RunRyder RC
 10  Topic Subscribe
WATCH
 5 pages [ <<    <    ( 1 )     2      3     NEXT    >> ] 11052 views POST REPLY
Scorpion Power Scorpion Power
HelicopterAerial Photography and Video › 45 degree flybar setup
09-02-2009 09:51 AM  8 years agoPost 1
SeismicCWave

rrVeteran

Hilo, Hawaii

My Posts: All  Forum  Topic

Ok, no one seems to be very interested in the main discussion forum. I guess every one is trying to figure how best to get their helicopters flying as straight and as nimble as possible in FAI or 3D.

However I have been more intrigued with the stability of our helicopter for AP use. So I have been wondering about these entry level helicopters that concentrate more on stability for the beginners. The one that started it all was the Hirobo XRB. First it was the wired version then the wireless which spawned a whole world of clones. The most interesting thing about these helis is not so much the coaxial setup which is really neat but the 45 degree flybar setup.

My aeronautically engineering friend seems to think that the 45 degree flybar setup contribute a lot to the stability of the helicopter.

I couldn't find too much written about the theory of the 45 degree flybar setup in full scale helicopters. The only one that has done any work on the 45 degree setup was Dana from the gasser forum. He fabricated a different head for I believe three of his helicopters from a small clone to his Predator gasser. He seemed to think that it does increase stability but did not elaborate why.

Since I couldn't find anymore information on it. I have decided to build me one to do some testing on my own. So I looked around in my work shop and see what I could find to use instead of starting from scratch. I found my old Schluter Scout 60 head being the best candidate. The head comes in two pieces so it is easy to rotate the flybar carrier and the main blade carrier. Which is exactly what I did.

I finished the head yesterday and making a long story short. I put it on my Logo 10 with 120 degree eCCPM swash. After swapping the aileron and elevator servos I managed to get it flying. I had two flights on it so far and it is more stable.

So my question is how come not more people are investigating this setup for aerial photography use.

Let's start a discussion here and may be I can learn more.

OK here are some preliminary photos to get going. I have more photos and information if any one is interested. Maybe we can get a trend of 45 degree flybars for our AP ships.

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 10:11 AM  8 years agoPost 2
nooobs

rrElite Veteran

web

My Posts: All  Forum  Topic

...

PM  EMAIL  Attn:RR  Quote
09-02-2009 04:00 PM  8 years agoPost 3
ßeta

rrNovice

ToonTown

My Posts: All  Forum  Topic

I believe the 45 degree phasing of flybar to rotor will only work on the smaller micro helis due to their relatively low headspeed. Gyroscopic precession dictates that a force applied manifests 90 degrees later in the direction of rotation. But this seems to only "magically" happen above a certain headspeed. I believe that headpseed is a function of the RPM, number of blades, rotor diameter and mass of the head/blades. A multi, non-flybar head has some strange responses to control inputs prior to complete spoolup and proper head RPM. Due to the fact that gyroscopic precession has not yet taken effect. The smaller micro helis are I believe working outside the full force of gyrscopic precession and therefore can get away with 45 degree flybar.

My prediction is your controls will be out of phase. You might need to install an AP2000i, Helicommand, or Gyrobot and use either of those devices for their head phasing ability. It would be interesting to see if you could set the phasing properly with one of those devices and get more stability than a 90 degree flybar.

PM  EMAIL  Attn:RR  Quote
09-02-2009 05:54 PM  8 years agoPost 4
AceBird

rrElite Veteran

Utica, NY USA

My Posts: All  Forum  Topic

So my question is how come not more people are investigating this setup for aerial photography use.

Let's start a discussion here and may be I can learn more.
I would tend to believe it is just geometry. You may be decreasing control input by the cos. of 45 degrees which will make it feel soft. How are you measuring stability?
I believe the 45 degree phasing of flybar to rotor will only work on the smaller micro helis due to their relatively low headspeed.
Don’t smaller helis run higher headspeeds than larger ones?

Ace
What could be more fun?

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 06:00 PM  8 years agoPost 5
ßeta

rrNovice

ToonTown

My Posts: All  Forum  Topic

I guess headspeed alone was not the proper variable in my thoery of when gyroscopic precession kicks in. More correctly I'd guess it would be a function of the moment of inertia of the rotor system of which Micro helis have a much smaller value.

PM  EMAIL  Attn:RR  Quote
09-02-2009 07:24 PM  8 years agoPost 6
SeismicCWave

rrVeteran

Hilo, Hawaii

My Posts: All  Forum  Topic

From the first flight my initial reaction is that the phasing is off a little. Then after flying it for a little longer. I was wondering if the phasing is off in most other helicopter with 90 degree flybar setup.

I do have an AP 2000i on the Logo 10 for testing. So I dialed in some phasing adjustment. I put in the wrong value (positive 10 degrees) at first. Then when I put in negative values the helicopter reacted even more favorably. At minus 15 degree the helicopter will lift straight up off the pavement with absolutely no cyclic input from me. That is pretty rare since most helicopter I flew needed some cyclic input to correct for drift.

Acebird, I have no clue how to measure stability. It is all a gut feel. That is the reason why I couldn't definitively jump to any conclusion. My Logo 10 has been extremely stable with a normal 90 degree flybar setup so this is not adding too much to the stability. During my test flights there are absolutely no wind either so that made it hard to test an stability issue. Right now I am just glad that the mechanical portion of the setup has been resolved and I actually have a flying platform to do more tests.

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 07:37 PM  8 years agoPost 7
SeismicCWave

rrVeteran

Hilo, Hawaii

My Posts: All  Forum  Topic

Ros, I am not quite ready to lift a video camera in the air with this setup yet. It is still in the testing stage. I will after I get comfortable with the setup.

Beta, I think the setup can work in helicopter of different sizes and rotor head speed. I believe the major factor may be the softness/stiffness of the blades and teetering.

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 07:53 PM  8 years agoPost 8
jgoodsell

rrApprentice

Sherbrooke, Qc, Canada

My Posts: All  Forum  Topic

here is a related post

http://www.runryder.com/helicopter/t241309p1

I remembered seeing this a long time ago. I need to re read about it but I guess it's part of the info you are looking for !

Jeffrey

It seams that Gravity is worst around here !

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
09-02-2009 07:54 PM  8 years agoPost 9
GyroFreak

rrProfessor

Orlando Florida ...28N 81W

My Posts: All  Forum  Topic

Siesmic, Is the Flybar leading or lagging the main blade leading edge by 45 degrees ? Did you change only the flybar angel or the swash to flybar mixer also. Maybe I'm missing something here, but I am definatly interrested in the outcome of your experiment with details.
Thanks
Paul

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 07:58 PM  8 years agoPost 10
GyroFreak

rrProfessor

Orlando Florida ...28N 81W

My Posts: All  Forum  Topic

On reinspection of your pictures, it looks like flybar is leading the mains (clockwise rotation ?) and you acually changed the main rotor angel only, the flybar and mixer to swash stayed the same . Am i off base here ?

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 08:06 PM  8 years agoPost 11
SeismicCWave

rrVeteran

Hilo, Hawaii

My Posts: All  Forum  Topic

Jeffrey, that was an interesting thread. The flybar on the Diamont actually changes angle as it flaps up and down.

Gyrofreak, the flybar normally leads the main blade by 90 degree in a normal bird. I advanced the main blade 45 degrees closer to the flybar. I only changed the angle of the main blade with relation to the flybar. However I am using a Schluter Scout 60 head so the washout unit is already 45 degree offset. If you look at a normal 90 degree setup the washout unit generally runs parallel to the main blade grips. This one has the washout unit running perpendicular to the main blade grips.

I setup the linkages so that the main blade will respond at 90 degrees to my input still. That's the reason I had to swap the aileron and elevator servo input. My swash actually tilt from side to side when I want elevator input.

I will post more pictures after I test fly it this morning.

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 08:48 PM  8 years agoPost 12
SeismicCWave

rrVeteran

Hilo, Hawaii

My Posts: All  Forum  Topic

Test flight number 3. I reinforced the Bell/Hiller mixing arm so the blades won't flutter. Dialed in negative 22 degrees for phasing. Did some fast forward flight and it was tracking like a good 90 degree setup. No bad habits. The wind was up just a little. Blowing a slight breeze. Maybe 5 to 7 mph and the helicopter was hovering very stable. Is it any better than a 90 degree setup? I don't think so. It is worth all the trouble in making it work. Yes at least for me.

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 09:49 PM  8 years agoPost 13
bill the greek

rrKey Veteran

Greece

My Posts: All  Forum  Topic

Be carefull when you play/modified your heads.
Keep in mind there is no forgive in this rpms..

Bill

Vasilis

Nobody is Perfect but who want to be Nobody...

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 10:20 PM  8 years agoPost 14
SeismicCWave

rrVeteran

Hilo, Hawaii

My Posts: All  Forum  Topic

Bill, thank you. Yes, I am very careful and conservative when it comes to testing. So far it is no different then a normal 90 degree setup I have flown. It does seem a little more stable but there is no way I can quantify it.

PM  EMAIL  GALLERY  Attn:RR  Quote
09-02-2009 10:26 PM  8 years agoPost 15
ßeta

rrNovice

ToonTown

My Posts: All  Forum  Topic

a simple test might be to hover in a no wind condition (in a gym if possible) over a point on the ground. Then time how many seconds pass until it floats beyond a set radius on the ground (maybe 10M?)

Try both in and out of ground effect at least 10x and record the results. Do the same test with a standard 90 degree arrangement and record the results. Average each set of tests and compare numbers.

Another test might be to put the helicopter in a shallow bank or pitch from hover, perhaps 5 degrees. Time how long it takes the helicopter to travel 10M. Do the same with 45 and 90 flybar. Compare numbers.

Might make for a fun weekend project. We'd surely be interested in your numbers. And do use a 2nd person as spotter/timer.

PM  EMAIL  Attn:RR  Quote
09-02-2009 11:04 PM  8 years agoPost 16
copperclad

rrElite Veteran

NY

My Posts: All  Forum  Topic

Hi
i have been working on these heads for about a year , and i can tell you there is a pronounced improvement in stability , the best way to see what SeismicCWave and i are trying to say , is to get ahold of either a Hirobo Quark or one of the new E-flight mSR's and see for yourself

i first caught on to this a while ago after flying a Quark , and it is an amazing little heli , i knew that the stability i was seeing was probably due to the 45 degree head , so i bought a Century HBCP and started working on it in order to see if i could duplicate what i was seeing in a Quark , first i went over the head to fit everything to the nuts and had the head glassy smooth , i ran good servos and a 401 gyro , i played around with verious length flybars and flybar weights , and can honestly say the handling of the HBCP is nothing to write home about , so i went down into the shop and made a 45 degree yoke for it , and with changing this one part the difference is night and day , this is not something you would see in a video , but trust me , you would not miss it the first time you tried to fly it

with this first success i proceded to work my way up through larger and larger machines , and found out that this has nothing to do with size , it works as well or better on the larger machines

i do have a theory as to why and how this works , but it is only a theory , what i do know is that it does work , Hirobo came up with it ( to the best of my knowledge ) , and you are starting to see other companies following suit , like E-flite's mSR , and there are a few others

one last thing that i would like to mention , i am sorry , but i will not produce these for anyone , so please do not ask , they are a labor of love and were made to satisfy my own curiosity , i am glad to help anyone one trying to build their own , and will be happy to answer any questions i can , cheers

here are a few photos , and there are more photos in my gallery , enjoy

PM  EMAIL  GALLERY  Attn:RR  Quote
09-03-2009 06:55 PM  8 years agoPost 17
SeismicCWave

rrVeteran

Hilo, Hawaii

My Posts: All  Forum  Topic

Dana,

What's your theory? Please share.

PM  EMAIL  GALLERY  Attn:RR  Quote
09-04-2009 01:03 AM  8 years agoPost 18
AceBird

rrElite Veteran

Utica, NY USA

My Posts: All  Forum  Topic

this is not something you would see in a video ,
Well if you are talking about stability and not response you would see it in a video.
Another test might be to put the helicopter in a shallow bank or pitch from hover, perhaps 5 degrees.
I thought you were on to it but I guess not. You could measure the loss of elevation least being more stable. You could time how long it takes to hover if it ever does before you loose sight. Time or distance but the key is hover from a banked attitude, that's stability. No different than a heli with an APi or a helicommand.

If you are not talking about stability but rather response then I think it is geometry of the links (reduced throws).

Ace
What could be more fun?

PM  EMAIL  GALLERY  Attn:RR  Quote
09-04-2009 01:04 AM  8 years agoPost 19
copperclad

rrElite Veteran

NY

My Posts: All  Forum  Topic

Hi Hansen

in a nutshell , i think it is a hybrid between a standard bell hiller flybar and a stabilizer bar , if you look at the setup on a Quark it has elements of both , like a flybar it has bell hiller mixing and paddles that change their angle of attack dependent on the swash , but like a stabilizer bar it is heavily weighted and set 45 degrees off the spindle

with the setups i have done , i have been careful to keep everything standard with the exception of advancing the spindle , the relationship of the swash , washout , washout arms , mixing arms , and flybar are all left as stock , the only thing changed is the position of the spindle , i do not change phasing between the swash and the flybar

i did convert a E-sky Belt CP and i messed it up , i retarded the flybar instead of advancing the spindle, it flew about like a standard machine , i realized immediately that i had done something wrong , and it took me about a week to realize the mistake i had made

kindest regards

PM  EMAIL  GALLERY  Attn:RR  Quote
09-04-2009 01:56 AM  8 years agoPost 20
Stet

rrElite Veteran

Key Largo FL

My Posts: All  Forum  Topic

I think to have a valid comparison you would have to change the location of the swashplate upper ring links to match the 45 degree phase offset.

Otherwise, you are taking the 90 degree input point and applying it to the flybar in a 45 degree retarded position which will definately affect your phasing relationship. If the swash upper links were equally retarded, then I think that what you would have is simply a reduction of cyclic input with no phasing error. The paddle would have less time to move before its input would be realized at the blade grip.

On my XRB, the flybar is offset similarly, but it is not a paddle which drives the blade angle, rather it is a dead weight to dampen it's motion. And it is fixed pitch.

And don't be confused by the Robbe 45 degree offset, it has nothing to do with mixing, rather it is a design for more efficient mechanical control geometry. It is basically doing exactly the same thing as any other 90 degree setup.

For all that trouble, you could just go flybarless and be better off than flybar anyway.

keepin' it real

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 5 pages [ <<    <    ( 1 )     2      3     NEXT    >> ] 11052 views POST REPLY
Scorpion Power Scorpion Power
HelicopterAerial Photography and Video › 45 degree flybar setup
 Print TOPIC  Make Suggestion 

 10  Topic Subscribe

Monday, October 23 - 2:35 pm - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online