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Real Raptors . Mikado Modellhubschrauber . GrandRC

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Main Discussion > Best 3D rotorhead available today!
 
 
Wayne Mann
Senior Heliman
Location: United States of America

Hi Andy,

It looks like you could flip the grips with no problems, but it isn't something that you would want to do with a free floating axle as it would mess collective control up too much, expecially with medium to softer dampers. Example: when the helicopter ballons up in gusty winds the axle will compresses the dampers vertically, this vertical movement of the axle relative to the head block will pull more pitch into the blades aggravating the balloning problem. Even with a ball supporting the axle in the center you will still have some collective issues with trailing arms to some degree depending on how much angle is in the pushrods that goes from the bell mixer to the swash plate and the flybar carrier. Example: when the axle lags and compresses the dampers due to torque in the system any angle in those two pushrods will have an effect on the collective.

You may also need to flip the flybar pitch arms over on Augusto's head into the trailig position depending on how much delta and in what direction you are trying to run it. It doesn't look like he has any droop built into the arms so that wouldn't be a problem.

When a free floating axle head with leading pitch arms is set up with "0" delta, assuming that the dampers are not ridgid and there is some movement in the axle there is correcting delta in the rotorhead when the model is under power and flying. Example: under pressure from torque in the system when the axle lags in the head block and compresses the dampers this moves the blade pitch arm ball or bell mixer (in this case) off center creating a small amount of correcting delta. However the amount created from this is so small it would not be detectable by mere mortals...Curtis maybe.

Rotorheads like the ones on most Hirobo's which have a ball bearing pivot for the teeter in the head don't suffer from collective issues because of pushrod angles because the blade holders can not lead and lag like a free floating axle. However I have spent a lot of time with the off center teeter type heads like on Hirobo's and I do not care for these heads for contest work because they trim change it windy weather much worse than free floating axle heads. I can put massive amounts of uncorrecting delta in the Hirobo type of head and it will slow down the trim change problem, but even as good as I can make it, it's still much worse than axle heads. Flapping heads like on old Concept 30s and 60s are the same way. There is no way to stop or even minimizing trim changes do to wind.

I hope this helps.


Wayne Mann
03-08-2006 Over year old.
 
 
Augusto
rrAdvertiser
Location: San Diego, CA

Waynne,

This effect that you see as a collective issue on FAI when using that configuration is something we actually look for in 3D with moderation and it's what we call "POP". It's a collective sort of power steering effect that we like and look for when doing sudden stops and tic-tocs. We adjust it by selecting different harder dampener durometer combinations as well as a the center limiter carefully so it doesn't become an issue while doing fast passes or in gusty winds. It's certainly an interesting setup to try.

As you mentioned on the hirobo heads the center is held in place with a bearing and that is one of the reasons why it doesn't have any "POP" for 3D. One of the reasons why we have so many finely spaced delta positions is because it allows you to adjust all the different configurations and match for instance this dampening selected for the "POP" very precisely to the cyclics response for your flying style. Larger graduations on delta spacings adjustments instead of those finelly spaced ones will miss that "sweet spot" that you look for when adjusting for the perfect 3D feel.

Augusto.

Avant Aurora Ultimate
03-08-2006 Over year old.
 
 
KC
Elite Veteran
Location: WA

interesting thread! cool looking rotorhead

'why dont more people do competition and why does everyone do 3d?'

its simple,

you are promoting it to each other and expecting new blood to come to you.....take the show to new funflies and different regions.

And pull a Curtis, show you can rock with your heli and do the classics.

its like being the only heli guy at a plane field, they'll give you respect if you can fly a plane with them....

Then theres the cost of flying at a national or world level, you guys who do it know its a sacrafice to stay there as much as it was to get there.

anyone who has tried it will also know that.....competition is really exclusive.

bad thing? good thing? bad if you want to make it grow.

why more 3d pilots than f3c?...adrenaline. when you get the hang of extreme 3d the only other thing like it in r/c is flying fast...its all the same thing, moving fast or flying fast...fast is fun.

doing 3d to be noticed is one aspect of "3d", but so is artistic aerobatics, freestyle, etc.

you f3c guys know how much crap you get about being hovering fools, but its the same for 3d guys being "showoffs" or whatever.....hey we're all out to fly helis and have our ways to get that thrill.

the cool thing is that our styles can run together or go apart, theres room for more experimentation in the competition format as well.
03-08-2006 Over year old.
HOMEPAGE  
 
 
steve9534
Key Veteran
Location: yakima, wa.

Augusto

This is a friendly question. I am curious as to why having a floating axle and correcting delta will give more "POP", as you describe it, in the collective feel. Both theoretically should dampen the collective response as the axle moves in the head. First because the axle has some up and down movement and second because the up and down movement itself affects the collective input to blunt the response. The center pivoting heads behave as a solid head with respect to collective inputs and I don't know how to resolve what you've said about the collective feel with what I know of the theory. Thanks. steve.
03-08-2006 Over year old.
 
 
Augusto
rrAdvertiser
Location: San Diego, CA

Steve,

Because when you flip to trailing edge as they were mentioning above it reverses.

Augusto.

Avant Aurora Ultimate
03-08-2006 Over year old.
 
 
steve9534
Key Veteran
Location: yakima, wa.

Augusto

I'm sorry, but I don't understand the reply. I was referring to the head as it comes with the main blade actuating arms leading. The head as pictured has a number of possible settings for correcting delta, and I presumed that the delta setting you were referring to is correcting, as opposed to un-correcting. Thanks. steve.
03-08-2006 Over year old.
 
 
Augusto
rrAdvertiser
Location: San Diego, CA

The pop is not coming from the delta. I was referring to the question about trailing edge configurations and floating axles.

Augusto.

Avant Aurora Ultimate
03-08-2006 Over year old.
 
 
steve9534
Key Veteran
Location: yakima, wa.

Augusto

The delta offset will affect the collective response. If you put the main blade holders so that the actuating arms trail, there will be some uncorrecting delta effect on the collective response that would magnify any collective input. Is this what you're referring to? Thanks. steve.
03-08-2006 Over year old.
 
 
Wayne Mann
Senior Heliman
Location: United States of America

I was sent a PM and I would rather answer the question here. I was asked why I didn't think uncorrecting delta on a Hirobo type bearing pivoting type head would have the same effect as it does on a floating axle head to reduce trim changes in windy weather.

In an earlier post I said that the Hirobo type heads didn't stop trim changing no matter how much uncorrecting delta that I used. That was sorta the wrong answer or statement. What I should have said is that large amounts of uncorrecting (over 25mm) does help with trim changes, but it's a different kind of help. The delta only slow down the trim change or the response to the wind. If I hold the model sideways to the wind and hold it perfectly still with cyclics then let go of the cyclics it will trim change the same (total) amount with or without delta. The uncorrecting delta acts like expo. It makes the model respond to the wind in slow motion while gradually picking up speed. An axle head when set up right the delta actually reduces the (total) amount of trim change proportional to how much uncorrecting delta is used.

I think at this point that I should put a disclaimer in this thread. When using large amounts of uncorrecting delta (over 15mm) the rotorhead is very unstable at low rotor speeds when running up the model on the ground or in the air if you bleed the head speed down too low in an outo. However high flybar authority setting really add to this probem. However I have never done any testing with large amounts of uncorrecting delta with low flybar settings. So if you are wanting to experiment with this send me a PM and I will give you some basic guide lines for experimenting.

I hope this helps


Wayne Mann
03-08-2006 Over year old.
 
 
racingstripe
Veteran
Location: Sacramento, CA

Hi Steve,

What do you think of this...

Delta offset shouldn't affect collective response. It's whether the pitch inputs are leading or trailing that's relevent (in a floating axle head).

You can have correcting delta offset with trailing pitch arms, the control point would have to be outboard of the flap axis.

With that, I do see your point about leading pitch arms defeating 'POP'. It would make sense that you would want trailing pitch control arms for the 'POP' response.

andy-
03-08-2006 Over year old.
HOMEPAGE  
 
 
Augusto
rrAdvertiser
Location: San Diego, CA

Steve,

The delta differential will only act when there is a component of rotation around the center of the axle. If there is pure translational movement on the spindle up and down while still being horizontal such as when pure collective is applied then the amount of deflection is dependent on two things. First is how much it compresses both sides of the dampeners at the same time and in the same direction and second the distance between the ball links and the axle. This deflection on pure collective is not affected by what delta position you're at.

The way to adjust that response is by either limiting that translational movement with harder dampening or a by a combination of the harder dampening and flipping the mixing arm installation which in this head gives you an additional 5mm of radius that will lower the total blade angle of deflection for the same compression rate.

Once that's done you can then independently adjust the cyclics response which generates rotation around the center of the axle by adjusting the delta spacing.

Augusto.

Avant Aurora Ultimate
03-08-2006 Over year old.
 
 
Wayne Mann
Senior Heliman
Location: United States of America

Sorry I forgot to answer the question that was asked of me. I do not know why bearing pivoting heads like Hirobo's do not respond well to delta. I have a Kyosho head that is a floating axle with a ball bearing pivot and it responds just like the Hirobo heads. There is a lot of stability gains to be had by letting the axle lead and lag (mostly lag) some. I have some ideas as to why this is, but I can't prove any of them through any testing. All I know for sure is when you stop the axle from being able to load up against the dampers sideways you loose stability.

There is a head in Europe that has adjustable lead lag in the flybar, meaning you can advance or retard the flybar in relation to the main blades. I have never seen the guy that did this post what if any improvements this made in flight perforance. I wouldn't mind trying this, but I don't have the means to munipulate the flybar in this manner.

Andy, trailing pitch arms on an axle head with softer dampers makes the collective very jumpy in windy weather. This absolutely sucks for F3C type flying. With leading pitch arms when the axle is stressed and rises in the head block it acts like a correcting delta by pulling pitch out of the blades in an effort to help make the collective more stable. How soft the head is set up and the distance from the center of the axle to the pitch arm ball or center of the balls on the bell mixer if the mixer is on the pitch arm determine how much the correcting or uncorrecting effect is.

Strangely thought uncorrecting delta with metal blade grips is much more stable on cyclics with trailing pitch arms than with leading pitch arms. With tailing pitch arms I can make the cyclics so stable in windy weather it's scary, BUT (and I'll bet you knew a but was comming), the collective SUCKS.


Wayne Mann
03-08-2006 Over year old.
 
 
Augusto
rrAdvertiser
Location: San Diego, CA

LoL Waynne. I know what you mean. With soft dampening in that configuration the collective can get pretty nasty.

Regarding the metal and plastic issue that you mention. I was also mystified about it for some time until I figured out what the mechanism that makes them different was.

To illustrate the mechanism I found imagine you have an axle that is solid with no dampening whatsoever. In this case the dampening from a pure collective input will only come from the natural flexion of the plastic itself under the stress.

If you look at the geometry of the plastic grip you will find that in most plastic grips the grip arm starts near the outside close to the thrust bearing.

When flexing from the blade's torque this pitch arm is rotated and the ball end rotates towards a location that's opposite to where the blades are flexing to. In other words when the blades try to go up the ball at the end trys to go down as a reaction to the flexing of the grip.

Being the case that the ball at the end of the arm is fixed to the rod the bladegrip has no other way to react other than rotating and changing the blade's angle of attack. It actually increases the angle when going up for instance augmenting the collective effect.

The same mechanism acts both for cyclics and collective since the deflection happens when some torque is applied around the grip's bearings.

Augusto.

Avant Aurora Ultimate
03-08-2006 Over year old.
 
 
steve9534
Key Veteran
Location: yakima, wa.

Delta

Looking back on my responses, I realize I'm not using the term delta quite the same as the rest of you all. I meant the effect of any up and down movement of the blade holders, whether by pivoting on a fixed point as the Raptor or Hirobo heads do, or movement of a dampened axle and it's effect on the pitch of the blades. You all are correct that the collective effect is not dependent on the amount the main blade mixers or control balls are offset from center, but on whether the actuating arms lead or trail. Andy is correct that a floating axle head will have the collective inputs blunted somewhat if the control arms lead and the collective inputs will be similarly amplified if they trail. The amount will depend on the amount up and down movement of the axle and the distance from the center of the axle to the control input point, be it ball or mixer. A head with a solid pivot point like the Hirobo or Raptor heads will be unaffected. Conceptually, it seems easier for me to consider this as a form of delta input, but I see what you're saying that it's not really a correct use of the term. Part of the problem I've seen in previous discussions of this type is that we don't all understand the terms the same and I'm afraid I'm guilty this time. Any consensus on what you all want to call this? Steve.
03-09-2006 Over year old.
 
 
KC
Elite Veteran
Location: WA

wonder why heli competition isnt growing


when will the rotorhead be available for the real world?
03-09-2006 Over year old.
HOMEPAGE  
 
 
steve9534
Key Veteran
Location: yakima, wa.

KC

I enjoy these discussions a lot. It's big part of the hobby for me. I don't compete because I haven't got 40 hours a week to put into practicing, and even if I did, I'd still lose. No matter how much I practice, I'm still going to be 50 years old with 10 diopters of correction in my eyes, and I'll never be able to see whether the heli is perfectly centered over the cones and don't have the reflexes to correct it like some others do even if I could. Getting a heli to fly the very best it can and understanding why is a lot of fun. We're really fortunate to have the chance to talk with guys like Wayne and Augusto who've put so much time and thought into the hobby. I spent years racing motorcycles and the top guys would never give away their secrets like the heli guys are willing to do. Thanks again. steve.
03-09-2006 Over year old.
 
 
KC
Elite Veteran
Location: WA

I hear ya

I dont compete because I dont get why anyone would go to those lengths......I understand why but just don't get it.

Is it just me or are the f3c guys missing how the other 90% fly......their game is never going to grow if no one can understand it, let alone see it....

Pop musicians go on tour, top 3d pilots get around the country to all 4 corners....no f3c pilot of merit has ever been spotted in these waters

here I see Gordie Meade asking why f3c isnt growing... you being rhetorical? heh heh.

Anyways, I like the looks of this rotorhead and glad to know its out now.

Having tried some of Augustos other products, I feel he makes good stuff and it is good to see more stuff being made for 3d demands.

it would be great to see the two styles come together a little more often in competition, some variety.
03-09-2006 Over year old.
HOMEPAGE  
 
 
Wayne Mann
Senior Heliman
Location: United States of America

That's not true KC. Years ago when I was still at Miniature Timmy and myself used to go to the Puallop trade show. That is very beautiful country out there. I would love to take a trip on the motorcylce out there in the near future.


Wayne Mann
03-09-2006 Over year old.
 
 
seattle_helo
Key Veteran
Location: Washington State, USA

This discussion is fascinating. I enjoy attempting to truly understand what is going on with our machines and this kind of info from people who know what they are talking about is tremendous. Wayne, if you ever get out this way again please let us know. It would be great to meet you someday.

nick
03-09-2006 Over year old.
HOMEPAGE  
 
 
KC
Elite Veteran
Location: WA

Hi Wayne!

Puyallup is a good trade show. It has been set in February for atleast the last decade. The winds or the rain, not to mention the small size of the place for demos, makes it just a showcase for indoor flying though

our first big fun fly kicks off around May each year.

that leaves about 5 months out of the year to entice new blood into our ritual. the core of guys who fly through the whole winter are about 30-40 total that I can think of...and this is a 1.5 million person area for 50 miles around Seattle...small numbers for a big place.

we're mostly mentally unstable after that many winters....we need some pros out here!

our biggest flying venues since your last visit are now Snohomish and Brooks but they are set right in the middle of the contest schedule for either XFC, 3DM or f3c

it is a great place to live here, just expensive...the hobby does ok out here but we dont have much for heli hobby shops..hard place for them.

the other side of the state is totally different than side left of the mountains, a big desert of good dirt turned into farm land.

wheat fields all over the place, lots of places to fly...lots of great pilots on that side too.

do come on up someday!....name your flying climate, we got it
03-09-2006 Over year old.
HOMEPAGE  
 
 
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