RunRyder - Intermittant wobble

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Audacity Models Pantera 50 - Tiger 50 > Intermittant wobble

SilverBullet
Senior Heliman
Location: Bentonville, AR USA

http://runryder.com/helicopter/t435223p1/

Ok, I have done everything I can think of short of pulling the engine and checking the runout on the clutch. I lubed the dampers, loosened the main blade grips on the blades so they can swing a little more freely (How loose should they be?), lubed the swashplate, lubed bearings, tightened all bolts in the frame around the bearing blocks, and balanced main blades. The heli still wobbles. It seems to wobble more side to side. It wobbles noticeably stronger when I am lowering the throttle and descending in a hover. If I raise the throttle to pull out, the wobble seems to disappear. It wobbles some on spool up if I spool up slow.

The heli only has about 10-15 flights of mostly hovering and some very slow FF. It has never been crashed or landed hard. It started doing this with the woodies, so I switched to the Radix, and it is still doing it. Everything is tight and lubed. My first 8-10 flights with the heli were smooth as can be, this just started recently.

By the way, I installed my new Pro Muffler and it runs great. I have my main needle out two clicks over 1.5 turns, and it is at 220 degrees when I land. I richened it two more clicks and it is still around 220 when I land. Do I need to richen it some more? 30% CP with an OS50 Hyper. With the governor, I was running 1650 RPMs in Normal. Bottom plate is warm, but I can stick my finger on it for over 5 seconds. Temp sensor is mounted on the side of the cylinder immediately below the blue cooling fins.

06-18-2008 03:42 AM

Mr.HillBilly
Senior Heliman
Location: Salesville, OH - USA

Take your head speed up to at least 1750 and see if it smooths out. Mine has the shakes until I get the head speed up. You prob. will run a little cooler after you take your head speed up also.

06-18-2008 03:49 AM

jbeech
rrAdvertiser
Location: Sanford, FL (Orlando area)

No clue on the wobble but the engine temps are fine.

John Beech - GM (and janitor)
Audacity Models

06-18-2008 03:49 AM

Divot
Veteran
Location: Mesa, AZ

Silver,

Have you tried a different set of blades? I recently encountered a set that was warped. I know this is a long shot just thought I would throw it out there.

06-18-2008 04:00 AM

flybarless
Key Veteran
Location: Torrington, CT

Check your main blade tension in the grips, I had a problem like that and it was because the blades were too tight in the grips.

Just remember -- if the world didn't suck, we would fall off.

06-18-2008 01:47 PM

HOMEPAGE

SilverBullet
Senior Heliman
Location: Bentonville, AR USA

Is there a good test for tension? How do you know if they are too tight or loose? I loosened them before and it seemed to help. I don't want to risk a boom strike.

06-18-2008 03:12 PM

jbeech
rrAdvertiser
Location: Sanford, FL (Orlando area)

Basically, with the blades stretched out, they should be loose enough to "not" swing free when you turn the model onto its side, but touching the tip of one of the blades (while it's still on its side) should allow the blade to swing free. However, ultimately, it's a judgement call about how tight.

Also, make sure to lube the dampers in the head block where the spindle shaft slides through.

Finally, ensure the thrust bearings are properly assembled. There's a short video within the manual (online only of course) demonstrating proper thrust bearing assembly.

John Beech - GM (and janitor)
Audacity Models

06-18-2008 03:54 PM

billrad
Senior Heliman
Location: Rineyville, KY

I had this same exact problem.

Maybe this will work for you.

1. Tighten all the hex head bolts around the bearing blocks, etc. I thought mine were tight, but they weren't.

2. Crank up your headspeed to at least 1800 in normal, 1850 in idle up 1. I use a multigov with optical sensor.

3. Mine never wobbled until I had some time on the airframe (with no crashes), so some of it is wear, but I don't know enough engineering wise to figure it out. My bet is it is in the head somewhere. Also, the harder my dampeners, the more wobble at low speed I experienced.

4. See if one main blade is significantly heavier than the other one. A long shot, but with woodies, this can happen more so than glass or Cf.

Billrad

I may not be able to turn a kit into a plane, but I can turn a plane into a kit...

06-19-2008 03:34 AM

HOMEPAGE

SilverBullet
Senior Heliman
Location: Bentonville, AR USA

I took the headspeed to 1750 and loosened the tension on the blade grips and it really seemed to help. I still have slight wobble when I let off the throttle. I will try 1800 and see how it does. I also seem to have some slop in the stock plastic swash, so I don't know how much that would affect it.

With the stock plastic head, what is a safe headspeed? I am running Radix 600 CF blades. I am just doing very basic FF.

06-19-2008 03:58 AM

Mr.HillBilly
Senior Heliman
Location: Salesville, OH - USA

Do you still have a wobble when you are hovering at 1750 or just when spooling up and down?

06-19-2008 10:31 PM

SilverBullet
Senior Heliman
Location: Bentonville, AR USA

seems like now it is only happening when I lower the collective, more so when I don't have the governor on. Loosening the blades and upping the headspeed definitely made a difference.

06-20-2008 12:50 AM

heli_headcase
Key Veteran
Location: Hovering around Atlanta

Headspeed: Crank it up

SilverBullet,

The Pantera was designed to be an advanced aerobatic/3D trainer and has somewhat stiff damping to allow rapid cyclic action. This stiffness dictates higher head speed than you may feel comfortable flying. The stiffer the head, the more wobble prone at the lower RPM settings. It's a compromise we all have to live with.

You've already proven it to yourself by upping the speed a little the wobble goes away. Set your pitch and throttle curves so you can't enter the "Wobble Zone" under any flying regimes. It's simple, don't lift off the ground until the head is up to flight RPM and give yourself enough negative pitch so the heli will descend while some throttle holds the head speed up.

As to max RPM the head can take: I run my Pantera at up to 2200-2300 with carbon blades, OS 50 Hyper, Pro muffler, and it's tough enough to take it. Don't be shy about going 1900 for most flying maneuvers, 1800 for hover. Trust me, you'll get used to it and then ask for more

HHC

So many heli's - too little time...

06-20-2008 02:29 AM

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Audacity Models Pantera 50 - Tiger 50 > Intermittant wobble

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