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HelicopterSynergy R/COther › Synergy Tail Failure ... Again!!!!!
08-07-2007 10:52 AM  10 years agoPost 21
Revolution man

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France

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Before my second crash I mounted screws of better quality, but it broke nevertheless

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08-07-2007 10:59 AM  10 years agoPost 22
Revolution man

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France

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I think that the mechanics of Synergy Tail is of bad quality. One would need two ball bearings to avoid the beats which make work the screws and a bearing thrust ball for the maintenance in translation. I am a technician methods in a company of mechanics of precision

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08-08-2007 07:52 AM  10 years agoPost 23
chem

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Dijon - France

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I think there is a real design problem on this tail rotor or bad component choice, but what are they?

At present, I'm prefering not fly with my Synergy. I'll wait for news from Synergy RC, hoping for they replied!!!

Chem

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08-08-2007 09:57 AM  10 years agoPost 24
milli21

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france

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I agree with chem, Synergy RC have to find a solution for this problem
All the synergy is built with serious (5 mm fly bar, 14 mm main tail, high quality linkage etc etc...) but small screw for the tail rotor hub.

2 solutions

1) Synergy RC modification to put 4 mm screw

2) Hyperformance up grade...

To be continued
Have a nice day

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08-08-2007 12:52 PM  10 years agoPost 25
excellone

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Arlington, Virginia

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What gyro / gyro settings and head speed?

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08-08-2007 01:41 PM  10 years agoPost 26
John Benario

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Las Vegas

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The Schluter tail rotor uses a 2.5 mm bolt to hold the grip to the hub and it has proven to be satisfactory, so the 3 mm bolt is sized properly. There are a number of possibilities.

The first issue is the hardware included in the kit is of poor quality. I replaced particular bolts on mine with better parts.

The second issue is the supplied washers are very soft, and have a too large id. This issue is most noticeable on the 5 mm id washers under the main blade spindle bolts. Those washers on mine almost sheared from the blade loads. I replaced the 3 mm id washers in my tail with better ones and the 5 mm ones on the main blade spindle with machined steel ones.

The problem with the washers is when they compress the bolt loses preload which exacerbates other issues.

With the soft bolts overtightening is a possiblity. Proper tightening torque for high quality 3 mm bolts is 17 oz-in. That is about the same grip strength in your hand as a strong handshake. The stock bolts are not high quality so the tightening torque would probably be more like a loose handshake.

My experience with the Synergy tail is that it is a good, reliable design, if built properly.

I use Loctite 290 (DO NOT use blue loctite 242), hand tighten the bolts, and then turn maybe an 1/8 turn more. It is the loctite that holds them in, not the tightening torque.

The other nuisance build areas of the tail are having to ream the pitch fork holes for the 2 mm pins, replacing the 2 mm pins with hardened ones (JR), working the 2 mm holes in the pitch links by hand until they are a smooth fit on the 2 mm pins, shimming the tail output shaft so it is precisely spaced in the tail gearbox. I also use the black balls because the chrome balls are very tight in the links and cause a lot of friction in the tail assembly.

John Benario

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08-08-2007 07:29 PM  10 years agoPost 27
chem

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Dijon - France

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What gyro / gyro settings and head speed?
Gyro: GY601
Gain: 34%
HS: 1930 rpm

Chem

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08-09-2007 01:12 AM  10 years agoPost 28
excellone

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Arlington, Virginia

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Were you in F3C or 3D?

There are 7 of us at our field are setting gyro to 3D with
Control Delay I (Rudder Stick Operated), Right and Left = 15
Control Delay D (Rudder Stick Returned), Right and Left = 50.

No tail failures yet even with some MA people like the beast getting a pull.

Those gyros can rip the best tail control systems apart. I believe there should be another radial bearing at the end to take some lateral load or go to the 4mm MA type hub.

George

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08-12-2007 05:48 PM  10 years agoPost 29
jamesbrown

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somewhere in the sky

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My friend also have the same problem after about 15 flight.I think the quality of the bolt have to be improved.I change the bolts with the better one,so i don't get the same problem.We used the standard tail blade given from the kit.

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08-20-2007 10:27 AM  10 years agoPost 30
Airasj

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South Africa

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Bolt size????

Hi,

Saying that the bolt is 3mm and other uses 2.5mm therfore it is OK is wrong. You can only say that if the material is the same, the the tail blade weight is the same and the rotational speed is the same.

If you look carefully to the pic, you will see som beach marks and a final failure. This is typial of a fatigue failure which is due to cyclic loads. A small crack starts due to the stress concentration caused by the threads and will grow due to the cyclic loads imposed.

A way to protect against fatigue is to use prestress. The washer/underlying structures deform a bit during the prestress(elastically). As the work load starts to pick up the underlying structure relaxes a bit. This has the result that the amplitude of the cyclic load is reduced, thus longer fatigue life.

To me a part like the tail rotor bolt should be designed for a suitably long life (pref infinite that is stress never above 168MPA) for mild steel).

I therefore think the bolt is plainly undersize for the loads imposed.

Regards
Attie

Ps ( I am a structural Engineer at a Aircraft factory)

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08-20-2007 02:45 PM  10 years agoPost 31
jakeg1999

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San Diego, CA

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Anyone try the Kasama tail? Got one coming in the mail. I ordered it, because my blade grips seemed to wear fast and develop slop.....

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08-26-2007 12:35 AM  10 years agoPost 32
rchaas

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Tulsa, OK

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My SHCS failed today, and the tail flew off, hit the main rotor and led to an uncontrolled crash. I had previously read this thread, had gone back and checked those bolts, changed them out and made sure they weren't too tight (however tight that is!). Still failed. The cap sheared off where it meets the shaft of the bolt, just as on the pics at the top of this thread.

I hope Synergy RC, or perhaps Hyperformance RC are working on a fix for this.

I guess til then i'll change those bolts frequently.

Robbie

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12-09-2007 07:41 PM  9 years agoPost 33
chem

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Dijon - France

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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 )
So, just at the end of this fifteenth flight, in hovering, one tail grip failed again!!!!

Exactly like the first time, it's a tail grip bolt which broke off.

This time I'm really sure I didn't overtighten these bolts.

I'm fully dishearted by this third crash. In total, it's 3 serious crashs for only 46 flights
I don't know what to do. I really like this heli but I'm not very motivated to flight with the Synergy again.

Best regards,

Chem

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12-09-2007 08:06 PM  9 years agoPost 34
heli-hurley

rrApprentice

st.neots

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Why do people always persist to say the screw was overtightened or bad assembly when this is clearly a flaw in design. I don't have a synergy so this is my outside looking in point of view but after reading many posts on the tail failing i just find it really annoying to read people always saying user error in assembly when its clearly a fault.
Why do they do it?

My heli works as an ornament.......at least it stays in one piece!!!

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12-09-2007 10:09 PM  9 years agoPost 35
chem

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Dijon - France

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I totally agree with you Heli-Hurley. I'll wait for some days before taking a decision about my Synergy.
I really love this machine but it becomes a very expensive pleasure and I'm very tempted to rebuild and sell it.

Chem

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12-09-2007 11:13 PM  9 years agoPost 36
P.J.

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Ireland

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Chem,

If you don't trush the tail hub you could always put on an aftermarket hub

Also Synergy has alot of new upgrades coming out, If you sell the Synergy you'll regret It

P.J.

SAB Heli Division
Hyperion
Spektrum RC
Scorpion Systems
Spartan rc

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12-09-2007 11:50 PM  9 years agoPost 37
creightoncarr

rrKey Veteran

Missouri City, Texas​- USA

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I feel for you chem. It's happened to me to. I've since replaced the tail assembly with the Kasama for piece of mind. Too many accounts of the head of that bolt shearing off. Don't listen to everyone telling you that you overtightened it (unless of course you did ). They'll say that every time and act like there's no problem until it happens to them. Some people just have sh*t luck - I'm one of them.

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12-10-2007 12:19 AM  9 years agoPost 38
Droid

rrElite Veteran

Deep down in the​Southwest- UK

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If you sell the Synergy you'll regret It
Why.... i never looked back There's other capable machines out there.

Remember the statements about the machine that never required any upgrades, seems like my joke about hyperformance manufacturing the synergy wasn't that far from the truth 12 months on.......

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12-10-2007 01:30 AM  9 years agoPost 39
bellecrank

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Canada

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If you like the heli, 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.

For example, check with the Predator guys, I have never heard of their tail rotor ever throwing a tail blade.

I believe you can get the total tail rotor assembly (CN2235) for about $40.00.

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12-10-2007 06:00 AM  9 years agoPost 40
Paul Susbauer

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Hillsboro, OR

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The Synergy uses a 6mm output shaft. Seems like most of them have 5mm output shafts if I'm not mistaken? I know my Freya does, I checked this in case one of them would work. I opted for the Kasama unit instead.

--Paul

Ineptitude - If you can't learn to do something well, learn to enjoy doing it poorly.

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HelicopterSynergy R/COther › Synergy Tail Failure ... Again!!!!!
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