500 Derek's Trex 500 hover test
- Thread starter Derek
- Start date
Derek
Well-Known Member
Ok, just got done working on the 500.
I removed the entire tail section and set it aside. Removed the tail boom and the tail boom block (or whatever that plastic piece is called that the tail boom mounts in). Removed the original tail belt and I took a good look at the belt. There are threads sticking out on a good majority of the belt and the belt was, in fact, missing a bunch of teeth (well, they were worn down, not necessarily "missing"). It looked, to me, like there were "worn" spots on the belt. Ok...tossed that belt across the room, lol, and put the new belt on. Reassembled the tail boom block (or whatever it's called, lol), attached the tail boom, then moved over to the tail rotor. I took apart each and every little part. Took out each and every little screw, bolt, nut, washer, bearing, etc. Then put it all back together after repacking the thrust bearings with new grease and oiled the bearings on the rear. Put everything back together (used a bit of thread lock where applicable).
I moved to the tail servo next. I wanted to take off the control horn and rotate it to see if it would sit more-so at 90 degrees. The way that it was set was that the horn was pointing more to 12:30 (clock reference), instead of 12:00. I tried each of the 4 arms on the control horn and each position was still in the same position. So,I guess 12:30 will just have to do. I put it all together and turned on the Tx and plugged in the heli battery (after disconnecting the ESC wires, of course...safety) because I wanted to reset the limits on the gyro. I noticed that the tail rotor blades were no longer "in line" with each other. That's odd! I rechecked that the boom block was in position. I rechecked the tail boom was inserted into the block as far as it would go. Hmmm! As puzzled as I was, I just adjusted the length of the tail servo pushrod a few turns and now the tail blades are nearly perfectly "in line" with each other.
I guess I'm just waiting for tomorrow to try the 500 hovering again to see if the tail issues were solved because of the belt. I sure hope so. I still have to take back the defective servo that I bought and then try the "new" servo to see if it reacts differently than the one that I already have.
So anyway..that was fun! It took me back to when I bought the 500 and spent the time building it. I really enjoyed the build.
I removed the entire tail section and set it aside. Removed the tail boom and the tail boom block (or whatever that plastic piece is called that the tail boom mounts in). Removed the original tail belt and I took a good look at the belt. There are threads sticking out on a good majority of the belt and the belt was, in fact, missing a bunch of teeth (well, they were worn down, not necessarily "missing"). It looked, to me, like there were "worn" spots on the belt. Ok...tossed that belt across the room, lol, and put the new belt on. Reassembled the tail boom block (or whatever it's called, lol), attached the tail boom, then moved over to the tail rotor. I took apart each and every little part. Took out each and every little screw, bolt, nut, washer, bearing, etc. Then put it all back together after repacking the thrust bearings with new grease and oiled the bearings on the rear. Put everything back together (used a bit of thread lock where applicable).
I moved to the tail servo next. I wanted to take off the control horn and rotate it to see if it would sit more-so at 90 degrees. The way that it was set was that the horn was pointing more to 12:30 (clock reference), instead of 12:00. I tried each of the 4 arms on the control horn and each position was still in the same position. So,I guess 12:30 will just have to do. I put it all together and turned on the Tx and plugged in the heli battery (after disconnecting the ESC wires, of course...safety) because I wanted to reset the limits on the gyro. I noticed that the tail rotor blades were no longer "in line" with each other. That's odd! I rechecked that the boom block was in position. I rechecked the tail boom was inserted into the block as far as it would go. Hmmm! As puzzled as I was, I just adjusted the length of the tail servo pushrod a few turns and now the tail blades are nearly perfectly "in line" with each other.
I guess I'm just waiting for tomorrow to try the 500 hovering again to see if the tail issues were solved because of the belt. I sure hope so. I still have to take back the defective servo that I bought and then try the "new" servo to see if it reacts differently than the one that I already have.
So anyway..that was fun! It took me back to when I bought the 500 and spent the time building it. I really enjoyed the build.
Tony
Staff member
The blades should NOT line up when the servo is centered. You NEED a little right thrust. This will be done with the slider right in the middle of the tail shaft.
The servo should have the arm at 90º to the control rod. If you are at the 12:30 position, then you need to use sub trim to center the servo horn.
I'm now wondering if having the blades "perfectly inline" is not what is causing your hunting issues. The gyro senses that it's turning, gives servo input, goes back to the original heading, then sets the blades right back to being inline thus not giving ANY thrust to counter the main blades.
The servo should have the arm at 90º to the control rod. If you are at the 12:30 position, then you need to use sub trim to center the servo horn.
I'm now wondering if having the blades "perfectly inline" is not what is causing your hunting issues. The gyro senses that it's turning, gives servo input, goes back to the original heading, then sets the blades right back to being inline thus not giving ANY thrust to counter the main blades.
Derek
Well-Known Member
Ok, that will just about piss me off if the reason for these tail issues was from my unintentional and inexperienced sabotage!!
I tried to use the sub trim to 90 the servo horn and I give the Tx just a bit of adjustment and the servo rotates all the way over to the one side. So, I just put it back to 0.
To get the tail blades to have a bit of right thrust, with the tail blades folded up, should the first tail blade be pointed to the right a bit or the left?
I tried to use the sub trim to 90 the servo horn and I give the Tx just a bit of adjustment and the servo rotates all the way over to the one side. So, I just put it back to 0.
To get the tail blades to have a bit of right thrust, with the tail blades folded up, should the first tail blade be pointed to the right a bit or the left?
Tony
Staff member
The rear blade (if both are facing straight up) should point to the right. Basically, point the trailing edge to the right. But only slightly.
and you need to put the servo arm to 90 to the link. After you do that, unplug the battery then plug it back in to reinitialize the gyro.
and you need to put the servo arm to 90 to the link. After you do that, unplug the battery then plug it back in to reinitialize the gyro.
Derek
Well-Known Member
I was wondering about that, but forgot to ask. I had that problem, lol. Went to Subtrims and tried to move the servo, just a little bit, and the servo arm moved all the way to the one side. So, I just moved it back to 0. I have to work tonight and tomorrow but, on my next day off, I'll disconnect the tail servo from the gyro and connect it to the Rx and Subtrim the servo to 90.
Ken Jackson
Active Member
We've all been there, Hang in there Derek
Westy
LEGEND
good on ya! I had some major issues with my 450 last year and no one could really help .... had to figure it out by way of logical elimination of possibilities. turned out to be one faulty servo! even tested fine on the servo tester..... but not in service.
Feels good to actually solve it! .... you will be grinning like a Cheshire cat
Feels good to actually solve it! .... you will be grinning like a Cheshire cat
Tony
Staff member
YES, you must be in rate mode when setting the sub trim. Plugging in the servo to the Rx doesn't always work as the gyro could actually be sending a different centering position.
Derek, when we sat on skype, I explained this all to you. Put the gyro switch in rate mode, center the arm 90 to the linkage, and then center the slider so there is the same gap on the right and left side of the slider. This will give you a slight bit of right thrust and should solve the hunting issues.
This doesn't rule out the servo pot being worn out, but you need to set the tail up properly as I stated above.
Derek, when we sat on skype, I explained this all to you. Put the gyro switch in rate mode, center the arm 90 to the linkage, and then center the slider so there is the same gap on the right and left side of the slider. This will give you a slight bit of right thrust and should solve the hunting issues.
This doesn't rule out the servo pot being worn out, but you need to set the tail up properly as I stated above.
Tony
Staff member
YES, you must be in rate mode when setting the sub trim. Plugging in the servo to the Rx doesn't always work as the gyro could actually be sending a different centering position.
Derek, when we sat on skype, I explained this all to you. Put the gyro switch in rate mode, center the arm 90 to the linkage, and then center the slider so there is the same gap on the right and left side of the slider. This will give you a slight bit of right thrust and should solve the hunting issues.
This doesn't rule out the servo pot being worn out, but you need to set the tail up properly as I stated above.
Derek, when we sat on skype, I explained this all to you. Put the gyro switch in rate mode, center the arm 90 to the linkage, and then center the slider so there is the same gap on the right and left side of the slider. This will give you a slight bit of right thrust and should solve the hunting issues.
This doesn't rule out the servo pot being worn out, but you need to set the tail up properly as I stated above.
Derek
Well-Known Member
I must have forgotten that part of our conversation. Sitting here, now, I do remember you tell me that. I must have just been hastey and forgotten. I will make that adjustment when I get home in the morning. So, do I need to have the gyro in Rate Mode in order to sub trim the servo arm? After that, centering the slider will naturally give me a bit of right thrust, yes?
Derek
Well-Known Member
coolgabsi
Super Mod & DEAL KING!
you are not really missing anything. But I have never had to subtrim the tail servo. I am not saying you and tony didnt cover this, Tony knows what he is doing..
What I suggest doing..
take off the subtrim .. put it at 0
put the heli gyro in rate mode
then try putting the servo horn back on , rotating it by 90 degrees every time till you get a 90 WITHOUT any subrtim adjustment.
If this horn all 4 positions fail, try another servo horn. All horns ARE NOT the same. So that other one more than likely one position might just hit perfect 90.
you dont have to have the push rod connected. The horn needs to be 90 to the servo casing.. not necassarily to the push rod. Right now in your bird, th e way its constructed, it is coming out to be 90 to both case and push rod may be. But all you need is 90 to the servo casing.
Do this first.
Once you do that, you will have to redo your travel adjustment in GP780.
Also check for trim on the radio.. by chance if it is bumped. The way it looked, doesnt seem likely. but cant harm to give it a glance.
What I suggest doing..
take off the subtrim .. put it at 0
put the heli gyro in rate mode
then try putting the servo horn back on , rotating it by 90 degrees every time till you get a 90 WITHOUT any subrtim adjustment.
If this horn all 4 positions fail, try another servo horn. All horns ARE NOT the same. So that other one more than likely one position might just hit perfect 90.
you dont have to have the push rod connected. The horn needs to be 90 to the servo casing.. not necassarily to the push rod. Right now in your bird, th e way its constructed, it is coming out to be 90 to both case and push rod may be. But all you need is 90 to the servo casing.
Do this first.
Once you do that, you will have to redo your travel adjustment in GP780.
Also check for trim on the radio.. by chance if it is bumped. The way it looked, doesnt seem likely. but cant harm to give it a glance.