Logo 400 SE spec analysis

[Kalpazan]

Vibes from motor usually get amplified by something else so you will rarely see any spikes spinning only the motor. Major vibes come usually when you put the TR and especially the tail blades.

When you do these tests take special care if shafts and bearings are fine. Like, check if the motor shaft is OK.

[egaus]

Believe me, I am totally familiar with vibrations being amplified by the TR. I just wanted to ensure that the motor was running nice and smooth. It is.

I'm running a new hardened main shaft. I'm running new tail output shaft, tail pulley shaft. I've rolled them on glass. They appear straight.

How do I check the motor shaft?

Thanks,

e

[Kalpazan]

I use a combination of methods to check a shaft. First, just look at it as it is spinning. If it is too much bent you will spot it immediately. Then, touch it loosely with a screwdriver. You may also put a drop of oil on your finger and try that instead but I kind of don't like that method very much as it might be dangerous with shafts that has some flat spots on them.

Btw, bent motor shaft will wear the bearings very quickly and you will sure notice it immediately. I don't believe that's the case for you but it is no harm to check anyway.

[JohnDoe.]

Another way to check is to use a straight edge. That's what I do. Also try another motor if you have not as it could be bent or tweaked.

[egaus]

Here is the spektrum analysis run at IU2 with only the main and pinion engaged. The boom assembly has been removed. Notice the spike correlates with my last analysis done with everything minus main blades at around 175Hz, though it is barely present here at 70.

This is running a new (never flown) main gear and main shaft bearings. The OWB is original.

All up, no mains: https://www.helifreak.com/attachment...7&d=1336843412

e

[Kalpazan]

How's the main shaft spinning if you try it by hand? Also, may you try to increase the RPM and take another screenshot from the analyzer to see?

[egaus]

The shaft feels very smooth spinning both ways.

I don't want to go much higher, I'll never even use IU2. That test was right around 2200 HS. I want to run around 2000 I think, sport fly.

Just did another test at lower RPM, lower vibe = 62. Went a little bit higher, 3%, same result.

e

[Kalpazan]

Well, if it is not high spot in the main gear that is hitting the pinion too hard then I am out of ideas. :-(

[egaus]

I can feel the high spot on the main gear. I set the mesh for a tiny bit of wiggle on that spot.

I inspected the boom assembly. It turns smoothly. The belt has a quarter turn. There is a tiny axial wiggle in the pulley up front, even with the washers.

Is the vibration level of 62-70 with only pinion/main gear acceptable?

I could run another test with the boom but no belt, then move on to boom belt/no hub, etc..

Thanks!

e

[maarset]

I believe that is a good level.

[Tommy649]

Hey guys,

I have discovered something that has taken my vib levels from 3000+ to 300 with tail blades on and mains off. I am not sure if anyone has experimented with this but it is TOO simple. (stock tail)
Make sure the 3 bolts clamping the tail together are not over tightened. I was getting a little drift and some wack vibe numbers. I messed around with all the typical things like 90 the boom, gear mesh, balance tail blades etc and nothing brought my numbers down until I loosened off the 3 bolts until the were just snug.


Try it if your still having troubles.


Tom

[Kalpazan]

Good point. I noticed something similar on the carbon tail. If the four front screws are too tight there will be more vibes and the shaft won't spin as freely as possible. But careful as if they are too lose that's also not good either.

[Tommy649]

I can't believe it was something as simple as bolt tension causing that much vibration. I just took it out for a spin and it flys smooth and locked in again with no more drifting. Do you know the CF tail part number for the logo 400? I can't seem to find it..

[Kalpazan]

MIK3062 Carbon tail rotor upgrade set for LOGO 10/400

[Tommy649]

Perfect, thank you.

[JohnDoe.]

Spot on before I had an issue with my 5003d I did adjust the belt and tighten down the tail kinda tight.