What is this noise?

[tempest]

Hey all

I don't know if this is normal but on all those helifreak videos i have saw there was no screaming noise on a MA Heli.

It only does it when i am in positive pitch (About 4-5 degs)

On negative pitch it sounds good.

I am not sure if it is from the gears.

Thanks for help

Andrew

[DavidH]

Gear noise. Check your main shaft and make sure it is not moving.

Don't know how many flights you have on heli. But most of them make the high pitch gear noise sound first several flights.

David

[tempest]

i burned 9 Liters of Fuel (about 15 flights)

Main shaft is moving a bit (0.3mm).

[DavidH]

Main shaft is moving a bit (0.3mm).

That is why the noise increases when the heli is picked up in a hover. And then when it is on the ground and no load the noise goes away. It is the front pinion against the crown gear. The mesh gets tighter when picking the model up, it puts more load against the crown gear.

David

[WillJames]

Here is a thread on Crown Gear Mesh that might help you. DavidH Dr Ben, Russ Mc and others in the thread talk about main shaft split collars and how to setup a proper mesh. It is pretty informative read and I hope it may help.

http://www.helifreak.com/about3352.html

[tempest]

Thanks for helping me guys!!!

There is no gap!!! But the gear is not moving that smooth like bevor!

Ohh well i will go out and test it right now!!

I will post in 20 min a video again and see if it works better!!

andrew

[WillJames]

You may also want to polish your pinion as that quiets it down and makes it smooth if the pinion is rough now. (anodizing is rough)

[Yellowjacket]

If your split collar is loose allowing the main shaft to move check for cracks in it.
Make sure NOT to over tighten it.

Bill

[tempest]

Damn man!

Its really bad now!!

I loosen the split collar and pulled the rotorhead up so there is no gap by the gear(I did not pull to much and over tighten it)!

the front pinion and the crown gear work really smooth and there is no gap!

I checked by pulling the rotorhead up and down! Nothing is moving!

Andrew

[DavidH]

It has been posting quiet a few times on here how most set the gear mesh on the front pinion.

1st. The back edge of the front pinion needs to be flush with the outer edge of the teeth on the crown gear or just a little inside the edge of the teeth.

2nd. Loosen both split collars. Hold the heli up by the rotor head and give a downward jerk of the heli. Continue holding the heli by the rotor head. Push the lower collar down against the lower bearing block. Tighten the collar, do not overtighten it and break the ears. It does not have to be monster grip tight to grip to the mainshaft and hold it.

3rd. Now set the heli down. Push the upper collar up against the bearing in the upper bearing block. Tighten the collar. Again do not overtighten it.

4th. Rotate the rotor head and see if the rotation is smooth between the crown gear and front pinion. I do not worry if it is just a little rough. I fly it one or two flights and recheck it. If it does not smooth out by then, I then reset the mesh.

David

[tempest]

Yeah i reset the front pinion. It was not 100% perfectly (Was more out of the edge)

I will go out and try again!! Hope it works!!!!

Andrew

[tempest]

GOOD NEWS!!!!!!

It works perfect!!!

The gears run really smooth with a really nice sound!!!

THANKS FOR THE HELP GUYS!!!

Andrew

[LS1Chris]

If your split collar is loose allowing the main shaft to move check for cracks in it.
Make sure NOT to over tighten it.

Bill

I had a major crash with my X-Cell due to the set screw collars at my flying field. Was hovering like 30-40 ft stable, then all of a sudden it went right into the ground like I had idle-up engaged and had full negative pitch.

Parts flew all over, cut the tail off, ripped the canopy off and chopped it into pieces, looked like a white falling dome of canopy pieces at that time, and main blades damaged bad.

It was a mystery to me for the first 2 days while being worried how much all this is going to cost me to rebuild.

Then while taking it apart, I found the upper main shaft collar halfway in the collective/elevator mixer section, which caused the pitch to go negative when the mainshaft shifted upwards.
I didn't get it, I had those set screws tighted so tight that the allen wrench is going to slip if I go any further.

Pretty sure this was the cause.
Everything was ok including the radio system and I was the only one at the field flying that day.

After that, I never used set screws collars again for mainshaft and got spilt collars from Hobbies & Heli Intl. and used that.
A few months later MA came out with spilt collars. (over 4 years ago)

[DavidH]

I had a major crash with my X-Cell due to the set screw collars at my flying field. Was hovering like 30-40 ft stable, then all of a sudden it went right into the ground like I had idle-up engaged and had full negative pitch.

The top collar slipping in all probability did not cause the crash. With both collars loose the main shaft is not going to shift any when the heli is hovering upright. All the weight of the heli is hanging on the mainshaft, so it is in the position that it is normally in with both collars installed.
Just my opinion, but I would think something else was at fault with the crash and not the collar.

David

[LS1Chris]

I had a major crash with my X-Cell due to the set screw collars at my flying field. Was hovering like 30-40 ft stable, then all of a sudden it went right into the ground like I had idle-up engaged and had full negative pitch.

The top collar slipping in all probability did not cause the crash. With both collars loose the main shaft is not going to shift any when the heli is hovering upright. All the weight of the heli is hanging on the mainshaft, so it is in the position that it is normally in with both collars installed.
Just my opinion, but I would think something else was at fault with the crash and not the collar.

David

It was not from just taking off to a hover, I was doing loops and rolls before then came into a hover to check the fuel.

The bottom collar was still on as before, the top collar wasn't, it shifted.

If you look at it, the top collar moved, the mainshaft went up, with the collective locked in at hover by the servos, this caused negative pitch to be fed. There was no glitches or failsafe, the radios operated the whole time It stayed level down the whole time.
Winds were light, no microburst as some thought was, auto hub bearing worked fine still.

Either the set screws were prob worn out from some use from switching gears and fine sanding the mainshaft to allow the swashplate to move up/down freely with light lube.

I considered drilling indent into the mainshaft after this crash until I discovered spilt collars.

[DavidH]

The bottom collar was still on as before, the top collar wasn't, it shifted.

The mainshaft will not move in the bottom collar is still in place. I would not recommend flying with just one collar. But the model will fly fine with the bottom collar only holding the mainshaft. The collar is against the bearing in the lower bearing block. The auto hub is against the lower bearing on the other side. So the main shaft can not move.
On the split collars I have had the top collar slide down the shaft , because the years had broken. I didn't even know it was loose till I took the canopy off and saw it . I had been flying the pattern in F3C competition.

David