Getting rid of the flybar

Getting rid of the flybar

Post by Boguslaw Gajdeczk » Sun, 15 Nov 1998 04:00:00



Hi Everybody,

  This is to hopefully trigger some interesting
discussion, as this group has  been lately
infested with questions and answers like
 " are Futaba transmitters better than JR ?"
I remember much more in-depth discussions
here. I do not mean to offend anybody, however.

    The question is what would be wrong with replacing
the flybar with all the mechanical parts that go
with it (seesaw, mixing levers, etc.) with two
gyroscopes polarized 90 deg. Well, perhaps stronger
and faster (by how much ?) servos would be needed.
Mixing the control inputs can be done electronically
much easier than having it done mechanically (as with
the flybar arrangement). In the age of solid state
electronics is the flybar a dinosaur ?

  PS.
       I just have on my desk an article from
August, 1948 issue of Aeronautical Engineering Review
introducing the invention of the flybar (Stanley Hiller).
There is a picture of a fellow hovering his little
open***pit heli about 1 ft. over the ground
totally hands-off !  

Regards, Boggie

--
Dr. Boguslaw Gajdeczko
Engine Combustion Lab.
Princeton University

 
 
 

Getting rid of the flybar

Post by Boguslaw Gajdeczk » Sun, 15 Nov 1998 04:00:00


Hi Everybody,

  This is to hopefully trigger some interesting
discussion, as this group has  been lately
infested with questions and answers like
 " are Futaba transmitters better than JR ?"
I remember much more in-depth discussions
here. I do not mean to offend anybody, however.

    The question is what would be wrong with replacing
the flybar with all the mechanical parts that go
with it (seesaw, mixing levers, etc.) with two
gyroscopes polarized 90 deg. Well, perhaps stronger
and faster (by how much ?) servos would be needed.
Mixing the control inputs can be done electronically
much easier than having it done mechanically (as with
the flybar arrangement). In the age of solid state
electronics is the flybar a dinosaur ?

  PS.
       I just have on my desk an article from
August, 1948 issue of Aeronautical Engineering Review
introducing the invention of the flybar (Stanley Hiller).
There is a picture of a fellow hovering his little
open***pit heli about 1 ft. over the ground
totally hands-off !  

Regards, Boggie

--
Dr. Boguslaw Gajdeczko
Engine Combustion Lab.
Princeton University


 
 
 

Getting rid of the flybar

Post by Donovan R. Do » Wed, 18 Nov 1998 04:00:00


Morning Boggie
        Way back when there was a model helicopter manufactured in the USA
called the Horizon, without a flybar. A friend of mine insisted I have a
flight with it. It flew well. The servos were relatively weak back them
compared to what is available today.
        I had and flew a Schulter flybar-less Heliboy. It was very stable but
not that suitable for aerobatics.
Cheers
Don Dow
Quote:

> Hi Everybody,

>   This is to hopefully trigger some interesting
> discussion, as this group has  been lately
> infested with questions and answers like
>  " are Futaba transmitters better than JR ?"
> I remember much more in-depth discussions
> here. I do not mean to offend anybody, however.

>     The question is what would be wrong with replacing
> the flybar with all the mechanical parts that go
> with it (seesaw, mixing levers, etc.) with two
> gyroscopes polarized 90 deg. Well, perhaps stronger
> and faster (by how much ?) servos would be needed.
> Mixing the control inputs can be done electronically
> much easier than having it done mechanically (as with
> the flybar arrangement). In the age of solid state
> electronics is the flybar a dinosaur ?

>   PS.
>        I just have on my desk an article from
> August, 1948 issue of Aeronautical Engineering Review
> introducing the invention of the flybar (Stanley Hiller).
> There is a picture of a fellow hovering his little
> open***pit heli about 1 ft. over the ground
> totally hands-off !

> Regards, Boggie

> --
> Dr. Boguslaw Gajdeczko
> Engine Combustion Lab.
> Princeton University


 
 
 

Getting rid of the flybar

Post by Stefan Kiritzo » Wed, 18 Nov 1998 04:00:00


I have hovered my Intrepid gas with locked fly bar. If hovers fine,
but I was afraid to try FF or anything more than hover.
To reduce the weight, I tried to hover my Concept EP without
fly bar and it was totally unstable and I was not able to
keep it even a second in hover. After redesigning the controls
for total slop free (including my own carbon fiber frames
for EP) I was able to hover the heli but it was like
kissing a tiger - dangerous but no fun at all. (Well,
Concept EP is hardly a tiger, it is more like mouse :), but
anyway, with the light inexpensive gyros I think that this
is a good idea to experiment.

BTW, my CF frame for EP weights 1/4 of the original body set.
(about 120 grams less)

Stefan

Quote:

> Hi Everybody,

>   This is to hopefully trigger some interesting
> discussion, as this group has  been lately
> infested with questions and answers like
>  " are Futaba transmitters better than JR ?"
> I remember much more in-depth discussions
> here. I do not mean to offend anybody, however.

>     The question is what would be wrong with replacing
> the flybar with all the mechanical parts that go
> with it (seesaw, mixing levers, etc.) with two
> gyroscopes polarized 90 deg. Well, perhaps stronger
> and faster (by how much ?) servos would be needed.
> Mixing the control inputs can be done electronically
> much easier than having it done mechanically (as with
> the flybar arrangement). In the age of solid state
> electronics is the flybar a dinosaur ?

>   PS.
>        I just have on my desk an article from
> August, 1948 issue of Aeronautical Engineering Review
> introducing the invention of the flybar (Stanley Hiller).
> There is a picture of a fellow hovering his little
> open***pit heli about 1 ft. over the ground
> totally hands-off !

> Regards, Boggie

> --
> Dr. Boguslaw Gajdeczko
> Engine Combustion Lab.
> Princeton University


 
 
 

Getting rid of the flybar

Post by Guillaume Hasto » Fri, 20 Nov 1998 04:00:00


Hello Boguslaw,

Quote:
> ??? The question is what would be wrong with replacing
> the flybar with all the mechanical parts that go
> with it (seesaw, mixing levers, etc.) with two
> gyroscopes polarized 90 deg.

I've tried it on a Futura and it works very well. There was no
differencefor hovering ( 200 gr blades do the stabilizing job ) and the
pitch up
tendency that occurs with rigid heads ( non-flybar ) was reduced.
The gyros i used were not HH. I'm sure 2 CSMs would do a great
job. I noticed much more power on rolling circles. Plus i liked the look

of the heli much better.

Quote:
> Well, perhaps stronger
> and faster (by how much ?) servos would be needed.

Nope... Shorter arms , that's all. Mixing levers reduce the pitch
throw.So without them, you just have to reduce the servo arm length. The
torque
applied on the servos will remain pretty much the same...

Quote:
> Mixing the control inputs can be done electronically
> much easier than having it done mechanically (as with
> the flybar arrangement).

It's not really a "mixing" i think... It's a stabilization system. And
yes, iagree with you 100%, it can be done a more elegant way than
mechanically ;-)
H1, H3 or H4 mixing would still have to be done... ( H = collective
servos )

Quote:
> In the age of solid state electronics is the flybar a dinosaur ?

Not yet, because our HH gyros still have quite poor performance compared

to what's found in the industry. But in several years, i'm sure it's
what the flybar
is going to be: a dinosaur...

Bye? :-)

Guillaume
?