in linear then you head speed is probably too low.

Bob

xf100t · 09-26-2009, 06:30 PM

Quote:

Originally Posted by Finless

Probably too low a head speed. The 450 Pro really likes higher head speed. What is your throttle curve? If you left in linear then you head speed is probably too low.

Bob

It's a sport, not a pro. I don't know if that makes a difference though, I only have the pro. Does a belt make a higher headspeed more unstable? That doesn't seem like a rational theory...

Finless · 09-26-2009, 06:35 PM

A wobble of the heli is usually caused by tight dampening and low head speed. The sport has the same head as the Pro. Head speed needs to be up there or you will get a wobble. Not a shake like something is bent, a wobble.

Bob

Buffaloirish · 09-26-2009, 06:38 PM

Any wobble that isn't actually a mechanical problem should be experienced at headspeeds to low to take off. If your in the air and you have a wobble something mechanical is going on any electric CP heli. I'm telling you, check those bearings in the main shaft block... It took me days to figure that one out. You are talking about a head wobble, not the whole heli right?

09-26-2009, 06:35 AM	#1
hallstu Registered Users Join Date: Sep 2009 Location: Australia	T-Rex 450 sport head wobble Hi to all, i have just purchased & built a trex 450 sport & i'm getting really bad head wobble. I have balanced the blade. I have checked main shaft & thats ok. I have check the flybar & thats ok. I have weighted the paddles & they are the same. I was wondering if anyone know what it could be.

09-26-2009, 08:06 AM	#2
michael503 Registered Users My HF Map location Join Date: Mar 2007 Location: Tuscaloosa, Alabama	We need some more info. when does it wobble? all the time? just at spool up? does the nose bob up and down? ?? __________________ -Michael

09-26-2009, 08:07 AM	#3
jonnyk Registered Users Join Date: Aug 2009 Location: Missouri	That leaves either the feathering shaft or headblock. If it is a vibration and not a wobble there are a million more possibilities including bearings, motor, belt, tail. __________________ Exi 450 v2, exi s1123 x3, hk401b+mks ds480, plush 40 esc Align 450 pro, spartan ds 760, futaba 9257 Align 500 ESP, spartan ds 760+ Turnigy BLS980

09-26-2009, 08:54 AM	#4
Buffaloirish Registered Users Join Date: May 2009 Location: Buffalo, NY	After my most recent 450 pro/street in front of my house conference I replaced feathering shaft, flybar, blades, boom, TT, TT gears front/back, tail rotor shaft, and main rotor shaft. Balanced everything out and got her up only se see a tail vibration and a head wobble. My two main gears had that goofy Align wobble from day one so I didn't think anything of it but I had some fresh ones in the tool box so I swapped them and tail vibe was gone as well as a reduced head wobble but it was still there. Upon further investigation I found a bent/dented lower bearing in the main shaft/servo block trying to hide on me. That was the head wobble. Inspect those things good. __________________ ~ Derick ~ To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

09-26-2009, 12:02 PM	#5
Finless Team Taco VP My HF Map location Join Date: Nov 2005 Location: Stanton, Ca. USA	Probably too low a head speed. The 450 Pro really likes higher head speed. What is your throttle curve? If you left in linear then you head speed is probably too low. Bob __________________ "Don't Taco My Pack Dude!" To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. *To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.* *To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.* *To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.* *To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.*

09-26-2009, 06:35 PM	#7
Finless Team Taco VP My HF Map location Join Date: Nov 2005 Location: Stanton, Ca. USA	A wobble of the heli is usually caused by tight dampening and low head speed. The sport has the same head as the Pro. Head speed needs to be up there or you will get a wobble. Not a shake like something is bent, a wobble. Bob __________________ "Don't Taco My Pack Dude!" To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. *To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.* *To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.* *To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.* *To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.*

09-26-2009, 06:38 PM	#8
Buffaloirish Registered Users Join Date: May 2009 Location: Buffalo, NY	Any wobble that isn't actually a mechanical problem should be experienced at headspeeds to low to take off. If your in the air and you have a wobble something mechanical is going on any electric CP heli. I'm telling you, check those bearings in the main shaft block... It took me days to figure that one out. You are talking about a head wobble, not the whole heli right? __________________ ~ Derick ~ To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

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