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HelicopterCentury Radikal G20-30 N640 Hawk Predator › Radikal G20 Lt G10 head (blade grip offset)
04-08-2011 02:02 AM  6 years agoPost 1
10poundlawndart

rrNovice

Peterborough, Ontario, Canada

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Hi Guys; I'd like your input please.

With the original LT head and stock grips I would notice that one blade grip would be .012" to 018" (varied, flight to flight) further away from the head block than the other. I was able to balance everything out with some practice, it hovered well with zero vibrations anywhere in the heli. I'm blessed wtih a clutch with zero runout, good tail set up etc. Fuel laid still in the tank, training gear did not vibrate......

I was doing a nose in hover, 3' up, it started to slide towards me from about 20' away, panic set in, smacked the tail down hard,,,,,, you know the rest. So, along with all of the other bits, I needed a new LT head, but went with the heavier blade grips. All assembled, running great, but again one blade grip is about .012" further from the head block than the other. Has anyone noticed this? I am reluctant to overly tighten the nuts on the feathering shaft, in case I damage the thrust bearings. I did once, snug them up, but after a short hover, the variance in blade grip to head block spacing reappeared. Thanks for helping. Jon, Peterborough. NOT MY PHOTO, it keeps appearing, anyone know how to get rid of it?

it is best to remain silent and be thought a fool, than to speak up and remove all doubt

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04-08-2011 05:24 AM  6 years agoPost 2
rbort

rrProfessor

Franklin, MA - USA

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I saw this same exact issue

On the Radikal 20 that I had during the build. I worked at it back and forth trying to figure out why and eventually ended up swapping the blade grips from one side to the other and it didn't make it perfect but it helped narrow the gap between the two.

You ought to try swapping out the grips and see if that helps as well.

-=>Raja.

MA 1005 H280, 4118 flts
Raptor 90 H300, 274 flts
Spectra 27 3DMax, 3187 flts
Whiplash V1 27 3DMax, 1418 flts
Whiplash V2 H300, 174 flts

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04-08-2011 06:28 AM  6 years agoPost 3
Gearhead

rrMaster

Vt

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sounds like the Spindle is floating, and or a Dampener has shifted in it's seat,,
after your Dampeners were installed you could have pushed one out a bit as you installed the Spindle (done that on my Raven), so after a few flights you would see the Grips offset a bit,, or you could have compressed one Dampener into it's Seat as you installed the Spindle, ether is easy to do with very Stiff and Tight Dampeners,
I have read where guys have had such stiff Dampeners they made Jigs to hold the Dampeners from sliding when installing their Spindles..

Jim
Buzz Buzz Buzz

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04-09-2011 12:39 AM  6 years agoPost 4
10poundlawndart

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Peterborough, Ontario, Canada

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Radikal G20 Lt G10 head (blade grip offset)

Hello Raja and Gearhead;

Thanks for your info.
I think the spindle is floating back and forth in the head block and dampeners. I have tried black dampeners and now back to red ones, as I need the softer response due to my very low flight skills.

It is not a big deal I suppose, just I notice it moves around.

Have tried switching blade grips also Raja. I may try snugging the spindle nuts up a bit more, hopefully won't put flat spots on the balls in the thrust bearings though. As it is now, I keep the spindle nuts tight enough that the thrust bearings are slightly notchy, by tugging the blade grips outward to simulate centrifical force when in flight, they go silky smooth. Maybe I should just FLYIT?

As it lurking in my basement now, I can firmly grasp both blade grips and force it to slide back and forth slightly, as though the dampeners are allowing some side to side play, which I accept as likely normal. As I know the feathering shaft has to offer some 'play' in the rotor assembly. I wasn't panicky, just wondering about it all.

Gearhead, the spindle slides easily through the dampeners when installing same, the dampener spacers seem to do their job also. The dampeners are not squashed or crushed, but geeex they sure wear out fast, like a set of dampeners to a half gallon of Coleman.

It is as much fun to work on them and learn than it is to fly (well maybe not)

Jon, Peterborough.

THAT DUMB PHOTO IS THERE AGAIN, can't delete the &^$#_( thing.

it is best to remain silent and be thought a fool, than to speak up and remove all doubt

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04-09-2011 03:51 AM  6 years agoPost 5
Gearhead

rrMaster

Vt

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edited

the soft dampeners are great for newer pilots, but as for your Thrust Bearings the Balls most likely were damaged in an earlier crash, they should be replaced ASAP, and the Spindle Nuts should be tighten all the way down snug but not over tightened,
the only time I have a notchy Bearing on my Raven (s) is if there is a bad Bearing or if one of the Dampeners is not seated correctly and it's putting to much pressure on the Radial Bearings as I tighten down the Spindle Nuts

BTW, what grease are you using on your Dampeners ??, I would think they should last longer than 1/2 a gallon

Jim
Buzz Buzz Buzz

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04-09-2011 04:37 AM  6 years agoPost 6
rbort

rrProfessor

Franklin, MA - USA

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To get rid of the photo

Click on clipboard up top in any forum.

Then click on empty to the right.

That should stop the picture from appearing in your posts, which, I assume you're previewing before sending which in fact adds the picture.

MA 1005 H280, 4118 flts
Raptor 90 H300, 274 flts
Spectra 27 3DMax, 3187 flts
Whiplash V1 27 3DMax, 1418 flts
Whiplash V2 H300, 174 flts

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04-11-2011 02:49 AM  6 years agoPost 7
10poundlawndart

rrNovice

Peterborough, Ontario, Canada

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Radikal G20 Lt G10 head (blade grip offset)

Raja;
Thanks for the tip to get rid of the renegade photo, it kept popping up like a 'whack-a-mole' at the fall fair.

Gearhead; I've tried dielectric grease in the past, and the ones that are in the head now have O-ring grease, that I have here from a pool supply place, it is for O rings on pool pumps etc.

I think I figured it out men. I've been reluctant to snug up the spindle nuts too tight, this has left some 'end to end' play, I have noticed. I just tightened them up a bit more, the uneven spacing between the head block and HD blade grips has all but disappeared. Less than .006" now, so I'm happy with that.

The notchyness (is that a word?) has diminished in the thrust bearings, not sure why! The dampeners (this pair) were starting to shred after only 4 tanks, I guess that the spindle was floating sideways and causing the dampeners to give up the ghost. so I guess I have learned something, that makes for a good day. Oddly I wasn't getting any vibrations. Can't stop my knees from shaking yet though, any ideas? Jon......Peterborough.

it is best to remain silent and be thought a fool, than to speak up and remove all doubt

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04-11-2011 03:02 AM  6 years agoPost 8
Gearhead

rrMaster

Vt

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a few sips of this before each flight will help with the shaking

Jim
Buzz Buzz Buzz

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04-11-2011 03:05 AM  6 years agoPost 9
Gearhead

rrMaster

Vt

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with the O-rings the only thing I can think of is it's the Grease,, try some Dielectric Grease when you change them and see what happens

Jim
Buzz Buzz Buzz

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04-12-2011 05:24 AM  6 years agoPost 10
az_heliguy

rrKey Veteran

San Tan Valley, AZ

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easy fix...

go to your lhs and get some hpi car shims, not sure if this is a 6mm or 8mm spindle, but the shims are available in both sizes. just get a pack, remove the blade grips and place an equal number of shims on both sides along with the spindle washer until the lateral play is gone and problem is solved

ive done this on several helis and very quick, reliable and cheap solution.

Mastercard Team Pilot :)

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04-12-2011 07:09 AM  6 years agoPost 11
Gearhead

rrMaster

Vt

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""not sure if this is a 6mm or 8mm spindle""

aaah,,, it's 7mm

Jim
Buzz Buzz Buzz

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04-13-2011 12:24 PM  6 years agoPost 12
10poundlawndart

rrNovice

Peterborough, Ontario, Canada

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Radikal G20 Lt G10 head (blade grip offset)

Hello Guys;

I really appreciate your tips and hints. Very helpfull.
I am using the two flat metal washers that are called for in the head before you install the rubber dampeners. This seems to cause some of the dampener to be exposed just outside of the head block. With the aluminum spacers in place and everything snugged up, I can see a bit of the dampener sitting outside of the recess that it goes into. An amount equal to about one and a half of the thickness of one of the washers that go in first. I think it is the bit of rubber that is exposed that is causing the shredding of the dampeners. On yours,,,, can you see any of the rubber exposed outside of the head? Jon......Peterborough

it is best to remain silent and be thought a fool, than to speak up and remove all doubt

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04-14-2011 12:38 AM  6 years agoPost 13
permagrin2010

rrApprentice

Surrey

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Floating axle head designs tend to find their own center once they spool up. Have you tried flying it?

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04-14-2011 12:18 PM  6 years agoPost 14
10poundlawndart

rrNovice

Peterborough, Ontario, Canada

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Radikal G20 Lt G10 head (blade grip offset)

Hello Permagrin2010 and all;
Yes Sir, it hovers ok. I can't fly yet, still hovering with training gear. The head is vibration free, so bieng a bit offset as I have described apparently is not enough to unbalance the blades at head speed. I'm using 640 woodies, at 1600 RPM in a hover. I had a nice set of 620 carbons but used them to slice the boom in half.

I understand the floating - self-centering concept. A concept that applies here. Thanks every one for your tips.
Jon......Peterborough

it is best to remain silent and be thought a fool, than to speak up and remove all doubt

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05-08-2011 03:34 AM  6 years agoPost 15
10poundlawndart

rrNovice

Peterborough, Ontario, Canada

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Radikal G20 Lt G10 head (blade grip offset)

Update, shredding red dampeners solved,,,,,,,,,

Hi Guys;

I ended up removing the two aluminum washers that go in the head block before the dampeners. Now, the dampeners sit totally inside the hole in the head. Before, the dampeners used to sit a bit outside, and was too compressed (pinched) with the aluminum spacer. The shredding has stopped.
Jon.....Peterborough.

it is best to remain silent and be thought a fool, than to speak up and remove all doubt

PM  EMAIL  Attn:RR
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