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HelicopterMain Discussion › Throttle servo setup... uggg!
06-06-2012 11:23 AM  5 years agoPost 1
punkin71

rrApprentice

illinois

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In the middle of installing a futaba s9253 on my vibe 50, this is the part of building a nitro heli that causes me the most grief. I have very little problem with any other part of setup be it gyro/tail, ccpm or fbl, radio setup, etc. Trying to keep endpoints close to -100 +100 for gov, getting arms at the correct angle, man it's like a black art to me! I'll get it done just takes a while. Just needed to vent.. Any others have the same problem?

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06-06-2012 11:29 AM  5 years agoPost 2
rstekeur

rrApprentice

Ft Myers, FL

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Im in the same boat. I wish there was a video somewhere

Even a stopped clock is right twice a day

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06-06-2012 12:03 PM  5 years agoPost 3
McKrackin

rrProfessor

Lucasville,Ohio

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Adjust the end points to get full range of motion both ways.
Add the two together and divide by two.

Make the result the end point in both directions.

Set the throttle stick to 50%

Remove the throttle arm on the carb.
Close the throttle barrel manually.
Put the arm back on but leave it loose.

Lower the throttle stick to zero and tighten the arm on the carb.

Now the end points are equal in both directions.

Adjust the ball on the links in or out to get closer to 100%

I literally never use the word literally right.

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06-06-2012 12:04 PM  5 years agoPost 4
Richardmid1

rrProfessor

Leeds, England

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Center the servo arm by plugging it straight into the throttle channel and going to mid stick (check throttle curve is linear, 0-100).

Put the servo arm 90 degrees to the carb arms pivot point.

Adjust the link so the carb arm is parallel to the servo arm remembering to keep the carb in the half open position. (throttle trim should be fully down).

Now use different servo arm holes to get as close to fully open and fully closed without binding.

Now use throttle end points to fine tune open and closed position, between 80 and 120 is fine for most governors.

Engine should now idle at mid throttle trim.

60% of the time, it works every time!

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06-06-2012 12:13 PM  5 years agoPost 5
McKrackin

rrProfessor

Lucasville,Ohio

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Also correct.
I forgot the part about trim and the two arms being parallel.

I literally never use the word literally right.

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06-06-2012 02:15 PM  5 years agoPost 6
marc8090

rrElite Veteran

Long Island, N.Y.

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Richardmid1 has the right way of doing it. Your endpoints do NOT need to be the same on the throttle. If you do it the way he says you will have the carb half open at half stick, fully open at full stick, and fully closed at low stick with the trim full down or throttle cut engaged. As long as the endpoints give decent resolution you'll be good to go.

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06-06-2012 02:23 PM  5 years agoPost 7
McKrackin

rrProfessor

Lucasville,Ohio

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The end points being the same is also correct.

If it's fully closed at 0% throttle and fully open at 100% throttle...where do you think it is at 50% throttle?
Half open.

If your end points are +95 and -95...Where is it at 0?
Half open at half throttle.

If your end points are +120 and -80 there is no way the carb is half open at 0 but I guess it won't matter because half throttle will actually not be 0 but rather +20.

The throttle looks better and is easier to understand if 50% throttle is 0 on the movement scale.

The servo horn and throttle arm should be parallel and in the center of the arc at half throttle as well.

I literally never use the word literally right.

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06-06-2012 09:33 PM  5 years agoPost 8
Dood

rrProfessor

Wescanson

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Look here. It is a PERFECT throttle setup (done by me).

Look at the yellow lines. They're the same length. Your linkage (from ball to ball) must be the same length as the distance from the center of the servo output shaft to the center of the carb barrel arm.

Look at the red lines. They're also the same length. Attach the ball at the same distance from center on both your servo arm and your carburetor arm.

By getting both of these measurements correct, you won't have any problem getting 100-100 endpoints without binding.
100H will get you WOT, 100L will be very close to idle, and there will be a little extra at the bottom to fully lower your throttle trim without binding.

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06-06-2012 10:09 PM  5 years agoPost 9
McKrackin

rrProfessor

Lucasville,Ohio

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The push/pull link makes it pretty easy to get them parallel but I don't have one

Nice set up Dood.

I literally never use the word literally right.

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06-06-2012 10:16 PM  5 years agoPost 10
Dood

rrProfessor

Wescanson

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The P/P setup on a throttle is overkill, but serves a purpose. I did it because 1) I had the extra parts, and 2) it is supposed to limit wear and tear on the carb barrel.

The key is to get the rods the proper length. One you have that, everything else falls into place.

Here's a hint: Set up your throttle linkage with the carb arm screw LOOSE. With the throttle stick fully raised, manually open the carb to the most open position, and tighten down the screw. Simple!!

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06-06-2012 10:43 PM  5 years agoPost 11
McKrackin

rrProfessor

Lucasville,Ohio

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Here's a hint: Set up your throttle linkage with the carb arm screw LOOSE. With the throttle stick fully raised, manually open the carb to the most open position, and tighten down the screw. Simple!!
My throttle closes with CW rotation so I set it with the barrel fully closed.

When I tighten the screw,it forces the barrel tight closed while tightening it.

If I did it fully open,the hex driver will be trying to close the carb while the servo holds the link open.

I literally never use the word literally right.

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06-07-2012 12:42 AM  5 years agoPost 12
punkin71

rrApprentice

illinois

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Got it all lined out now, only took about 1.5 hours after work today! Endpoints came out to 99/91 so my throttlemax will be happy with that. Also had to reverse throttle channel from the old hitec 5925 servo as I expected it would need to be done. Gonna do a test hover tomorrow after work in the back yard, reprogram Idle 1 and 2 headspeeds I'm sure all wil go fine

Thanks for all the responses and help!

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06-07-2012 12:49 AM  5 years agoPost 13
McKrackin

rrProfessor

Lucasville,Ohio

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I also have a Hitec throttle servo.
Just got it and had to reverse the throttle channel.

My Switchglo Pro is Y'd in my throttle so it lights the plug at low throttle and turns off at higher throttle.

Took me a while to realize my Switchglo is also reversible.lol...

I had the throttle servo horn and throttle arm all screwed up for a couple of days to keep from reversing the throttle.

Servo horn pointed up and throttle control arm pointed down

Finally remembered the SGP is reversible so all is right now

Just thought I'd share.

I literally never use the word literally right.

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06-07-2012 05:57 PM  5 years agoPost 14
marc8090

rrElite Veteran

Long Island, N.Y.

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If you had exactly full throttle at 100% endpoints, and exactly full closed at 100% endpoints, go to mid stick on a carb with marks on it (like OS) and half stick will NOT be half throttle. Because of throttle trim only working at low stick, or throttle cut if the radio has it, you WILL have different travels from half to full throttle, and from half to closed. This is one area where you don't need, or want for that matter even endpoints.

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06-07-2012 06:05 PM  5 years agoPost 15
Dood

rrProfessor

Wescanson

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and half stick will NOT be half throttle
Mine is. If yours isn't, you didn't get the servo at 90°, you didn't get the linkage the right length.
This is one area where you don't need, or want for that matter even endpoints.
Some governors/ radios REQUIRE that your endpoints are at exactly 100-100, for example the 8FG.
Not 98, not 99, but 100.

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06-07-2012 06:09 PM  5 years agoPost 16
McKrackin

rrProfessor

Lucasville,Ohio

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My end points are identical and 50% throttle and 50% trim is almost exactly half open on the carb.

It's an OS91HZ-PS

Trim is just basically applying throttle so if you set it up at -100% and zero trim and +100% with 50% trim....50% throttle and 50% trim is almost exactly half open.

Your mistake is still having the trim at 0% when you set your high end point...Set trim to 50% when setting high end point.

I literally never use the word literally right.

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06-07-2012 06:35 PM  5 years agoPost 17
Dood

rrProfessor

Wescanson

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If you had exactly full throttle at 100% endpoints, and exactly full closed at 100% endpoints, go to mid stick on a carb with marks on it (like OS) and half stick will NOT be half throttle.
Look where the tick mark is in this picture. That's at mid stick with the servo wheel and carb arm both at 90°, parallel to each other.
If you can't achieve this result, it means you did it wrong.

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06-07-2012 07:11 PM  5 years agoPost 18
jgunpilot

rrKey Veteran

Pollock, LA

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I don't even want to think about all the carb barrels I've worn out. Let's just leave that one alone.

OK, it's zero. But the PP linkage might have other advantages, so I'm for it.

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06-07-2012 08:00 PM  5 years agoPost 19
McKrackin

rrProfessor

Lucasville,Ohio

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Full open
+50% trim
+100% travel
Center
-100% travel
-50% trim
Full closed

I literally never use the word literally right.

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06-08-2012 12:40 AM  5 years agoPost 20
punkin71

rrApprentice

illinois

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Was able to test hover in the back yard today and all went smooth as silk. my revmax limiter seems to respond faster with the 9253. The 7 year old Hitec mg servo I was using before had a lot of slop in the gears but it was used as a steering servo back when I raced 8th scale buggy so that's understandable.

Anyhow, can't wait to get the heli out this sunday to test it proper!

I do like the idea of P/P on throttle, would make setup much easier for me, the second link could always be removed after setup if one want to.

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HelicopterMain Discussion › Throttle servo setup... uggg!
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