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Hirobo Embla - SRB Quark - Lepton
› Lepton tail vibration
10-24-2006 10:19 AM  12 years agoPost 1
lmf

rrNovice

Singapore

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Hi,

I noticed slight vibration on my Lepton tail during its first flight 2 days ago. After the flight I've checked all my blades balance and they are perfectly fine. Today when I flew it again (2nd flight) with more aggresive pitch up/down and after that flight, the tail is vibrating like crazy. I landed it, took off the blades, spool up and everything is smooth and fine. After I put back the main blades, the tail starts vibrating slightly just like before. It seems like after some hard maneuvers, the vibration will be very strong.

Any advice?

Cheers,
Lim

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10-24-2006 10:33 PM  12 years agoPost 2
Vigor Wiken

rrNovice

Mölnlycke, Sweden

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Try to remove your boom brace, i had tail vibrations and the stopt when i removed my boom brace

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10-26-2006 05:16 AM  12 years agoPost 3
lmf

rrNovice

Singapore

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Hi Vigor, no luck. Removed the boom brace and it is still vibrating.

I can feel very minor high pitch vibration without the main blades on. However, once I install the main blades, the vibration becomes visible on the tail fin. The spindle shaft is very tight on the dampers and it could have cause the spindle to be stuck sitting off balance to one side. I could feel one side of the blade grips being able to move more freely than the other side. I wonder if this could be the cause.

Cheers,
Lim

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10-26-2006 05:44 AM  12 years agoPost 4
TMoore

rrMaster

Cookeville, TN

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Try a new set of mains.

TM

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10-26-2006 08:50 AM  11 years agoPost 5
lmf

rrNovice

Singapore

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Hi TM, too bad I do not have another set of main frp blades. I may try with other type of blades. My Lepton is brand new. It will be very unfortunate if the main blades are giving problem.

Cheers,
Lim

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10-26-2006 01:53 PM  11 years agoPost 6
lawrenmd

rrApprentice

Orlando FL.

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Ok maybe some new information. I installed new MAH blades (They fly great) and the vibe seemed to have gone away, wrong. What I noticed today was that there was no vibe at the beginning of the flight. Normal mild 3D stuff, still good to go. If I invert the heli and apply full pitch -11 degrees of pitch the vibration starts. After landing I moved the spindle in the head by pushing up and down on the grips, this fixed it for a few manuevers. I then took out the spindle and lubricated the heck out of it and the dampers with silicone grease. Few again with no problems. Maybe this will help? I will post more when I get few more flights in.

Dave

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10-26-2006 04:39 PM  11 years agoPost 7
lmf

rrNovice

Singapore

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OK, I've tried switching the blades and also tried another set of blades. Still vibe. I'm going to try to lube the feathering shaft and the dampers which are extremely tight and stiff.

Cheers,
Lim

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10-29-2006 05:31 AM  11 years agoPost 8
lmf

rrNovice

Singapore

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Hi,

I've lube the feathering shaft and still no luck. The vibe is getting worse. However, without main blades, no problem.

Any suggestions?

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10-29-2006 06:41 AM  11 years agoPost 9
TMoore

rrMaster

Cookeville, TN

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See my first post above. Either balance the existing blades or try a known good set.

TM

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10-29-2006 11:30 AM  11 years agoPost 10
lmf

rrNovice

Singapore

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Hi TM, I've balanced the main blades and also tried changing another set of different blades. It still vibes and getting worse now.

Lim

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10-29-2006 12:16 PM  11 years agoPost 11
lmf

rrNovice

Singapore

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Hi Bill, I've tried spinning without the main blades. No vibes. The vibes only start when I put on the main blades. Occasionnally after putting on the main blades, it may not start to vibe immediately. It will only start to vibe after a flight. But most of the time, once the main blades are on, the vibe will start.

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10-29-2006 01:26 PM  11 years agoPost 12
Voyager

rrApprentice

Canada

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Have you tried running the mains loose. I mean to a point of considering them way too loose?
I find mine usually vibrates if they are tight as I would put them on other helis.

... Rob

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10-29-2006 04:46 PM  11 years agoPost 13
ethinger

rrNovice

phnom penh Cambodia

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lmf,
if there is time, we can meet when we are free to try my main blades... and i will give yours a try so we can make sure if its the main blades problem...

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10-29-2006 11:45 PM  11 years agoPost 14
TMoore

rrMaster

Cookeville, TN

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How did you balance the mains?

TM

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11-03-2006 01:15 PM  11 years agoPost 15
lmf

rrNovice

Singapore

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Hi,

Voyager, I'll try your suggestion.

ethinger, it will be great to try and see if the mains are giving problem. However, I'm still very busy with work these few weeks. I'll contact you when I'm ready. Thanks for the offer.

Bill, I'm not sure if the tracking is out when it is vibrating. But I did check the tracking before flight and everything seems ok. I'll check that again.

TM, I balance the blades with a see-saw type blade balancer which balance the C of G and the weight. I've also balanced the blades' weight using weighing scale.

Cheers,
Lim

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11-03-2006 02:45 PM  11 years agoPost 16
TMoore

rrMaster

Cookeville, TN

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It sounds like the chordwise CG is probably off making the blades lead or lag relative to one another. I've seen this before and it will make the heli shake.

Try using a razor blade and plot the chordwise CG to make sure that it is in the correct location relative to the other blade.

TM

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11-04-2006 11:22 AM  11 years agoPost 17
lmf

rrNovice

Singapore

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Hi TM, I do not understand what you mean by plot the clockwise CG using a razor blade. Do you have the details on how do it?

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11-05-2006 03:25 AM  11 years agoPost 18
TMoore

rrMaster

Cookeville, TN

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Stand a razor blade up in a vise, or use a round pencil on a table, lay the blade on the razor blade at a 45 degree angle in one direction in a position so that it balances perfectly level and then do it in the opposite direction. When you do it each way take a pencil and scribe a line on the blades right at the razor blade and then do it again so it forms an intersection point on the blade. If you do both blades the intersection should be in the same location on each blade if the Chordal CG's are inline with each other. If they aren't that is most likely the source of your vibration.

TM

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