Really angry now ... again tail mounts snapping.

solentlife

I've been flying the 450 for days now without any problems ... tail fine ... all as should be.

Today - I go out and then vibration, sounds .. starboard boom strut comes of tail fitting,

then tail rotor assembly twists to right (looking at back end as flying).

I down the 450 ... back to bench and check her over ... I find thread stripped in boom fitting for strut - so I find a small suitable self-tapper to sort it.
All straight ... tightened up ... fine.

Go out and again strange noise which is deeper tone than normal sounds ... and tail twists to LEFT this time !! Boom / struts OK.

Back to bench and check it over ... find canopy rod on one side is loose ... so that's loctited up and fixed. tail assembly is put back straight and this time a drop of loctite dropped in joint to boom before tightening.

Out again and she spins up fine ... then strange deeper tone noise again and tail mount snaps ...

So what is happening ?? Could it be that I'm tightening belt too much ? Seems unlikely as it's way I've done it since getting the 450 ages ago.

T-R-E-V · Posted: Sat Sep 03, 2011 10:26 pm Post subject:

How ironic is that, Shocked

We have just finished discussing the importance of tail booms, Rolling Eyes

And you prove firsthand the devastation that can be coursed without them. Crying or Very sad

Sorry found out this the hard way. Nice photos. Wink

Trev.

pjdog · Posted: Sat Sep 03, 2011 10:39 pm Post subject:

I've had plastic tail assemblies come apart like that but not a metal one?

I've had carbon Fiber tail booms fracture at the tail assembly like that but not a metal boom?

I bent a metal boom with a hard landing.

I'm thinking maybe a defective tail assembly. It does happen. I had a tail assembly on a brand new heli fracture right away. So has Tombo242. Very first spin up. These things are not perfect.

jack

tombo242 · Posted: Sat Sep 03, 2011 11:30 pm Post subject:

Well this one sheared and it had the knighthead bars (tail boom supports) fitted and secured.

Tom.

solentlife · Posted: Sun Sep 04, 2011 12:14 am Post subject:

I can accept 1 maybe 2 going with hard knocks etc. ---- but to actually see one just sheer off and not even airborne ?

I am totally lost on this now ...

nick_onelove · Posted: Sun Sep 04, 2011 2:28 am Post subject:

Yeahhh, this is way over my head, I just wanted to grab an email notification for this thread. Good luck!

Skyepuncher · Posted: Sun Sep 04, 2011 2:49 am Post subject:

You mentioned a strange noise before this happened. Makes Me
wonder if You had a bearing fail, & then seize in the tail rotor.
Have you had a chance to check that?
Scott

solentlife · Posted: Sun Sep 04, 2011 3:06 am Post subject:

tombo242 · Posted: Sun Sep 04, 2011 3:39 pm Post subject:

Nothing wrong with the bearings in mine Skyepuncher, smooth, free and in my spares box. The metal on the break lines showed crystalised fracture over some 75% of the break. It is possible that a very slight imbalance in the tail rotor assembly could cause this. I now balance my whole tail rotor assembly instead of just the blades and haven't had the fracture problem again. . . . (yet)!

Tom.

solentlife · Posted: Sun Sep 04, 2011 11:19 pm Post subject:

Andrejs at flying today pointed me to this :

an all-in-one Tarot integrated tail unit .........

Now that looks a lot better than the bolt together jobbie ...

Anyone used one ? Any ideas / thoughts on it ?

solentlife · Posted: Tue Sep 13, 2011 12:53 pm Post subject:

New standard tail mount arrived - the two piece job, while waiting all-in-one.

Fitted ... flew ... fine ... no strange noises ...

BUT I did run with a belt slacker than usual and that appears to help.

nick_onelove · Posted: Tue Sep 13, 2011 3:55 pm Post subject:

Well at the very least it's good to hear you're back in the air.

lightning · Extreme 3D Joined: 13 Aug 2011 Posts: 166

very interesting problem....but no doubt frustrating not to mention expensive.shear direction ....is it always the same index?as in the same direction.drawing on knowledge of much larger machinery i would like to guess [yeah just a guess] a combination of belt tension and rotor balance.in this instance over tensioning could possibly cause the rotor to become unbalanced and compound the problem, however this seems to be in the opposite direction to the twist in the belt ;not in the direction one would assume.did you have any bearing falure?do you know any mechanical engineers? good luck with this one .dont you just love the challenge!!

solentlife · Posted: Tue Sep 13, 2011 6:48 pm Post subject: Re: tail rotor

lightning · Extreme 3D Joined: 13 Aug 2011 Posts: 166

i know the soviet tractors you refer to.....all too well .they are as twitchy as a Razz

nervous cat.and just as unpredictable....not to say i dont like cats.both directions eh ?this is a wonderful problem you have or have had.im mean that literally .....cos its got me wondering.you see , i love a mental challenge .....not to say im mental.hehe....but solving engineering problems is my job and i get a kind of warm fuzzy satisfaction when one is sorted.....sick isnt it.twist to the left twist to the right....you know the rest of the song lol.hope you find the cause mate!!