Re: Flybar speculations... was Re: Large Scale turbine Jet Ranger at 3D masters

>> The system would simply try to maintain a position 90 degrees to
>> the axis of rotation, that being the rotor mast!
>
>The crux of the debate.
>
>Based upon your statement, I am going to speculate that what you are missing
>is that the AXIS of
>the flybar rotation is NOT the mast centerline.
>

If that's true, then you're right. I'm missing it completely because at this
point, I totally disagree with that statement.

To try to clarify this, I'm talking about mounting the rotor hub w/flybar to
the rotor mast and spin the darn thing. The flybar will then be going around
in circles with the spinning rotor mast. The flybars center, the teeter point,
will be centered on the rotor mast, the axis of rotation in this case. That's
the ONLY center of rotation that's relevant in this conversation. As I think
we've already agreed, the rotation of the flybar itself, IE: the cyclic
movements that would matter if the paddles were in place, are irrelevant in
this conversation.

>The MIDDLE of the bar is ON the mast CENTERLINE, but the AXIS of rotation of
>the bar and the
>AXIS of rotation of the mast are NOT the same (except when bar and mast are
>perfectly
>perpendicular)
>

Oops, I don't think so. The flybars "middle", the hinge point on which it
teeters up and down, being mounted on the mast centerline, IS it's axis of
rotation when it's spinning with the rotor mast. Just because the flybar is
not in a plane, 90 degrees to the rotor mast at a given point in time, "does
not" mean that the axis of rotation is different and that's why ti will try to
reestablish a position, 90 degrees to the rotor mast.

>The axis of rotation of the bar is defined by whatever plane the BAR is
>spinning in . . . which
>may or may not be perpendicular to the mast.
>
I don't see how you're coming up with that.

<pause to think about light that just came on! ;-) >

Oh, wait a minute. Let's see if I'm getting this right. You're contention is
that the axis of rotation is "always" 90 degrees to the plane or rotation.
"So", if the flybar isn't 90 degrees to the rotor mast, then it's axis of
rotation will not be parallel to the rotor mast and I think, you're saying that
it will want to stay that way. If the flybar were totally independant of the
rotor mast and hub, I'd agree with that but it's not. The flybar's teeter
hinge is solidly tied to the axis of rotation of the rotor mast, via the rotor
hub. It is, therefore, influenced "by" the axis of rotation of the rotor mast.
If the flybar isn't 90 degrees to the rotor mast, then it's axis of rotation
(as I think you're defining it) is wobbling in space relative to the axis of
rotation of the mast and it will not like that. It's natural preference will
be to line back up with the rotor mast and that will put the flybar back into
an orientation of 90 degrees to the rotor mast.

>Centrifugal force is always perpendicular to the axis of rotation of any
>mass . . at least so I
>was taught. If you accept that as fact,

I do!

then you must concede that the
>centrifugal force exerted
>by the bar will attempt to pull the end of the bar exactly 90 degrees from
>the AXIS of rotation
>of the BAR itself . . not to be confused with the CENTER of rotation or
>mass.
>
Well, because the two (flybar and rotor mast) are tied to each other, the
center of rotation and the flybars axis of rotation will want to be the same,
thus establishing (or at least trying to) that position, 90 degrees to the
rotor mast.

>Another way to state this is to imagine the mast vertical and the bar tracing
>a perfectly
>horizontal plane. Incline the mast 10 degrees from vertical. Centrifugal
>force on the bar does
>NOT change unless it's axis changes. The bar (gyroscope) axis is still
>vertical where the mast
>axis is not 10 degrees from vertical.
>

I totally agree with this IF the mast and flybar were completely independant of
each other. Problem is, they're not! I refer back to what I stated above.

>Your contention the centrifugal force will pull the bar 90 degrees from a
>rotation axis is
>absolutely correct . . . you're just looking at the wrong axis
>
>Just to confuse things a little further, centrifugal force and gyroscopic
>force are different
>animals . . . 'G' forces are centrifugal, but there is no gyroscopic effect
>to speak of.
>

I'd agree with that in a free flying mass. Example, a fixed wing aircraft in a
turn. The aircraft will experience centrifugal force but no gyroscopic effect.

>The solid armature of an actual gyroscope contains centrifugal force, but
>that force has nothing
>to do with the gyroscopic function.

Oh boy! <BG> "That's" an entirely different discussion. Centrifugal force
may be "different" from gyroscopic function but to say they have nothing to do
with each other is incorrect.

Here's how I look at it. We all know the law of nature that states; "Any
object, set in motion, will tend to remain in motion and it will tend to
"TRAVEL IN A STRAIGHT LINE." For the purposes of what I'm about to say, it's
the "travel in a straight line" part that's important.

If a mass is traveling through space at 100 mph, it will maintain that 100 mph
and it will (absent any gravitational forces) continue to infinity in a
STRAIGHT LINE at 100 mph.

Now, let's tether that mass to a fixed point so that it's now traveling
"around" that point in a circle at 100 mph. The point is now the axis of
rotation. The mass is also now experiencing centrifugal force because it's
trying to go in a straight line but it can't, it's being restrained to that
central point. As a result, the "straight line" that it's experiencing is the
"plane of rotation" that it is established in and it will not want to deviate
from that plane of rotation.

Gyroscopic function comes into play if a force is applied that tries to change
the plane of rotation.

Getting back to our free flying mass in space for a moment. If we introduce a
gravitational force to the equation, the mass will start to turn in the
direction of that gravity. The amount of turn will be dictated by a balance of
the masses forward inertia and the strength of the gravitational pull. If the
inertia is stronger, the mass will see a small turn and then break free. If
they balance, the mass will enter orbit of the gravitational point, and if the
gravity is stronger, the mass with spiral in to impact.

On our gyroscope, because the mass has forward inertia along the plane of
rotation, it tries to maintain that plane of rotation. A force applied to
change that plane is reacted to somewhere up to 90 degrees along the plane, in
the direction of rotation. That's why a helicopters cyclic commands are
applied 90 degrees "ahead" of the point where we really want the rotor system
to tilt.

What I'm trying to say in this long winded explination is that, while I agree
that centrufugal force and gyroscopic function are seperate things, they ARE
related to each other. While you can have centrifugal force without gyroscopic
function, you can't have gyroscopic function without centrifugal force.

FWIW,
Fly Safe,
Steve R.

> in circles with the spinning rotor mast. The flybars center, the teeter point,
> will be centered on the rotor mast, the axis of rotation in this case. That's
> the ONLY center of rotation that's relevant in this conversation.

I'm convinced that you (and others) are mixing "center" and "axis".

Center is a point, axis is a line. There is no such thing as perpedicular to a point.

PLug that into your thinking and see if you don't get a different perspective.

If you have a rubber ball floating in a swimming pool and you place your finger on top and pull
towards you, it's axis of rotation goes from your left to right. If you were to place your
finger on top and pull sideways, the axis of rotation would go from behind you to in front of
you. IN each case, the center of rotation is the same, but the axis is very different.

Both centrifugal and gyroscopic forces are relative to rotation AXIS . . . i.e. a line in space,
not a point.

If the flybar is tettered at all, then it is out of perpendicular to the mast AXIS (centerline
in our example), then it's own AXIS (perpendicular to the plane of the bar) will be different.

Incidentally, it would not be wobbling, just rotating about it's own AXIS.


> Oh, wait a minute. Let's see if I'm getting this right. You're contention is
> that the axis of rotation is "always" 90 degrees to the plane or rotation.

Yes.

> "So", if the flybar isn't 90 degrees to the rotor mast, then it's axis of
> rotation will not be parallel to the rotor mast and I think, you're saying that
> it will want to stay that way.

Provided it is spinning, yes.

> If the flybar were totally independant of the
> rotor mast and hub, I'd agree with that but it's not. The flybar's teeter
> hinge is solidly tied to the axis of rotation of the rotor mast, via the rotor
> hub.

Here again, I thing you are considering a point as if it were an axis. The bar ans mast are only
'solidly' connected at a single point. They are NOT solidly connected by AXIS. The hinge alows
the rotation axis of the bar abnd the mast to deviate from each other.

The condition is similar to what happens in an automotive U-joint or CV joint. Both of these
mechanisms transfer rotational power through a point while allowing the axis of rotation to be
different on each side of that point.

In fact, it may be useful to understanding the concepts if one were to mentally cut away the
mast above the flybar and consider the hinge to be an actual U-joint, which is in fact what is.


> rotation of the mast and it will not like that. It's natural preference will
> be to line back up with the rotor mast and that will put the flybar back into
> an orientation of 90 degrees to the rotor mast.
>

Well here we come full circle. If you can let go of the natural fixation on 'point' you may see
that there is no 'natural preference' for the bar to spin on the same axis as the mast so long
as there is no connection between those axis.

The bearing friction provides a very small connection . . at 30 to 50 seconds response time,
obviously not quite enough . . . .and the physical dampers (mechanical on a real heli,
aerodynamic on our models) are needed to force the bar to follow the mast.

> What you guys are saying it totally over my head, but it seems pretty
> obvious to me that if you spin the rotor head with the flybar paddles
> removed, the flybar will move to, and hold itself at 90 degrees to the main
> shaft.

Were that true, then it begs two questions:

1) If the bar naturally wants to follow the mast, how does it provide any stabilization at all?

2) What are those paddles for?

Steve Simpson wrote:
>> What you guys are saying it totally over my head, but it seems pretty
>> obvious to me that if you spin the rotor head with the flybar paddles
>> removed, the flybar will move to, and hold itself at 90 degrees to
>> the main
>> shaft.
>
> Were that true, then it begs two questions:
>
> 1) If the bar naturally wants to follow the mast, how does it provide
> any stabilization at all?
>
> 2) What are those paddles for?

shall I remove blades & flybar paddles from my Sceadu and film it to stick
on the web? Perhaps you're right but my instinct tells me not. My helis not
good for anything else so I might as well..

"Carl Farrington" <carl@000compsup000.net> wrote in message
news:bh9d53$ri$1$8302bc10@news.demon.co.uk...
> Steve Simpson wrote:
> >> What you guys are saying it totally over my head, but it seems pretty
> >> obvious to me that if you spin the rotor head with the flybar paddles
> >> removed, the flybar will move to, and hold itself at 90 degrees to
> >> the main
> >> shaft.
> >
> > Were that true, then it begs two questions:
> >
> > 1) If the bar naturally wants to follow the mast, how does it provide
> > any stabilization at all?
> >
> > 2) What are those paddles for?
>
> shall I remove blades & flybar paddles from my Sceadu and film it to stick
> on the web? Perhaps you're right but my instinct tells me not. My helis
not
> good for anything else so I might as well..

Give me a ring first Carl. I'll hold the camera or I'll fly the heli, I
don't mind which.



--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk

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Beav wrote:
> "Carl Farrington" <carl@000compsup000.net> wrote in message
> news:bh9d53$ri$1$8302bc10@news.demon.co.uk...
>> Steve Simpson wrote:
>>>> What you guys are saying it totally over my head, but it seems
>>>> pretty obvious to me that if you spin the rotor head with the
>>>> flybar paddles removed, the flybar will move to, and hold itself
>>>> at 90 degrees to
>>>> the main
>>>> shaft.
>>>
>>> Were that true, then it begs two questions:
>>>
>>> 1) If the bar naturally wants to follow the mast, how does it
>>> provide any stabilization at all?
>>>
>>> 2) What are those paddles for?
>>
>> shall I remove blades & flybar paddles from my Sceadu and film it to
>> stick on the web? Perhaps you're right but my instinct tells me not.
>> My helis not good for anything else so I might as well..
>
> Give me a ring first Carl. I'll hold the camera or I'll fly the heli,
> I don't mind which.

How can you fly it without blades? I was thinking just getting the rotor
spinning to see if the flybar aligns on a plane 90 degrees to the main shaft
(which is what I reckon will happen), or if it maintains it's position where
it's put.

Am I totally missing the point?

<<>
> Give me a ring first Carl. I'll hold the camera or I'll fly the heli,
> I don't mind which.

How can you fly it without blades? I was thinking just getting the rotor
spinning to see if the flybar aligns on a plane 90 degrees to the main shaft
(which is what I reckon will happen), or if it maintains it's position where
it's put.

Am I totally missing the point?


>>>>>>>>>>


Beavis don't need no stinkin blades to fly a
helicopter.........................

"Carl Farrington" <carl@000compsup000.net> wrote in message
news:bhblq3$8s2$1$8302bc10@news.demon.co.uk...
> Beav wrote:
> > "Carl Farrington" <carl@000compsup000.net> wrote in message
> > news:bh9d53$ri$1$8302bc10@news.demon.co.uk...
> >> Steve Simpson wrote:
> >>>> What you guys are saying it totally over my head, but it seems
> >>>> pretty obvious to me that if you spin the rotor head with the
> >>>> flybar paddles removed, the flybar will move to, and hold itself
> >>>> at 90 degrees to
> >>>> the main
> >>>> shaft.
> >>>
> >>> Were that true, then it begs two questions:
> >>>
> >>> 1) If the bar naturally wants to follow the mast, how does it
> >>> provide any stabilization at all?
> >>>
> >>> 2) What are those paddles for?
> >>
> >> shall I remove blades & flybar paddles from my Sceadu and film it to
> >> stick on the web? Perhaps you're right but my instinct tells me not.
> >> My helis not good for anything else so I might as well..
> >
> > Give me a ring first Carl. I'll hold the camera or I'll fly the heli,
> > I don't mind which.
>
> How can you fly it without blades?

Oh we'll leave THEM on so that the experiment has some real value. If the
heli flies Ok, WE'LL know it does and if not, YOU'LL know it doesn't :-))

I was thinking just getting the rotor
> spinning to see if the flybar aligns on a plane 90 degrees to the main
shaft
> (which is what I reckon will happen), or if it maintains it's position
where
> it's put.

And how are you going to subsequently move the heli to a new position? Don't
tell me you're going to rock it around wi' t'boom:-))

Get it up in t'air without them paddles and then it's discussion over:-))


>
> Am I totally missing the point?

Probably, just like me.


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk
>
>

> > Give me a ring first Carl. I'll hold the camera or I'll fly the heli,
> > I don't mind which.
>
> How can you fly it without blades? I was thinking just getting the rotor
> spinning to see if the flybar aligns on a plane 90 degrees to the main shaft
> (which is what I reckon will happen), or if it maintains it's position where
> it's put.


No cheating, Carl! The original question was about the handling of the heli in flight.

To answer the question, you need to see if the bar will FOLLOW the mast with no paddles or
links, so you must hover and then tilt the mast with cyclic input.

If I am wrong, the bar will follow the mast via some physics unknown to me and you will be able
to fly around fine, albeit a bit sluggish. If I am right, . . . . well, you didn't like that
heli so much anyway . . . . it will all boil down to how well the bar resists bending once it
runs out of hinge travel. It is does bend, the resulting out of balance condition may make for
an interesting landing . . . . . particularly with no stabilization.

For the record, I was only kidding about trying this out with an actual model heli. I think the
result could be very bad and do not recommend you try it, . . . . but if you insist, I will
provide the web space to post the video.

> How can you fly it without blades? I was thinking just getting the rotor
> spinning to see if the flybar aligns on a plane 90 degrees to the main shaft
> (which is what I reckon will happen), or if it maintains it's position where
> it's put.


Without bladers there will be no downwash from the
blades while hovering,this might have some effect on the flybar.

"Courseyauto" <courseyauto@aol.com> wrote in message
news:20030813123457.21906.00000739@mb-m07.aol.com...
>
> > How can you fly it without blades? I was thinking just getting the rotor
> > spinning to see if the flybar aligns on a plane 90 degrees to the main
shaft
> > (which is what I reckon will happen), or if it maintains it's position
where
> > it's put.
>
>
> Without bladers there will be no downwash from the
> blades while hovering,this might have some effect on the flybar.

What about all those little heli's where the flybar is ABOVE the blades
Doug? Or don't they count? :-)


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk

> Without bladers there will be no downwash from the
> blades while hovering,this might have some effect on the flybar.

What about all those little heli's where the flybar is ABOVE the blades
Doug? Or don't they count? :-)

>>>>>

Only in an inverted hover.............

"Courseyauto" <courseyauto@aol.com> wrote in message
news:20030813154645.21906.00000744@mb-m07.aol.com...
>
> > Without bladers there will be no downwash from
the
> > blades while hovering,this might have some effect on the flybar.
>
> What about all those little heli's where the flybar is ABOVE the blades
> Doug? Or don't they count? :-)
>
> >>>>>
>
> Only in an inverted hover.............

Well we'll have to wait and see if someone can get a paddle-less heli
inverted to see if that's true:-)


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk

Well we'll have to wait and see if someone can get a paddle-less heli
inverted to see if that's true:-)


--
Beav
>>>

I have flown my xcells numerous times with the flybar lock still on,to be
honest i couldn't tell a lot of difference. I know what your going to say but
these were some 20gm sab paddles so they were fairly quick when they were
enabled without the lock in place. DOUG

"Courseyauto" <courseyauto@aol.com> wrote in message
news:20030813195125.28318.00000395@mb-m10.aol.com...
>
> Well we'll have to wait and see if someone can get a paddle-less heli
> inverted to see if that's true:-)
>
>
> --
> Beav
> >>>
>
> I have flown my xcells numerous times with the flybar lock still on,to be
> honest i couldn't tell a lot of difference.

Yeah, but that's not the same as simply removing the paddles, and the times
I've flown with a lock on, I've been VERY aware that the heli isn't behaving
as normal. Usually because the heli won't manoeuvre nearly half as well as
it does with the lock in the box where it belongs.

I know what your going to say but
> these were some 20gm sab paddles so they were fairly quick when they were
> enabled without the lock in place

If you couldn't tell much difference, SOMETHING about your heli is't working
properly.



--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk