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MX400 Problem.

Old 01-04-2007, 09:48 PM
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Default MX400 Problem.

I just got an MX400 and i'm having a problem. The swashplate moves in the right direction and all, but when I press just foward, back, left or right, the heli moves in wierd places like halfway between foward and left, kind of like diagonal. I have no idea why it does this though. Can anyone help me?
Old 01-05-2007, 05:41 PM
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Default RE: MX400 Problem.

It's probably in the radio. What kind of radio or you using and have you set it up for mechanical CCPM instead of electronic CCPM? With eCCPM it uses 3 servo's which work together...which is what your problem is sounding like...If it's set to eCCPM and you have a mechanical CCPM setup it will cause this.
Old 01-05-2007, 05:53 PM
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Default RE: MX400 Problem.

I just uploaded a video, and its set to mechanical CCPM

http://coasterfuel.com/picture.avi

I think the problem is that one blade moves when I move the elevator, the other one doesn't move when I use the elevator.
Old 01-05-2007, 06:29 PM
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Default RE: MX400 Problem.

I just now came in from flying my MX400Pro/DX6, so I am primed and pumped for your problem.
My heli is a sweeet flyer by the way, but I admit that it has a few TRex parts on it, like 315mm fiber blades and the SE tail rotor system and pitch slider.

From your video it looks completely normal to me.
Darn.
Old 01-05-2007, 06:33 PM
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Default RE: MX400 Problem.

ORIGINAL: Philng

I just got an MX400 and i'm having a problem. The swashplate moves in the right direction and all, but when I press just foward, back, left or right, the heli moves in wierd places like halfway between foward and left, kind of like diagonal. I have no idea why it does this though. Can anyone help me?
Are you talking about in flight? That would be a problem. Are you talking about spinning the rotor disc and restraining the heli on the ground while you wiggle the cyclic? You will not be able to tell this way, the disc will not repond correctly as it will in the air. Are you talking about exactly what you showed in the video? This is completely normal as far as I could see.

The swashplate should move exactly as you move the right stick, that is, its tilt should be in exactly the same direction as you are moving the stick, and when you move the left stick the pitch tray should lift the swash evenly (the collective pitch) without disturbing the aileron or elevator deflections (the cyclic pitch).

But don't expect the rotor disc to behave this way while the heli is restrained. It can't. But in flight it will.

Old 01-05-2007, 06:55 PM
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Default RE: MX400 Problem.

I have also tried to get someone to hold it up while I run it, when I add a little elevator, it goes diagonals, it doesn't go foward or backwards.
Old 01-05-2007, 07:08 PM
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Default RE: MX400 Problem.

ORIGINAL: Philng

I have also tried to get someone to hold it up while I run it, when I add a little elevator, it goes diagonals, it doesn't go foward or backwards.
I am telling you, when the helicopter is restrained, the motion of the rotor disc is nothing like the way it will move if the heli is free to respond.

As long as the swash is moving correctly, as I said above, and the linkages are hooked up right in the head and are approximately the right length, it will be OK in flight.
In flight, not while restrained.

If it isn't responding in the correct direction while it is not restrained, like as you are getting light on the skids during the runup to maiden hover, then we might have something to worry about.
But not so far.

Old 01-05-2007, 07:14 PM
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Default RE: MX400 Problem.

I let my dad hold it VERY lightly just to see how it would look like in flight and it still had that problem.
Old 01-05-2007, 07:25 PM
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Default RE: MX400 Problem.

ORIGINAL: Philng

I let my dad hold it VERY lightly just to see how it would look like in flight and it still had that problem.
That's very brave. Let me see if mine does the same thing.

OK, just checked, very scary but I did it.

Now remember, this is a perfectly flying MX400Pro, mechanical ccpm just like yours, I just flew off an entire battery pack not half an hour ago so I know the heli is working perfectly.

With the helicopter restrained, if I give it back elevator (cyclic) the rotor disc tilts back and to the right. If I give it forward cyclic, the disc tilts forward and to the left.

Right and left cyclic give a purer left-right tilt but there is some fore-aft tilt too.

This is at about 1/3 throttle, not willing to go higher on my bench, but the effect will be magnified at higher power settings.

Any restraint that keeps the helicopter from following the disc motion will upset it. If you think about it, the disc doesn't really move very much at all _with respect to the helicopter_ while it is in flight, because it makes the heli frame move along with it. If you are preventing this motion, the disc moves in unnatural ways.



Old 01-05-2007, 07:40 PM
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Default RE: MX400 Problem.

hey, thanks for your time! I am currently charging the battery and getting ready to fly it.
Old 01-05-2007, 07:46 PM
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Default RE: MX400 Problem.

Great! Just run up slowly and as it gets light on the skids, check to see if the whole heli moves like it should. On mine I can raise one skid up or even tilt the nose forward, way before it is really light enough to lift off and hover.

I'll bet that there is no real problem at all.

By the way, this isn't your very first helicopter is it?

Old 01-05-2007, 08:22 PM
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Default RE: MX400 Problem.

naw, I have a blade CP and It didn't have enough power to do good forward flights.
Old 01-05-2007, 08:37 PM
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Default RE: MX400 Problem.

OK, good, you will be amazed at the difference, but you'll be fine, just use a little expo if your radio will support it, the heli is very stable but it will scoot if you deflect the controls very much.
Not like the blade, but it's bigger and faster so things can still get sideways quick.
Just go slow and easy.
Old 01-05-2007, 08:41 PM
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Default RE: MX400 Problem.

I'm surprised you didn't notice the disc precession thing on the Blade, it does it too.
I have a BCPP, stock, and another all-brushless with gyro and hs56 servos. That one has plenty of forward power!
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Old 01-05-2007, 10:15 PM
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Default RE: MX400 Problem.

nice.

I just tried to hover it, it seems that the tail is moving towards the right and rudder adjustments aren't enoguh, also it doesn't lift off. It doesn't seem to have enough thrust even at full power.
Old 01-06-2007, 12:09 AM
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Default RE: MX400 Problem.

OK, we will get it set up right. Do you have a gyro, what radio are you using, do you have a tailboom servo mount for the tail, and do you have a pitch gauge?
A lot of questions at once I know.
The lack of lift is probably a pitch setting issue but might be related to the seesaw.
The tail swinging is probably a rigging issue.

I had several problems with mine, the tail pitch slider can easily bind and give erratic tail performance.
There is a part in the head, the seesaw, which can come loose easily unless you locktite the screws. Do you have a metal center hub and seesaw or is it plastic, and how does the seesaw mount? (there were 2 types, one with ball bearings here and one without).
Old 01-06-2007, 03:17 AM
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Default RE: MX400 Problem.

Yeah, everything looks right from your vid. Trust me (and Jellyson) it's weird getting used to how a heli flies and what the controls do where there's no power applied (or when it's held ((Oh the the PAIN!(((and the scars)))...But once you understand it it's really kind of amazing. Buy really the tail all depends on the gyrol...I bought a crappy used MX400 off of some other site and it had a GWS p003 and it sucked, it would always sping to the left ($30 gyro, what do you excpect). I swapped it for my good gyro I was going to put in the MX450, a CSM 420e, and hey!, wouldn't you know it!, it held the tail...except for when I needed to turn about 15 feet up to regain my tail-in....but that's a different story that people are trying to blame on belt static...
Old 01-06-2007, 03:20 AM
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Default RE: MX400 Problem.

And also, the reason one blade moves and the other didn't when you moved the eleveator is dependant on the flybar. Keep it horizontal and both blades should move the same.
Old 01-06-2007, 08:18 AM
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Default RE: MX400 Problem.

I've tried to set those linkages so they make the pitch greater, but I pretty much maxed them out so they can't go more.
Old 01-06-2007, 08:42 AM
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Default RE: MX400 Problem.

Also, when I spool up the heli, it would shake at a certain point then when the RPM gets higher, it stops. Is that also a problem?
Old 01-06-2007, 12:31 PM
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Default RE: MX400 Problem.

ORIGINAL: Philng

I've tried to set those linkages so they make the pitch greater, but I pretty much maxed them out so they can't go more.
The recommeded pitch range is -8 to +8 degrees, I have set mine at about 9 1/2 degrees to get a slightly lower headspeed for indoor hovering, but I get a little binding at max collective.

If you have too much pitch the headspeed will be too slow, the motor will bog down and it won't lift off. This helicopter will want a higher headspeed than you are used to with the Blade CP, for sure.

A little shaking is normal as long as it smooths out as you said. The blades are finding their lead/lag positions to balance lift, and before this happens you might get more or less vibration. If it doesn't smooth out then there might be someting wrong like badly out-of-balance blades.
Old 01-06-2007, 01:28 PM
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Default RE: MX400 Problem.

thanks, I will try to get the pitch of those blades up
Old 01-06-2007, 08:45 PM
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Default RE: MX400 Problem.

heh, old owner had the radio on mode 1, then switched the elevator and collective servo. I switched it back and it looks like it has enough lift.

One more problem, the tail doesn't seem to have enough power to keep the heli in one spot, the heli turns to the left when it is almost ready to hover. I have tightened the belt and everything but it doesn't seem to have enough power. Also, I have set the movements of the tail drive as far as it could go.
Old 01-06-2007, 09:07 PM
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Default RE: MX400 Problem.

sorry for the triple post, but I got it hovering for a few seconds, the movement seems VERY erratic and it doesn't go to where I tell it to. (I have experience though)
Old 01-09-2007, 10:58 AM
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Default RE: MX400 Problem.

I've had my MX400 Pro for about a month now. Like you, I had a lot of experience with smaller heli's but the learning curve for this more serious machine was steep. It takes a while to get the control throws, trims, transmitter settings gyro settings etc. to a place that is comfortable fo my flying style. After my first tip-over I made some giant training gear out of dowels and plastic golf balls. I would hover it a bit, make some adjustments, and cut off about three inches from each leg of the training gear. I repeated this process until everything was set up to my liking.

I also had trouble getting enough positive pitch at first but after some fiddling around it's fine now. Make sure the aileron and elevator servos are not bumping into each other when the collective arm moves up and down.

It's flying great now. I would recommend the aluminum main hub upgrade and get some spare landing gear struts.

I find that I get much longer flight times if the belt is not too tight. Good luck!

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