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Old May 08, 2005, 04:52 AM
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thanhTran's Avatar
Germantown, MD, US
Joined Sep 2004
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ARK X 400 build problem

I'll post the problem I face when building an ARK X 400 in this thread or some pictures when building it here

Here is one that I face now before I can do some hovering with it:



The problem is that the servo linkage won't be straight when connecting the link to the lever. HS56 servo is too high for this.

How would you fix that problem?

Thanks

Thanh
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Old May 08, 2005, 05:18 AM
Official Old Git!
Hampshire, UK
Joined Sep 2000
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Quote:
Originally Posted by thanhTran
I'll post the problem I face when building an ARK X 400 in this thread or some pictures when building it here

Here is one that I face now before I can do some hovering with it:



The problem is that the servo linkage won't be straight when connecting the link to the lever. HS56 servo is too high for this.

How would you fix that problem?

Thanks

Thanh

Thanh,

I'm unsure of what your problem is, it looks like you are concerned that the link is leaning out slightly (due to the servo height).

I don't this will represent any real problem for you, certainly not for hovering etc.
You'll be amazed how much slop, and misallignment helis can fly with - but the better you get them the nicer they are to fly (and when you are pushing the envelope, e.g. 3D flying then they start playing a part in producing problems).

You could, of course look at turning the 'Z' link up side down, so the 'Z' comes into the upper face of the servo arm, goes through, and comes out underneath!

Cheers,
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Old May 08, 2005, 06:09 AM
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I'm assuming a ball link on the underside of the servo arm will rub on the case? I guess that's going to depend on how long the arm is and how far it needs to travel.

Hard to tell from a pic, but a ball on the outside of the arm will make the pushrod angled quite a bit. I'm sure that would work but it's not the ideal situation, I think.

The HS-56 servos are really great but their odd dimensions, relative to most other servos, can be a challenge at times.

Anyway, if you want to retain the z-bend, you can try bending it. Keep in mind it's going to get a little shorter. If it ends up too short, maybe you could use a longer link? Again, not the ideal situation, but certainly usable for something like this.
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Old May 08, 2005, 06:15 AM
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One more thought...you could space out the ball on the collective swing arm thing. Again, not ideal but I'm pretty sure that will work, or at least help some.
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Old May 08, 2005, 06:29 AM
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Lateral thinking cap on/// Is it possible to mount the servo >behind< the side plate? This would involve removing the side plate to do it, and there might not be enough clearance at the back of the servo, but it would line things up properly. Otherwise, there is no great harm in having a bend in the linkage rod, provided it is stiff enough not to flex in use.

My $0.02..
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Old May 08, 2005, 06:43 AM
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Let it lean and go fly
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Old May 08, 2005, 11:49 AM
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Get rid of the z-bends
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Old May 08, 2005, 02:13 PM
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Mount the HS-56 from the inside. In other words have the servos mounting tab holes on the inside of the frame. You'll have to take off the one mounting tabs on the 56s so they'll slide in from the back. The linkage may not be straight up and down put it'll be a lot closer then what you have now.

Just FYI before you screw the ball linkage screw in you should use a little bit of CA on the screw as the hole seems slightly larger for the screw.
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Old May 08, 2005, 02:25 PM
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thanhTran's Avatar
Germantown, MD, US
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Hi Everyone,

Thanks very much for taking your time to give me answers.

The link will not be shorter if I bend it like ScotY suggested.

Tonnyscott, I already have the servo mount behind the plate . That only saves 1mm of servo height. All 4 servos were already behind the chassis plate.

If I let it lean, it touches the servo cases during its travel towards one of its limit ends.

I finally chose the bent method . it limits the negative pitch a little. But this could be saved by using longer servo arm to increase servo throw.

Thanks
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Old May 08, 2005, 02:27 PM
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Germantown, MD, US
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Elevator problem

I also found that the elevator control is very tought compared to the aileron and only have limitted travels. Is this true? or is it my build problem. I already have the Z bent 10mm away from the ceter of elevator servo arm.

Thanh
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Old May 08, 2005, 02:31 PM
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Quote:
Originally Posted by TheX
Get rid of the z-bends
While I don't particularly care for z-bends, they aren't always that bad. This is assuming one end has a ball link for adjustability and the pushrod run is fairly straight. If you have slop where the z-bend goes into the servo arm, just use some medium CA and let it wick into the hole in the arm...apply with the z-bend in place. The CA won't bond well and will effectively get rid of all the slop.
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Old May 08, 2005, 02:35 PM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
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Quote:
Originally Posted by mdttb
Mount the HS-56 from the inside. In other words have the servos mounting tab holes on the inside of the frame. You'll have to take off the one mounting tabs on the 56s so they'll slide in from the back. The linkage may not be straight up and down put it'll be a lot closer then what you have now.

Just FYI before you screw the ball linkage screw in you should use a little bit of CA on the screw as the hole seems slightly larger for the screw.

Thanks Todd, in the picture, the servo already behinds the frame plate. Looks closely you wont' see the ear right at the shiny screw. I have had the servo mounted from inside the frame. That's why I said in another thread that it will take ALOT of time to fix this helicopter after a crash if I have to replace the servos. All 3 servos are mounted this way.

I used a longer screw for the collective ball link as the stock one kept falling off. It's weird to have steel screws (fine thread) to screw to plastic like this design.

Do you have problem with the elevator arm? It's tought to move and even toughter when the flybar is at 3 & 9 o'clock position . I've already smooth out all ball links that I even see some slop some where. When moving the elevator click, the frame even moves a bit.


thanh
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Old May 08, 2005, 02:40 PM
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Quote:
Originally Posted by ScotY
While I don't particularly care for z-bends, they aren't always that bad. This is assuming one end has a ball link for adjustability and the pushrod run is fairly straight. If you have slop where the z-bend goes into the servo arm, just use some medium CA and let it wick into the hole in the arm...apply with the z-bend in place. The CA won't bond well and will effectively get rid of all the slop.
True, but if he were to lean the link over to attach to the mechanism it would be pulling the z-bend part way out of the servo arm making it even worse.
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Old May 08, 2005, 02:50 PM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
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collective problem

Here is the result of the changes to the linkage and servo arm




The problem now is that negative pitch is very little. If I make negative pitch large enough by moving the servo arm around the servo shaft, there will be reduce pitch in positive range AND the pitch is NOT 0 WHEN the stick is at the MIDDLE. I currently have all pitch curve and throttle curve FLAT in the TX.

Any suggestion? I don't think I need much negative pitch at the moment as I don't do any 3D yet, but just afraid that I could need it in a loop.
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Old May 08, 2005, 02:51 PM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
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Quote:
Originally Posted by TheX
True, but if he were to lean the link over to attach to the mechanism it would be pulling the z-bend part way out of the servo arm making it even worse.

Right, it touches the servo case. But i don't see how a EZconnector would be able to fit in this case. During servo travels, the connector would definitely hit the servo case.

Thanks

Thanh
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