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Old May 07, 2012, 03:45 PM
STO
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450 Sport V2 tail issues

So after the head exploded during the maiden flight of my new 450 Sport V2 (don't ask) my good friend and heli expert helped me put things back together and get it set up right and proper. Sunday we were out at the field to test her. He flew a quick test flight and brought it back because the tail was doing funky things like not holding as it should and at one point spinning around unexpectedly. This freaked him out and he's an expert at least compared to me. We got it on the bench and checked gyro settings (Align GP 780). He changed the delay from green to red as per the manual otherwise all was as stated for this heli and servo set up. Checked the servo alignment. Then tried it again. You could see the tail wag as it fought to hold and this was during hovering not aggressive flying. He once again brought it back down and scratched his head. He has tried a few different settings and no luck. It seems the tail won't hold consistently. It's intermittent at best. This problem was present before the head exploded. So it's never flown right.

He did note the the stock tail servo that comes with the kit (DS420) is pretty small compared to the larger Align one he uses on his 450 and wondered if the servo is just not up to that task.

He's going to try a different servo and see if that makes a difference or if the gyro is not working properly.

I was wondering if anyone else has had difficulty with this combination with the tail not holding. It's extremely disappointing for a new machine to not work as it should. He's afraid to fly it as is. No way I will attempt it until this gets sorted out. Going back to my trusty SA hybrid for now.
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Old May 07, 2012, 04:58 PM
OlliW
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The problem can be the bearings in the tail rotor holder. Then I got my new Trex450 Sport (V1) about 1 year ago I at the beginning also had huge problems, since the tail would be smooth on the ground but in hover the would be very sloppy and waggy... at some point the tail would even be blocked after flight. I could suggest to replace the tail rotor holder bearings by some known high quality bearings.
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Old May 07, 2012, 06:47 PM
STO
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Originally Posted by OlliW View Post
The problem can be the bearings in the tail rotor holder. Then I got my new Trex450 Sport (V1) about 1 year ago I at the beginning also had huge problems, since the tail would be smooth on the ground but in hover the would be very sloppy and waggy... at some point the tail would even be blocked after flight. I could suggest to replace the tail rotor holder bearings by some known high quality bearings.
Thanks I'll check that out. Though I thought Align was considered high quality
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Old May 07, 2012, 07:18 PM
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are your gyro in HH mode or rate mode. What is the gain. If you tail wag, it may be your gyro gain too high, try to lower it. Usually, gyro gain is slightly different in hovering and normal flight.

What is the center distance of tail linkage rod from the center of tail servo horn. You may need to adjust tail servo horn center distance to compensate the tail servo speed. What tx you are using.

DS420 is small in size and torque but metal gear used in 450 sport while DS520 is bigger in size (your friend 450 use, I think) and torque but plastic gear, used in 450 pro.
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Old May 07, 2012, 10:30 PM
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I am betting if that tail is the same POS design as the Pro V2 that I have then it is the bearings. I replaced my bearings two times now and have less than 10 min flight time. I ordered some better Boca bearings for mine now but that still isn't going to fix a poorly designed tail.
Align 450 Prov2 tail problem (0 min 42 sec)
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Old May 07, 2012, 10:42 PM
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Originally Posted by STO View Post
Thanks I'll check that out. Though I thought Align was considered high quality
Align is not the best but the bearings would be good enough. I would suggest looking for vibrations. something is not correctly installed which is causing vibrations. Personally I'd strip the whole thing apart with your expert friend and let him show you how to put it together expertly. lol
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Old May 08, 2012, 07:44 AM
STO
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Align is not the best but the bearings would be good enough. I would suggest looking for vibrations. something is not correctly installed which is causing vibrations. Personally I'd strip the whole thing apart with your expert friend and let him show you how to put it together expertly. lol
The gyro is mounted using the foam pad that comes with the kit. My friend did say that it's a pretty thin pad and could also be contributing to the problem.

We will look at everything again but he's trying a dfferent, larger servo to see if that helps. We looked at gain settings as well. He has many years experience building and flying helis so I am fortunate to have his help but it's always good to seek other opinions and specifically if anyone else had had similar problems with this set up.

Thanks.
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Old May 08, 2012, 08:20 AM
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Tail kicking during flight can be from binding in the pitch mechanism itself and it doesnt take much at all. Disconnect the tail linkage from the pitch slider and move the pitch slider by hand. It should be moving smooth as silk all the way from end to end.

It's not unusual, because of the curved arc that the pitch slider makes, for there to be a slight binding just as you pass the apex of the arc. This is usually about mid shaft right where the the pitch slider is in hover. This tiny amount of bind can cause the gyro to overcompensate trying to hold the tail and the result will be slow kick from side to side as if the gyro can't hold.

If this does appear to be an issue, simply take the rotor off the shaft and polish the tail shaft with very fine sandpaper until you can't feel anything as the pitch slider brass bushing moves on the shaft.

May or may not be the issue,but it's worth checking into and this is of course assuming you have servo that is fast enough to handle the tail properly and all other obvious settings check out.
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Old May 08, 2012, 09:09 AM
OlliW
Joined Sep 2009
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Quote:
I thought Align was considered high quality
even if scaled by price, compared to that of clones such as HK, CopterX, Tarot in my humble opinion Align is definitely so much better quality... however, it too has it's weak points... (there is a reason why there are much more pricier 450er on the market...)... after I had figured out the tail bearing thing in my case I actually read on the web that it's kind of a known thing...

anyhow, that's just one of the possible reasons (but it's maybe not among the usual suspects hence I mentioned it)

Quote:
simply take the rotor off the shaft and polish the tail shaft with very fine sandpaper
You are kidding? You never would get it polished with sandpaper to a point which is close to what you get with a new (Align) tail shaft.
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Old May 08, 2012, 01:59 PM
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Originally Posted by OlliW View Post
even if scaled by price, compared to that of clones such as HK, CopterX, Tarot in my humble opinion Align is definitely so much better quality... however, it too has it's weak points... (there is a reason why there are much more pricier 450er on the market...)... after I had figured out the tail bearing thing in my case I actually read on the web that it's kind of a known thing...

anyhow, that's just one of the possible reasons (but it's maybe not among the usual suspects hence I mentioned it)

You are kidding? You never would get it polished with sandpaper to a point which is close to what you get with a new (Align) tail shaft.
No I'm not kidding and what are you talking about? He has an Align shaft now so what exactly would replacing a part with another of the same part accomplish? All tail shafts can sometimes suffer from the slight binding issue I described. It has nothing to do with the shaft itself, but rather the physics of using the bell crank design that doesnt have a linear motion. There can be a little binding as the pitch arm swings through the apex of the arc. Polishing the shaft will remove just enough material to make it smooth as silk. We aren't talking about turning a 3mm shaft down to 2mm for crap sake and only dealing in microns of material here.

I didn't make the suggestion because I "think" it might work...........I've have this same tail kick issue before and it works just fine because I've actually DONE it, assuming binding is the cause here. Just wrap some very fine sandpaper around the shaft while the heli is running slowly without any blades on it. Very simple and takes 5 minutes to do.
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Old May 09, 2012, 09:37 AM
STO
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Ok so my friend is dropping by tonight and I will have him read these helpful posts. Since he is much more knowledgeable about these things and he knows exactly what the tail was doing while he was flying it to give him concern hopefully he can determine if the bearings could be the culprit. The gyro is programmed for HH and I am using a digital servo (DS420).

I do appreciate all the help. I was though wondering if those that had tail issues with this machine were also using the same set up i.e. Align Gyro GP 780 and (DS420) servo.

Cheers.
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Old May 09, 2012, 09:40 AM
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STO pull the mains off and spool the heli, make sure you can move the tail both ways with no binding. If you have binding check the tail bearing's real good, my guess is you have a bad bearing just like I have twice so far. I haven't flown a full pack in my new 450 yet.
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Old May 09, 2012, 01:31 PM
STO
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Originally Posted by Raydee View Post
STO pull the mains off and spool the heli, make sure you can move the tail both ways with no binding. If you have binding check the tail bearing's real good, my guess is you have a bad bearing just like I have twice so far. I haven't flown a full pack in my new 450 yet.
Thanks Raydee. So are you using the same set up and I presume you have the 450 Sport V2?
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Old May 09, 2012, 01:38 PM
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I am running the Pro V2 but the tail is the exact same I believe.
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Old May 09, 2012, 08:25 PM
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+1 on the tail blade holder bearings, especially the outer ones. I'm on my 3rd set with my Align 450 Sport v1. They are often damaged in a crash. The symptoms are exactly what you are experiencing.

Re the servo, it's hard to find something better than the DS420, without going larger or spending a lot of money. The MKS DS95i is the ultimate. I'm currently using a KST DS115MG, and it works very well.
http://www.alofthobbies.com/kst-ds115-servo.html
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