Logo 400 SE spec analysis

[galensk]

Originally Posted by Bullfrog98

Placing a mini v-bar above the tail boom is probably not a good idea as the vibes are worst there. Perhaps try moving the v-bar down to the bottom of the frame, change the way it is mounted, try different tape, check that the wires are not inadvertently transferring vibration to the v-bar, make sure the v-bar unit is not touching the frame etc...

.

Indeed something to check with care ! some use the CHP plate to mount the Mini-V
http://www.readyheli.com/CHP-L404-Cu...e_p_32310.html
/Kurt

[Yoda DK]

something is wrong with my logo mechanical. i can feel real bad vibes in my hand when spooling it up.i'll go over it again wenn balancer gets here.

i have the sensor kable facing forward on the heli.i'll try turning it around. so i can route sensor kabel away from maingear and tail gear. wenn i zip tie it to the frame i'll put some soft foam between sensor kable and frame. hope that will prevent vibes from frame getting in the sensor kable. don't know what else to do

[Bullfrog98]

Originally Posted by galensk

Indeed something to check with care ! some use the CHP plate to mount the Mini-V

Yes, I have that plate just to mount the main part of my full size v-bar. Anyone putting a mini v-bar on there should mount the CHP plate with decent vibration absorbing foam or something similar, as the two mounting shelves at the back of the frame where you mount the plate can move independently causing all sorts of vibration issues.

Originally Posted by Yoda DK

something is wrong with my logo mechanical. i can feel real bad vibes in my hand when spooling it up.i'll go over it again wenn balancer gets here.

I am sorry to hear you guys are having so many mechanical issues with your 400's. Besides initially not aligning my boom correctly I have had very few mechanical issues with my 400, although it must be said that even on a good day the 400 has more vibrations than the 500/600 on a not so good day.


Have you checked your tail boom supports? The epoxy holding the ends into the carbon tube can sometimes separate, or the carbon tube can split at the ends. This effectively nullifies any dampening and support that the struts should be providing and can result in a lot of "tail shake".

[galensk]

A positive note is that altough the 400 is more critical for vibrations and that I also had "the mechanical trouble" to get it right, it is one hell of a machine to fly once you have it properly aligned. I love it since, and would buy another or convert to SE in case of a crash...

Going through the troubles it came down to mechanical alignment in the end...boom mounting and sensor placement...al lot of help came from "Mr Mell" !!! Thanks !!!

Another HF "pgleesonuk" went through the same issues and ended up with very impressive results : [ame]http://www.youtube.com/watch?v=s3iHHq3bRtI[/ame]

see also his history in VBAR forum : http://www.vstabi.info/forum/read.php?26,49944,49977

Don't give up guys ! A good flying Logo400 is defenitely worth the effort

/Kurt

[egaus]

Ah yes, the famous Glass of Water on the Tail of a Logo 400 vid. I referenced that earlier. I'm going to work on this some more this week. My vibration is most definitely mechanical and is not only obvious at target RPM, it's a little scary to even spool up that high on the bench due to the shaking and noise exhibited.

I don't know why I would continue to keep fiddling with the front part of the tail since everything looks and measures perfect.

That said, probably would be a good idea to invest in a remote sensor type Vbar and put it under the tail.

I had the pleasure of flying mine a handful of times, thought it was great, now I want it back.

e

[galensk]

Good luck, keep us posted
/Kurt

[Yoda DK]

how do i post the analyze vib file? every time i tested heli. i saved them. but they don't show wenn i try to post them here

well i got the dubro balancer to day. and the align balancer i have used was way off. hat to put alot off tape on to balance it out.

first vibe test.with out tail rotor and blades. was like 100
second test with tail rotor and blades hit 1200. i balanced the hole tail rotor with blades on. and it is spot on

[Bullfrog98]

What tail blades are you using?

[egaus]

You need to take a screen shot/snippet of the spec analysis screen, saved as .jpg or .png and use the 'Go Advanced' options, manage attachments, browse to upload pic(s), then hit the upload button.

Your log file is just going to have vibration warnings in it, which you already know about. They could range from Raised vibrations to High or Extreme vibrations.

I'm using both Edge and Radix 72mm. On two seperate hubs, each one balanced magnetically. Same result. One big spike right near 200hz. Vibe hits at target RPM only, at the very end of spool up.

I'm wondering if these vibrations would quiet down once the heli is in the air.

e

[Yoda DK]

Bull: i'm using edge 86mm

egaus: thanks mate. i'm getting several spikes
175,50 Hz, 10530rpm, vibes1264
187,20Hz, 11,232rpm vibes 834
206,70 Hz 12,402rpm vibes 443
214,50Hz 12,870 rpm vibes 374

i'll look at it again tomorow tired of messing with that heli now

[Bullfrog98]

Originally Posted by Yoda DK

Bull: i'm using edge 86mm

If you still have the plastic blades that came with the heli give them a try and see what happens with the vibes. For some or other reason Logos and Edge tail blades don't always gel very nicely.

[Yoda DK]

Hi bull: it came with 72mm edge blades. i sold them to a friend. so can't test them

well i have a update. ordered shims. so i can do the "Mr Mel mod" they should arrive tomorrow. i balanced tail blades. tail rotor. and tail rotor with bolts. one bolt was way heavier then the other fixed that. and everything balances perfect now

just a moment a go. i was sitting and looking at my logo. thinking if i should find a knife and stab it in the heart! kidding
no i noticed that main gear and front tail gear didn't lign up. the bom and mainshaft is 90degree excactly. but tail gear sits 3mm higher then the maingear. here is what i'm thinking. it doesn't matter if shaft and bom is 90degree if maingear and tail gear doesn't lign up. i loosened the bolts.and pushed on the bom up to get them to lign up. and i had to go alot past 90degree to get them to lign up.

when looking,at the heli from the side. with the tail pointing right. maingear is closer to the frame in the back then in the front. that would explain why bom needs to get past 90degree to lign up. or am i way off here?

[MrMel]

Yoda DK, you need to try other blades or check them carefully, it takes so little at those RPM's, for sample, the hole for the bolt can be drilled at an angle, it has happend to a friend of mine with other blades, with it, it caused havoc on the vibrations.

Blades are always first suspect, so get some plastic or borrow a set to try.

[galensk]

Originally Posted by Yoda DK

no i noticed that main gear and front tail gear didn't lign up. the bom and mainshaft is 90degree excactly. but tail gear sits 3mm higher then the maingear. here is what i'm thinking. it doesn't matter if shaft and bom is 90degree if maingear and tail gear doesn't lign up. i loosened the bolts.and pushed on the bom up to get them to lign up. and i had to go alot past 90degree to get them to lign up.

when looking,at the heli from the side. with the tail pointing right. maingear is closer to the frame in the back then in the front. that would explain why bom needs to get past 90degree to lign up. or am i way off here?

Maybe you can compare with some pics :

[Bullfrog98]

@ Yoda, Mr Mel is right, there are so many things that can go wrong with carbon blades during production. If I have vibe issues with the tail the first thing i do is try some trusty plastic blades.
My reasoning behind this is that generally a batch of plastic blades all come from the same mould and will generally therefor be more uniform. They are not as "sexy" to fly but generally I find them far less troublesome.

The way I normally check the boom is to: make sure the heli is stable (cant rock back and forth), put my digital pitch gauge horizontally standing up on the main gear (side of the heli) and zero it, then stick it on the tail boom and check it is zero.
In theory this should be the same as what you did with the main shaft, but who knows?!? Once I am happy with that i still eyeball the main gear to tail drive gear mesh and position just to make sure everything "looks right".

You seem to have been very careful with your setup and checked that everything is true and square so if you are still having vibe issues there must be some mechanical issues you are not seeing. Also, what sort of headspeeds are you guys running?

[Yoda DK]

thanks alot for the response guys! really nice of you

Mr Mel: i'll try some edge 72mm first then i'll buy some plastic blades if the edge don't work out. i just pulled of the 86mm edge and put them on my balancer and let them hang loose down. wenn looking at then on the root. they are not same lenght. its only a hair in difference. so maybe the holes not line up

galensk : thanks for the pics. wenn my mainshaft and bom are 90degree. my tail gear sits 3mm up on the maingear. not alitle below like your's do

Bull: i will try plastic blades. don't care if it look sexy or not. i just want to fly this baby i have tried 2 sets of KBDD blades on my 450. didn't like them. they made heli vibrate even though i have balanced them. so i don't know what to use on the logo would like to use 85-86mm blades on it

i'll make sure heli is stable next time i set up. i use paper wenn setting mesh. and i think it works great. think mesh is right on.

headspeed idle1 is 2135 and idle2 is 2269

[galensk]

Originally Posted by Yoda DK

my tail gear sits 3mm up on the maingear. not alitle below like your's do

strange...3mm looks alot to me. Out of interest in this matter I tend to check every 400 I see ( even in the Mikado stand on 3DM this year ) They are all or the same height or about 1 mm down. Their isn't something somewhere reversed isn't it ? maingear or tailgear ? Should be difficult to do when following the instruction manual I think...

/Kurt

[MrMel]

Or shims in wrong place.

[Yoda DK]

Originally Posted by galensk

strange...3mm looks alot to me. Out of interest in this matter I tend to check every 400 I see ( even in the Mikado stand on 3DM this year ) They are all or the same height or about 1 mm down. Their isn't something somewhere reversed isn't it ? maingear or tailgear ? Should be difficult to do when following the instruction manual I think...

/Kurt

hmm i just looked everything over again.and it's just like manual says. i'm using mod 0.7 but that shouldn't make a difference right? i have to push hard to get gears to line up

[galensk]

I have no experience with MOD 0.7... shims in place like Mr MEL suggested ? Also did you check the HIGH spot on the maingear ? I found the high spot on a place in the maingear and put the paper in between on that spot for both the tailgear and the pinion while setting the backlash.

Maybe you can make some pictures so we can compare ?

/Kurt