Hi,

I got a T-Rex 450 from Tarot and I'm using Align servo for cyclic and Futaba servo for my heli's tail. My receiver is an OrangeDSM2 9Ch and TX is Spektrum DX7. I also got Flymentor installed and working properly when hovering I can let go the Radio TX and my Heli will stay on one location.

My problem is when I'm on my second battery I noticed that my helicopter start loosing elevation from time to time. Attached is the setup on my CC ESC and the log I collected on my last flight. I'm just hovering my heli in front of my drive way, not a forward flight on this log.

Can some please help me if this is related to ESC setup?

Thanks,

Allan

Are you logging throttle? if so post another screen shot with that included.

Looks like your problem is the voltage. When you plugged in the battery, according to the log it was only 11.2. I am assuming this was a 3s battery which should have been 12.6. Near the end of your hover the voltage drops very quickly to 8v. This would cause the problem.
In short if this was a 3s pack, it was not fully charged. What do you have LVC set to? It should have shut down sooner than the graph shows.

Steve

Yeah, something is deffinatly wrong with his voltage. I was just wondering why his motor output rose quickly to near 100% at the end there but his rpm never rose. Could that be a slipping pinion or a bad one way bearing?

Originally Posted by neoalchemist74

Yeah, something is deffinatly wrong with his voltage. I was just wondering why his motor output rose quickly to near 100% at the end there but his rpm never rose. Could that be a slipping pinion or a bad one way bearing?

No - looks like he's running the gov mode so as the voltage drops, Motor Power Out will increase to try & maintain the head speed just as its designed to but theres just nothing left there when the bottom fell out of the pack.

Steve

Hi Guys,

Thanks, for responding to my posting. I should have told you that I used a battery that's not fully charge on that test flight sorry for that.

Today I did use a fully charge battery from yesterday night and manage to do a test flight again. I don't know if the head speed is not enough it looks like that the data gather seems to be fine. The drop on the middle is when I land the heli to check something on it.

I've seen video of other 450pro and specially those with scale fuselage, I notice that most of them maintain altitude even just hovering or even flying low and slow. My Heli when I turn rudder left or right, bank left or right or forward or backward it looses a bit of altitude.

I attached the csv file so incase you want to view it on your own Castle Graph View to turn on and off some value for easier viewing you can do so.

Setup:
Tarot 450Pro
Flymentor Flight Stabilization
Orange DSM2 9CH
Align servo for cyclic
Futaba servo rudder
Sky Lipo 3S 3000mAh
Castle Lite 50
AKE ICEcold 480R3800TF
13T Pinion
150T Main Gear

I would greatly appreciate it if you can give some hints where to look at as I run out of idea to try.

Thanks,

Allan

Flying your lipos until they drop to below 9.0V is a great recipe for either a VERY short life, or worse, a lipo fire

You should not be trying to get 12 minutes out a lipo (even a 3000mAh, unless a very low headspeed is used) by flying until the heli cannot stay airborne. Keep that up for another few flights and you will probably be buying new lipos.

The first log showed a lipo that should have been on charge because it was close to 80% discharged. Most people find that a 3s lipo discharged to about 80% will have a voltage of about 11.1-11.2V. Yours will probably be taking 100% or more of capacity

My guess is that at a headspeed of 2800rpm and discharged to 80% (around 2400mAh) on your lipos you would probably be using at least 260mAh/minute, so around 8minutes would be a good place to start, and check your mAh put back and adjust your flight time if necessary. This lines up with about 11V according to your log.

If you fly until the lipo cannot deliver enough volts to maintain the desired headspeed, the heli will start dropping when there is not enough lift to keep it airborne.

The logs look fine - you are just pushing it too far.

Colin

Hi Colin,

Thanks again for the advice, I will adjust my time flight then. But can you explain why I'm loosing altitude during my first minute of flight if the power output and RPM data log looks good? As I said that's happening when I start to move the helo forward backward bank right or left and even on rudder left or right. It's not a significant drop but I'm noticing it when I'm hovering 2feet from the ground.



Thanks,

Allan

I think it's just a matter of collective managment. No heli will maintain perfect altitude for very long without adding or taking away collective - hovering or in flight.

Sorry I'm still learning all of this and even though I am nearly two years on this hobby I haven't got all the knowledge needed. And I thank all the guys who share information to forum like this.

So going back to my original question, it is normal that heli will not maintain altitude when adding or removing collective in hovering or in flight. What's the purpose of governor then? I thought head speed will be maintain so that when there cyclic input it will be same thru out the flight. I'm maybe wrong this is just based from what I read about governor on some forum.


Allan

Hi Alan
All the gov does is maintain headspeed as much as possible no matter the load on the disc which has no relation to maintaining altitude. In a perfect world, in theory, with constant headspeed and a set pitch we should be able to maintain altitude but when you throw in a little wind, cyclic inputs etc things change over the airfoil of the blades & then collective inputs must be used to maintain altitude.
I don't think anythings wrong - its just welcome to the wonderful world of Helis!

As Steve mentions... the GOV just maintains the HS... You may flatten the pitch curve around center a bit for a test to see if you are slightly changing pitch when adding a rudder input as this is very easy to do. You may also want to get out of ground effect as this can cause weird things also.