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HelicopterAerial Photography and Video › 45 degree flybar setup
09-07-2009 12:20 AM  8 years agoPost 41
copperclad

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. I am not sure if I agree since there is no direct linkage to the main grip
Hi Hansen
i looked at it the same way , i heard every one referring to it as bell hiller , and i was looking at the linkage thinking " no way " , of coarse as smooth as it flies , and after seeing the link i posted , and there is Horizon calling it bell hiller

http://www.horizonhobby.com/Product...ProdID=EFLH3080

i am on vacation so i don't have another machine in front of me to compare , but i am going to give it a good going over when i can sit it next to some of my other helis , whatever they are onto with this new linkage is very interesting and well worth studying a bit more

i am tempted to scale it up a bit and add collective pitch , it would make a good project , cheers

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09-07-2009 04:13 AM  8 years agoPost 42
SeismicCWave

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>> there is Horizon calling it bell hiller<<

LOL Horizon is a marketing machine. They will call it what ever suits their purpose to sell helis.

The reason is probably because Bell/Hiller is used so much in the layman's realm that it is bound to be misused.

Basically we have been using a Bell/Hiller hybrid in our models. Bell first designed the head with a flybar and no paddles. Look at the Bell 47 and the UH-1. They are gyro stabilizers. So to get the blades going they have to link the blade to the swash. The flybar is a mechanical stabilizer. So the Hirobo XRB and the Blade CX has a Bell stablizer on the top rotor.

Hiller rotor head is a flybar with weights and paddles. The swash is linked to the flybar the flybar moves then control the main blade. The flybar is not designed as a stabilizer but a power steering. The human only move a lighter flybar with paddles and that in turn control the heavier main blades.

So the Blade CX has no Hiller control because the top rotor is not linked to the swash.

Anything else we fly is a hybrid of Bell flybar stabilizer and Hiller paddle control. We mix them together with the Bell/Hiller mixing arm either on the main blade grip or the flybar cage.

I think you may have scaled it up by making your Predator head.

I just test flew my Trex 450. This time with a set of flybar weight. I believe the 45 degree angle flybar can only enhance stability when it acts as a mechanical gyro. It flew much better. I also took it through some aerobatics and it can loop and roll and sustain an inverted flight with no ill effect.

I am just waiting for more wind to test the stability now.

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09-07-2009 01:43 PM  8 years agoPost 43
copperclad

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I just test flew my Trex 450. This time with a set of flybar weight. I believe the 45 degree angle flybar can only enhance stability when it acts as a mechanical gyro. It flew much better. I also took it through some aerobatics and it can loop and roll and sustain an inverted flight with no ill effect.
Hi Hansen

i have been adding weights to all of mine , the Quark flybar paddles have quite a weight in them and it is hard to tell but the mSR seems weighted also

great breakdown on bell hiller , and you are probably right , that marketing will say anything , my thinking is to power up the mSR sitting next to a straight bell hiller head , and compare the two action for action , this will help me wrap my mind around the new linkage on the mSR , and see where it is different

i have heard conversations about positive and negative stability , where positive stability is like placing a marble in a large bowl , the marble will center itself in the bottom of the bowl

the coaxials fall into this category , at any point if you release the sticks , a coaxial will go back into a hover , and most can barely be forced past anything but a hover

negative stability is like placing the marble on top of a large ball and it takes constant corrections to keep it there , or it will roll off

of coarse , standard RC helis fall into this group , that is why it is so hard to learn , let go of the sticks for even a few seconds and you are looking at a re kit

talking along these lines i see the 45 degree head might be described as a large ball with a small bowl shaped depression in the top , you have a very stable hover , but once you break out into FFF the handling is closer to a standard setup

i saw a mSR video on youtube , hovers right out of the box , two or three clicks of trim and it is doing 20 second hands off hovers , and is looking like it would do a minute pretty easy , but push a little forward and it will really get to going , it rips around quite well for a FP heli

cheers

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09-07-2009 09:25 PM  8 years agoPost 44
SeismicCWave

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>>i have heard conversations about positive and negative stability<<

That's aero engineers' term for flying stability. Our helicopter can never be described as positively stable unless it has some electronic stability augmentation.

Your ball on a ball description is very accurate. Some times I look at it as balancing a broom stick with your finger.

I think the entry level coaxial helicopters (not the full scale or some bigger models) are mostly neutrally stable. It may return to hover but it takes a while.

The mSR is really cool. I got one for my birthday. That's what started this whole 45 degree flybar investigation I am doing.

Now the next investigation is if there is a difference in the 45 degree flybar setup when the Bell/Hiller mixing arm is located on the main grip or the flybar cage.

I am trying like hell to get my aeronautical engineer friend to be interested in helping me with this. So far he is not biting.

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09-08-2009 12:33 AM  8 years agoPost 45
copperclad

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That's what started this whole 45 degree flybar investigation I am doing.
Hi Hansen
it is an amazing little machine , they are incredibly stable , it may look like a simple head design , but i am thinking a lot of work went into it , kindest regards

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09-08-2009 12:46 AM  8 years agoPost 46
AceBird

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of coarse , standard RC helis fall into this group , that is why it is so hard to learn , let go of the sticks for even a few seconds and you are looking at a re kit
If you lower the headspeed and add pitch the heli will become more stable like full scale.

Ace
What could be more fun?

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09-08-2009 02:19 AM  8 years agoPost 47
SeismicCWave

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>>it is an amazing little machine , they are incredibly stable , it may look like a simple head design , but i am thinking a lot of work went into it <<

Yes, at first the Hirobo engineers really did a great job coming up with something that flew so well with a tether. Then the Taiwanese engineers picked up on the idea and started all the clones. The Asian engineers working with Horizon went one up on Hirobo with the Blade CX and they refined the concept to the mCX and now the mSR. I was real skeptical at first about how something so small can fly well. Having my bitter pill from the Piccolo days. I really wonder what if we had a 45 degree flybar with the Piccolo.

>>If you lower the headspeed and add pitch the heli will become more stable like full scale.<<

I don't think so Ace. I bet you there is an optimum head speed for every size helicopter. Too slow and you get the dreaded wobble. The full scale helis are dealing with a much larger Reynolds number than we can. OTOH as you increase rotor head diameter you can slow the head speed down. Stability is a function of rotor diameter more than head speed. Sometimes upping the head speed makes a small heli more stable.

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09-08-2009 02:24 PM  8 years agoPost 48
copperclad

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Yes, at first the Hirobo engineers really did a great job coming up with something that flew so well with a tether. Then the Taiwanese engineers picked up on the idea and started all the clones. The Asian engineers working with Horizon went one up on Hirobo with the Blade CX and they refined the concept to the mCX and now the mSR. I was real skeptical at first about how something so small can fly well. Having my bitter pill from the Piccolo days. I really wonder what if we had a 45 degree flybar with the Piccolo.
Hi Hansen

YES , i just wanted to add , a few years ago , Hirobo came out with the Quark , it is a single rotor FP , and is the first machine i had seen with the 45 degree head , it is larger than the mSR but was a total mind blower at the time , i had never seen anything as small , that was anywhere near as smooth , they were a bit spendy and never seemed to make it to the mainstream , but i see it as Hirobo has come up with some really innovative products , and it is great to see the industry following suit

these little machines seem to be breaking some ground , in the mechanical design of the heads , and for such small airframes are pretty incredible

cheers

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09-08-2009 06:47 PM  8 years agoPost 49
SeismicCWave

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>>Hirobo came out with the Quark , it is a single rotor FP<<

Seems like there are some really good Hirobo engineers. I have to look closer at the Quark. You are right about Hirobo being more expensive. Even their XRB was $100 more expensive than the others.

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09-08-2009 10:12 PM  8 years agoPost 50
copperclad

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Hi Hansen

here are a few photos of my Quark , it is an interesting design , more components to the head than the mSR has , it looks to be bell hiller with a mixing lever , and one control rod going down to the washout , and another going down to the top of the swash , cheers

.

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09-08-2009 10:44 PM  8 years agoPost 51
SeismicCWave

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>>it looks to be bell hiller with a mixing lever , and one control rod going down to the washout <<

It sure does look like a Bell/Hiller mixer going to the blade. That looked more like what we normally fly except only fixed pitch.

I would like to get inside the head of one of these Hirobo engineers.

Oh never mind I can't understand Japanese.

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09-08-2009 10:48 PM  8 years agoPost 52
copperclad

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Hi Hansen
the Hirobo seems to be made from a high quality nylon , and it is pretty much unbreakable , you pay more , but they do produce a very good product , i am glad other companies are looking at the 45 degree setup

i just got back from my trip , and will have some time to look over the mSR head , cheers

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09-08-2009 11:05 PM  8 years agoPost 53
SeismicCWave

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>>i just got back from my trip , and will have some time to look over the mSR head <<

Now, that's dangerous. Pretty soon you will be making 45 degree heads again.

I am going to look into converting another head soon. I think it will probably be a Trex 600 or 700 head.

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09-08-2009 11:18 PM  8 years agoPost 54
copperclad

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Now, that's dangerous. Pretty soon you will be making 45 degree heads again.
Hi Hansen
LOL , you have read my mind exactly , i am pretty keen on making an exact mSR head out of something closer to a 300 or 400 , i want to stick with fixed pitch for the first one , but am very interested if it will translate into a 450 CP , , i will post photos , cheers

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09-09-2009 12:28 AM  8 years agoPost 55
SeismicCWave

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>> you have read my mind exactly , i am pretty keen on making an exact mSR head out of something closer to a 300 or 400<<

Wouldn't it be better to make one exactly like the Quark. I believe that is easier to translate into collective pitch afterwards.

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09-09-2009 01:09 AM  8 years agoPost 56
copperclad

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Hi Hansen
i have a Century Hummingbird FP , and i am thinking i can just run a longer main shaft , and remake the flybar and linkage setup , to convert it to a mSR on steroids , i find that even with baby steps , something valuable is learned , what has my interest is how simple the mSR design looks , cheers

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09-09-2009 01:41 AM  8 years agoPost 57
SeismicCWave

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>> remake the flybar and linkage setup , to convert it to a mSR on steroids<<

That makes sense. Keep me posted with pictures. Don't forget a heavy flybar weight.

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09-10-2009 05:13 PM  8 years agoPost 58
copperclad

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Hi Hansen
just posting in a few photos , i have to pick up a couple of 2-56 linkage rods for the flybar , but i wanted to show progress so far

the grey plastic piece is the flybar hub , in the second photo you can see the pilot hole for the flybar

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09-10-2009 07:33 PM  8 years agoPost 59
SeismicCWave

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Looks like a nice simple modification. This is exciting. Let's see how it flies.

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09-10-2009 08:11 PM  8 years agoPost 60
copperclad

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Hi Hansen
one thing nice about the HBFP is that it doesn't have the fixed blade grip like most FP's , with the independent blade grips , it would be easy to go to a 3 servo ECCPM swash for pitch changes

from what i am able to see so far , if the swash is help with three servos , and allowed to slide up and down with pitch input , the flybar hub will be happy to follow the swash , as the hub slides up and down the main shaft the blade grips will change pitch

i was worried that once it was using two blade grips instead of one , that the pair would be able to just flop around , but now that the system is together i can see that there is little to no play in the grips , and CP looks very feasible

i have what i need to finish , if i am able to finish up tonight , i might have time tomorrow to try it , cheers

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HelicopterAerial Photography and Video › 45 degree flybar setup
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