Logo 400 SE spec analysis

[agagescu]

I run 2200 IU1 and 2400 IU2 governed by Jive. I haven't actually tached it, just going by HS calc. It was most noticeable ramping up to 2200. I'd guess around 2000.

I took that tail apart for the millionth time. Mesh, tail angle, belt tension, tr shaft, tr hub, grips, etc. quadruple checked everything and ran it up without blades. Managed to get it down to 360 so I was pretty psyched. That's where it was before yesterday's crash.

I took it outside to get 2900+ in IU1 in a hover. Before anyone says tr blade balance; theyre the same blades from before the crash which were perfect. 86mm edge.

This heli is such a love hate relationship and right now I'm hating it. I'm so ready to chuck this thing out the window.

[Bullfrog98]

How did it fly while in the hover???

I regularly check my v-bar logs and often I will get a whole flight with "high vibration" errors even though I get sub-300's on the bench with the main blades off. The heli still flies great though so I just fly it like that.

[agagescu]

It was a little twitchy, enough so that I put it down. Unfortunately I've had high enough vibes on this heli and others to be able to tell when the VBAR is about lo lose it. This was just on the border line.

I have a BT module and check the vibes and logs after most flights with my phone. After I replaced the stock tail I was getting the cleanest logs. All green with good health messages. A couple of high vibe warnings only when doing tic tocs and some antenna switches.

Although the QUK solved whatever issue I was having, I don't think there is anything wrong with the stock tail. I must have tweaked mine on a landing at some point and I'm not able to tell exactly what i did. Now the QUK is doing the same. On both, the bearings were super sooth, the hub looks straight (I spin it in a drill and look & feel for runout), the TR shaft looks / feels straight.

I don't know what to try next. A dial indicator, perhaps a new tail or I might just sell this bad boy.

[maarset]

I use a magnetic prop balancer on my logo tails. Just pull the tail hub off the tail output shaft and put it on the balancer with the blades on. Sometimes the tail blade bolts are of different length and can cause vibs. Also spooling up the 400 on the bench with no main blades and tail stripped down to just the tail shaft helps. You can visually see if the tail output shaft is bent.

With my Logo 400 I constantly had to fight tail vibrations with a black full size vbar and 5.0 software. Once I went with a full size blue line vbar unit it flew so much better and was much more tolerant to vibrations.

[Bullfrog98]

Originally Posted by maarset

With my Logo 400 I constantly had to fight tail vibrations with a black full size vbar and 5.0 software. Once I went with a full size blue line vbar unit it flew so much better and was much more tolerant to vibrations.

I had exactly the the same thing with my black sensor, once I changed to a blue one it was like a new heli

[agagescu]

Originally Posted by maarset

I use a magnetic prop balancer on my logo tails. Just pull the tail hub off the tail output shaft and put it on the balancer with the blades on. Sometimes the tail blade bolts are of different length and can cause vibs. Also spooling up the 400 on the bench with no main blades and tail stripped down to just the tail shaft helps. You can visually see if the tail output shaft is bent.

With my Logo 400 I constantly had to fight tail vibrations with a black full size vbar and 5.0 software. Once I went with a full size blue line vbar unit it flew so much better and was much more tolerant to vibrations.

Thanks maarset, I'm ordering a magnetic prop balancer now. I'd put the whole assembly on a robart high point although I admit I haven't done it since the crash.

I've run it up with the tail stripped down to just tr shaft, put some grease on my finger and felt it at IU1 speed and it looked & felt fine. I'm running a mini blue line on chp plate on the bottom of the frame. I do have a brand new full size blue line that was intended for my 7hv that I can try.

Then again I might just put it on my 7hv and fly that instead

Thanks guys

[Bullfrog98]

Try move the mini v-bar to the top back, above where the boom meets the frame. Mount the chp plate there with some decent foam tape and then mount the mini v-bar on top of that. Make sure the chp plate does not touch the sides of the frames, and the wires do not transmit vibes from the frame to the v-bar.

I tried mounting my full size sensor on a chp plate at the bottom back/middle of the frame and the vibes were horrendously bad. Mounting it at the bottom right at the back without the plate was surprisingly fine. Mounting the sensor just a few millimetres forward on the chp plate pushed the vibes up 5 to 10 times more.

[agagescu]

Thanks bullfrog, that's where I had it originally (first setup). I was experimenting with locations when I first got it and found the bottom of the frame worked better for me, CHP plate and stock mikado tape. About 300 less from 700+ something to just over 300.

I had about 50 flights on it when the stock tail started acting up. 10-15 more flights troubleshooting that stock tail and then about 10 more flights with the QUK tail. When the tail is behaving, the vbar is happier down there.

I will try the magnetic balancer next, then the full size vbar with the sensor in different locations. It's a sad day when my aligns are more reliable than my logo.

[Bullfrog98]

Cool, I guess every heli is different

[egaus]

Hey guys,

I just finished bench testing my Logo 400 SE. I'm using the Quick UK tail. Vibes were not an issue. Max was 286 with no spikes with stock tail blades on. Guess I need to learn how to properly build a logo tail, eh?

One other thing I did was to mount my mini Vbar unit underneath. It was simple to put it there, wish I had done that to begin with. Wires fit nicely.

I'll try to re-maiden it this weekend, see how it goes.

Cheers,

e

[maarset]

AWESOME!!!!!

[egaus]

Well, seems I spoke to soon. Yesterday's bench test never reached full RPM as I had the throttle curve lower than it should have been for some reason. I put it back to 52% using 17T, 1400Kv motor (Mini Pyro 400-14) aiming for about 2100 rpm.

Just as the motor reached target RPM, I got the same result as a few months ago, strong, loud vibration.

I just rebuilt this helicopter from the ground up with new frames, boom, new UK tail, balanced tail, carbon tail box, new tail shaft, new bearings, the list goes on. Now I'm back at square one again. Extremely disappointed. I just don't get it.

This is not a complicated build, everything went together just fine. The boom is perfectly squared to the main shaft.

If there is anyone in the Seattle area that could help me in person, please get in touch.

Gonna go fly my quad.

e

[JohnDoe.]

How bad is the vibration ? This thread has been going on for a while. I had a vib in my 400 and all I did was change a tail rotor hub and that was it. The only time I had an issue is when my flybarless unit was not mounted correctly.

[egaus]

Well, I posted the pic, so you can see it's over 1000. I wrote that the vibration is strong and loud, I don't know what else to say. I have three separate complete tail assemblies I have used, multiple sets of blades. I've used a magnetic balancer to balance all three as complete units. I moved the Vbar to the lower spot but that has nothing to do with the actual cause of the vibration. Believe me, it is not a minor vibration. I've been over this thing a thousand times, it is practically a new kit at this point because I've replaced everything except the motor, servos, landing gear.

I am completely stumped. My Logo 600 flies like a dream.

One thing about the Logo 400 that I see is that it appears that the belt would rub the edge of the boom at the tail side. How tight do you run your belt? Mine is firm, but not as tight as it could be.When I pinch it, it feels right. There is no belt tensioner on my tail box.

Yeah, this thread is long and has been going on for a while now. I put this heli down for a few months as it was giving me a headache.

e

[JohnDoe.]

I am running the plastic tail with the MIK4104 tensionerand have not had an issue. If you are running the carbon tail try the stock one. It's a long shot but who knows it might just be the ticket for you. As far as the belt I run it snug and let the tensioner do the rest. Also have you tried to spool up the heli without rotor head and tail boom and tail gear (that drives the belt) then add the gear into play and see if the vib is there if not move on to the rotor head and if there is no vib then add your tail assembly ( minus the hub).

[egaus]

Thanks. I started with the stock plastic tail and didn't like it because I could not feel the belt tension. The vibrations are present with either. MIK4104 doesn't look like it would work with the carbon tail I have?

Yep, run it with no tail and start adding things - did it. Everything is fine until I actually put the blades on the grips. I've done this with three separate tail assemblies and as many sets of blades - edge, stock and another pair of carbons.

Now you see where I'm at, I really have no where else to go with my $1,500 static model. I need someone more experienced to help in person I think.

e

[JohnDoe.]

Vib with the main or tail blades ?How tight are you running the blades ? Also yes the part I referred to is for the plastic unit.

[maarset]

Looking at the screen shot it looks like maybe motor bearings? Or maybe main bearings? When it is on the bench with no blades it helps to touch different parts of your heli to see where the vibs are.

Keep trying, keep trying, don't give up, don't give up

-Yo Gaba Gaba


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[agagescu]

I got the magnetic balancer, balanced the whole tail assembly on it. It was .02g off. 1/2" square of scotch tape balanced it out. That got my vibes up to about double! Not what I was expecting. Close to 5000 now in a hover. I really wasn't expecting those levels otherwise I would've never put it in the air.

Now I've purchased MIK3052 (tail rotor hub & thrust + radial bearings) and will rebuild the stock tail. Nothing like throwing money at it blindly. Right now I'm suspecting the QUK TR hub got tweaked but I don't have any way of checking. Because if it is tweaked, it is so slight that I'd only pick it up with a dial indicator.

A lot of the guys at the field have said to try different types of tape, a gyro plate, etc, etc. the problem I have with that is that I KNOW this heli flying perfectly with the current mounting position and tape combo. To start changing tape, etc. is just trying find a way to hide whatever the actual problem is.

Like egaus, I have a very expensive hangar queen.

[egaus]

Originally Posted by agagescu

To start changing tape, etc. is just trying find a way to hide whatever the actual problem is.

Exactly!

JD - Doing all my testing on the floor inside w/ no mains or head block even.

If it is a motor bearing I will sh*t a brick, that Mini Pyro motor was almost $250, barely been run.

I've run it up before with the tail/boom off and the motor sounded fine. I've held my finger on it and looked at it, it seems to run true, as well as the main shaft, which has brand new bearings.

The issue must be with something I have either not yet replaced, which isn't much, or my mesh and boom angle or some ridiculous oversight. The mesh is great, a tiny bit of play between pinion and main, main and tail gear. Boom angle has been checked to be 90 degrees about 937 times.

I've built three good flying helicopters, I'm no pro but I think I should be able to make this thing work.

Setting it down for a day. I'm not giving up, just modifying my strategy.

e