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Spartan RC Spartan RC - Quark, DS760 Gyros and other Spartan RC Electronics Factory Support |
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05-01-2011, 09:02 PM | #1 (permalink) | ||
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Join Date: Feb 2009
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Thinking out loud.... DS760 / 3400g / Rave 450 = meh...
I stole the Hitec 5065 cyclic 5084 tail servos off my Rave for the Mini Protos as they were better suited for FBL. I replaced the servos with JR DS285s and 3400g (my 3500g is down with a stripped gear). I had previously been flying the Rave with a Quark but stole that gyro for my Gaui 200 so I replaced the Quark with a Spartan DS760 which I have heard is just as good. Anyway... long story short... the tail sucked on the Rave now. Bounces to a stop in one direction and slides to a stop in the other.
I borrowed a buddies Flash Link cable and I updated the firmware from 2 to 2.1. I played around with settings with no real spectacular results. I decided to move the ball out one hole on the servo arm which should effectively speed up the servo at the loss of some TQ. All this really did from what I could tell was make me lower the gain. I am down to 25% (Spektrum gear EPA) for gain. I was still getting a bounce on CCW stops and a slide on CW stops. I decided to keep messing with the settings. In the end, I used the Flash Link to get the servo arm at 90°, reprogrammed the servo limits which were very skewed now, turned deceleration all the way down, turned acceleration half way down, turned stop gain up to 150 on CW and down to 50 on CCW. After those adjustments, it seems that the tail is livable. I really need to get the 3500g on the tail..... but now I am curious about the effects of ball position on gyro performance. The Spartan manual states: Quote:
Quote:
Rave 450 Beam E4 Outrage G5 Furion 450 Mini Protos Trex 450 Pro
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Ivan |
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05-02-2011, 10:39 AM | #2 (permalink) |
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Join Date: Aug 2010
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These are just some thoughts about what you are saying.
I think what Spartan is saying, is that the heli manufacturer is the one that designed in the total travel on the tail rotor shaft, the mechanical linkages etc that determine the limits of pitch. You would hope (!) that they thought this out a bit ). If the rotor shaft is too short, you might not get enough pitch, and if too long, there is more than you need, and in addition, the shaft can flex more than if it were shorter (and adequate for the job). Now the tail is doing two things--compensating for the main rotor torque, and secondly giving you rudder inputs to yaw the heli. Both are just applications of thrust on a lever arm. As far as the heli is concerned, it is the total torque that matters, not how it is being made. The level arm is pretty much set by your tail boom length, so for that it is pretty much fixed unless you are really into modding the heli. So the thing we are varying all the time is thrust. I know I have made this story too long, but the thrust (more or less) is a combination of 3 things, pitch, rpm, and blade size. Increasing any of these 3 things will produce more thrust. What I am getting at is that simply looking only at pitch is ignoring these other variables. It is true that pitch is the thing the gyro is changing, and is the largest factor, but my guess is that the difference you are showing in your photos of different helis is probably on the scale of the differences we have from running different head (and hence tail) rpm, and using non-stock blades on the tail. Now what was the point I trying to get at???? Oh yes, probably doesn't matter that much---except if you are at the extremes (high or low rpm, large or small blades, or too much or too little pitch). As long as you are in a nominal middle area, the gyro can probably cope ok. Why does your signature have so much meaning to me? |
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