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Synergy R/C Synergy N9 > Synergy Tail Failure ... Again!!!!!
 
 
chem
Heliman
Location: Dijon - France

Quote 
check around with flyers of other brands of 90 size helis and see if the tail rotor from one of them would fit on your Synergy.

I already thought using another heli's tail rotor, but which one?

Maybe a Kasama tail rotor assembly? Don't know...
But this time I need to be sure of my choice!!!

Chem
12-10-2007 06:13 AM
HOMEPAGE  
 
 
himaxkeith
Senior Heliman
Location: Atlantic City NJ. USA

You could have a hardware issue there is alot of hardware out there with the bolt heads are spot welded to the shank of the bolt instead of being all one piece like an grade 8 bolt or an NSA or AN bolt or maybe the tail hub is not true or the shaft or blade size or balance could be off also. once you sling a tail blade i would replace both screws in case you stressed the other screw and check the tail hub and shaft to make sure there true
12-10-2007 07:10 AM
 
 
Doug L
Veteran
Location: Minnesota

Thats gotta be disappointing to have it happen multiple times. I'm at 34 gallons thru 2 N9's with no failures. Only issues so far has been engine problems, but I'll agree that things can be a little hit and miss with Synergy QC. It's still been the best machine I've ever owned, and the best flying heli in my book. (ok, so it's a short story) I agree with others here who say to just get a bolt somewhere else, but putting Kasama parts on certainly won't hurt.

Droid, how can you say you've never looked back? You're in here all the time. What are you flying now?

-----------------------------
12-11-2007 03:52 AM
HOMEPAGE  
 
 
PIGROLL
Senior Heliman
Location: Pig Pen

Chem, Did your main blade grip break and if so can you post a picture? Was the ball link still connected to the bell mixer and the broken main grip?Curious.

The cheese slipped off my cracker a long time ago
12-11-2007 01:16 PM
 
 
chem
Heliman
Location: Dijon - France

Quote 
Chem, Did your main blade grip break and if so can you post a picture? Was the ball link still connected to the bell mixer and the broken main grip?Curious.

PigRoll, I suppose you're talking about my second crash

Chem
12-11-2007 05:03 PM
HOMEPAGE  
 
 
airboss
Elite Veteran
Location: OC ,california

i have tested the kit screws and found them to be low grade, when repairing or adjusting ,replace the screws with new high qual, this will eliminate problems.

Synergy N9..FlyBlackstarr.org.., Helifreak.com..,Insane Canopy..
12-11-2007 09:11 PM
 
 
cdrking
Elite Veteran
Location: Seattle

Quote 
this will eliminate problems.
Promise? I know of two guys that have had failures with upgraded bolts. They are also excellent builders.

Jeff

To hover is divine, the alternative is rather PLANE.
12-11-2007 09:12 PM
 
 
airboss
Elite Veteran
Location: OC ,california

the screws are the weak link. i used a standard weha hex locked the screws in question to my vise, in different positions and was able to easily break them. when i purchased high grade screws from the local industrial supply store, i was not able to break the screw with the weha, so i then used a T handle hex and was able to break the screw. i repeated this test,5x, with many screws from the kit and again with the purchased screws and results were the same.i have seen many posts about the hardware breaking in the main shaft and the fan hub ect..replace or crash, i replaced all.

Synergy N9..FlyBlackstarr.org.., Helifreak.com..,Insane Canopy..
12-11-2007 09:28 PM
 
 
cdrking
Elite Veteran
Location: Seattle

Did you replace the washer in the tail hub also?

Jeff

To hover is divine, the alternative is rather PLANE.
12-11-2007 09:30 PM
 
 
airboss
Elite Veteran
Location: OC ,california

yes ,those washers were concave shape after 10 flights.

Synergy N9..FlyBlackstarr.org.., Helifreak.com..,Insane Canopy..
12-11-2007 09:35 PM
 
 
chem
Heliman
Location: Dijon - France

Airboss,

On my last Synergy I did use neither kit bolts nor kit washers but high grade bolts (12.9) and better quality washers.
But as you can see, despite of this, the bolt failed again!!!

I think the problem is elsewhere, but what is it?

Chem
12-11-2007 09:42 PM
HOMEPAGE  
 
 
PIGROLL
Senior Heliman
Location: Pig Pen

Chem.

The cheese slipped off my cracker a long time ago
12-11-2007 10:12 PM
 
 
j5coat
Veteran
Location: Phoenix

you must have something else that is contributing to this as well. Not saying that the TR does not have a problem as i have had this happen to me. Just saying it seems that there might be some vibration adding to the stress the bolts are already taking. I put a set of align tail blades one mine (97mm and a couple grams lighter) in hopes that this will never happen again. oh and also changed the bolts out.

Trex 700, Trex 600n
12-11-2007 10:16 PM
 
 
PIGROLL
Senior Heliman
Location: Pig Pen

[quote]Chem,
My Posts This: Topic Forum Hi,

4 days ago, that was the fifteenth flight of my brand new Synergy.
(The first one is dead in a second crash because of a ball link failure on the main grip bell mixer, only 5 flights after the first crash... Yes, I have really bad luck )
I am wondering about the crash where you think that you had a ball link failure.

The cheese slipped off my cracker a long time ago
12-11-2007 10:17 PM
 
 
creightoncarr
Veteran
Location: Missouri City, Texas - USA

Quote 

I think the problem is elsewhere, but what is it?

I think that the main problem is in the design of the tail. Using better quality fasteners helps but obviously is not a guarantee. I think that the single radial bearing design allows for to great of a side load and occasionally the heads of the bolts shear off. I would imagine that with the new tail design we'll stop seeing this happen with any regularity.
12-11-2007 10:24 PM
 
 
Long Nguyen K.
Senior Heliman
Location: SoCal, USA

One radical bearing in a tail grip could be the reason for the failures. I myself have been testing the Kasama tail which is full metal,does have 2 radical bearings and 1 thrust bearing. After having gone through 3 gallons on it there is no improvement in flight quality over the stock ones. Actually, I feel that the Kasama puts more load on the tail servo and as the result I got the tail blowing out sometimes when doing tictocs.

So now, I'm planning to put the stock one back there. I tried to put 1 more radical bearing into the stock tail grips and used the kasama hub instead but unfortunately, the hub was lightly shorter and needed. Not stop there, I found that the Kasama tail came with a new design of the hex screws. Those screws are purposely machined so that you dont have to use the washers. I don't know if they are stronger but I'm just giving them a try.



Long Nguyen
My SHAVER is cutting rice!
12-12-2007 04:55 AM
HOMEPAGE  
 
 
creightoncarr
Veteran
Location: Missouri City, Texas - USA

Quote 
Actually, I feel that the Kasama puts more load on the tail servo and as the result I got the tail blowing out sometimes when doing tictocs.

That's interesting. I finally got the Kasama tail on my N9 and I've been having problems with the tail letting go as well.

http://media.putfile.com/N9-tail-letting-go

Prior to the Kasama tail unit the tail was rock solid (that is, until the bolt sheared and the grip was thrown). The only change in the setup between then and now is the Kasama tail. I've been looking at everything else but had not seriously thought about trying the stock tail again. I even swapped out a perfectly good and new 9256 for a BLS251 thinking maybe I had a bum servo. I like the design of the Kasama tail, however, and I know there are guys using it with no problems so I kinda hope I find my problems lies elsewhere.
12-12-2007 01:25 PM
 
 
Camel Jokey
Heliman
Location: Who knows?

Gentlemen.

I would like to add my opinion.

First to qualify myself, I am a licensed aircraft engineer & have been for more that 20 years, I am also an aviation accident investigator & a consultant for several nameless American large aircraft manufacturers. Failures of this nature plagued aviation when the first pressurized aircraft were manufactured many years ago, a good example of this is the De-Haviland Comet.

Statistically the amount of failure’s versus the amount of flying indicates without any shadow of a doubt that there is a design flaw.

The bolt in question is quite obviously not strong enough for the designed application & for what ever reason is breaking due to stress.

I would suggest that the Synergy design team put their heads together urgently before someone is seriously injured when one of these grips comes off at the wrong moment & injures someone.

Having read the thread & heard so many reports from many, many people it is my opinion that any lawyer worth his salt would be able to pull Millions of dollars out of Synergy for someone suffering an injury.

The simplest & easiest solution for this, to my mind is, Synergy Helicopters issues a warning to owners on its web site, to use only 95mm tail blades & provides new replacement hardened bolts for each & every kit sold.

Whilst this could be viewed as an admission of guilt by some & would doubtless prove, a little costly for Synergy Helicopters, it would show commitment to it's customers & would be without question be cheaper than a law suit.

Let the games begin......!
12-12-2007 03:28 PM
 
 
Droid
Elite Veteran
Location: Deep down in the Southwest- UK

Quote 
Statistically the amount of failure’s versus the amount of flying indicates without any shadow of a doubt that there is a design floor.


Flooring engineer did you say??


I know you meant flaw...just can't help myself, and for Synergy to do anything about design flaws will require a radical rethink of the engineering processes that go into the manufacture of this kit. I had never owned such a substandard POS in all my RC life..... and i once owned a century hummingbird.
12-12-2007 06:54 PM
 
 
Fernando
Senior Heliman
Location: Madrid

To me this is not the bolt, it is the radial bearing together with thee size of the disk.

Just remember this same fault with the MA one exactly at the same point. Also remember the MA has got one single radial bearing and the point of breakage is a 4mm less the thread size... with 95 blades.

I suspect that chanching the screw will not make it different, neither reducing the disk.
12-12-2007 06:57 PM
 
 
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Synergy R/C Synergy N9 > Synergy Tail Failure ... Again!!!!!
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