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mCP X Blade Micro CPx Helicopters Information and Help


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Old 04-08-2011, 06:32 AM   #121 (permalink)
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Quote:
Originally Posted by clintfisher View Post
I've been thinking, we need a thread on the taxonomy of vibrations in this heli, and maybe tips and tricks for recognizing and fixing them. Some vibrations, for example, blades slightly out of balance, can trigger ball-slop vibration. In this case, grommets may seem to fix the problem, but are really just masking the real blade-balance problem, as it was with my MCPx #1.

So far, I've come up with:

* servo jitter (clean servos)
* bent feathering shaft (replace shaft)
* swash/ball slop (grommet fix)
* blades unbalanced (balance blades)
* main rotor shaft cracked (replace shaft)
* tail boom cracked
* tail rotor changed shape (re-pitch or replace tail rotor)

Did I miss any?


BTW, the toothpick-blade-balancer is stupid-easy, and worked great for me. It is referenced in this thread:
https://www.helifreak.com/showthread.php?p=2803426
Good list!

I would add:

* Main gear spun on main shaft

P.S. Thanks for the link to the blade balancing thread. I'm having a hard time keeping up with all of the great suggestions around here so it's nice to be referred to them.

P.P.S. This may be over analyzing it and/or not feasible, but if it possible to differentiate between different types of "shakes" and specify which problem causes which that might be helpful to others. For example, I think a bent feathering shaft causes periodic vibrations on and off throughout flight where as unbalanced blades cause a continuous vibration. I'll take a crack at it although I certainly don't know all the answers myself but maybe collectively (pun intended) we can all compile the info.
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Old 04-08-2011, 11:19 AM   #122 (permalink)
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I think you could also add collective servo linkage at the servo and the fact that the left and right linkages have the two 90 deg bends. With the bends, there is an angular variance. I believe that's why the gromits on the swash help so much. The prevent the linkages from rotating.
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Old 04-08-2011, 02:21 PM   #123 (permalink)
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Originally Posted by mejmea View Post
Good list!

I would add:

* Main gear spun on main shaft

P.S. Thanks for the link to the blade balancing thread. I'm having a hard time keeping up with all of the great suggestions around here so it's nice to be referred to them.

P.P.S. This may be over analyzing it and/or not feasible, but if it possible to differentiate between different types of "shakes" and specify which problem causes which that might be helpful to others. For example, I think a bent feathering shaft causes periodic vibrations on and off throughout flight where as unbalanced blades cause a continuous vibration. I'll take a crack at it although I certainly don't know all the answers myself but maybe collectively (pun intended) we can all compile the info.
Hah! Can't believe I forgot "main gear loose" or "main gear spun". I guess I'm so used to popping that thing back into place that I've taken it for granted!

And as for as differentiating between kinds of shakes, that's going to be the intent of the new thread. I'm just collecting types of shakes right now, and figured this would be a great thread to do so in.
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Old 04-08-2011, 03:11 PM   #124 (permalink)
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Originally Posted by clintfisher View Post
Hah! Can't believe I forgot "main gear loose" or "main gear spun". I guess I'm so used to popping that thing back into place that I've taken it for granted!

And as for as differentiating between kinds of shakes, that's going to be the intent of the new thread. I'm just collecting types of shakes right now, and figured this would be a great thread to do so in.
I hear you - even when I hit TH it seems like my gear often spins on the shaft a bit. This list will be a great tool. I just thought of adding "worn dampeners" to the list too. I haven't seen posts about changing them at all and I wonder if they're being forgotten by everyone? I can't say I've got proof that they cause shakes but it seems reasonable since it affects larger helis. I got some shakes right now that I need to sort out and I'm going to try the dampeners first because I don't have a bent feathering shaft but it's the same sort of intermittent shake during flight and is noticeably worse at higher rpm like when I'm in idle up.
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Old 04-08-2011, 10:29 PM   #125 (permalink)
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I think you should definitely add worn dampeners to the list. I changed mine out and it helped quite a bit. It wasn't horrible with the worn ones but there was a definite vibration/shake. It was primarily intermittent and you could see it in shaking of the vertical stabilizer when it was subtle and in the whole heli occasionally when it wasn't so subtle. I changed back and forth between the worn and new ones twice to verify it and it was consistent.
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Old 04-09-2011, 06:38 AM   #126 (permalink)
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Worn/loose swash plate (not the balls but the swash assembly)?
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Old 04-10-2011, 01:46 AM   #127 (permalink)
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My fix for a cracked tail boom was a bit of thin CA, worked like a charm. I now have a vibe-free heli.
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Old 04-10-2011, 07:35 AM   #128 (permalink)
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Quote:
Originally Posted by Cullen Colapietro View Post
My fix for a cracked tail boom was a bit of thin CA, worked like a charm. I now have a vibe-free heli.
A few of the local guys are just coating the boom with CA as a precaution.
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Old 04-10-2011, 07:47 AM   #129 (permalink)
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A few of the local guys are just coating the boom with CA as a precaution.
Interesting. Do you think that really increases the strength of the boom on a proactive basis? I have a hard time understanding how a thin layer of CA, with no other reinforcement, helps the strength of the carbon fiber. I know it's used for wound closure but one hopes that wounds are not subsequently subjected to significant tension like a crashing mCPX tail boom may be. Maybe I'm missing something however....and if so, I'd love to know exactly what they are doing and if people have found that it makes a difference. Are they painting on thin CA over the entire boom?

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Old 04-10-2011, 11:57 AM   #130 (permalink)
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Interesting. Do you think that really increases the strength of the boom on a proactive basis? I have a hard time understanding how a thin layer of CA, with no other reinforcement, helps the strength of the carbon fiber. I know it's used for wound closure but one hopes that wounds are not subsequently subjected to significant tension like a crashing mCPX tail boom may be. Maybe I'm missing something however....and if so, I'd love to know exactly what they are doing and if people have found that it makes a difference. Are they painting on thin CA over the entire boom?

Coating the boom with a layer of CA does make the tailboom stronger if you use ultra thin CA, it gets into the fibers better It can still snap in a crash at the frame but it's much harder to split it across the lenght of the boom
I always do this BEFORE I start using the boom so the CA doesn't tough the motorwires and are still usable after a crash.

Another mod I recently did was to mount an MSR O ring between the 3in1 board and frame, they absorbe some of the vibrations and prevent the screws falling out the board if have to remove it for some reason.

Grtz Rudi
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Old 04-10-2011, 12:19 PM   #131 (permalink)
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Originally Posted by kmkflyer View Post
Coating the boom with a layer of CA does make the tailboom stronger if you use ultra thin CA, it gets into the fibers better It can still snap in a crash at the frame but it's much harder to split it across the lenght of the boom
I always do this BEFORE I start using the boom so the CA doesn't tough the motorwires and are still usable after a crash.

Another mod I recently did was to mount an MSR O ring between the 3in1 board and frame, they absorbe some of the vibrations and prevent the screws falling out the board if have to remove it for some reason.

Grtz Rudi
Thank you. I hadn't considered/realized it would soak in but with that, it now makes sense to me. One point of clarification. Is there actually an "ultra-thin" CA? I've seen "Thin", "Medium", and "Thick", but not "ultra-thin".

Good tip about the 3 in 1 board and the o rings too.
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Old 04-10-2011, 01:16 PM   #132 (permalink)
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Quote:
Originally Posted by kmkflyer View Post
Coating the boom with a layer of CA does make the tailboom stronger if you use ultra thin CA, it gets into the fibers better It can still snap in a crash at the frame but it's much harder to split it across the lenght of the boom
I always do this BEFORE I start using the boom so the CA doesn't tough the motorwires and are still usable after a crash.
One of the guys did the coating with the boom still on the heli and accidentally got some in the area where the boom plugs into the frame. He's anticipating having to replace the frame the next time the boom breaks. Doing it before putting it on the heli during replacement sounds like an ideal time.
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Old 04-10-2011, 02:09 PM   #133 (permalink)
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Thank you. I hadn't considered/realized it would soak in but with that, it now makes sense to me. One point of clarification. Is there actually an "ultra-thin" CA? I've seen "Thin", "Medium", and "Thick", but not "ultra-thin".

Good tip about the 3 in 1 board and the o rings too.
Yes there is an industrial CA extra thin from a company in Europe called Bison it's as thin as water, but I don't know if it's available in the US but I guess 'thin' will also do.

Grtz Rudi
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Old 04-10-2011, 02:19 PM   #134 (permalink)
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Originally Posted by TheBum View Post
One of the guys did the coating with the boom still on the heli and accidentally got some in the area where the boom plugs into the frame. He's anticipating having to replace the frame the next time the boom breaks. Doing it before putting it on the heli during replacement sounds like an ideal time.
I also use it to 'thicken' the main shaft where the main gear is located to prevent it from sliding down so easy when crashing. Slide the shaft tru the bearing then aply some CA to the shaft with a toothpick, let it dry for 10 minutes and then push the gear over it, it will 'lock' in place much better as you increase the tension a little bit Downside is that you will have to remove your mainshaft from below instead of up because the slightly thicker shaft will not pass the bearing, unless you sand it down.

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Old 04-14-2011, 01:50 AM   #135 (permalink)
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Default Main Shaft too thin!

Well, I got some 3mm x 1.2mm carbon fiber tube from rcfoam.com and finally got around to sliding a bearing down it. Wow! It's really 3mm! It fits the bearing like a glove with *zero* play, whereas the stock main rotor shaft is way too thin, and there's a lot of slop between the shaft and the shaft bearings. And, if you take away the fluff around the screwholes in the shaft, there's play between the shaft and the head.

Haven't cut and drilled the new 3mm CF up yet to make a new rotorshaft, but feeling zero slop between the new tube and bearings gives me great hope. I'll post to this thread with my results. (and I'll do it grommet-free first!). Looks like the I.D. of the tube is a little less, which may stiffen up the shaft too and reduce cracking.

I'm pretty excited about this fix. I think it will do a lot to reduce my root cause of the gyro shakes.
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Old 04-14-2011, 05:02 PM   #136 (permalink)
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Well, I got some 3mm x 1.2mm carbon fiber tube from rcfoam.com and finally got around to sliding a bearing down it. Wow! It's really 3mm! It fits the bearing like a glove with *zero* play, whereas the stock main rotor shaft is way too thin, and there's a lot of slop between the shaft and the shaft bearings. And, if you take away the fluff around the screwholes in the shaft, there's play between the shaft and the head.

Haven't cut and drilled the new 3mm CF up yet to make a new rotorshaft, but feeling zero slop between the new tube and bearings gives me great hope. I'll post to this thread with my results. (and I'll do it grommet-free first!). Looks like the I.D. of the tube is a little less, which may stiffen up the shaft too and reduce cracking.

I'm pretty excited about this fix. I think it will do a lot to reduce my root cause of the gyro shakes.
Update: I still haven't cut the new shaft, but I did run into a little issue: The swashplate sleeve diameter is 3mm too, and it seems to be a bit too snug on the new CF tube. However, the tube is not 100% uniform. There are areas on the tube where the swash could slide easily, and other areas where it will bind.

So, we have a dilemma: If the shaft tube is nice and snug with the bearings, it will be too snug with the swash. If it's loose enough for the swash, it may be sloppy with the bearings.
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Old 04-15-2011, 09:16 AM   #137 (permalink)
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Default general question

when i set up my mcp on my dx6i do i have the thottle stick in the center or down
i set it up with the stick down and it wont lift off the floor could this be the problem
new to this sport
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Old 04-15-2011, 10:36 AM   #138 (permalink)
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Originally Posted by heli tas View Post
when i set up my mcp on my dx6i do i have the thottle stick in the center or down
i set it up with the stick down and it wont lift off the floor could this be the problem
new to this sport
Try this method (I'm being fairly detailed since you said you were new, I don't mean to be insulting )

1) Turn on your radio, select the proper model in memory, make sure your throttle is all the way down, and then also turn on your throttle hold switch (top, upper, back right corner of the Dx6i). I believe your throttle hold switch is programmed to zero throttle by default in the Dx6i but it wouldn't hurt to check it.

2) Power up your heli. Carefully give a little throttle/collective/pitch to verify that your throttle is inactive.

3) Pivot your blades in the grip so that they are as close to 90 degrees to the feathering shaft as they can be (it won't quite be 90 degrees). See the 1st picture below.

4) Get down and look across the blades and then move your pitch stick up and down. Verify that when you move the stick up the blades move up and when you move the stick down the blades move down. (see 2nd and 3rd pictures). If that's all good then you know that your pitch channel isn't reversed on the radio. If it is reversed, then change it in the radio and go to step 5.

5) Set your stick to the mid point. Your blades should be horizontal and parallel to each other (sorry, no picture handy). Note that it does not seem uncommon that Horizon shipped mCPXs with some negative pitch when the stick is at the mid point. If your blades are not horizontal you have a couple of choices:

a) Disconnect each servo/swash ball link one by one and turn it a couple of turns in whichever direction it needs to go to make the blades level. I would start with perhaps 2 turns based on my experience. Make sure you turn all three links the same number of turns and in the same direction.

or

b) Go into the subtrim menu on your radio and adjust the pitch subtrim to make the blades level.

Note that even if you use method a) you may need to adjust the subtrim a little bit afterwards to get things perfect. Also note that if you use method b) only you should check your servo travel when you are all done to make sure that you aren't bottoming them out. Do this by giving full collective (pos) and the full cyclic (in all directions) while carefully watching the servos to make sure they don't stop moving before your sticks do. Then repeat with full negative collective.

6) Make sure your radio settings are as recommended by Horizon (or however you prefer them) and give it a try. With the above method and the Horizon settings you should expect to be able to hover with the collective between 1/2-3/4.

There is a good discussion of setting pitch in the link below.

https://www.helifreak.com/showthread.php?t=293106

Good luck, I hope this helps and let us know how it goes!



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Last edited by Finless; 04-15-2011 at 03:23 PM.. Reason: editd post so it did not scoll off page
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Old 04-15-2011, 03:22 PM   #139 (permalink)
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My god... I just did this servo clean up. MAN you better have a good tiny phillips screw driver and it should be magnetic. This stuff is TINY! Had to use my desk lighted magnifying glass.

Needless to say after well over 50 flights mine started having intermittent wobbles. Cleaning up the servos works!

I am not going to do a video as it is just too tiny to even try to video properly.

Bob
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Old 04-15-2011, 04:45 PM   #140 (permalink)
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My god... I just did this servo clean up. MAN you better have a good tiny phillips screw driver and it should be magnetic. This stuff is TINY! Had to use my desk lighted magnifying glass.

Needless to say after well over 50 flights mine started having intermittent wobbles. Cleaning up the servos works!

I am not going to do a video as it is just too tiny to even try to video properly.

Bob
(chuckle)

I was thinking the same thing we I got in there to do that -- "If I am going to have to *do* microsurgery, then I want to get *paid* to do microsurgery..."

To me, a lot has to do with just mentally getting ready for the fact that your time isn't going to largely be spent "doing" but instead with tracking, finding, manipulating, locating, itty bitty stuff. So when I slow my pace, and my tolerance level to that, it is better, but still not the most enjoyable work in the world. I don't know how watch makers did it in the old days.
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