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View Full Version : Tail Vibration After One Battery but No Crash


rbflapjack
09-25-2009, 10:10 PM
Ok, this thing is driving me crazy!!:arggg: I have rebuilt this thing four times and each time get the same result. First flight after rebuild: smooth as silk. Land.....(not hard, on grass), change battery, and BAM! the next flight the tail starts in with a high freq vibration. I have changed everything I can think of (main shaft, feathering shaft, both tail drive gears, boom, all tail bearings). The only thing weird I notice is that after rebuild, the belt is nice and centered in the window. On the second flight (with vibration) when I look at the belt, it is on the lower edge but still on the tail drive. Today it seemed better on the third flight if I moved the belt back to the center (with a small screwdriver). Is this something I should have to do each flight (doesn't make sense).:confused:

I am about to give up and buy a Trex 450 but wanted to give this one last shot. Any help would be great. Thanks! :thumbup:

Guzziman
09-25-2009, 10:18 PM
Make sure belt is set right then put something on boom near where it
comes out of the frame to stop the boom froom movng in.could possibly be that
all is good to begin with but after a flight the tail boom has been pulled
back inside frame check belt before first flight then after if belt is looser may be
your problem.

Guzziman
09-25-2009, 10:18 PM
i put a hose clamp on mine no dramas since.

conetica
09-25-2009, 10:22 PM
I know your pain, 90% of all vibes will come from blades beening out of balance (by weight and CG) and also make sure your flybar paddels are aligned and to the mm from one side to the other. The b400 is known for getting a vibe on the horizontal stabilizer. Once all is balanced spool her up and put your finger tops on the boom no buzz no vibe even if the fin is still vibing. If your not sure pull the entire head off and spoll her up if there is no vibe you know it's in the main head, and the belt thing is normal and nothing to worrie about.

Sky1trek
09-26-2009, 12:14 AM
Yeah, my belt has always run low in the view port since 220 flights ago.

rbflapjack
09-26-2009, 08:54 AM
Thanks, I have pulled the head and I still get the same vibe. I think it may be the belt tension. I have balanced the main blades with no problem. I will try the hose clamp. It is just totally frustrating to get it perfectly smooth, land, and have the vibe on the next flight. I am thinking of going to a 450 pro with the Torque Tube just to eliminate this. Thanks.

RVFR
09-26-2009, 03:18 PM
OMG.. crazy Vibs, I hear and feel what you're talking about. Well Hell after like spending many $$ on this problem. LOL, I went ahead and replaced everything I could, actually I have a pretty trick B400, not that I can take advantage of it totally yet, still cool, anyway I'm still having a vib problem in the tail, it's really bad once it gets into over drive, I'm using a scorpion 2221-8 motor with a scorpion 45amp esc, talk about nice power, but once it gets in to hi po mode, things start to buz, so much that it doesn't take long before the tail and vert-hort stabs come off, yea crazy, seems to be ok when I don't ask for to much power, so I figured it was a bad set of TR blades, being out of sinc, sure enough, so I balanced them out, it helped a wee bit :shock: I still have the vibs . So now I'm thinking it's time to move to another Heli, no one I show it to has an answer, seems simple enough but sheeesh!! I like what I have, also have to much in it to call it quits here, and I love a challenge , but this is getting ridiculous :roll: in fact it's nice enough outside today maybe I'll jump back into this.......:arggg:

RVFR
09-26-2009, 03:20 PM
On second thought, maybe I should just box it up and send it to Sokal??

conetica
09-26-2009, 09:18 PM
Thanks, I have pulled the head and I still get the same vibe. I think it may be the belt tension. I have balanced the main blades with no problem. I will try the hose clamp. It is just totally frustrating to get it perfectly smooth, land, and have the vibe on the next flight. I am thinking of going to a 450 pro with the Torque Tube just to eliminate this. Thanks.

So your your problem is in the tail, try replacing the tail pitch slider, then if there is still vibes try a new tail rotor hub (could be bent), and then last resort replace bearings in the idel up pulley which runs off the main gear (they are a real prick to change just follow socals vids on this). And i know you said you have changed everything but make sure your tail shaft is not bent, and balancing tail blades with there screws can also help but you need a 0.000 gram scale for this.

Cailid
09-26-2009, 09:45 PM
The only thing weird I notice is that after rebuild, the belt is nice and centered in the window. On the second flight (with vibration) when I look at the belt, it is on the lower edge but still on the tail drive.

Tail drive gear slipping on the shaft maybe?

CoolKD
11-03-2009, 02:17 PM
This seem familiar... I fixed my tail vibe with a small pease of tape on one of the tailblades.
I just took a little pease of tape and stuck it on one random blade and spooled her up in F.Mode. Swing and a miss, my first pick was totaly wrong when the vibe got worse.
Then I took the tape off and put it on the other blade... WOW.. fixed.
I'm talking thin light tape here. Give it a try.
Sorry for some bad spelling:lol:

whoanelly
11-03-2009, 03:32 PM
I know your pain, 90% of all vibes will come from blades beening out of balance (by weight and CG) and also make sure your flybar paddels are aligned and to the mm from one side to the other. The b400 is known for getting a vibe on the horizontal stabilizer. Once all is balanced spool her up and put your finger tops on the boom no buzz no vibe even if the fin is still vibing. If your not sure pull the entire head off and spoll her up if there is no vibe you know it's in the main head, and the belt thing is normal and nothing to worrie about.

+1...:thumbup:

ingrahal
11-03-2009, 07:39 PM
OMG.. crazy Vibs, I hear and feel what you're talking about. Well Hell after like spending many $$ on this problem. LOL, I went ahead and replaced everything I could, actually I have a pretty trick B400, not that I can take advantage of it totally yet, still cool, anyway I'm still having a vib problem in the tail, it's really bad once it gets into over drive, I'm using a scorpion 2221-8 motor with a scorpion 45amp esc, talk about nice power, but once it gets in to hi po mode, things start to buz, so much that it doesn't take long before the tail and vert-hort stabs come off, yea crazy, seems to be ok when I don't ask for to much power, so I figured it was a bad set of TR blades, being out of sinc, sure enough, so I balanced them out, it helped a wee bit :shock: I still have the vibs . So now I'm thinking it's time to move to another Heli, no one I show it to has an answer, seems simple enough but sheeesh!! I like what I have, also have to much in it to call it quits here, and I love a challenge , but this is getting ridiculous :roll: in fact it's nice enough outside today maybe I'll jump back into this.......:arggg:

Yeah this tail vibe thing is a killer. Can you tach the tail rotor. I'd like to know what rpm the vibe starts. Mine starts at 12,500, but since I run a 9T pinion with stock motor I don't get the vibe in flight. If I take the main blades off and spin it up I can make it happen. I'm going to make it my mission to solve this thing.

whoanelly
11-03-2009, 10:32 PM
Yeah this tail vibe thing is a killer. Can you tach the tail rotor. I'd like to know what rpm the vibe starts. Mine starts at 12,500, but since I run a 9T pinion with stock motor I don't get the vibe in flight. If I take the main blades off and spin it up I can make it happen. I'm going to make it my mission to solve this thing.
ya but if you take the main blades off your really gonna rev this baby up..i would think no way to stop vibes in that situation.just from force..i think most people balance blades and not the whole head..ive done this before,,balanced blades then stuck the whole head in a hi bros balancer,,think thats the name of it..then it was off..slop in the flybar and off balance flybar is where i think the mystery lies..cause even when you put those little pain in the but washers in the flybar..there still is slack.this movemnent back and forth is where i really think it lies..its not solid..on my 600 and on the upgrade sonix head i just put on these items are solid,,and no vibrations.

ingrahal
11-04-2009, 08:30 AM
ya but if you take the main blades off your really gonna rev this baby up..i would think no way to stop vibes in that situation.just from force..i think most people balance blades and not the whole head..ive done this before,,balanced blades then stuck the whole head in a hi bros balancer,,think thats the name of it..then it was off..slop in the flybar and off balance flybar is where i think the mystery lies..cause even when you put those little pain in the but washers in the flybar..there still is slack.this movemnent back and forth is where i really think it lies..its not solid..on my 600 and on the upgrade sonix head i just put on these items are solid,,and no vibrations.

Understood, but that limits my head speed to 2500. All my vibes are in the tail. I use the Dubro balancer to balance both. On the main rotor I balance the head with just the flybar. Much more accurate than measuring. Then add the blades. Here is where it gets tricky. You have to tighted down the grips so the blades won't move on their own then using the edge of the bench get them straight with each other and perpendicular to the flybar otherwise one whole side will be heavy. Once you get that you can get the whole head balanced to within a 1" piece of 1/4" stripping tape. Never have vibes from main rotor. I have done the same with the tail rotor but still have vibes above 12,500 rpm.

whoanelly
11-04-2009, 09:40 AM
i gotcha,,ya they can be a pain in the butt sometimes..beleive me ,ive tried many things trying to chase those rascals down..:DH well i allways appretiate yur knowledge and i hope you find it.let me know.:cheers