WARNING ball links breaking in flight......

[george0079]

So far, I've broken 3 ball links on the blade grips while pitch pumping.... Is anyone else seeing these weak ball links? Or, is this just an isolated case? Did I get a bad set in my kit?

The first time I thought it was a fluke. The second time, I tore the head down to double check setup and travels.... The third time, I grounded it. It won't fly again until I change all the links to another brand, or this problem is resolved.

[cbdane]

So far, I've broken 3 ball links on the blade grips while pitch pumping.... Is anyone else seeing these weak ball links? Or, is this just an isolated case? Did I get a bad set in my kit?

The first time I thought it was a fluke. The second time, I tore the head down to double check setup and travels.... The third time, I grounded it. It won't fly again until I change all the links to another brand, or this problem is resolved.

Wow, sounds like the first days of the 600E all over again... I did notice that the plastic is definitely less compliant than that used on my two 600's and I wondered whether it could be more brittle. All in all, though, I've been impressed with the links and was going to retrofit my scale heli with them. Anyone else have any bad experience?

[nwolsink]

I really hope this is an isolated case

[CoronaL]

So far, I've broken 3 ball links on the blade grips while pitch pumping.... Is anyone else seeing these weak ball links? Or, is this just an isolated case? Did I get a bad set in my kit?

The first time I thought it was a fluke. The second time, I tore the head down to double check setup and travels.... The third time, I grounded it. It won't fly again until I change all the links to another brand, or this problem is resolved.
can you post a pic of where they are breaking?
would like to keep an eye out for fatigue on mine

I'm a bit worried since alot of the links I have, I used my helimax ball link tool, which is metal and seemed to shave just a touch of the eye of the links when I would use it. The links are so damm hard to turn, unlike the 600's which I could just do by hand. I ended up finishing the kit using 2 hex drivers inserted in opposite balls and turning them that way. Not sure if that is proper either.

I did a ton of power loops yesterday though. Very high G's and I was worried about something snapping at the bottom of the loops, but all good so far. My buddy and I commented about how that would have been a definate re-kit should something have broken and the heli had gone in at the bottom of the loop :bawl

[nwolsink]

Would Avant ballinks fit the 700N?

[erniefritz]

LOL, here we go again.... :) one person has a problem and everyone jumps ship . lol...

[CoronaL]

LOL, here we go again.... :) one person has a problem and everyone jumps ship . lol...
lol
I'm still on board

[erniefritz]

good to hear. I think this is and isolated incident. several 700's are flying at my field along with an Align Pilot and none have had problems.
I don't doubt George is having problems so i wonder if a bad batch of links came out? i would be interested to see if all links broke in the same place? george , is there a way you can post hirez pics of the 3 broken links?

[cbdane]

LOL, here we go again.... :) one person has a problem and everyone jumps ship . lol...

No way. Lashed to the wheel.

Same noise way back on the 600 and hundreds and hundreds (and hundreds of flights later, I never had a problem with one ball link.

[george0079]

OK. Good. It looks like my case is isolated. Thanks for all of the replies.

I'm not trying to bash Align, or the 700. I'm a huge Align fan. I'm just really upset about this. I do hope hope no one else see's this problem.

For the record.... I did use a ball link tool, and ball link pliers to build the links. I did NOT size them. No un-due forces were applied to the ends of the links, and I did check the head for binding, or any unusual stress.

The links all broke in the exact same spot. The top half of the link, right at the blade grip ball.

I'll try to post some pics later...

[marcelosouto]

No George, I guess you are not the only one isolated case.

http://www.helifreak.com/showthread.php?t=85723

After we stress over all kind of possibilities, we strongly notice that the main one reason for crash was exactly a main grip link broke.

[irandchare]

hi all my crash question is one ball link grip
http://www.helifreak.com/showthread.php?p=787466#post787466

[CoronaL]

now you guys will make more paranoid than ever :O
I love my power loops:bawl

[CoronaL]

was thinking about this last night, actually past couple of nights. I inspected my links, and aside from the scarring of my ball link tool, all are fine.

I have a theory on why this is occuring, but until I can think it through a bit more and discuss it with a couple of heli and engineering friends I won't disclose my thoughts or the fix yet. Stay tuned :)

[cbdane]

I have a theory on why this is occuring, but until I can think it through a bit more and discuss it with a couple of heli and engineering friends I won't disclose my thoughts or the fix yet. Stay tuned :)

Your audience is holding its breath... ;)

[CoronaL]

Your audience is holding its breath... ;)
IF I'm right, which I'm probably NOT lol, I think that 98%+ of people will not have a problem, probably even more. I don't "think" it's a defective part, I think it's something else, but before I go on record I want to research it a bit first before I completely make a fool of myself. :oops:

[loiphin]

Hell, I cant even get mine off the ground. I am missing one of the hex mounts from the plastic clutch bearing housing in my kit :( Trying to get hold of the supplier to send me a replacement...

[Filby]

Any news on this??

[CoronaL]

Well here goes my theory. I may be very well off base, but I noticed this during my build. FWIW I think the ball links are actually quite decent.

On setup of the head, I noticed that at default JR x9303 settings for swash of 60/60/60 I had to tone the pitch down to 53 or so. Maybe the aileron and elev too I forget. But if in the head setup you are trying to max for 14 deg of +/- pitch which people will b/c Align reps have stated you CAN AND max cyclics there is an interaction on the head that you won’t see when the head is static. You will see the swash and arms clearing and no binding while static. Most people will setup a head and watch the ?washout pin/swash interaction, and also make sure the servos or arms don’t bind. On the Rex700 though, you can back them off and think you are getting max deflection allowed, but when you spin the head around I think it was either at the 10 o’clock or 3 o’clock position as I recall, the flybar cage would violently react like a sea saw, as one of the arms would hit something; not sure which one. I’m “guessing” that there amy be too much travel in the setup and something is hitting in flight, or has hit in flight and weakened the ball. As this occurs, I’m theorizing that since the flybar is rather flexible nothing breaks there, but the shock is transmitted through the head, and for lack of a better explanation the weakest “link” breaks.

Again, I could be way off, but in the chance I’m not I'm throwing this out there for discussoin.

Like I said, I dunno why but I tend to think about things and try to find solutions… 95%+ of time I’m off base, but occasionally I’m not. Probably the same case here.

[stmpngrnd]

I kind of noticed that as well before I lowered my pitch to +12.5/-12.5. Nothing actually hit but at the corners you could feel the head tighten up and watch the link rods flex. There was definitely some resistence in the corners for sure. But this heli doesn't really need anything much over +12/-12 and at this pitch the head spins as free and smooth as can be at the corners something that I can't get on my Fury. At +12/-12 on that head I get 3 points of contact between links, rods and the head block.

Anyone running max pitch and flying aggressive would benefit from invesitagting this on the bench. Good post CoronaL:thumbup:

[cbdane]

.On setup of the head, I noticed that at default JR x9303 settings for swash of 60/60/60 I had to tone the pitch down to 53 or so. Maybe the aileron and elev too I forget. But if in the head setup you are trying to max for 14 deg of +/- pitch which people will b/c Align reps have stated you CAN AND max cyclics there is an interaction on the head that you won’t see when the head is static. You will see the swash and arms clearing and no binding while static. Most people will setup a head and watch the ?washout pin/swash interaction, and also make sure the servos or arms don’t bind. On the Rex700 though, you can back them off and think you are getting max deflection allowed, but when you spin the head around I think it was either at the 10 o’clock or 3 o’clock position as I recall, the flybar cage would violently react like a sea saw, as one of the arms would hit something; not sure which one. I’m “guessing” that there amy be too much travel in the setup and something is hitting in flight, or has hit in flight and weakened the ball. As this occurs, I’m theorizing that since the flybar is rather flexible nothing breaks there, but the shock is transmitted through the head, and for lack of a better explanation the weakest “link” breaks.

Again, I could be way off, but in the chance I’m not I'm throwing this out there for discussoin.

Like I said, I dunno why but I tend to think about things and try to find solutions… 95%+ of time I’m off base, but occasionally I’m not. Probably the same case here.

I agree (not with the 95%+ part ;)) and I saw the same thing. I used the electronic cyclic ring on my transmitter to keep the controls out of the corners where binding can be the biggest problem. If your transmitter doesn't have this feature, I've seen mechanical cyclic rings at ReadyHeli and other places.

[Finless]

Most helis and every Trex I have built, if you max out everything (maximum possible swashplate diflection and max possible pitch) you will get seesaw binding in the head when at a max pitch and full diflection. Pro's run this for the "pop and lock" style control but they are good enough that they are never full pitch and full aileron or elevator AND for sure never in a corner... Even if you get there (in a corner) you have basically completely stalled the head (blades) and are probably crashing ;)

Bob

[trextuning]

One of the Align factory pilots had a crash due to this only last week. I know he is running maxed out pitch and cyclics. Both ball links had broken half way round the circle of the ball link on the blade grips.

[nwolsink]

But still the ballinks shouldn't break, than the material is too hard

[nwolsink]

How many cyclic deflection should the 700N have 7 / 8 degrees??