Scale Heli Question: Flybarless Setup?

[BloodClod]

Hi guys (probably Super Hornet will answer )

What's the principle of going flybarless? I'm thinking of trying that on a Mini-Titan Cobra project but this is new to me.

I've seen the pictures of Super Hornet's 2-bladed flybarless setup for his cobra, but I'm wondering why more gyros are needed - is this to make up for the stability of the flybar system?

If so, then in addition to the rudder gyro we need to install 2 more - one for elevator and one for aileron?

Am I right to also understand that with 120 CCPM setup we can't just connect the gyros so easily because of the servo interaction?

Thanks.

Thinking of trying this and learning something new.


Oh... since we're on the topic of the Cobra, in the other thread you guys were talking about using normal model paints to paint the PTEG fuselage. How's the adhesion of the paint? Does it scratch off/crack easily? Wondering if polycarbonate paint would do better?

[Super-Hornet]

Hi BloodClod

Principle of going flybarless or/and multibladed:
1. More scale look. In scale competition in U.S. or U.K, (AMA?), there is an extra point if u go for flybarless or multibladed.
2. In 3D point of view, you can have very fast response in cyclics and collective.

In our normal flybar+weight (Why weight, I explain later), the stability of the heli comes from the flybar of able to auto-level itself when the heli is tilted by external force (like wind). Since the flybar also control the pitch of the blade grips, it in terms auto adjust the cyclics of the heli in order to stabilize the heli.

Now, why I said weight and not paddles? That is because paddles do have weight. Since the paddles is always at 0 pitch until user apply cyclic on it, therefore, the paddles is just a weight on its own. It is the weight of the paddles that stabilize the flybar...or make the flybar to tilt on the opposite direction of the external force. Actually a flybar+weight behave just like a simple mechanical gyro but very effective one.

Now, if u take away the flybar, there is no auto stability from the flybar...thus making the heli very difficult to hover, let alone fly it.

So, to compensate this, we need something to replace the missing auto stability. Thus by using a gyro to sense the changes in the aileron and elevator axis, we can then make the gyro to "mimic" the behaviour of the flybar+weight and auto control the swash plate as if there is an auto cyclic control to stabilize it.

In eCCPM, each cyclic movement is control by at least 2 or more servo. On different cyclic and collective movement, those 2 or more servo are move either same position or opposite to each other. Because of that, u can't just connect a gyro just like we did on the tail servo. In mCCPM, each aileron and elevator is control by just one servo. In other word, only one channel is use. Because of that, we can simply add one gyro on each aileron and elevator. Therefore, in order to implement gyro to eCCPM, we need to change the heli (from the TX to RX point of view) to become mCCPM like. By using mCCPM setting on TX, we can just connect gyro on aileron channel and elevator channel. Then after the gyro (the output of gyro), we need another circuitry to convert that mCCPM configuration to a eCCPM configuration in order for your eCCPM heli to work.

Nowadays, most real helicopter has gyro build in for the stability. It is called Stability Controlled Augmentation System (SCAS or SAS). But there are some heli do not have gyro stability at all. Correct me if I'm wrong, I think Robinson 22 and Jet Ranger do not have SCAS. But why without gyro the heli still flyable? Again, if I not wrong, this is because for bigger heli, the blades are much heavier than or normal TRex450/Mini-Titan heli. Having heavier blades also have some sort of gyroscopic effect that will stabilize the heli. That is why for bigger heli, u can actually go flybarless and still fly without any gyro assist. Same thing goes that for 4 bladed heli, it is more stable than 2 bladed heli and 6 bladed heli are more stable than 4 bladed heli and so on.

SH

[Super-Hornet]

As for the AH-1W SuperCobra, I use Tamiya 100ml spray paint type. I use "Dark Ghost Grey" for the top portion and "Light Ghost Grey" for the rest. I think it is AS-25 and AS-26. I spray white primer first (tamiya also) and then dark/light ghost grey. I spray on the outside because if spray on inside, the outcome will become very "plastic" look. So far no visible paint scratches. Oh, I do not use clear lacquer. If u want to use clear lacquer, use Tamiya Flat clea lacquer instead.

SH

[BloodClod]

thanks for the detailed explanation! Understood!

I suppose a Piezo rate gyro would work for the elevator and aileron gyro? After installing these gyros and going flybarless, do you find it more or less stable than with the flybar?

[Super-Hornet]

For cyclic gyro, u can use whatever gyro u want...be it piezo or electronics based like GY240/GY401. So long it can sense the rotational motion and auto adjust the cyclic. Most would prefer non heading hold type of gyro (or turn off the AVCS in GY240/GY401) but there are few to prefer heading hold on it.

Of course using different gyro will give u a different stability effect but it is all depend on how much u willing to spend. If u can afford GY611, hell, go ahead if u want to.

How stable your heli is all depend on the rotor head design, the linkages configuration and the gyro configuration. If u tweak it well, it can be as stable as flybar. On hover, it can be even be more stable than flybarred if u want it to but overall flying flybarless does feel different that flybarred type.

SH

[JYZoom]

flybarless - Exiting time

Now is really an exciting time for flybalress electronic that assist in making 2-blades and mutli-blades heli much stable and while maintaining the aggressive cyclic response.

Till now you have the
- VSTABI from Mikado (3 -axis )
- CSM (2 axis )
(exclude - Helicommand cause not proven for 3D, at least no one use in any major 3D competition )

You now have 4 more options now coming into the market now or within 30-60days.

Category - 2 Axis still need a tail gyro
1) SK360 Digital Flybar - $329.95 (usd) from http://www.skookumrobotics.com/ (SHIPPING NOW)

2) probar - 2 Axis - no pricing yet , around U$300

Category - 3 Axis ( from Germany )

1) Gyrobot - EUR 549 - 3 axis from http://www.lf-technik.de/shop/index....3_GyroBot.html

2) AC-3x - EUR 495 from http://www.eheli-tuning.de/

Jonathan
(Treid VSTABI, now on CSM flybarless)

[Super-Hornet]

Most of the above most likely work on the principle of mimicking the flybar behaviour.

For Helicommander method, it works by something similar to "Auto-Hover" behaviour on a real helicopter. It constantly sensing the ground plan and adjust the swash plate movement instead.

With that in mind, IMHO, helicommander might not be suitable for 3D because when heli is in inverted or in 90Degree, the sensors do not have plane surface to sense to.

But helicommander is suitable for Aerial photography whereby u can just let go of hands and then control the camera instead. It is also suitable for scale flying be cause u are NOT GOING to do 3D on it.

SH

[pilot_bear]

talking about gyro, i have some question, can i say that
a. a rate gyro job is to stop a movement while,
b. a headlock gyro job is to correct back a movement ?

if the above is correct, can i safely said that a headlock gyro
would be a better choice to use as a hovering/level maintaining aids ?

[Super-Hornet]

Again, the idea of putting gyros in cyclics is to mimic the flybar.

If u have small size heli like TRex450/Mini-Titan, u can try this experiment. U took out the blades, hold it in your hand and spin it up. No need to spin fast...just fast enough so u can see the flybar+paddles spinning.

While the flybar is turning, u notice it is in plane level or horizontal level. When u tilt the heli forward (nose down for example), u will notice the flybar will tilt in the opposite direction to the direction u tilt the heli. Actually the flybar still in level position but it appears that the flybar is tilted backward in relation to the heli. After about 1 second or less, the flybar will then till forward to the same direction to the heli body and remain there. Final outcome is that, u have an heli tilted forward with swash plate and flybar in same direction or level to the heli body.

If u translate that "behavior" to gyro, it is like a non heading hold gyro, It other word, it final outcome is always back to the original position.

If u use heading hold, chances u will end up heli that may not return to the level position. Furthermore, each time u spin up the heli, u need to make sure the swash plate are level before u spin up (Just like the tail blades will not in 0 pitch if u move heli around prior to spinning)

SH

[JYZoom]

csm

some expert told me with CSM flybarless, it bring you to a whole new level as you can have headlock function turn on with flybarless. It help with some 3D move once you get to into position and keep it lock.

I don't know because my skill level is way before that.

Jonathan

[Super-Hornet]

Enabling heading hold while doing 3D... I can only suspect it is like having a variable paddles weight. If u using lighther paddles, your cyclic response become very fast by reducing the auto stability.

SH

[JYZoom]

out of context.

I know this is out of context as we are suppose to be talking about scale heli.

But to complete the story on HH mode for flybarless.

The Headlock mode stays where ever you put your cyclic stick so caution when spooling up in this mode (1) because any input from your cyclic stick will tip your model while on the ground in which ever command has been given and you could stuff your model . The benefit of headlock is that the model holds in what ever position you put the stick so for instance doing a pie dish once in the manoeuvre it will stay locked there till you either flick back to normal mode or change stick direction or when inverted the model will stay straight and level in headlock you will understand when you are flying what I am saying but at first the headlock could bite you until you get used to it so take your time in this mode the CSM system really is the dogs bollocks just take your time till you are fully used to it best of luck.

Jonathan

[zattan22]

flybarless will mean to mod the flybar system
or dont install the flybar?

[JYZoom]

another thread

flybarless will mean to mod the flybar system
or dont install the flybar?

Very simple. Take a look at another thread and some of superhornet threads and you will know what to do.

Jonathan

[Super-Hornet]

Hi Jonathan... I believe BloodClod don't mind we go off topic a bit but I think the info u gave is still related to Flybarless. So, overall it is still OK right?!

SH