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Old Feb 21, 2007, 11:26 PM
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Joined Feb 2007
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My CX2 pulling hard right when I try to take off

Hello All,

I am at this point very frustrated. I want to give fixing it one more try before I have to slink back to the hobby store that I bought teh CX2 from and have a "professional" help me.

History:
All was working great. Then a bad accident. Broke teh top off of the inner shaft and then the posts that hold the lower blades on to the lower rotor head.
I replaced inner and outer shaft, flybar, both lower and upper blades.
I also installed teh Boomtown hobbies boom tail and skid upgrade. ( Hands down, the boomtown hobbies mod was best upgrade money I have spent on this heli thus far.)

I have the E-flite aluminum inner shaft and head and the Micro heli lower rotor upgrade in place. What seems to happen is that when I give it stick, it has a slight shake, then when it gets enough stick to take off itt pulls to the right. It pulls so much that I can slide it across the floor. If it has enough stick it will lift off and then go to the right.

Observations:
1. seems to be some vibration in the shaft. (visible)
2. Swashplate is level left to right when looking from the rear, but seems to be pitched upward front to back; pitched up towards the nose
3. When I hold it in my hand and gun it, it wants to pull out of my hands to the right; in addition, when doing this if I look at the blades, the space between the blades (looking at them from the back) on the left side of the shaft seems to get smaller with more stick. so basically the more stick it gets while holding it from moving, the lower blades seem to bend upward towards the upper blades on teh left side; and conversely as I ease the stick the space decreases back to normal.

Can anyone help? or is it off the hobby store.... defeated and shameful

Jack
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Old Feb 21, 2007, 11:35 PM
The Shadows are coming!
Sirion's Avatar
Glen Forrest, Western Australia
Joined Dec 2006
1,373 Posts
Your heli sounds like me when I have to visit the chiropracter it seems to have developed a lean and twist .

I think it would help if you track Klondikes down on one of these threads and send him a PM - he's written a few guidelines on these sorts of problems and I think his heli has been moded like yours. He'll probably tell you to resetup the swashplate, etc or he might know off the cuff. You might need to adjust the pots also.

Give him a try but don't tell him I sent you .

Good luck.
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Old Feb 21, 2007, 11:52 PM
Lean is Mean
xtreme's Avatar
L.I. NY
Joined Dec 2003
158 Posts
Check the swash. It could have seperated in the crash. If thats ok pop off the right link end, looking from the back of the bird, & turn it out, counter clockwise, to adjust the swash to the left. You have obviously checked the trim on the transmitter I hope.

Joe
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Old Feb 22, 2007, 12:41 AM
Crashin' n learnin'
klondikes's Avatar
Hopkinsville, KY
Joined Dec 2006
807 Posts
Quote:
Originally Posted by zipdaman12
Observations:
1. seems to be some vibration in the shaft. (visible)
2. Swashplate is level left to right when looking from the rear, but seems to be pitched upward front to back; pitched up towards the nose
3. When I hold it in my hand and gun it, it wants to pull out of my hands to the right; in addition, when doing this if I look at the blades, the space between the blades (looking at them from the back) on the left side of the shaft seems to get smaller with more stick. so basically the more stick it gets while holding it from moving, the lower blades seem to bend upward towards the upper blades on teh left side; and conversely as I ease the stick the space decreases back to normal.

Can anyone help? or is it off the hobby store.... defeated and shameful

Jack
You can fix it Jack. No need for a hobby store unless you need to buy parts.

It sounds like you have 2 different problems. Your item 1 is one problem and your items 2 and 3 are a different problem.

Item 1 is either a shaft not straight or an imbalance problem. Often, if the vibration is not too bad it will not affect the heli when head speed is high enough for liftoff and flight. The higher RPM often overtakes the vibration. If it is a bad vibration you need to first determine which set of blades are causing the vibration. To do this throttle up (I am asuming you know to use the correct order for powering up and that is, in this order, turn on tx, wait for solid red light on tx, plug LiPo into heli, wait for solid green light on 4-in-1) the rotors slowly with the rudder on full left then full right. This should make each set of blades spin independently and you can then isolate which set is causing the wobble. For the set causing the wobble, check the appropriate shaft for straightness. I do this by removing the shaft and spinning it like an umbrella in my fingers. Usually you can see the wobble and either bend the shaft in the correct direction to eliminate the wobble or replace the shaft. If the shaft is straight and the wobble is still there you can try balancing the blades. Here is a link that shows how to check blade balance between two coffee cups. http://www.rcgroups.com/forums/showp...&postcount=572. If the blades are not balanced you can either add a small piece of tape to the light blade or use a sharp knife and trim some flash off the edges of the heavy blade. If the wobble is from the upper blades you need to check your flybar for straightness and beind it to be as straight as possible. Usually somewhere in all of the above you will find the source of the imbalance and be able to fix it. That should take care of your problem #1.

Problems 2 and 3 sound like they are swashplate related. First, check the swashplate to be sure it has not split as xtreme suggests in the first part of his post above. The top of the swashplate can come loose from the bottom of the swashplate. This can be glued back together carefully so as not to glue the bearing into not spinning or, as I would advise, replace the swashplate. Once you know the swashplate is OK the next thing to check is that the main rotor hub is installed correctly. You said you have an aluminum hub so it must be the Microheli aluminum hub. I know this because the E-Flight aluminum hub will not be available for a few more days or weeks. I have not heard good reports on the Microheli hub. Normally the top hole on the hub MUST be aligned with the hole in the outer shaft. I am not sure that this is true with the Microheli hub but I would start there. I am attaching a dis-assembly manual put together by areonuts here at RC Groups. His section on the outer shaft shows and describes these holes and their relationship to the main rotor hub. Once you know that the swashplate is good and the main rotor hub is properly aligned with the holes in the outer shaft you can fix your problems 2 and 3.

To fix problem 2 and 3 you need to level your swashplate. Xtreme has the right idea in his reply above but this does not need to be guesswork. I have attached a "How-To" that describes the systemic, methodical way to level a swashplate. Hint - it is not eyeballed. Follow the attached "How-To" and you will be able to get the movement to the right eliminated.

If all of the above is correct your heli should hover hands free for a few seconds at least - maybe for 5 or 10 seconds or more.

Good luck. Let us know how it works or if there are still problems.

klondikes
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Old Feb 22, 2007, 04:55 PM
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mtfly2000's Avatar
washington
Joined Dec 2006
1,620 Posts
One thing that wasn't yet mentioned is to make sure your flybar teter-toters freely. I've seen where that can cause the symptoms you're describing.
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Old Feb 22, 2007, 07:59 PM
Crashin' n learnin'
klondikes's Avatar
Hopkinsville, KY
Joined Dec 2006
807 Posts
Quote:
Originally Posted by mtfly2000
One thing that wasn't yet mentioned is to make sure your flybar teter-toters freely. I've seen where that can cause the symptoms you're describing.
Good point. The flybar does need to be free moving and straight. Any binding in the flybar will cause problems in flight and the dreaded TBE (toilet bowl effect).

klondikes
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Old Feb 23, 2007, 09:58 AM
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Joined Feb 2007
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Thanks Guys,

I will also try to take a few pics this afternoon. I have a spare swashplate that I may install anyway.

One more question. The micro heli ain rotor hub: Should the bottom of teh hub sit directly on teh swashplate? When I look at the swashplate from teh side (with the servo arms at 90's) it seems to be slanted toward the nose of the copter. I can't level it because the main rotor hub is attached and won't allow the front to move down.

I will share more this afternoon.

Jack
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Old Feb 23, 2007, 10:14 AM
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Joined Feb 2007
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Quote:
Originally Posted by klondikes
You said you have an aluminum hub so it must be the Microheli aluminum hub. I know this because the E-Flight aluminum hub will not be available for a few more days or weeks. I have not heard good reports on the Microheli hub. Normally the top hole on the hub MUST be aligned with the hole in the outer shaft. I am not sure that this is true with the Microheli hub but I would start there. I am attaching a dis-assembly manual put together by areonuts here at RC Groups. His section on the outer shaft shows and describes these holes and their relationship to the main rotor hub.

klondikes
The top holes on teh lower rotor hub need to line up to the holes so the screws go into the shaft right?

Jack
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Old Feb 23, 2007, 10:21 AM
2012 ZX14R ....faster than you
CCbusa05's Avatar
USA, NV, Carson City
Joined Sep 2006
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That is correct. Be careful not to over tighten them or the screw ends might protrude through the holes and make contact with the inner shaft.
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Old Feb 23, 2007, 10:36 AM
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Quote:
Originally Posted by CCbusa05
That is correct. Be careful not to over tighten them or the screw ends might protrude through the holes and make contact with the inner shaft.
Interesting.... so these screws should NOT make contact with the inner shaft? They are basically just stitting in that hole? How is it held on then.... Only the bottom screws making contact with the outer shaft?

Jack
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Old Feb 23, 2007, 01:50 PM
Crashin' n learnin'
klondikes's Avatar
Hopkinsville, KY
Joined Dec 2006
807 Posts
Quote:
Originally Posted by zipdaman12
Interesting.... so these screws should NOT make contact with the inner shaft? They are basically just stitting in that hole? How is it held on then.... Only the bottom screws making contact with the outer shaft?

Jack
Yup. The top screws pass into the holes and set the height of the hub on the shaft. Without the bottom screws these have some, yet minimal, movement. The bottom screws will secure the hub to the shaft and stop this small amount of play.

As for the attitude of the swashplate, how it sits at rest means nothing. How the heli hovers means everything. The level of the swashplate, as described in my "How-To", is to hover well with the trim controls near center. So, whether the swashplate is tilted back or forward a bit when you look at it has no indication of how it controls the heli at hover. Center of gravity on the heli will affect swashplate angle when at rest so it is always prefered to have the heli as close to hanging straight as possible when suspended by the flybar so that its balance is close to center.

The holes in the outer shaft set the height of the hub which sets the height of the rotors. The rotors are connected to the swashplate with two fixed length linkages meaning that the center of the swahplate is fixed in height below the main rotors. The horns on the swashplate are held by the adjustable links to the servos which are hard mounted to the frame. So, because of this chain of connections, the height of the main rotor hub is critical to maintaining the swashplate height within the adjustment range of the only adjustable part of the system - the links between the servos and the swashplate horns. If the main rotor hub is too high you will run out of adjustment on the servo links and will not be able to stop rearward movement of the heli. If the main rotor hub is mounter to low you will run out of adjustment before you get the heli to stop moving forward. Anywhere in between these two extreems is acceptable with the center being prefered. This center is where the holes in the outer shaft are targeted to be.

I take it that your heli is now flying well? I hope so. They are much more fun to fly when you can control them instead of them causing you to constantly react to their uncontrollable movements.

Happy flying.

klondikes
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Old Feb 23, 2007, 03:03 PM
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Joined Feb 2007
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Thanks for the info, Actually it is not flying at all. I haven't had time to break it apart. I plan to go down and work on it in a few.

Jack
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Old Feb 27, 2007, 03:57 PM
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OK, so it was a combination of a bent outer shaft and an issue with the micro heli lower rotor head. Simple shaft replacement took care of #1.

As far as #2...
The blades fit into the hub ok, but when the blades were screwed together they didn't move freely. Not even close to how the upper blades did. I tried drilling out the holes in the blades a bit bit it didn't help. It is clearly a defect in the micro-heli part. I am somewhat dissapointed. I can't return it either. Now I have to wait for the LHS near me to get an actual e-flite lower head as well as an aluminum swashplate. I keep breaking thoise also

Well that's it for now...

Anyone have issues with the microheli lower rotor?

Jack
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Old Feb 27, 2007, 07:26 PM
Crashin' n learnin'
klondikes's Avatar
Hopkinsville, KY
Joined Dec 2006
807 Posts
I have sworn to only use E-Flight parts. I have seen negatives on the Microheli parts all over RC Groups. For me, if it is made by Microheli I am going to avoid it like a bad disease.

klondikes
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