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HelicopterScale Model RC Helicopters › R22 Scale Rotor head with 2.5 rotor diameter and Bavarian Demon 3SX set up
JR Guy

Senior Heliman

Waikawa Beach New Zealand

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Can anyone please advise what the best "Rigid setup" is in the Bavarian Demon 3sx for a 2.5m rotor Diameter?
All my mechanical set up is as per the letter however when I get to lift off speed the blades make a sound Like there out of sink with each other.
The sort of noise you get when you go into a hard turn and the blades cavitate. any suggestions welcome. Colin

JR Guy

04-11-2017 09:08 AM
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JuanRodriguez

Elite Veteran

The Villages, Florida

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Sounds like a tracking issue to me ....

Unplug your motor for safety.....

Switch your controller to rate mode (ie, non-heading hold) and move the throttle/pitch stick to 1/2 stick . Now measure the pitch of EACH blade. If you have 3D set up , that pitch should be 0. If not, match the pitch of one of the blades to the other by adjusting your links until the are both reading 0 (or as close as possible to 0)

When I follow the above procedure, my tracking is usually right on ....

Been there, done that and old enough to know better.....

04-11-2017 10:54 AM
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Peter Wales

Elite Veteran

Orlando Fl

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I'm guessing he does not want a 3D setup

if he has a 3D setup now when he starts the motor, the pitch will be -10 or so and that's what makes a funny noise.

Check your pitch curve in the way Juan suggested, but make sure it is in the order of -2, 5, 10 and then check that at mid stick both blades are exactly the same at 5 degrees, or so. The exact value will not matter as you can tune that with your pitch curve, but that will get you off the ground.

Peter Wales
http://scalehelicopters.org

04-11-2017 01:00 PM
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JR Guy

Senior Heliman

Waikawa Beach New Zealand

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Thanks Juan and Peter

JR Guy

04-11-2017 07:41 PM
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JR Guy

Senior Heliman

Waikawa Beach New Zealand

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I have totally stripped down the Rotor Head and re-built it checking the build plan.The mechanical set up is as per the letter.
In the Bavarian Demon under the heading "Rigid" I found a pot slider to set up pitch curve Top Stick and a slider to set mid stick and put the TX back to Linear. How ever I don,t understand the term P Portion.
It states P portion is to reduce "Shivering" Shivering is what is going on just before lift off. So! this morning I lifted off with the so called shivering and I had to fight the heli to maintain a level hover.
I have changed the P portion up and down and am still at a loss.
Any Answers before I refit the Flybar head? Cheers Colin

JR Guy

04-12-2017 11:10 PM
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JuanRodriguez

Elite Veteran

The Villages, Florida

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It might be better if you didn't have two posts going on the same topic....

Just a thought.....

Been there, done that and old enough to know better.....

04-12-2017 11:36 PM
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JR Guy

Senior Heliman

Waikawa Beach New Zealand

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I was hoping the Bavarian Rep might read the Flybarless Thread. However I take your point. Colin

JR Guy

04-13-2017 01:01 AM
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modtron

Key Veteran

Oxford. UK

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Colin,

Best thing would be to email Joachim at Bavarian....
joe@bavariandemon.com

His English is excellent and he will nail your issue straight away.

modtron
Oxford UK

04-13-2017 07:18 AM
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JR Guy

Senior Heliman

Waikawa Beach New Zealand

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After a couple of helping PM's I have set up the Vario flybarless rotor head again with the Bavarian Demon.
I still have the terrible vibration before take-off.
So today I replaced the flybar and the blades I was using in the Flybarless head and put the heli into hover with no problems what so ever. This is now telling me I have a faulty Vario flybarless head. I purchased the Vario conversion last year and cut the flybar support off my original Hub.
I'm now wandering if this now requires balancing. I will take it to an engineer tomorrow and see if the head is out of balance.

JR Guy

04-16-2017 10:36 PM
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Mojave

Elite Veteran

Palos Verdes, Ca. USA

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Let us know if the head block is out of tolerance. I have 2 brand new spare Vario rotor heads if you need parts.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

04-17-2017 04:53 PM
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JR Guy

Senior Heliman

Waikawa Beach New Zealand

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Thanks Barry, I have just come from our local engineer and I think he has found a problem.
We put the head complete into his lathe and he set a gauge on one of the bolts then turned the head to the other bolt.
One bolt is out by 1/16 of an inch. Could this be causing the vibration.
At speed in the lathe the head looks ok.
Also I see there is a part vario sell for the head when using a FBL Gyro part no 702/81 rocker block for FBL conversion. What does it do?
Colin

JR Guy

04-18-2017 01:44 AM
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Mojave

Elite Veteran

Palos Verdes, Ca. USA

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Your VR22 head block is true, no wobble? 1/16th of an inch is enough to throw the balance off, but I'm confused as to where the head was indicated from. What bolts did the machinist indicate, the blade grip retaining bolts (grip to spindle bolts) or the blade bolts? I looked at the drawings for that head and couldn't see where the rocker block would come into play. Maybe someone else can chime in on this...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

04-18-2017 03:14 AM
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JR Guy

Senior Heliman

Waikawa Beach New Zealand

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Barry its the Blade bolts, I'm trying to upload a video. The link is the video. Colin

https://drive.google.com/open?id=0B...WGJidThFbUNNbVU

JR Guy

04-18-2017 07:32 AM
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Mojave

Elite Veteran

Palos Verdes, Ca. USA

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I'm assuming that the main shaft is running true? Have you disassembled the head and verified that all of the parts are installed correctly and in the correct orientation? Also, have you spun it at speed in the lathe? When I check a head block I chuck it in the lathe bare, no parts installed. Then I indicate the head block on one side with a dial indicator, then rotate the block and see what the difference is from side to side. This will tell you if the head block is running true. If it is, then you need to look into it farther to determine what other parts may be causing the issue.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

04-19-2017 02:13 AM
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PETER ROB

Elite Veteran

Devon UK

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Colin, I have been watching your posts and the reply's
I have never found the head (centre block) to be the cause for vibration
Following Barry's post's
Start from the head
Check spindle not bent
check rubbers are correct orientation and the same both sides,not miss shapened, and greased
Build the rest of blade grips as build manuel
Assemble with end bolts up tight
Now check that the blade grips are tight up on the rubbers and do not need shimming to take up any slack,(I have found on 2 occasions that the feathering spindle is too long),You can shim or reduce length of spindle
If everything is OK, check that your blade bolts are not bent, if you over spin the head, too high head speed, or the blades are too heavy, they will distort
Finally check the holes in your blade grips, with aggressive flying, I have found on many occasions that the bottom hole in particular will get elongated, allowing the blades to flap (for a better word)
All this is if the unit has been flown (second hand), if all new, a lot of this is not required, as Vario head units built to the manual, are rarely at fault
It then just leaves your blades, and I know from past experiences you are hot on checking blades
Good hunting, hope some of this helps
Peter R

04-19-2017 08:51 AM
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JR Guy

Senior Heliman

Waikawa Beach New Zealand

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Thankyou Barry and Peter I will go over every thing again on the weekend.
I will also get a video of what is happening when reaching hover head speed. cheers. Colin

JR Guy

04-19-2017 04:56 PM
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JestRR

Veteran

Florence, Oregon

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what pitch are you spooking up at? If your blades are going through 0 degrees, that may be causing some problems. I always spool up at just below hover. 2-3 degrees. I know the OF heads were and still are notorious for resonance when going through 0 degrees on the ground....$.02

Mike Spinner
Florence OR
SCALE JUNKIE!!
NORTHWEST SCALEWORKS

04-30-2017 04:51 AM
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HelicopterScale Model RC Helicopters › R22 Scale Rotor head with 2.5 rotor diameter and Bavarian Demon 3SX set up
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