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HomeAircraftHelicopterFlybarless Rotor Head SystemsSkookum › Skookum SK-720 Flybarless System
04-07-2010 11:02 PM  8 years agoPost 41
Goto

rrNovice

UK

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Gyroscopes
There is confusion here regarding centrifugal forces and gyroscopic principles.

Centrifugal forces are not directly involved in the way a flybar works. In essence a flybar is a gyroscope deployed as a damping force on an unstable rotating wing (the blades, and if you don't think they're unstable, disconnect your flybar, don't add any electronics and wind down your headspeed to the point where you can see and feel the effect).

The flybar works in two ways. Firstly it acts to counter the effect of gyroscopic precession which would otherwise place the timing of the reaction of the blades to an input from the swashplate at ninety degrees to the plane of intended action. The flybar instead responds to this input and initiates movement in the rotorblade (change of pitch) ninety degrees ahead of the swash input (bringing the action into the correct phase).

The action of the flybar that we're most interested in here is the damping effect, caused by the rotating mass of the paddles. Centrifugal forces act only in trying to make the paddles fly off the end of the flybar. The law of conservation of angular momentum is the one that tries to stop the paddles from changing the plane of rotation, creating the damping effect in the roterhead, stabilising the rotor disk and keeping the following rate of the blades under control. This is why heavier paddles are more stable than lightweight ones, for a given pivot point or chordwise CofG.

We use threaded rod-ends, grub screws and even cyano to counter the effects of centrifugal forces, and good servoes to fight the gyroscopic inertia of the flybar.

The electronic flybar substitutes force the rotordisc into a damped, controlled condition through sensing and countering the unwanted movements of the rotordisc, ultimately through bruteforce via the servoes, reacting (as with tail stabilisation) very quickly to tiny perturbations before they become significant instabilities.

(My first post on RR, too long, hopefully helpful).

Mark

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04-08-2010 12:46 AM  8 years agoPost 42
iHover

rrVeteran

Berne , NY

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Have you guys thrown this far enough off topic yet? Heres an idea open a thread on the topic and lets use this one to discuss the SK 720

You had me at Hover

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04-10-2010 12:18 AM  8 years agoPost 43
blade slayer

rrApprentice

Maryland

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gyroscopes??? isn't this the sk720 flybarless thread?
i'd like to know if anyone has tried it yet and how it works.
can you guys talk about the sk 720 ?

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04-10-2010 01:03 AM  8 years agoPost 44
t2o

rrNovice

Pleasureville Ky

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It works awesome. The flight control and tail are super strong. The wobbly piro is gone. This thing rocks. I have one in a Swift and am working on putting one in a Predator 90 but life is getting in the way of that project. I have never used any other contoller but a Skookum so I cannot compare it to anything but the 360 and it is stronger than the 360 in every area.

Cheers.

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04-10-2010 11:36 AM  8 years agoPost 45
Ben-T-Spindle

rrProfessor

Central Illinois

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Now that the first production run has need sold lets hear some actual flight reports instead of all this gibber-jabber.

... BTS

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04-10-2010 02:50 PM  8 years agoPost 46
blade3d

rrElite Veteran

New Jersey USA

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We need to put one in the hands of a VBar guru

Blade3d

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04-12-2010 03:12 AM  8 years agoPost 47
Rogman88

rrElite Veteran

West Monroe, LA

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I did enjoy the off topic about piro optimization and wobbly acting forces etc. I'm looking hard at this as my first FBL setup, as well as Vbar. I'm leaning towards this one now because I am assuming vbar lacks the "heading hold" for the cyclic. I'm still a little skeptical until I hear some more guys talk about their real world experiences with it. Anyone have some video's of helis flying with the 720? I'm going to youtube it now...
Here found one by a guy at the recent Las Vegas fun fly. He does some piros prior to his flight and appears to be "wobble free". Of course this guy looks to be a pro so can probably make corrections on the fly.

http://www.youtube.com/watch?v=qWnC63kGDi0

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04-12-2010 03:28 AM  8 years agoPost 48
Ronald Thomas

rrMaster

Gainesville, Fl, USA

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I'm leaning towards this one now because I am assuming vbar lacks the "heading hold" for the cyclic.
That would be incorrect

Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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04-12-2010 05:07 AM  8 years agoPost 49
gologo

rrKey Veteran

Sedalia, Mo USA

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Now that the first production run has need sold lets hear some actual flight reports instead of all this gibber-jabber.

[quote]We need to put one in the hands of a VBar guru
A......MEN!

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04-12-2010 05:13 PM  8 years agoPost 50
Rogman88

rrElite Veteran

West Monroe, LA

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I'm leaning towards this one now because I am assuming vbar lacks the "heading hold" for the cyclic.
That would be incorrect
Great then it's now back to a toss up. Go with what I know has been proven (vbar) or go with the latest and greatest that's just recently hit the market

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04-12-2010 05:35 PM  8 years agoPost 51
theflyingman2

rrApprentice

Winter Haven, FL USA

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A Flybar on a heli will try to keep the disk in the same plane of operation, with out a flybar you have to do all of the corrections your self.... you can try this. get rid of all the mess on the head, and run links directly from the swash to the blade grips. turn down your rates(quite a bit) and fly your heli. You will notice that it is more unstable then before. your heli will still fly. You can even do some aerobatics with it. Trust me my trex 500 flew like this. It is just more unstable, now put your flybar back on, and you will see, how much "correction" the flybar is doing all the time. (By correction, i mean anything that keeps the heli from falling out of the sky). Depending on the way the fbl system works, it may either try to mimic a flybar or, just be a stabilization system. If you want to know how a stabilization system feels, you can take a Raptor, or another heli that uses mechanical mixing (a heli that uses 1 servo for alie, and 1 for elev, and 1 for pit) then take 2 heading hold gyros, and put one on the alie, and 1 on the elev. this is essentially what a stabilization system does. It takes input from the receiver, combines that input with the corrections needed from the gyro error, and then (in most cases, sends it through a ccpm mixer. (anyone remember the CSM system?)

sorry to go further off topic

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04-12-2010 11:27 PM  8 years agoPost 52
panzlflyer

rrApprentice

Goldsboro,NC,USA

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Vbar piros the length of the field without any cyclic input on the 600 and 700 we just setup, looked kinda weird to me it was so steady.
Will find out on the Skookum as mine shipped today.
Ive had the 360 and the 3g, so far the Vbar is a winner due to the 3 axis,(wont talk about the 3g) the 360 was good so I imagine the 720 will be, Skookum isnt exactly new to this now.

T700,450Pro,Spirit Pro,Beast+, Qav 500,Futaba18SZ

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04-13-2010 03:48 AM  8 years agoPost 53
hhart

rrApprentice

San Jose, CA

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Guys,

The Skokum 720 has piro to cyclic compensation just like Vbar. I checked it out on the bench this past weekend when a guy showed up in local mini funfly.

BeastX has the same feature. Under setup menu, 'N', reverses the compensation direction if the unit mounted upside down.

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04-13-2010 03:53 AM  8 years agoPost 54
Ronald Thomas

rrMaster

Gainesville, Fl, USA

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BeastX has the same feature. Under setup menu, 'N', reverses the compensation direction if the unit mounted upside down.
You have one? How does it fly?

Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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04-13-2010 04:18 AM  8 years agoPost 55
HilliHeli

rrVeteran

S.MI./FL.

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Vbar piros the length of the field without any cyclic input on the 600 and 700 we just setup, looked kinda weird to me it was so steady.
Inverted as well but, back to the SK720 ......

!Antriebe, die bewegen!
Henseleit-Helicopters.de
Jazz', Jives & vbar's
Futaba FASST / FASSTest

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04-13-2010 09:26 AM  8 years agoPost 56
jongurley

rrApprentice

North Carolina

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Inverted as well
Hmmmm I will try that this week when me and panzlflyer get back together for farther VBAR tuning.

HeliWerks Inc. Team Factory Pilot
Team Thomco Hobbies
Thompson Heli Consultants Inc.

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04-13-2010 11:33 AM  8 years agoPost 57
Ben-T-Spindle

rrProfessor

Central Illinois

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Does anyone have them in stock or is it pre-order only?

... BTS

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04-13-2010 12:25 PM  8 years agoPost 58
blade slayer

rrApprentice

Maryland

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i started to like the SK 720 already,but i wish they made it with the censor separate from the main system,it might be a little difficult to find a good spot on my 600 or 700 ,i guess it needs to be mounted flat and level...
does anyone have a pic of the SK 720 installed?...please share

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04-13-2010 03:11 PM  8 years agoPost 59
Rogman88

rrElite Veteran

West Monroe, LA

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Great Panzle! I'm glad you're going to have experience with both. I eagerly await your review and that review will be a large facter as to which one I get. I'm not only curious as to the flight characteristics but also the "black box" feature when you plug it to the computer to see your stick movements in flight. Should be able to help distinguish between "dumb thumbs" and hardware mishaps during flight. Thanks!

Roger

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04-13-2010 05:37 PM  8 years agoPost 60
mharpo

rrApprentice

Louisville, KY

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The good news is that HeliDirect has shipped the first batch and mine are due in tomorrow. The bad news is that the self-leveling feature was disabled on all the units, but will be available with a firmware update by the end of the month...

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HomeAircraftHelicopterFlybarless Rotor Head SystemsSkookum › Skookum SK-720 Flybarless System
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