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HomeAircraftHelicopterHelicopter Main Discussion › Raptor 50 titan, tail vertical bounce
10-29-2013 06:12 AM  5 years agoPost 1
doctor

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Clear blue sky

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Hi,

This Sunday TT titan 50 showed a strange prob. As i was flipping it, the tail bounced vertically as if like a spring motion.

No crashes, belt is tight. Gyro is working perfect as the tail feels locked in.

Only change i have made was to put NHP tail blades from align ones. and, replaced turnigy carbon main to Align 3G blades.

These NHP tail blades were earlier on raptor 30. I chipped the align tail blades so had to replace them.

Can the tail blades causing the vertical bounce?

Doc

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10-29-2013 07:03 AM  5 years agoPost 2
jbiter

rrKey Veteran

Sebring, FL

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Blades out of balance, bent tail hub or a bent tail shaft would be places to look

Jeff

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10-29-2013 01:40 PM  5 years agoPost 3
co_rotorhead

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Centennial, CO, USA

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When troubleshooting a problem that seems to have just suddenly appeared, the first place to start looking is what has changed. In this case you changed 2 things: the main and tail blades. Start troubleshooting by backing out the changes one at a time.

I am assuming you were not seeing this bounce with the Turnigy main blades and Align tails. Since you can't put the original tail blades back on as they are chipped, start with the main blades and put the Turnigys back on. If the bounce persists with the Turnigys on, leave them on and then try a different pair of tail blades.

If you can get it back to its original, "no bounce" state, then you can change one thing at a time to discover which was causing your issue.

Good luck.

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10-29-2013 01:55 PM  5 years agoPost 4
wrongler

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Brewerton, New York

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How many times did it bounce? Could it have been static?

Bill Whittaker

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10-29-2013 02:37 PM  5 years agoPost 5
Santiago P

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South West, Ohio

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As i was flipping it, the tail bounced vertically as if like a spring motion.
How tight are those main blades? Too tight will make the heli shake, oscilate, and/or bounce the tail while is flipping, or doing continuous rotations.

S

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10-29-2013 02:42 PM  5 years agoPost 6
doctor

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Clear blue sky

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With static developing aint the heli shake continuously. Why only during flipping?

Ahhh the main blades are not very tight as they are on my gaui x5 FES. surely will hold the rappy horizontal and see if they fall own by weight or following a jerk.

The bounce occurred only during flipping then it stabilises as if nothing happened. I even did pirouetting circles without a prob.

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10-29-2013 02:46 PM  5 years agoPost 7
Richardmid1

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Leeds, England

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Is this Raptor flybarred or FBL?

A vertical tail bounce during quick elevator inputs is usually due to soft or worn head dampeners or low head speed.

60% of the time, it works every time!

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10-29-2013 03:48 PM  5 years agoPost 8
doctor

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Clear blue sky

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Its a Flybarred raptor.

Hmmm let me check the dampers.
Also, if the dampers get wornout, the tracking changes? (Sorry for my noob questioons.)
Can i check the dampers without dissasembling the head? I mean removing the balls links and moving the main grips to see if there is a vertical or horizontal play?

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10-29-2013 04:06 PM  5 years agoPost 9
Santiago P

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South West, Ohio

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One more thing, Main Grips.

If you are using the plastic main grips, they wear out inside, around the bearings and then you start showing a bit of play, which leads to tracking and shaking issues as yours.

Every, 50 to 100 flights I changed the grips along whatever other thing showed wear, or if I start noticing bounce or more than momentary tracking issues.

They are only like $9 for a pair.

S

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10-29-2013 04:10 PM  5 years agoPost 10
Richardmid1

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Leeds, England

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No the tracking won't change.

You can check how much movement the head has by rocking the blade grips with your hands like a see-saw. You can also push and pull on one of the blade grips to see if the feathering spindle moves in and out.

Also check for loose ball links while you are checking the head, I like to move the blade grips as if increasing and decreasing collective pitch but without moving the servos, you will feel if there is excessive play and by watching the links as you do this you will see if a ball link is backing out or if you have a worn bearing in the mixing arms.

60% of the time, it works every time!

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10-29-2013 05:38 PM  5 years agoPost 11
jschenck

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La Vista, NE.

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A vertical tail bounce during quick elevator inputs is usually due to soft or worn head dampeners or low head speed.
+1

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10-29-2013 06:17 PM  5 years agoPost 12
wc_wickedclown (RIP)

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long beach calif

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vertical bounce
yep low head speed

Insha Allah made in america

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10-30-2013 01:28 PM  5 years agoPost 13
doctor

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Clear blue sky

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Hi,

I havent changed the throttle curves. How can there be a variation in head speed. Nothing other than main blades n tails blades have been changed. Does Align 3G FBL blades need a higher heaad speed??

I have following check point now:

1. Checking the dampers and blade grips. (Can be done at home)
2. Messing around with the throttle curve(will have to wait till weekend)

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10-30-2013 02:25 PM  5 years agoPost 14
Richardmid1

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Leeds, England

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I would not have thought the Align 3G blades required a higher HS. The 3G blades are also heavily weighted for FBL and that could be your problem. You want the standard Align 600D blades for flybarred.

Also if you are not running a governor a change of blades, especially heavier ones, or a change of weather can change your HS.

I think your main problem is trying to 3D a flybarred heli with FBL blades.

60% of the time, it works every time!

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10-30-2013 05:34 PM  5 years agoPost 15
nobato1

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USA

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I think your main problem is trying to 3D a flybarred heli with FBL blades.
that makes no sense at all

why on earth would fbl blades cause unstable behavior on flybarred heli?

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10-30-2013 05:43 PM  5 years agoPost 16
jschenck

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La Vista, NE.

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It's possible that heavier blades may cause worn dampers to bounce more - but agree that in general FBL blades will fly fine on FB machines. FAI blades are even heavier and fly well on FB heli's

My vote - put a $5 set of dampers in there, make sure they are lubed and try again.

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10-30-2013 07:18 PM  5 years agoPost 17
Richardmid1

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Leeds, England

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We are not talking about unstable behaviour, just an elevator bounce. A flybarred raptor 50 with possibly the blue dampeners installed? really isn't designed for fbl blades.

60% of the time, it works every time!

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10-30-2013 07:58 PM  5 years agoPost 18
AirWolfRC

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42½ N, 83½ W

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how fast was that "bounce" ?
. . and was it steady or did it damp out ?

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10-30-2013 08:13 PM  5 years agoPost 19
jwatts007

rrNovice

England

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Could the ELE links on the push pull set up be different lengths...that would cause it....

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10-30-2013 09:20 PM  5 years agoPost 20
Santiago P

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South West, Ohio

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blue dampenrs not designed to work with FBL, nonsense!

FYI,

I' ve flown plenty of R50 hours with blue dampeners and blades ranging from unstable to stable, FAI, and FBL, and NONE cause elevator bounce on hover, nor in stationary flips, or high speed aerobatics.

I have seen a few helis with tail "vertical bounce" during flips, and every case I witness was attributed to blades grips too tight, not allowing the blade to settle in lead-lag.

Also:
If the RPM is too low, it will result in the partial blade stalling, unstalling quickly ( loud noise) during the flip, and/or spindle bumping, which in turn may look like a tail bounce.

doctor,
What RPM is the heli flying during the flips?
How much cylic pitch are you commanding?

Santiago

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