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SAB
Other › No swash driver
01-29-2012 10:51 PM  6 years agoPost 1
VDUBS

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Moorestown, New Jersey

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Just looking over the pics of this machine and I don't see a swash driver?? Are they doing something different or am I just missing something here? I don't see anything on the head that will keep the phasing correct and stop the swash from lagging behind. Someone with a kit could chime in here and answer this for me.

Kyle

Quicksilver

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01-29-2012 11:01 PM  6 years agoPost 2
Dood

rrProfessor

Wescanson

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The rigid control links connecting the swash to the grips drive the swash.
The same design is used on the Compass 7HV and the ALign DFC head. Even Quick World Wide is jumping on the bandwagon.

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01-29-2012 11:30 PM  6 years agoPost 3
SynergyAero

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Stuart, Florida - USA

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Yup, Compass has been using this type of head for a little while, and now Align has released one as an upgrade to the 700 and 550. Compass also sells this type of FBL head under the brand name "Trax":

IMO, the SAB version seems a little more robust than the others. They use an extra set of bolts and bearings, to hold the connecting rods/drivers to the rotor grips.

Cris

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01-30-2012 05:15 AM  6 years agoPost 4
VDUBS

rrNovice

Moorestown, New Jersey

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swash driver
Thanks guys I thought there was someone out there with a new flybarless head and they called it Rigid flybarless head but I had never seen one.

Quicksilver

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02-01-2012 05:08 PM  6 years agoPost 5
heliaddict2424

rrApprentice

SCV SoCal.

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Design flaw.
I guess none of these manufactures thought about phasing because they all have the same problem phasing will change in flight not good...

Team MikadoUSA Team Scorpion

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02-01-2012 05:11 PM  6 years agoPost 6
RCHeliJim

rrElite Veteran

Orem, UT USA

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I am not seeing where the phasing would change on the SAB head. The line between the upper swash and grips cant move. No matter which angle the swash is at, that line seems like it would stay parallel to the main shaft. Can you expand on your thoughts?



Go Fly, Have Fun!!
-Team Quick UK

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02-01-2012 05:40 PM  6 years agoPost 7
heliaddict2424

rrApprentice

SCV SoCal.

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Sorry for the chicken scratch drawing.

Sorry in a hurry but I hope this explains the problem the second drawing shows the disc at extreme angle just to get point across. Bottom line it looks good but does not work well Jan has the right idea on the TDR.

Team MikadoUSA Team Scorpion

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02-01-2012 05:43 PM  6 years agoPost 8
RCHeliJim

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Orem, UT USA

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If you look at the design of their system, the blade grip rotates on the opposite axis of whats in your drawing, the arm and driver will stay parallel to the mainshaft, not move side-to-side as your drawing shows.



Go Fly, Have Fun!!
-Team Quick UK

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02-01-2012 05:46 PM  6 years agoPost 9
heliaddict2424

rrApprentice

SCV SoCal.

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Not sure I follow you?

Team MikadoUSA Team Scorpion

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02-01-2012 05:56 PM  6 years agoPost 10
heliaddict2424

rrApprentice

SCV SoCal.

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If anyone can correct me please do but I looked into this design for the Robo300 we are design and opted not to use this method because of the issues with it. Again if im missing something let me know.

Team MikadoUSA Team Scorpion

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02-01-2012 06:07 PM  6 years agoPost 11
RCHeliJim

rrElite Veteran

Orem, UT USA

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I dont think the damping in this head will allow enough movement at that arm to incur any change at the swash ball that would be significant.



Go Fly, Have Fun!!
-Team Quick UK

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02-01-2012 06:12 PM  6 years agoPost 12
3Dmuse

rrApprentice

Ontario, Canada

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Sorry for the chicken scratch drawing.

Sorry in a hurry but I hope this explains the problem the second drawing shows the disc at extreme angle just to get point across. Bottom line it looks good but does not work well Jan has the right idea on the TDR.
helliaddict2424
It looks to me that in the second drawing, the one in which you have the extreme angle on the rotor head, the spindle is not perpendicular to the main shaft - this angle cannot be that extreme, no matter how soft the damping is.

Even if this angle were significant, the pitch of both blades would change by the same amount, but in opposite directions. I don't see a problem with this?

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02-01-2012 07:20 PM  6 years agoPost 13
eddiscus

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Dumont, NJ-USA

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Also another point is even if the spindle shaft goes out of perpendicular with the main shaft due to damper compression the force imparted on the links would not rotate the intermidiate swash due to the fact that the force on the links will be in the same direction. I would be more worried of the bending moment stress on the bolt connecting the push rod yoke to the main grip.

As mentioned the movement at that point should be minimum enough as not to be an issue.

Logo Xxtreme 800
Logo 700
Citizen 142
Synergy 766
TDR 2

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02-01-2012 07:33 PM  6 years agoPost 14
heliaddict2424

rrApprentice

SCV SoCal.

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I am just stating what I have talked to Pros about who fly theses heads. Any FBL unit vbar in particular will have a bad reaction to the phasing changing even a little bit. Again it maybe fine for some but really seasoned pilots are noticing that it does not feel right in the air. I am staying away from this design I have a better way of doing it stay tuned. And if I ever get my Goblin I will be able to test first hand but I am still waiting..

Team MikadoUSA Team Scorpion

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02-01-2012 07:37 PM  6 years agoPost 15
heliaddict2424

rrApprentice

SCV SoCal.

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It looks to me that in the second drawing, the one in which you have the extreme angle on the rotor head, the spindle is not perpendicular to the main shaft - this angle cannot be that extreme, no matter how soft the damping is.

Even if this angle were significant, the pitch of both blades would change by the same amount, but in opposite directions. I don't see a problem with this?
LOL I know the angle is extreme I was trying to prove a point by over exaggerating. And Vbar does not like things happening that it is not telling the helicopter to do like pitch changing.

Team MikadoUSA Team Scorpion

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02-01-2012 07:56 PM  6 years agoPost 16
3Dmuse

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Ontario, Canada

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LOL I know the angle is extreme I was trying to prove a point by over exaggerating. And Vbar does not like things happening that it is not telling the helicopter to do like pitch changing.

helliaddict2424
As I wrote above, I don't think that the overall attitude of the rotorhead would change. This is because the pitch of each blade would change by the same amount, but in opposite direction to the pitch of the other blade, creating forces that would oppose the deviation from the 90 degrees angle between the spindle and the main shaft.

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02-01-2012 09:42 PM  6 years agoPost 17
SynergyAero

rrNovice

Stuart, Florida - USA

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Here's a good straight on shot of the rotor head... I don't see how any change in pitch, no matter how extreme, would cause the arm-to-swash angle to be anything but 90 degrees. Especially since the arms are held to the Blade grips with dual bolts and dual bearings:

The movement of the blade grips and the movement required to change the arm-to-swash angle are in two totally different planes. Don't see how one could affect the other.

Am I missing something?

Cris

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02-01-2012 09:43 PM  6 years agoPost 18
worldofmaya

rrApprentice

Graz, Styria - Austria

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LOL I know the angle is extreme I was trying to prove a point by over exaggerating. And Vbar does not like things happening that it is not telling the helicopter to do like pitch changing.
The "problem" is nothing new. A similar drawing was posted on HF technical support thread by SAB with an explanation which caused the Compass-dispute.
VBar is much more immune to a lot of things than some might think. Just speak with the VBar guys... the main problem would be ball links taking your drawing.
I thought the goblin isn't interesting for you?
-Klaus

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02-01-2012 09:45 PM  6 years agoPost 19
hams

rrApprentice

Ohio

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As I wrote above, I don't think that the overall attitude of the rotorhead would change. This is because the pitch of each blade would change by the same amount, but in opposite direction to the pitch of the other blade, creating forces that would oppose the deviation from the 90 degrees angle between the spindle and the main shaft.
Wrong, take a look at your heli next time you spool it up on the ground and move the ail or elev enough to tilt the heli and report back.

I get half nervous every time I am near a heli flying with this head design. I believe that having the links rigid and the head/feathering shaft not rigid is asking for trouble and fatigue is going to cause the links to fail.

You are designing "binding" into the head. Not for me, no way.

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02-01-2012 10:04 PM  6 years agoPost 20
3Dmuse

rrApprentice

Ontario, Canada

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As I wrote above, I don't think that the overall attitude of the rotorhead would change. This is because the pitch of each blade would change by the same amount, but in opposite direction to the pitch of the other blade, creating forces that would oppose the deviation from the 90 degrees angle between the spindle and the main shaft.
Wrong, take a look at your heli next time you spool it up on the ground and move the ail or elev enough to tilt the heli and report back.

I get half nervous every time I am near a heli flying with this head design. I believe that having the links rigid and the head/feathering shaft not rigid is asking for trouble and fatigue is going to cause the links to fail.

You are designing "binding" into the head. Not for me, no way.
You don't seem to have understood the problem raised by heliaddict2424. Don't forget that there are two blades and each creates opposing forces on the head that cancel each other:

http://www.helifreak.com/showpost.p...03&postcount=54
http://www.helistart.com/RotorheadTypes.aspx

As for the links being rigid and more prone to failure, if they are built strong enough I don't think there is a bigger potential danger to them than to plastic ball links, which can pop off the balls anytime.

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