Hey guys,

There are two thinhs bugging me about my HBK2. After flight the batteries get really warm. Almost hot to the touch- what is this an indicator of? I am running the Extreme plastic blades- not sure if that might be a factor...

The other thing is that my tail is bobbing up and down really fast. It isn't excessive, but it is definitely there. What is causing this?

Thanks for the help!

hi flyin...imho, a hot battery indicates that it's under a heavy load (heavy blades, mesh too tight, belt too tight, binding in controls, etc.) when you spin the head with your fingers, does it spin freely, and at least 3 or 4 revolutions? for the bobbing, try to safely check your tracking from idle to hover power...if there's a drastic change in tracking, you might have too much slop somewhere (broken flybar pivot, worn feather bushings, worn links, bent spindle/main shaft, uneven torque on blade grips, etc.) it's hard to diagnose a problem without actually seeing it...anyway, maybe i gave you some ideas...ken

what batteries, esc and motor?

tail bobbing is usually from unbalanced tail blades / system.

Mine did this too. I think it went away (or at least decreased a good deal) when I did the 43T tail upgrade. Seemed like the old belt just didn't quite mesh perfectly with the tail gear causing it to pop out a little bit. I chalked it up to "that's what you get with a belt driven heli for < $200" It's a great little heli for the price but it's not perfect.

Or maybe it is tail blade balance and changing the speed just got it out of it's resonance frequency. The bobble didn't really seem balance related but who knows. Hmm....


I'm more worried about figuring out my cyclic issue. That one still has me stumped.

Remember to NOT run your bats down either. I think its about 80% and thats it otherwise you'll ruin your bats.

Like others said... check for to tightness, binding etc and a little lube will do as well. Should spin freely.

Thanks to everyone for all of your input.

For the batteries- it seems like the gear mesh is ok. It wiggles a little so it isnt too tight. I am thinking it might be the belt being too tight- I will loosen it and see what happens...

I am running:

3800kv motor
Esky 25amp ESC
Extreme Blades
Extreme 43t belt
1200mAh 20C batteries

I will try to see if I can balance the blades- dont know if I can because they might be too small for my balancer.

They track perfectly while in flight though...

Ken, my rotor head only spins about a turn- way too tight on the belt, right? Also it seems like if I loosen it much more, the belt will rub up against the tail boom, and wear it down- am I just panicking?

Thanks again everyone- it is much appreciated.

My 2 cents.... the belt tension is a play with it. Too tight and the main rotor head won't spin freely enough and bogs the motor. To loose and it slips off or slips on the tail gear. So like the porridge it has to be jjuuuusstt right. I found on mine I can push the belt in about 1/4 the way with a pen, at the guide pulley. Helps??? hope so

that battery is capable of 24amps, your esc can pull 25amps so you're right on the border. If you have a larger capacity like 1500mah or 1800mah at 20C or a 25C battery it wouldn't get as hot.

Thanks Dawg- I will tinker with it and try to get it juuuusst right...

Druss- Wow, I didnt realize I was right on the border. Solutions?

I dont really have the money to go out and get new batteries- could I go with a 30A ESC?

Thanks!

Do check the threads on the bobbing of 450 class and other helis.

I also have a HBK2 but it never had any bobbing problem. My 450PRO had that same problem. I first thought the gyro was locked too tight but then realized the tail's unwanted movement was more up-down than side-side. So the gyro gain setting din't help.

It would appear that the common cause of the bobbing is too low a head speed. Increasing my headspeed at hover nailed it.

So the easiest should be to fix your throttle curve. If your setup setup does not allow you to do that, one or a combination of pinion upgrade, lighter blades, battery upgrade etc may do the trick. Before spending on stuff, I would try first to fly with a slightly heavier load so that a higher headspeed is required to hover. If the bobbing is lessened then isufficient headspeed is the culprit.