450 450 Pro vibration

cn63bug

cn63bug

Member
So I think that I have taken care of my tip over tendencies. But I have noticed another issue. I have a vibration that seems to come up while hovering. I took the mains off and checked the head and main shaft again and everything appears to be good. Spooled it up on the bench and everything was smooth. Now while hovering, it's not that smooth. I am thinking that the blades may be suspect. They are Align 325D Pro blades. Not the 3G, but the standard CF Pro blades. While checking the blades out, there is one blade that is .1g heavier than the other. It's actually less than .1, so I felt they were pretty close. On inspecting the straightness of the blades, I did notice that when looking along the trailing edge of the blades, the slightly heavier blade has the slightest curve in it. Didn't think it was that much of an issue as the tracking seems to be spot on. Pitch is 0 at midstick on both blades and +/- 9 at both positive and negative. Now one thing I will say that I noticed was that the blades were extremely tight when putting them in the blade grips. Ridiculously so. I have worked the blades back and forth while in the grips and have managed to loosen them somewhat, but they are still tight. I cannot get the blades to drop while holding the heli sideways. Anyone else have this kind of issue? And what other blades would anyone else suggest? I've had two sets of blade grips on the heli now and this tightness was the same way on both sets. When I measured the root on the Align blades, they measured 4.64mm and the grips measured 4.5mm. Any thought?
Thanks guys!
 
cn63bug

cn63bug

Member
helicc16 said:
Is this fly-bared heli? Did the vibrations start after a recent crash?
Click to expand...

Sorry, its flybarless. It did have a minor crash awhile ago, but everything was replaced after that.

- - - Updated - - -

Oh, and the day before when I flew it, it was smooth. But the next day, vibrations...
 
Westy

Westy

LEGEND
Hi There,

Ok .... I know you have probably done this but I will say it anyway .

1. have you checked the CG of the blades and matched them up?

2. Have you balanced the blades

3. When balancing the blades and bolted them together... are the brass inserts in the blades sitting perfectly? There should be no gap between the blades ... if there is, then one of the blade inserts is inlayed off centre and you will never get it right.

4. you need to do your tracking ... if the tracking is out, it will definitely cause a bad vibration.

try those things and you should fix it!
 
cn63bug

cn63bug

Member
Hey Westy,

OK, I have checked cg on the blades and that was good. The balance is good as well. I also checked that the inserts were good and they were. The only thing that I could think of on them was that 1 blade is less than 1 tenth of a gram heavier than the other, but the tracking was spot on, so I didn't think it was that big of a deal. Maybe wring in that thinking, but the flight before the last was very smooth and then the last flight wasn't horrible, but vibration was enough to make me nervous and set her down before it could cause any issues. If the blades are too tight in the grips, that seems to me that it would cause vibrations too, wouldn't it?
 
Westy

Westy

LEGEND
If you are running 3Gx... try running your DIR mode again .... what have you got your AIL and ELE Pots Dialed into?

- - - Updated - - -

1/10th of a gram would not do stuff all .... If the vibe is not there with no blades on.... then it is your blades. Try a known good set and see the difference
 
cn63bug

cn63bug

Member
Westy said:
If you are running 3Gx... try running your DIR mode again .... what have you got your AIL and ELE Pots Dialed into?

- - - Updated - - -

1/10th of a gram would not do stuff all .... If the vibe is not there with no blades on.... then it is your blades. Try a known good set and see the difference
Click to expand...

Aile and elev are at 105 on both. I'll have till wait until Tuesday when my lhs is open again to get a new set of blades to try.
Thanks
 
Tony

Tony

Staff member
Are you sure it's a vibration and not aileron or elevator shake? YOu may need to lower the pots as the gain may be too high. Video would help us out to know if it's a vibration or gyro shake.
 
cn63bug

cn63bug

Member
It had occurred to me that the gains may be still a little high. Can't check that until Monday because of the rain here this weekend. I just thought that the blades were way to tight in the grips as when I held it by the side and did a shake, they would not fall.
 
Westy

Westy

LEGEND
I actually adjusted mine on my 600 with 3Gx Today as I was getting a bit of tail bobbing and also after that Aileron shake the heli is now pretty stable.

Not sure what the values are now ... will plug it in and load up 3Gx interface and see in a tick!
 
helicc16

helicc16

the Smoothie Pilot
Blade tightness is not an exact science. You should be fine as long as the blades are not too loose or too tight, or one blade really tight and the other really loose. I've had vibrations problems before. But none of them was caused by the tightness of the blades.

I was going to ask what kind of vibrations you are having. Just remember that any time you change the cyclic pitch during the DIR set-up, you are also changing the gain values without touching the pots.

Therefore, anytime you have to do a DIR setup, you should always go back to the 3GX software to make sure you have the right gain values for AIL and ELE.

I use gain value of 110 on all of my 3GX powered helis. It works great.
 
cn63bug

cn63bug

Member
It seems that the blades were way too tight after all. I don't think that they were able to fully "seat" themselves when spooking up and were slightly off. I worked with them enough so that they were not too tight in the grips, but not loose either. The thing that bothered me about it was the blades were measuring 4.65mm at the root, but the blade grip opening was measuring only 4.5mm. Way tight to even insert the blades in the grips. They are not that tight now and its smooth taking off, flying and landing :)
I do think that I will trying to turn down the pots thought to maybe 95 and see if it slows it a bit. Most of my flying right now is done indoors and I don't want it to get away from too quickly and hit a support column in the building ;)
 
You must log in or register to reply here.
Top Bottom