xanadu_vector

My Feedback: (5)

Raptor 30 Pro, OS 37, JR XP8103, GY 401, Futaba S9254. Everything here is bench results, no flight testing.

Here's the situation. I'm building my first Raptor 30 using the stock mounted tail servo (non-boom mount). On the raptor technique setup section it says to use a ball at 13mm from the center of the servo. I set everything up and the throw is great and perfectly centered. The GY401 limit is just over 100 and the end point adjustments on the radio are 100% left and right rudder.

The problem is at half the throw of the rudder stick the rudder is at its limit, which also messes with my expo settings.

So I could change the end point adjustments in the radio, to get the full throw of the stick. I have to set them on 50% to get the stick and rudder to both max at the same time. The limit adjust on the gyro will only shorten the throw or bind the linkage at this point. Anyway I don't want to have my EPAs on 50%, I like everything to be set up mechanically as close as possible.

This leaves me with moving the ball closer to the center of the servo arm. I hear that 13mm out gives way better tail control though. Should I just put my EPAs on 50%? have any advice?

rusirius

You weren't specifc about which end points you are adjusting, etc... I also have a rappie with the GY401 and 9254 combo... My setup is basically like this... The gyro channel (6) has it's end points set to 100/100... The rudder channel (4) has it's end points set to 85... HOWEVER... The rudder channel end points DO NOT! adjust the amount of travel of the rudder... Basically changing the end points on the rudder channel will change the piro rate....

Are you checking this in HH mode or normal mode? If you are in heading hold mode and attempt to move the stick even a little bit, the tail rotor pitch will go full bore in that direction... Basically you are telling the heli to turn, but since it's not flying it CANT... So the gyro keeps feeding more and more input until it's maxed regardless of where the stick is at... If your in "normal" mode, then it will basically act "normal" like you would expect (assuming you don't move the heli around).

As for the limit on the gyro, make sure you are in normal mode, pop the linkage off the tail rotor servo, then throw the stick full in one direction and move the rotor all the way in that direction by hand... Adjust the limit on the gyro to match it... Throw it full the other way and test that side.... If your end points are set even on the radio, and it doesn't match up (one side matches, but the other is way off, then you need to adjust the length of your linkage accordingly...

Hope that makes sense... If you have any other questions I'll try to help as much as I can...

xanadu_vector

My Feedback: (5)

Thanks for your help. The gyro is in normal mode. I'm not having issues setting it up, I'm wonder which way to do it is better to start with, I mean eventually I'll flight test it both ways but here's the deal. Forget about everything except for these two things:

With the rudder ball 13mm from the center of the servo and rudder channel epa set at 100% the tail rotor pitch reaches full throw at half the throw of the rudder stick...

There're two ways to fix it, I could move the ball in on the servo arm causing less of a mechanical throw allowing me to turn up the limit on the gyro and keep the 100% epa on the rudder channel.

Or

I can leave the ball at 13mm and set my rudder epa at 50% each direction.

But... I don't want my epa to be at 50%, I also would like to keep the ball 13mm from the center of the servo. The linkage is perfectly aligned (both arms 90 degrees from rod on center, and it travels the same distance in each direction. Shortening or lenghting the linkage is totally out of the question.

So... EPA=50% (does this affect expo?) or move ball in on servo arm (13mm highly recommended)?

Thanks again for any advice.

rusirius

okay, your just getting too much movement out of the gyro then... set the EPA back to 100%... pop the link off the servo, turn everything on... put gyro in normal mode... shove the rudder all the way to the left... push the tail rotor in that direction as far as it will go... (the servo should be way past it now based on the conditions you described... ) Now turn the "limit" pot on the gyro until the servo matches up perfectly to the link.... Check it the other direction.. If the mechanical link is 90 degrees it should match up that way too.... Snap the link back on and it should work perfect and be linear through the whole movement of the rudder stick....

rusirius

I guess I could have made that a little bit clearer by saying, "The limit pot on the gyro is what adjusts the travel distance of the tail rotor servo..."

xanadu_vector

My Feedback: (5)

Okay I tried that, I get the same thing but to a lesser degree. Basically with all my epa's at 100% and the gyro limit all the way up the servo reaches its mechanical limit before the tx stick does. That basically means I have no choice but to turn down the epas, right? I connected the servo to the rx w/ out the gyro and with 100% epa it moves with the full throw of the stick. When the servo is connected to the gyro in non-hh mode the servo stops just short of the sticks movement to the left and a little more than that to the right (stick), even if I turn epa's past 100%. Is it a bad gyro? Or is this common?

xanadu_vector

My Feedback: (5)

To get the full swing of both the rudder servo and the tx stick with the gyro I have to use EPA Left 74% and Right 64%. With that setting and the limit on the gyro all the way up the stick and servo stop moving at the same time.

xanadu_vector

My Feedback: (5)

Oh the sub trims are centered and the switches on the gyro are check. The rx is a JR R700.

rusirius

you said you turned the limit up? I assume you meant down? (the lower the limit, the less total travel the servo will have...) With the limit turned all the way down, and the EPAs set for 100% you shouldn't get any more than about 1/4" movement out of the tail rotor servo (at 13 or 14mm).... If the limit is turned all the way down and your still getting way more movement out of the servo than your rotor allows, it sounds like you've got a bad gyro... Mine is set just below 100.. it's actually a tad less than the full movement of the tail rotor, but it's about all I can do without the linkage hitting part of the frame with full left rudder....

xanadu_vector

My Feedback: (5)

I can turn the limit down, and the servo only moves a little. When I turn it up, it moves further. When I turn the limit all the way up and my tx epa's are 100% the servo stops moving before the stick does, what I'm saying is when using the gyro the servo doesn't move as far as without the gyro. Without the gyro connected the servo will move until I can't move the stick any further. With the gyro (non-hh and hh) the servo stops at 74% of the throw of the left stick and 64% of the throw of the right stick.

xanadu_vector

My Feedback: (5)

It seems like the only way this will work is the gyro limit on 100, and the rudder end points L 58% and R 48%. With these setting when the stick hits full throw the rudder reaches max travel each direction. The slide bushing slides 5mm each direction evenly across the throw of the stick. The only thing is that this brings me back to my original problem. I've read that if you have to make drastic changes to epa or they are more than 5% from eachother then its some kind of setup problem...

I don't know why this is happening, the rudder epas both set at 100% and the gyro moving the servo further one direction then the other with trims and sub trims centered and not reaching full throw of the servo at the same time.

If I plug the servo into the rx bypassing the gyro it works fine, the servo reaches its limit as the stick does, and the same amount of travel each direction.

rusirius

Okay, so let me get this straight... no... wait... let me phrase it like this....

Okay, lets assume for the rest of this message that the epas on the radio are all at 100% and the gyro is in normal mode....

If you move the stick half way, and the servo stops... The only reason it should stop is because it's reaching it's mechanical limit and can turn no more... If that is happening, then by turning the limit down (towards 0) you are decreasing the amount of travel the gyro gives to the servo.... So, for example... your at half stick and you reach the mechanical limits of the servo... if you decrease the limit, the servo should move back, and therefore give you more "room" before reaching it's mechanical limit.

Now if that is not the case... Then is this happening... If your total linkage movement is 1/2 inch... and it reaches this point at half stick... you decrease the limit on the gyro, and now the total movement is only 1/4 inch, but it still won't move any further once you hit half stick??? So in other words, at 1/2 stick, the linkage has only moved 1/4 inch but still won't go any further???

If that's the case, it may be something in the gyro, but it may also be something in the radio... Are you sure there isn't any sort of mixing turned on? No collective/rudder mixing or anything like that?

I guess the point I'm trying to make is... If the servo won't move any further at half stick, it's got to be because the servo is reaching it's mechanical limit... By backing the limit on the gyro off, it should make the "distance" moved at half stick less... and therefore not at the limit... see what I mean? (sorry, it's hard to explain....) Let me try this....

If the servo itself has 100 points of total movement.... If the limit on the gyro is set too high, it will be trying to get say 200 points of total movement out of the servo... That means at half stick, it's already reached 100 and the servo can't move any more.... By decreasing the limit on the gyro, it will only try to get 100 points of movement, so at half stick it will only be calling for 50 points of movement, thus it can go on for the other half of the movement of the stick and get the other 50 points out of the servo... make sense?

xanadu_vector

My Feedback: (5)

There is no way to get the servo to its mechanical limit using the gyro. I can tell this by setting my epas at 100% and then doing these two things. (1) With gyro in normal mode full left stick gets me 74% of the travel that the servo has when plugged into the rx. In other words the gyro can only move the servo to 26% from its mechanical limit, and without the gyro I get 100% of the servo. (2) Moving to the right is the same thing, but it only travels 64%, leaving the servo 36% from its mechanical limit. This also makes the throw 10% off center compared to not using the gyro.

No mixing here at all. I am very proficient with this radio.

Yes, what you say makes sense. The thing is that with the gyro hooked up and the limit all the way up the stick stops moving the servo before its mechanical limit. With the gyro limit turned down I get the same thing, just less servo travel in the same amount of stick movement.

Either way, the only way I can get the linkage and the stick to reach its full potential at the same time is by turning down the epa because even with the gyro limit all the way up and the epas all the way up the servo stops moving before the stick does (and its not stopping because of it mechanical limit, its just not moving any further) To make matters worse it moves less in one direction than the other, which also means its not the mechanical limit of the servo.

Now I tested the servo connected directly to the rx and the tx moves it to its mechanical limits perfectly (same limit each direction). Should I assume the gyro is bad? By using the end points (L64% and R74%) it is configured and works fine, but the fact that the gyro wont turn the servo all the way bothers me. I mean its not that bad of a thing since if it did turn all the way the linkage would bind, but I don't want to use a bad gyro if thats the case you know?

xanadu_vector

My Feedback: (5)

Wait, turning the limit trim pot has to no effect on the travel of the tx stick in relation to the servo, it make the servo travel less but still leaves a dead zone at the end of the sticks throw.

The only way to get rid of the dead zone is with EPA, in my case anyway... Then after I get my end points to where the full limit on the gyro is good I can turn down the gyros limit to make the control throw the right distance. Of course this leaves me with low epas and the fact that they're 10% off from eachother

rusirius

hrmm.. okay, now i follow exactly what it's doing... The gyro is set for a digital servo? The gyro isn't reversed? Wait... that could definately do it... The gyro mixes itself with the rudder... If one or the other is reversed, when you went full rudder in one direction or the other it would be mixing a - and a + for example, and causing it to negate much of it's movement??? I'm guessing the gyro is set right... Easy enough to check... Turn the gyro on, let it init (it has to start up in HH mode, but then switch it to normal mode. Move the rudder stick to the right... It should PULL the linkage from the tail... If not, reverse the channel in the radio (channel 4)... Now recenter the stick and push the nose to the right (looking straight at the nose) or to the left if your looking up it's back side.... The linkage should PULL from the tail again... If it PUSHES then flip the reverse on the gyro....

If that still isn't it, what is the gyro sensitivity set for (channel 6)? Have you tried setting it to 100 for position 0 and 0 for position 1?

And if that doesn't fix it... I'm starting to run out of ideas....

rusirius

You know... the more I think about it... the more i'm convinced it's a reversed gyro or channel problem... Normally the EPA/ATV will NOT adjust the TRAVEL of the servo... It's basically just changing your piro rate... By dropping the EPA to 50 you should be effectively cutting the piro rate of the chopper in half (i'm sure you know, but just in case, the piro rate is how fast the tail will spin around).... Since your getting the full movement by setting it at 50, it sounds like your taking out some of the - mixing the gyro is putting in and therefore getting more of the + throw the radio is sending... If that makes sense.... Anyway.. make sure something isn't reversed...

xanadu_vector

My Feedback: (5)

Okay I just got off the phone with the heli tech where I purchased it. He said that it should travel the same amount each way. He also said that the dead stick is normal and that the gyro is still taking the tx signal, it just cant do anything with it because the heli isnt yawing on the bench.

About it moving further one direction than the other. I measure it this morning and it's fine. I know I was measuring correctly last night, although I did charge the batteries overnight.

Thanks for all your help, basically it looks like I spend too much time bench testing and not enough time flight testing. I just didn't want to get the gyro dirty if I was going to have to return it....

Oh and I've been saying that the epa is adjusting the throw of the stick, in relation to the servo, not the throw of the servo. And no, the channel is not reversed.

I think the reason for all the dead stick is giving the gyro just a little input without they heli yawing is going to max out the gyro right away, if the heli turned with the stick it would move the servo as much as the distance of the stick moved because it would be using less output since the heli would actually respond to the command. Less servo output means more stick travel.

Okay the bottom line is ON THE BENCH the servo will reach max throw with a small input of the tx stick because the gyro says "turn faster mr servo, the heli isn't yawing at all!" and this is true in both heading hold and non-heading hold mode.

In the AIR a small input from the tx stick causes the gyro to say to the servo "okay turn, wait thats good", with more stick the gyro asks more of the servo.

I know this is common sense to everyone that knows how a gyro works. But I had to type it all for my own benefit, and the fact that nobody else offered it up (probably because it common sense) but whatever it may help someone else who is BENCH TESTING a gyro.

rusirius

Yes, it should move the same amount in both directions... if your measuring the throw of the servo... The pitch of the tail rotor however will be "skewed" because of the torque of the engine... You will have much more pitch in that direction than the other...

I appoligize for not catching this earlier... I was thinking about your problem and comparing it to my setup... I kept checking and sure enough I had full throw with full stick in both directions... Then after reading your email it finally hit me.... I had the dual rates switch on which was knocking the piro rate way down... bumped it back up to 100 and sure enough basically the exact same thing, roughly half stick and it was at full movement... Yes, your right, even in normal mode the gyro is mixed in with the channel, so when you try to move it and it doesn't respond the gyro "adds" itself to the mix making it reach limits much quicker...

Again, sorry I didn't pick up on that sooner... These msg boards are great, but sometimes communicating in text can be a bi*$h...

xanadu_vector

My Feedback: (5)

I guess it does move the same amount in each direction, the linkage at the tail certainly moves the same amount each direction. I ended up with the gyro limit right at 100.

rusirius: Thanks for all your help, i really appreciate it! I know what you mean about the miscommunication. Thanks for checking it on your heli, that makes me feel a lot better to know before I take off.