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e-Ark X-400 - MX400 > Help me get my bird working
 
 
motorheadwannab
Heliman
Location: Phoenix, AZ - USA

Last christmas I bought myself an mx400, got it all built, aluminum head etc. I have tried flying it through the year and never had any success.

I have fixed the little things, balanced the blades got rid of electronic noise and chatter etc...

Here is my problem, I start powering up and the heli starts tilting left, I have corrected this with subtrim now. As I give it any input the heli will dip or rise I have tried using some mixing to fix it but it seems ridiculous!

I can't seem to get the helicopter to be at all controllable. Even when I get it in the air it wants to go everywhere and spin and if I try to fix it with control input it falls back to the ground.

Is it normal for a heli to hover at an angle? When mine is in the air it looks way tilted to the side even when its staying relatively still.

I know this is quite vague but hopefully someone can help me!

edit: I don't have a tach, could this be any part of my problem? Any way to tell if i'm too fast or slow?
12-11-2007 05:29 AM
 
 
copperclad
Elite Veteran
Location: ..

hi motorheadwannab

i think i can answer a few of your questions , first a small tilt to the side is normal , this is caused by force from the tail rotor , and you will see you will get used to it , i am guessing this is your first machine and you are up against common problems , when you are in a hover if the machine is only a foot off the ground , you will be in ground effect and it will be unstable , once you are about two feet or more it will smooth out , without knowing the headspeed you could be running at too low an RPM , this would also make the machine unstable and hard to fly , on option is to lowwer the pitch curve , this will make the machine spin up faster in order to lift off , it would also help , if you post back with your complete setup

TX
RX
battery
motor
servos
gyro
pinion size

you should think about getting a pitch guage , post back with more info and i am sure people will jump in with ideas
HTH , dana
12-11-2007 12:21 PM
HOMEPAGE  
 
 
motorheadwannab
Heliman
Location: Phoenix, AZ - USA

Thanks, ok here are some specs of what I have, most came from the rcexpert special.

Tx-JR 8103h
rx-castle creations berg 7ch
batteries-3xhextronik 20c 1700mah
motor-rcexpert 3200kv
servos- rcexpert 9g
gyro-telebee HH gyro
pinion-14tooth

OH and I have a pitch guage just not a tach. I have set it up as RADD recommends for the curves but who knows.
12-12-2007 04:21 AM
 
 
copperclad
Elite Veteran
Location: ..

hi motorheadwannab

the list looks great , it is a nice setup , i would disconnect the motor and set the pitch curve so you have a pitch range of -4 ~ +7 , and hook the motor back up and give it a try , play around with lifting off and landing and then adjusting the top of the pitch curve down maybe 10 points at a time ( you will have to adjust the middle point down to a little also to keep the line straight ) till it wont lift off , then run it back up a bit , this is one way to find your maximum headspeed without a tach , the higher the headspeed the more stable the machine will be

for instance , if you set the machine up and have 12 degrees at the top and try to fly , the machine can lift off at a very low headspeed and be tough to control , now say it is setup with the top maximum pitch at 5 degrees , the machine will only get airborn at a much higher headspeed , i would also say , if you were to set the machine up with 5 degrees maximum pitch and you were not able to lift off , i would say you needed a few more teeth on the pinion , these are ways you can mess around and get an idea of what is going on without a tach , don't be discouraged , setting up your first collective pitch machine is not easy


i am also hoping someone here might read this with a better idea of your motor pinion combo and be able to give us some info

let me know how you are making out , i have a 8301 so i can help with programming if you want , dana
12-12-2007 11:47 AM
HOMEPAGE  
 
 
motorheadwannab
Heliman
Location: Phoenix, AZ - USA

Awesome I hadn't thought about doing it quite like that. I am scared about finding my max headspeed though sounds like it could end up being a painful experience haha. I will go give that a shot and hopefully all goes well, I'll have to change the pitch so it is -4 to 7 but shouldn't take too long. Thanks!
12-13-2007 04:09 AM
 
 
motorheadwannab
Heliman
Location: Phoenix, AZ - USA

Ok well I just got done flying 2 batteries! It was loads of fun, I really think my headspeed was just too low and judging by how far I had to bring my pitch curve down...ya. It flew amazingly!

It still wants to drift all over the place and I need to trim it a little bit more but what a difference! I hovered it withith about a 5 foot box at eye level for about a minute...pretty good for me especially since its been a month since i've touched it! It started getting windy and dangerous but all is well, I realized how poorly my blade tracking is though...oh the joys Thanks copperclad
12-13-2007 04:57 AM
 
 
copperclad
Elite Veteran
Location: ..

hi motorheadwannab
that is good news , glad to hear you are in the air , if you can adjust your tracking you will see it hovers way better , the blades being out of track really rob the power , dana
12-13-2007 12:15 PM
HOMEPAGE  
 
 
motorheadwannab
Heliman
Location: Phoenix, AZ - USA

GRR! so my brother came into town with his cheap walkera and showed me up, his is soo stable i can't believe it! he can almost hover hands off. I know its unusual but still. So I go to fire mine up, it spools nice. then starts to lift up nicely and the throttle keeps increasing but pitch drops down. I can't figure out whats going on, my pitch and throttle curves are good i can't figure out the problem! any ideas people?!
12-21-2007 04:03 AM
 
 
JerryLu
Senior Heliman
Location: Gretton, Northants - England

"it spools nice. then starts to lift up nicely and the throttle keeps increasing but pitch drops down"

That sounds like the lipo is running out of legs. If your motor is pulling too many amps the lipo will stop giving out enough and the effect is reduced lift through reduced motor / head speed.

You might have 20C but only 1700mAh. May not be enough.

Was the LiPo fully charged?

Jerry
12-21-2007 08:31 PM
 
 
CrashnoBurn
Heliman
Location: Stanfield, Oregon

motorhead? what is the pitch on each blade at 0, 50, 100 throttle. my mx has blade pitches of -1 deg, +4 deg and +10 deg, with a throttle curve of 0, 85, 100 (DX6). It flys really nice and stable. Sounds like you just need the radio to be setup properly. I'm assuming that your heli is set up properly. Good luck, Carlos.


"The day my wife finds out how much I spend on me heli is the day she keeps from giving me more money!"
12-22-2007 05:36 AM
 
 
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e-Ark X-400 - MX400 > Help me get my bird working
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