osterizer

Pretty good, Tex. How are you? I hear the weather should be getting better over there now so you can go chop some more corn .

Heliman-1: I'd try an 11T pinion to start with.

osterizer

hikai- with that setup I'd be looking at tail binding, head speed, and gyro setup or tail range setup. When you power the heli up, the tail should start off with a little right pitch- what does yours look like?

dpleasants

The screw set is hel002. Their web site is www.rcscrewz.com

Ductapemaster

Well, I took my heli over to the hobby shop today to get it set up! First off we worked with getting the swash working correctly. I had to switch two servo leads and reverse a bunch of stuff in the radio...my darn radio manual doesn't say anything about which channel is which when hooking up the swash servos! Once we got it working, we took it out to the parking lot for a test flight. We spun it up and it didn't go anywhere! We realized that the pitch was backwards and we were giving more negative collective when it should be positive...not cool since we just got everything adjusted. To fix it we went the cheap route and I just reversed the pitch curve (starts at 100 and goes to 0) and we were set to go. Back out to the parking lot...we spooled it up, gave it a little collective...and...it flew!!!! I was ecstatic! And to think I wasn't the one flying it...

Well, that's my story...it still needs a bit of adjustment before I go fly. A little ESC programming and a small gyro gain adjustment and I'll have my first flight by myself!

Wish me luck!

-Dan

osterizer

Good deal, Dan! Glad it's working now- getting a little help there is the best way to get ther.

BTW, you just need to reverse the sign of the collective part of your swash mix. I could tell you how to do it on Futaba, but I don't have a Spektrum radio so I can't point you to just the right setting. Hopefully someone with a DX is listening in.....

Ductapemaster

I tried that already...it didn't seem to work, but maybe thats just me. They're set at 100% Aileron, 60% Elevator, and 60% Pitch. Should I just reverse the pitch value or should I do all of them? This means more readjusting...I better get used to it!

Thanks!

-Dan

EDIT: Anyone have suggestions on how to mount the battery? Mine just hangs off the end of the "mount" that comes with it...I don't really like this configuration and the body won't fit on it.

hikai

My Feedback: (2)

osterizer: The tail wants to turn right as the pitch or throttle increases. The normal throttle curve is 0 45 70 85 90: at mid stick or 0 pitch the main rotor turns about 2400 rpm. The KV of the brushless motor (OBL 29/35-10H) is 3500KV. The spur gear is 14T supplied with the MX450. The ESC is an ACE RC BLC-40 No. 8041-H. The motor and esc were removed from a Tunder Tiger MiniTitan. The normal pitch curve is 40 - 50 - 100. The main rotor pitch at the lowest throttle setting for the Normal Throttle and Pitch curves is about -2 degrees. The main rotor pitch at the highest throttle setting for the Normal Throttle and Pitch curves is about +8 degrees. The swash mix is set at 120 degrees with AIR +90, Elev +90 and Pitch +90.

easternav

Well I guess I'll give the mx another try. The last time I drove her tail first in the ground and desided that I was not going to rebuild it because I wanted a trex 450 se v2,but the price is just out of my range.[]So I give it one more try. Does any one know what kind or if any replacement parts can be bought to get better tracking? I have had one heck of a time trying to get them to track.

easternav

one more ? how far is the swashplate suppost to tilt? in deg.

osterizer

Wow- if you're using the Ripper you really need to back off from the 14T- more like an 11T! The 14T will spin the blades off the MX.

With that, next is the gyro and tail servo. Which are you using?

hikai

My Feedback: (2)

osterizer: The tail servo is a Futaba S3114 and the Gyro a Futaba GY401. I've checked the gyro by installing the gyro on different heli with a Futaba digital S9650 tail servo. The hovering was great with the Futaba GY401 gyro installed on the other heli. If the gyro is bypassed and the servo connected directly to the rudder channel of the receiver, the Futaba S3114 servo appears to be ok. Servo is centered with no movement of the rudder stick on the reciever, right stick the servo move in one direction and left stick the servo moves in the opposite direction. I also replaced the Spektrum AR6100 receiver with another Spektrum AR6100 receiver that I had to remove from an byplane. No luck... same symptoms. Any ideas would be appreciated.

osterizer

Hi, hikai. It sounds like you have things going in the right directions. I've used the 3154 (digital version of the 3114), so I'm pretty sure the 3114 should work. I assume you've tried increasing the gain so the gyro will come in sooner?

Also, it's probably fine, but you should also check the tail belt tension so you're sure it's not slipping.

Did you check the pitch range on the tail? When mine was set up at 2400, I'd have about 5 degrees right pitch at neutral versus flat, then full right was about 40 degrees, and left maybe 10 degrees. I had the ball on the servo arm 7 or 8 mm from the center, then trimmed the neutral position in rate mode to hold zero with no transmitter trim by adjusting the length of the pushrod. If you can get it adjusted properly in rate mode, then AVCS will hold without a problem.

hikai

My Feedback: (2)

Hi Osterizer. Changing the gain on the gyro has little or no affect on the symptoms of the problem. The belt tension is adjusted per the instructions and appears to be ok.. If I turn the main rotor and hold the tail rotor there is no slippage.
With the gyro in the non-heading mode the pitch of the tail rotor in the horizontal position is close to neutral (90 degrees) with the rudder stick of the transmitter in the neutral position. Full right stick the tail rotor turns about 10 degrees from the neutral position and full left stick the tail rotor turns about 15 degrees from the neutral position. The servo arm ball is between 7 and 8 mm from the center of the servo arm. You set your tail rotor pitch at 2400... what is 2400 in reference to??? It apprears that your tail rotor will move about 50 degrees from full right to full left stick on the rudder. What is the process to measure the tail rotor movement in degrees. It appears that your tail rotor will move 2x more than my tail rotor.

osterizer

Ductapemaster- I asked another RCU member who has an MX, and he has his mixes set to the following:

CP2= -75
CP3= +75
CP6= +75

You don't need to worry about the values, but you may get something from comparing the signs. I don't know which is the collective, aileron or elevator values (why doesn't spektrum give them useful names?) but reversing the sign of one of them should reverse the direction the collective moves with the stick.

Sorry if I'm not being more helpful-- I'm trying to find info on a radio I don't own .

osterizer

I think we might be getting somewhere here . The center is way off.

I don't have anything for measuring the pitch exactly, just an eyeball that's been looking at them for a while, so my numbers may be off a little, but not much. If you can tell that they're tilted then that's about 2 degrees; if they're obviously tilted, but not much, that's 5 degrees. If it's halfway between 0 and 90 then that's 45 degrees- you can interpolate the rest.

The way it works is, you need a lot more right pitch in the tail than you do left, so your neutral servo position needs to be right biased. (So we're speaking the same, when I say "right pitch" I mean that the trailing edge of the blade is angled to the right, and produces thrust to the right of the tail).

So, starting from the top (all of this with the motor off or better, disconnected):

- First, connect the tail servo directly to the rudder channel and center it. Disconnect the arm and attach it so that it is centered or as close as you can get it; if you have to compromise, compromise toward the front of the heli.
- Adjust the pushrod length so that in this position, the tail has about 5 degrees right pitch.

Power off, reconnect the servo to the gyro and the gyro to the receiver, then power back on.
- switch to rate mode and center everything, trims, subtrims, sticks. Set the limit pot on the 401 to max.
- just for grins, move the rudder to the right and verify you get lots of pitch, then to the left and verify you don't get anywhere near as much.
- back to the program, check, and if needed, adjust the length of the pushrod so you have about 5 degrees right trim with everything centered.
- switch to AVCS, and turn the heli 90 degrees left (nose pointing 90 degrees to the left); the gyro should put in at least 20 degrees total right pitch.
- turn 180 degrees to the left; you should have flat to maybe 10 degrees left pitch.

At 2400 RPM head speed (that's what that was referring to), this should hold the tail fine given the throttle and pitch curves you quoted.

Ductapemaster

Thanks for the suggested values osterizer. I will try them out and see how it goes.

The heli flew once again at the hands of our heli guy at the shop where I work today and we found a problem with it...we would take off and the heli would wobble in a small circle. At first we assumed that the blade tracking was off, but it seemed OK at 80% throttle. Then we adjusted the flybar and got everything completely straight on the head. It helped a bit but the problem was still there. From there we bumped up the head speed and we noticed that the drivetrain was "humming" and the heli sounded like it was nitro and not electric. A cool effect, but the cause isn't so "cool" as we found out.

When we were playing with the throttle hold/idle up settings on Sunday, we flipped the idle up switch on accident and flipped it off really quickly. This caused the drivetrain to backlash very quickly (the ESC wasn't programmed right at the time - brake was still set) and we thought we had ruined the one-way. Further inspection told us that it was fine so we reassembled the main shaft only to find that the gears were hitting eachother. We removed it all again and put a spacer between the gears (we thought it was in the right place above the main gear before). After that the heli flew fine, but today we discovered something worse.

The aluminum collar that houses the one-way in the main gear had backed out of the socket about 1/2 way and was sitting right up against the lower bearing holder and there were metal shavings all over the gear. Turns out that the backlash caused this as the one way is still good. I went over to the other hobby shop in my area and ordered another main gear/bearing set and we cleaned up the bearings with some bearing cleaner. They seem to still be fine as they're all still smooth so hopefully the new main gear is still good.

Man, the things already broken and I haven't even flown it yet! Oh well, now I have time to adjust the swash mix and pitch settings while its on the bench...

-Dan

osterizer

Well, there's a silver lining . We had a problem last summer with the bearing migrating out of the main gear, so this isn't horribly surprising. I haven't had it happen in a while, though.

Ductapemaster

Yeah, I know it's all part of this branch of RC...oh well, at least it hasn't been crashed yet! The less expensive the repair, the better! And BTW, it wasn't the bearing that backed out, it was the aluminum collar that holds the bearing into the main gear. I looked at it closely last night and it appears that the collar is actually threaded into the gear. It has a spiral cut in it and when I turned it with pliers it screwed into the plastic. It makes sense that the backlash from the motor would unscrew it.

The part is supposed to be in tomorrow so we'll see how it goes!

-Dan

hikai

My Feedback: (2)

Hi Osterizer, Much of your recommendations were done as the MX450 was being setup, however, I followed your recommendations.
The Futaba S3114 was properly centered and the control arm was in the proper position. However, tail rotor setup was not right biased. The pushrod was adjusted for about 5 degrees right pitch and the results were right rudder about 18 degrees and left rudder about 10 degrees. I used a fairly accurate level to make the measurements, however, it may be off by 1-2 degrees as the placement of the level next to the tail rotor blade was not a precise process. My concern after I made the adjustments was the ball links had only about 2-3 threaded turns...! With the GYRO restored (connected to receiver) the arm of the servo would move aft (toward the tail) if the heli was rotated left and move toward the heli if rotated right. It moved so quickly there was was practicle way to measure or estimate the amount of movement of the tail rotor. The 1st attempt to hover did not go well as the tail ball link detached from the linkage rod.. not a problem as the heli agressively rotated counter clockwise for a split second before it was on the ground. I ordered tail boom servo mounts and plan to move the tail servo... it will be easy and fast to adjust the tail rotor pitch with the tail servo on tail boom servo mounts. After I receive the mounts and make the adjustments, I'll forward the resuults. Thanks for the help. PS. I measured the length of the linkage rod to control the position of the tail rotor. The length was as indicated at the Tower Hobbies wed site about 31mm.

osterizer

Hikai- I figured that you would have followed through everything. I just wanted to go start to finish- sometimes hearing it said a different way gives me other ideas. The motion sounds right, btw. If you want to check the pitch range, you can leave it in AVCS and just move the rudder full right or left and hold it- the 401 will usually reduce pitch by about 10% or so from max when you move the stick back to center even if the heli isn't moving.

I had the tail pushrod come off a couple of times last year when I had other problems I was trying to work out (turned out to be a bent tail shaft in one case, and a dying bearing in the other). The most worrisome, I was about 10' off the ground, but I hit the throttle hold and got it down in a pretty clunky auto. The other one, it was maybe 3 or 4 feet up and the pushrod swung into the tail rotor when it let go- carbon fiber blade bits flying everywhere, pieces of CF pushrod lofted into the corners of the driveway... that one was more exciting . I use pushrod guides if I can now, so that the rod is less likely to disconnect, and if it does, it won't flop into the rotors.

Ductapemaster

The hobby shop near me just got in some Air Thunder 2200 3 cells...I hear they're pretty good...anyone have any experience with them? They supposedly can be discharged to 2V/cell (!) and overcharged without puffing.

Hopefully my main gear will arrive soon...im dying to fly

Thanks!

-Dan

osterizer

I've heard the claims, too, but people have reported good and bad results. I think the additional resilience is there to keep the battery from dying- as in, you still shouldn't discharge them to that level, or charge them at dangerous rates. But since I don't have any of them , you might do well with a search in the battery fora.

easternav

thanks to all those who replyed to my problems. guess I 'll try runrider maybe i'll get a better responce from them. I've been reading this one sence it started [>:]

osterizer

Not everyone notices everything, easternav.

- if your head parts are all in good order, then the best tracking upgrade for a 450 is a set of good blades. The stock ones were impossible to track for me. A set of good blades and it should work fine, but there are other things that may be wrong after that.

- I don't know degrees for the swash tilt- the manual describes setting the ranges to just below the point where the flybar control balls would collide with the grips being the correct limit.

dpleasants

I was having a terrible time tracking the stock main blades on my 450. And I believe it was due to a weight moving around in one of them. After that weight decided to come out and destroy both blades, I picked up a set of E-flite woodies for 13 bucks. They balanced and tracked great. I can't wait to get this thing in the air. Waiting on a new landing gear set. I broke mine putting the training gear on. Must have cracked with the damage from the blade explosion. GRRRRRRRRRRRRRRR.