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HelicopterMain Discussion › Vibration reference guide.
12-28-2008 12:11 PM  8 years agoPost 1
flying buffalo

rrApprentice

Darwin, NT,​Australia

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Hi all, I was thinking how helpful it would be to have a quick reference quide to solving vibration problems (big or small)based on the experiences of fellow pilots. We could break it down into the following areas,(feel free to add any others). Then under each heading list your fix for solving the particular vibration that you had. Try to keep it in point form for that "quick reference quide" appeal.

1)Tail Fin Vibrations (Horizontal and Vertical Fins)

2)Boom support Vibrations

3)Skid Wobble/Canopy Shake

4)Foaming Fuel/Unstable Fuel

Yesterday was history...tomorrow is mystery

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12-28-2008 12:37 PM  8 years agoPost 2
BarracudaHockey

rrMaster

Jacksonville FL

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High freqency vibrations are usually the engine, clutch, or fan and cause fin blur. Dial indicating for run out, and balance are generally the culprits.

Medium frequency vibration like the boom supports and skids and fuel foaming are usually in the tail drive system. Bent shafts (tail output, tail hub, torque tube if equipped or out of balance tail blades)

Low freqency stuff like canopy shaking or the wobbles is in the head somewhere. Blade balance, paddles not equidistant etc.

Andy
AMA 77227
http://www.jaxrc.com

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12-28-2008 02:42 PM  8 years agoPost 3
bigdad390

rrVeteran

East. Liverpool,​Ohio

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High freqency vibrations are usually the engine, clutch, or fan and cause fin blur. Dial indicating for run out, and balance are generally the culprits.

Medium frequency vibration like the boom supports and skids and fuel foaming are usually in the tail drive system. Bent shafts (tail output, tail hub, torque tube if equipped or out of balance tail blades)

Low freqency stuff like canopy shaking or the wobbles is in the head somewhere. Blade balance, paddles not equidistant etc.
exactly, although fuel foam can also be caused by high speed vibration, engine, fan etc.

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12-28-2008 02:54 PM  8 years agoPost 4
LaurenceGough

rrElite Veteran

Reading, UK

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What would canopy edge blur and a small percentage of the landing skids vibrating in flight come under? (even with main blades and flybar balanced...!)

Also only happens off the ground, no vibration at full speed on the ground at -5 to +5 or so (just before take off even when light on skids)

(No vibrations without head on)

Very strange...

This is a great idea for a thread!

www.laurencegough.com
Sponsors:
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OPTIFUEL
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Spektrum

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12-28-2008 07:09 PM  8 years agoPost 5
The Dude II

rrVeteran

IN - USA

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Excellent Idea!

As this community has great deal of knowledge and experience...I'd love to see this come to be.

Most life experiences tend to be cyclic in nature (no pun intended) and it would be great to have a handful of topics that are built, then locked here on RR for Reference...maybe a separate Reference forum here on RR.

Every few months we start again answering the same questions.

Glad to help...but wasteful spending time to lookup links or re-type answers/solutions that have already been addressed for another.

Bit of work here could open up more time for us elsewhere in life...say on the bench building or spending time with our families...ask my daughter..."Daddy, you done yet playing helis on the computer?!"

Balance:
Fan & Clutch (fuel foaming & increased general wear)
Adding Govonor Magnets
Drilling and adding dead weight to fan

Flybar & Paddles (head wobble)

Main Blades (head wobble)
Equal Weight Range
CG

Tail Blades (tail vibrations)
Equal Weight Range

Model Overall CG

Variences:
Dial Indicating Clutch Hubs

Checking shafts

Ball Links (sloppy/uncontrolled performance)

Techniques:
Thread Locker/Thin CA

"The Greaser"

DuBro Balancer

Drill & Tap set

Tempered Plate Glass
Blade Tightening

Grooming

Plenty to be expanded upon here.

lotta ins, lotta outs

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12-29-2008 12:29 AM  8 years agoPost 6
bosshoss

rrVeteran

Chicago, IL

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Let's make it comprehensive and sticky it to a forum.

Why Hover a Yak, when a Heli does it better?

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12-29-2008 08:22 AM  8 years agoPost 7
mickeyapples

rrVeteran

England

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frequently asked questions comes to mind

Live life on the edge. Stand next to me when I am flying

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02-08-2009 01:59 PM  8 years agoPost 8
jbdww

rrElite Veteran

Round Rock, Texas

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TTT I thought this thread needed to be moved to the top again because it is very helpful.

Skids Up
http://www.jbdww.com
http://twitter.com/jbdww/

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02-08-2009 04:04 PM  8 years agoPost 9
The Dude II

rrVeteran

IN - USA

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Been working on this...I now how about 14 pages compiled...though not all edited yet.

Here's a sample of a recent PM..based upon a post I put-up over where I "hang".

http://www.runryder.com/helicopter/t492566p1/

Based around having a better/easier tool for the job at hand...measuring pitch.

Even thinking this AM as I drink my coffee about getting a newer digital cam-corder that would allow me to shoot & edit more difficult things...like balancing the fan/clutch/hub assembly.

Symmetrical Cyclic & Collective Setup

There are three pitch measures on the Main Rotor Disc of any heli.

Collective (ascent & descent)- tied to flight mode switch(es) & Pitch Curve Functions (Actually an AFR function) as well as "Pitch" in the Swash Menu (global setting).

Pitch (as in Elevator...not Collective) - tied to ATVs, AFRs and Dual Rates as well as "Elevator" in the Swash Menu (global setting).

Roll (aileron) - tied to ATVs, AFRs and Dual Rates as well as "Aileron" in the Swash Menu (global setting).

Ideally, the cyclic (meaning both the aileron & elevator functions...AKA the right stick) will be equal for 360 degrees of rotation of the blades.
Reality is, the linkage/design is not perfect...hence the 4 different values I had...until I tweaked the AFRs for each function. All heli designs suffer from this in various degrees.
It's called a “compromise”.
Helicopter design and Life in general are full of them. Do I eat steak for dinner...or do I have the pork-chops?

Note: There's another setting on advanced radios like the JR12x, Futaba 12FG,Z & 14MZ...called Cyclic Ring...another sub-topic of this topic...for another time.
The CYCLIC RING feature does make EXTREME value of the higher priced radios. You may need to be well beyond the basics of rotary flight to truly appreciate the value of this adjustment though.

Why the Fuss?
Answer: Consistency!

A drawback to improper/unequal setup is that it can rob precious power.
You start to load the head prematurely...then the move isn't as crisp as it could be because the machine is laboring too hard.
Ideally, the craft should respond equally well on all controlled axis.

Examples:
Tumbles...the heli should flip forward at the same rate as it flips backwards.
Rolls...the heli should roll left at the same rate as it rolls right (more to this though!).
If a setup only has 9 degrees left cyclic and 11 degrees right...it will feel differently on the sticks & look different in the sky as well as.

Well after you learn the basics and get tired of "punching holes in the sky"...you may start to fly "truly aerobatic" moves.
At that point...these little inconsistencies in the model setup become apparent when you try to perform loops that are perfectly round..not egg or cursive "e" shapes.
This applies to ALL moves...not just loops!

How to Measure & Adjust:
This is where your technique & quality of your measuring device show their weight.

We measure Pitch (elevator) with the main blades perpendicular to the boom...you should have equal values of pitch for nose-up & nose-down. (my were 11 & 9.4 respectively...which meant the heli flipped "quicker" backwards than forwards...leaving me with a bit more "workload" as a pilot because the heli didn't fly the same in both commands. This adjustment is made in the AFR setting for the “elevator” function. Keep in mind that the ATV and Swash Menu “elevator” setting do set the maximum travels! Hierarchy is as follows: Swash Menu (global), ATV(global) then AFR(flight mode or dual rate).

We measure Roll (aileron) with the main blades parallel to the boom...you should have equal values of roll for left & right. (my were 9.5 & 10.5 respectively...which meant the heli rolled right "quicker" than left...again, leaving me to "figure this out when flying".This adjustment is made in the AFR setting for the “aileron” function. Keep in mind that the ATV and Swash Menu “aileron” setting do set the maximum travels! Hierarchy is as follows: Swash Menu (global), ATV(global) then AFR(flight mode or dual rate).

In Conclusion:
Once a machine is setup correctly...it will fly much easier and make you look better in the sky.
Grab your local "pro", give him an equally equipped machine that he's used to...with an incomplete setup and see if he can still pull-off the same moves and look as good as his personal machine.
There will be adjustments to the "stick choreography" made throughout the flight.
After landing, he'd probably say "we need to work on the setup...it flies, but it's too much work to make it look good!"

lotta ins, lotta outs

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