Logo 400 Help please

[aziz76]

I had just rebuilt my Logo 400 3D, for the 4th time now.... I just don't know what I'm doing wrong

The first 3 flight were simply amazing. The heli was locked in, felt very precise, and just flew really nicely. It was even confidence inspiring and I worked up the courage to try a few flips and rolls which were awesome.

Then flight 4! Shortly after take-off, I heard a snap and I lost tail control completely and the heli started piro and vibrate badly. For the first time, my usually inadequate emergency landing skills were ok and I managed to bring it down with only a moderate impact.

When I inspected the damage, it seems that it threw a tail blade. I had suspected this to be the case in my previous 3 incidents with this heli but then I wasn't sure because those times there was much more damage when it came down. The bolt that holds the blade to the grip ripped out of the grip.

My setup is as follows:
MiniPyro 400-14 w 18t Mod .5 pinion
Jive 100LV
Edge 425mm mains, Edge 82mm tail blades
Normal 45%, IUP1 55%, IUP2 65%

I suspected my head speed was very high going by the sound which is why my governor is set so low. I haven't tached it but in flight it doesn't feel like that high a head speed. I should be getting around 2250 rpm on IUP1, which is where it was at when all this happened.

I'm at loss for sure I am missing something. Any help would be much appreciated guys.

[Hati]

I would try the stock tail blades (72 mm?) for starters and drop the headspeed under 2000. Work your way up from there and only increase rpm by 100 at the time and inspect the grip after every flight closely.

How tight do you do your grip bolts up?

[aziz76]

Thanks Hati, I actually did try the stock plastic (which are 85mm).... But the same thing happened, that was crash #2.

I always try not to over tighten them so that they can still twist in the grip with moderate resistance, i.e. they don't flap about but they're not stiff either.

[Jays200]

I fly my 400SE with 86mm Edge tails at 2400HS with stock plastic tail blade grips and have never had this problem. I have noticed that the holes in the blade grips can get slightly elongated over time but that is probably to be expected spinning at 12000+ rpm. The blade grips are cheap and easy to replace so keep an eye on them and change them out.

I don't over tighten the blade grip bolts and only do them up tight enough so there is no side to side movement. Perhaps you could be doing up the bolts too tight and splitting the plastic.

It's OK to have the tail blades slightly loose than overly tight.

[aziz76]

Thanks Jason, I didn't think they were too tight, but I will give it another shot and make them looser. The crash stripped the gears on two of the cyclic servos (Futaba S9650) for the second time. I'm not liking these servos much, they seem very fragile.

What other servos do you guys recommend on the 400?

[BakedMopar]

I use the ds510m on cyclic and futaba bls251 on tail. Edge 72 @ 2600 rpm My guess is too tight on the blade bolts. I tighten mine up until it has very little resistance on the blade.

[Hati]

Just picked up the servos for my 400SE. I got BLS153s for cyclic and BLS257 for the tail. Such a nice looking little bird I decided to go for premium gear on it as this heli is definitely a keeper

[Jays200]

Originally Posted by aziz76

What other servos do you guys recommend on the 400?

I got sick of replacing plastic gears in the 510s and have used MKS 9660A+ metal gears since. They can be difficult to find but I got them for $50 ea from Hobbyking. Using the Mikado carbon servo arms and this setup has proven very durable.

I run the whole heli on 6V, no step down, with two BEC cables from the Jive.

[aziz76]

OK, I got it rebuilt and installed a JLog on it. I have attached the log files the last few tests. My suspicion of too high headspeed it seems is correct. For some reason, at 50% throttle on the Jive Gov I am getting a HS of nearly 3000 rpms! I had to take it all the way down to 20% to get the head speed to around 2300! Really strange.

I have even stepped down my pinion. I was running 18t before, now I am running 16.

Looking at the motor RPM that seems incredibly high as well. Its almost as if the motor is giving more than 1400kV??

Am I missing something guys? Thanks for your help.

[Jays200]

Sorry Aziz I can't help you since I'm now running Mod 0.7 with my Mini Pyro 1400.

FYI, 35%, 45%, and 55% gives me approx 2000, 2200 and 2400 but again Mod 0.7 with a 12T pinion and Jive 80+HV. I am contemplating a Pyro 600-9 or 600-11 with a 16T/17T Mod 0.7 pinion. I'd love to see how much I can squeeze out of this great little heli.

[aziz76]

Ok, working back from your head speeds Jays200 you get a motor rpm 27600 at a head speed of 2400 rpm. This with 55% on your Jive.

I am getting that motor rpm with 24% throttle on the jive (calibrated endpoints).