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two elevator servo help

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Old 08-24-2005, 07:25 AM
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hancho
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Default two elevator servo help

I have a hanger 9 cap 232 27%. I have done all I know to make the plane quit snapping when pulling back on the stick. If you go very slow it will not snap but if you move it over 1/4 stick it goes crazy. I have put a angle finder on the elevators and set end point the same. It looks like one side is moving a little faster than the other side. The servos are on different channels. I once had a plane that I put a Y in with a servo reverse but it failed in flight and I lost it, So I don't what to do that now. My servos are not digital so I can not program them. What do you all suggest me to do. Thanks Andy
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Old 08-24-2005, 05:32 PM
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Default RE: two elevator servo help

I doubt this has anything to do with the movement of the elevators with respect to each other. Airbatic planes (especially the Cap) will snap when given a lot of elevator. This is a "feature" of the plane and is what allows it to do dramatic maneuvers such as walls, etc. Try a high speed loop, but using only a very little elevator. in other words a loop with large diameter. If it can do this, then keep trying tighter loops until it snaps out. This is the tightest loop you will be able to do. You can also experiment with the CG. I fly a 35% cap and have gotten used to this behavior.
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Old 08-24-2005, 09:54 PM
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Default RE: two elevator servo help

I have a H 9 Cap 232 27% that does the same thing, I believe that it is because I use too much elevator at times. I will probably set up dual rates to reduce elevator throw for loops and landings.
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Old 08-25-2005, 05:40 AM
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Geistware
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Default RE: two elevator servo help

Reduce the elevator throw so that at full throttle, full elevator does a loop and not a snap.
After this, you are set
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Old 08-25-2005, 07:47 AM
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Default RE: two elevator servo help

I really don't agree with the comments to "live with it." Yes these planes will snap with enough elevator, however, like the full size it can be prevented completely. I also really doubt that a small amount of unequal elevator movement is causing this. You can completely prevent this if you could keep the plane from yawing during a hard elevator pull. (ie keep the ball centered) Both wings would stall at the same time and you would not get a wing drop. RC pilots don't have the luxury of knowing when the plane is yawing during flight unless it is a huge yaw. This is an easy fix! My guess is the right wing drops during a hard elevator pull. If this is the case, you will need to add left yaw (rudder) during the elevator input, or you can trim it to prevent this from happing. Get rid of some or most of the right engine thrust (if snapping right) or mix throttle to rudder to prevent some of the tendencies that a prop driven plane has from yawing left with power up & right with power down
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Old 08-30-2005, 02:16 PM
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Default RE: two elevator servo help

Like everyone else has aluded to, your snap problem may be related to the overall plane setup, not just the elevators.

Having said that, check out the geometry of your elevator servos. In order to get synchronizing movement both servos must be identical types, electrically centered, the physical connections must be identical (push rods same length, angles between the servo arm and surface control horns must be identical), and the endpoint movements +/- center must be identical. You cannot do this just by using the TX's Subtrim and Endpoint adjustments because combined they change the overall geometry of the servo's path and rate. There is two sure ways of accomplishing the centering and endpoints: 1) servo programming, e.g., Hitec, or 2) a JR Matchbox or Futaba MSA-10 Servo Synchronizer. I'm not familiar with the JR Matchbox or the Futaba Servo Synchronizer but am with the Hitec Programmer. I use the Hitec Programmer with Hitec Digital servos and set each elevator servo programming with the servo installed on the airplane -- I use Futaba's AILEVATOR programming. The programming process involves switching back and forth between the programmer and my Futaba 9C until the center is set on both and both sets of endpoints are set. All of this involves the assumption that given a proper neutral point each servo travels at exactly the same rate +/- a very minute time difference due to master/slave processing of the control movement. You can even eliminate this difference by using a 'Y'-connector instead -- use the programmer to reverse the direction of one of the servos.
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