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HomeAircraftHelicopterHIROBOHirobo SDX › Major bindings
02-04-2010 09:57 PM  8 years agoPost 1
arhennie

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Norway

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Tonight I finished building my new SDX.
I have build the head according to the manual with regards to placing of the ball links.
I set up the collective with +/- 11 degrees pitch and +/- 8 degrees on cyclic as this is what I have started with on all my heli's.
(I measure cyclic with the normal pitch-meter and measure blade pitching with full elevator or aileron at zero collective pitch).

With this setup I get some major bindings in the head. The pushrods from washout arms to the flybar lever hit the two jesus-bolts as well as this flybar lever hits the yoke.

I reduced the collective to +/- 10 and then I had to reduce cyclic to approxmate +/- 5 degrees (both elevator and aileron) to go clear.
Still I need to get a cyclic ring for my radio as I still have some major binding when the stick is in the corners.

Is it normal to run such low values on this heli?
What do you guys fly with?

arhennie

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02-04-2010 11:39 PM  8 years agoPost 2
Wyorcflyer

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Cheyenne, Wyoming USA

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Is it normal to run such low values on this heli?
What do you guys fly with?
I changed the ball locations on the mixing arm to get the roll rates and flip rates I wanted without binding the linkages. Instead of putting the balls in the far left holes respectively as shown in the manual at the bottom of page 21 I put them in the middle hole on each side of the arm. That effects cyclic and collective so you will be starting from scratch on your setup.

That solved the binding and gave me the performance I wanted. It did not seem to have a negative on stability either. The bird is still true with no quirks, hovers fine and FFF is great. No flybar weights either. That may not suit your style but you should be able to tune the head in a way that gives the performance you want with a little trial and error.

Hope that helps.

jack

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02-04-2010 11:51 PM  8 years agoPost 3
TheWoodCrafter

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Costa Mesa, Ca.

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I have my head setup like Jack.
No binding.
My collective is +-12.
Didn't measure cyclic.

Thanks, TheWoodCrafter

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02-05-2010 12:12 AM  8 years agoPost 4
John Benario

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Las Vegas

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I have +-13 degrees pitch, full swashplate throw, and no binding.

It may be that you are looking at the flybar when it is tilted to the stops, but in flight the flybar does not move off center very much.

John Benario

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02-05-2010 12:26 AM  8 years agoPost 5
Wyorcflyer

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Cheyenne, Wyoming USA

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It may be that you are looking at the flybar when it is tilted to the stops, but in flight the flybar does not move off center very much.
John that was my thought as well. I figured in flight it would not be an issue. A few cases later, inspection showed that my links were getting the crap beat out of them hitting the head bolts. Hence the change.

jack

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02-05-2010 03:46 AM  8 years agoPost 6
MRC-Hirobo

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Edison, NJ

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Check the hole in your main mast. You could have installed the main mast in the wrong hole.

MRC Host

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02-05-2010 04:02 AM  8 years agoPost 7
Andy.Kim

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Seattle, WA

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Also, it's not realistic to check the 4 corners for binding since you should not be there in regular flight.

I check for binding at 12, 3, 6, and 9 o'clock. I'm running 11 collective and 8 cyclic with no paddle weights. I have my head setup per instruction.

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02-05-2010 04:21 AM  8 years agoPost 8
Wyorcflyer

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Cheyenne, Wyoming USA

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Check the hole in your main mast. You could have installed the main mast in the wrong hole.
Good point Greg. The top head bolts and bottom bolts should be 181mm apart. That is tough to measure when assembled. If you use the correct holes the bottom mast bolts will be 90 degees off from the top mast bolts. If the top and bottom bolts are parallel then I believe they are in the wrong holes. Greg do you concur?

Jack

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02-05-2010 07:10 AM  8 years agoPost 9
arhennie

rrApprentice

Norway

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It may be that you are looking at the flybar when it is tilted to the stops, but in flight the flybar does not move off center very much.
No, I always check this with a level flybar. I test at zero as well as full pos and neg pitch. Then I spin the head and check for binding.
Also, it's not realistic to check the 4 corners for binding since you should not be there in regular flight.

I check for binding at 12, 3, 6, and 9 o'clock. I'm running 11 collective and 8 cyclic with no paddle weights. I have my head setup per instruction.
I agree, and right now I have clearance at 12, 3, 6 and 9. But to avvoid throwing the links by accident I will install a cyclic ring on my radio. But this have not been necessary so far on my previous heli's.
But I really dont understand how you are able to run those throws with a setup as per the manual without binding.
Good point Greg. The top head bolts and bottom bolts should be 181mm apart. That is tough to measure when assembled. If you use the correct holes the bottom mast bolts will be 90 degees off from the top mast bolts. If the top and bottom bolts are parallel then I believe they are in the wrong holes. Greg do you concur?
If I remember correctly it's two holes in the bottom and one in the top. In the bottom I think I was to use the upper hole. But this would not affect the issue with the jesus bolts, as by turning the head 90 deg, the whole head assembly with washout, flybar assembly and yoke will follow. Hence no change.

I think I will give it a try as it is right now. +/-10 is ok to start with, and I will see how +/- 5 on cyclic will work. Then I will probably try to move the balls as described by Wyorcflyer and TheWoodCrafter here.

I'm far from being an expert in these matters, but I think perhaps the actual cyclic throws measured, as I explained earlier, dont necessarily matters that much. As this measurement doesent say anything regarding the relation between bell and hiller.
I mean, the cyclic throw tells me how much the blades attack, but it says nothing about how much the paddles dampen the movement in flight. So I beleive movin those balls may have a big effect on roll rates and flip rates even if I dont change the cyclic throws. Am I correct?

arhennie

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02-05-2010 12:44 PM  8 years agoPost 10
rexxigpilot

rrProfessor

Florida

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That is correct! Move the B/H mixing arm balls to the middle positions and the SDX will give all the throw you can handle. I set mine up with ±13° collective and ±8.5-9° cyclic. No collisions at 12, 3, 6 and 9 o'clock even at full neg and pos collective. Slight binding at corners without cyclic ring engaged. Probably not enough to pop a link, but I have cyclic ring set on my 12Z anyway.

I keep going back and forth with no paddle weight and some. I recommend half the lead weight in each paddle. Try it without the weight first since you can't get the lead weights out once installed.

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02-05-2010 09:44 PM  8 years agoPost 11
Richardmid1

rrProfessor

Leeds, England

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You need to run swash mix % around 50 and just adjust the head to get the pitch you require. You cant get very much pitch with the standard stable head setup. If its fast cyclic and colletive you want then move both ball positions to the right and remove the paddle weights.

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