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Flybarless Rotor Head Systems > New Flybarless System

MrMel
Elite Veteran
Location: Lidingo, Sweden

Quote
2) your Sk uit is fitted right up the tail belt and it's pulley. It's possible that you get cyclic jumps when the static electricity generated by the gears and the belt ripping in the tail boom discharges

I sencond that as probably cause, it has already happen to others (Finless).

Its not just the unit it self, wires too close to a source can pick up the noise and carry it on.

04-24-2008 07:12 AM

alvinchai
Heliman
Location: Vancouver, British Columbia

Quote
I don't understand what difference it will make if I use either: --> short servo arms and direct linkage to the grips OR --> long servo arms with travel reducing arms before the grips ASSUMING that both setups will give 8 deg cyclic and +-11 deg collective, servo resolution is not compromised due to narrow servo travel, and that slop is not a factor.

A shorter servo arm may or may not effect resolution, but it may effect overall speed due to the longer distance travel.

I've tried direct link to the grips and honestly did not get very good results. The heli does not hold as good and I was not able to get it flying well after countless hours of tweaking the software.

I strongly suggest trying the reduction arm, you will be surprised how much better your heli will handle after this simple mod.

04-24-2008 07:44 AM

jyzoom
Heliman
Location: Singapore - jyhelistore

direct link and reduction

"A shorter servo arm may or may not effect resolution, but it may effect overall speed due to the longer distance travel.

I've tried direct link to the grips and honestly did not get very good results. The heli does not hold as good and I was not able to get it flying well after countless hours of tweaking the software.

I strongly suggest trying the reduction arm, you will be surprised how much better your heli will handle after this simple mod."

Is this comment related to 450 size heli or also apply to 500 size (trex 500) and bigger heli ?

Jonathan

MSHELI Protos - stock, Jazz80,cc bec@6V,9650s,spartan+9257,15T, Lipo2600-6S

04-24-2008 08:18 AM

HOMEPAGE

MrMel
Elite Veteran
Location: Lidingo, Sweden

I fly direct linkage (swash->bladegrips) on my lager .50 and .90 size ships, with REALLY good results.

Its all about slop, quality of servo's, geometry and so on.
There is no "this is better then that", each heli design provides its challenge.

Currently have 4 flybarless helis, and counting.

04-24-2008 08:54 AM

e-copter
Senior Heliman
Location: Nice, France

Hi,
as MrMel says, each rotor head is different and a particular attention is needed on each setup.

Difference between servo Travel and reduction is simply the following:

if you use longer arms, you reduce your servo speed and torque output, and each step on inputs is brought bigger at output.

If this is to bring then a reducer ( washout ) then you only get more slope.

Depending on your blade grips design, the best way is to setup a new model on a transmitter, use 50% swash travel and try to play witht he servo arms anchors to get the +11 / - 11 pitch . Then you need at least 7° on cyclic (for the SK 360) .

With using longer arms on servos, you will tweak the geometry as at max pitch, if you input cyclic, then your servos are for example all with arms up and the cyclic is a bit modified because each servo arm works in a circlular way.

i'll take a picture of the micro flybarless head we made in 2004 for the Gemini, we used Hitec hs 50 servos with short arms and anchors at 2nd hope, and could get a good ratio between torque output / speed / resolution on the head.

as Electronics now cure most of the flybarless problems ( this is the goal) i think anyway that a system must be designed for flying flybarles and not only be converted from flybar to flybarless with removing parts.

Anyway, waiting for furher videos

BEst regards,
Fabien

Too much is not enough....

04-24-2008 04:55 PM

alvinchai
Heliman
Location: Vancouver, British Columbia

Quote
Is this comment related to 450 size heli or also apply to 500 size (trex 500) and bigger heli ?

Hi Jonathan, I'm referring to the Mini Titan head setup of eric_b, which I used to test the SK360 in the 450. Depending on the head geometry of the particular heli, some work well and some do not.

From experience, larger helis are easier to setup compared to smaller helis like a 450, and are less fussy/sensitive to linkage and software changes. Smaller 450s do take a bit more time to get it setup good for flybarless, a little bit here and there goes a long way in terms of performance.

04-24-2008 05:50 PM

fran
Senior Heliman
Location: HP, South Carolina, USA

just fancinating and great info too.

Love it!

FRAN SR. FAI-F3C !!!!

04-24-2008 06:15 PM

jyzoom
Heliman
Location: Singapore - jyhelistore

agreed

Alvin,

Tks for the response. That is the same experience I have. I can get my vbar and csm to work easily on Trex 500 and logo type of heli. But getting it on mini-titan to work as well is a different story.

Jonathan

MSHELI Protos - stock, Jazz80,cc bec@6V,9650s,spartan+9257,15T, Lipo2600-6S

04-24-2008 09:58 PM

HOMEPAGE

Clearance
Senior Heliman
Location: Left Coast Canada

Interjection:

mCCPM systems appear to be simpler to setup = no cyclic interactions, no collective pitch adjustments to make via servo arm length or travel adjust. Just adjust the position of the balls on the travel-adjustment arms to give a cyclic throw of plus/minus 8 degrees and fly. But one day I'll have to convert my T-Rex 600N........ Ken

04-25-2008 04:35 AM

JKos
Elite Veteran
Location: Town of California in the state of Maryland

A thought on tip-over issues...

Are those who have had a tip-over on takeoff or otherwise eventful takeoff using a Spektrum receiver? If so, did you rebind the receiver after setting the transmitter to normal swash mode and centering the trims and zeroing the subtrims for cyclic channels?

Bruce,
When does the SK360 read the neutral values on the aileron and elevator channels?

The Spektrum receivers output the pulse widths learned during binding on all channels except throttle immediately upon power up. Those pulse widths are maintained until the link with the transmitter is established. Is it possible that the SK360 is initializing on the bound values which could be different than the neutrals from the transmitter? And, thus, the SK360 would be seeing a cyclic input (however small) during spool-up despite the user not touching the cyclic stick.

This has been a known issue when using V-Bar. Some folks have had odd behaviours until they rebound the receiver.

- John

Protos -- Logo 14 -- Logo 10

04-25-2008 10:47 PM

FrittsLogic
Senior Heliman
Location: Honolulu, Hawaii

Mine occurred while using Futaba FASST on a 14mz. Disc cyclic behavior was normal (not moving) until liftoff attempted.

Menehune Rotorworks Inc.

04-25-2008 11:09 PM

HOMEPAGE

Eury
Elite Veteran
Location: Ankeny, IA, USA.

Mine was on Spektrum, and yes, I rebound after setup, like I do anytime I do a setup with Spektrum.

Nick Crego
As I wind on down the road...

04-25-2008 11:40 PM

Bruce2.5D
Heliman
Location: Vancouver, Canada

>Bruce,
>When does the SK360 read the neutral values on the aileron and elevator channels?

When it first initializes (red LED turns green), a minimum of 5 seconds after power is applied. This was partly to give DX7's etc time to bind. Note there is an option during setup to use fixed neutrals, however during testing I measured a surprising amount of receiver temperature drift, so at-init neutral measurement is the better option.

I use a DX7 myself with a Trex450, and while I've had a few surprise cyclic tilts at takeoff, I've just cut throttle, let it wind down, wait 5 seconds and wind it back up. But I also have a habit of cycling power if the DX7 doesn't bind within a few seconds, and always wait 5 seconds after I walk back before take off. In fact I suspect that unless the setup is wrong, the difference is probably down to habits myself and beta testers have developed.

The only "tip over" scenario I've had in hundreds of personal test flights with a variety of gyros was when I once was in a hurry, loaded a setup file for the wrong helicopter, didn't preflight - and it thought left was right and...well it was over fast. The only other gyro-related crash since the first week of development was while testing just how low the head speed could be before it lost control (the blades stalled and it stumbled around as if drunk).

Eury and Frittslogic's problems were both unique in that I can't explain them yet. Their helis were not stable once in the air, either. Both are on their way back, in Eury's case his entire Blade 400, and I'm going to reserve judgement as to what was wrong until they're in hand for analysis.

04-26-2008 12:08 AM

heli_headcase
Veteran
Location: Hovering around Atlanta

Jumping in here...

Hi Bruce,

I just received word that a friend sent his SK-360 for me to play with. Rather shocked as we had just been discussing your system only 3 or 4 days prior and I was thinking of buying one for myself.

I have lots of developmental experience with using CSM gyros for 'barless work (look in my gallery if you dare :-) ) and was curious about trying out one of these units.

I've never had a cyclic tippover in all my testing of gyro enhanced swash control. Making sure the swash is dead level is high on my prelift checklist. Using the CSM gyros, I have the programming option to have the swash self-level over a predetermined length of time. Telling pilots not to stir the sticks is very important still but the decay time back to center help prevent the surprise tilt-lifts. I could write lots more but I'll reserve it for later.

HHC

So many heli's - too little time...

04-26-2008 01:21 AM

lesodell3
Senior Heliman
Location: michigan usa

ok so what is the BEST head setup for a trex500 ? and do you have pics of it

aah words to live by. "A side note, vigilante behaviour will be squelched!"

04-26-2008 01:16 PM

Unpoor
Heliman
Location: Ange Sweden

HOHO I tested mine today and I didnt taco it.. :-)

but it had issues.. it also like the others wanted to tip to the right, had to give left aileron not to flip it over, 2 small yanks and then I could take off, slugish so some more Bell gain will be needed and also it didnt stop when returning stick to middle, a second more of motion, no oscilation,
at full pitch to 8 meter it tilted to the right about 5-8 degrees, a tight loop sent it out leaning to the left, so theres lots to be done still..

but it flew :-) :-)

T-Rex 600N Pro SK360, Hurricane 550, T-Rex Hybrid, DX7

04-26-2008 05:32 PM

Bruce2.5D
Heliman
Location: Vancouver, Canada

Did it only try to go right at take off?

The heli will tend to drift a bit in flight if the gain is too low, due to normal unevenness, friction, and/or slop in the swash & linkages. Good mechanics, digital servos, and higher gain help.

Be aware that for damping gains, it is the ratio between the damping gain number and the "base" hiller elevator gain that counts when you use the Hiller Gain dial for field tuning (which unpoor isn't doing). Usually a damping gain of about 1/3 the hiller base gain # above it works well.

04-26-2008 06:20 PM

MrMel
Elite Veteran
Location: Lidingo, Sweden

Unpoor,

Have you checked phasing of your heli?
I ask because you run your link-arms not along main axle, if you havent adjusted the phasing in the program it could be WAY OFF.

(and that explains flight troubles you had and wrote about in the other forum)

04-26-2008 06:22 PM

Unpoor
Heliman
Location: Ange Sweden

it only tilted right when doing hard pitch pumping, and at takeoff, corrected some and then it seatled down and I could takeoff.
I have futaba 9252 on 6V, brought my laptop with me but got hungry so needed to go home.. lol

is phasing affecting my setup even if the ball on the swash is 90 degrees agint the blades? looking from above that is, it only leans abit cozz I didnt extend the bladegrip ballpin.

Got 45% swash mix,(moved the servoballs closer).
35% expo, will go down when more testing done.
14 +/- pitch and 9 cyclic, might be abit much..

T-Rex 600N Pro SK360, Hurricane 550, T-Rex Hybrid, DX7

04-26-2008 06:50 PM

MrMel
Elite Veteran
Location: Lidingo, Sweden

It comes down to how "good" your swashdriver is, if there is slop in the swashdriver your phasing will be off.

Its easier to see if that is the case with a link aligned to the main shaft.

Double-check, now you have the possibility to adjust, at least my T600N had phasing issues with the stock head (with paddles), so its worth looking at.

04-26-2008 07:06 PM

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