MT tail "twitch" near end of battery question

[3D Dave]

Hey guys. After looking through the posts, I can't seem to figure this out.

I have a slight problem with my MT tail wagging as the battery gets low (after about 6.5 minutes of hovering in a warm gym). I understand that the speed control does that to signal low voltage. The problem is, the voltage is NOT that low and when I'm in a cold indoor golf dome I seem to get my normal 8-10 minutes.

On the 2nd and 3rd packs today I landed immediately after the wag started and checked the voltage. It was 11.4v My Li-Po alarm is set to go off at 10.5 so that never alarmed either obviously.

I looked through the mini-Titan manual and there is no info. there about adjusting the stock Ace speed control voltage wagging trigger. Is there a way and is this the answer???

I did feel the speed control and it was pretty hot so I'm wondering if it's getting TOO hot and is signaling me that fact with the wagging?

I KNOW I should get more than 7 minutes hovering with the stock motor and 2200mAh 3S Li-Po's.

Otherwise the flights were great.

Can anyone confirm the cause/solution to my tail wag?

THANKS!!!

Dave D.

[john_3330]

Gyro gain too high? Due to alternating headspeed in normal flight mode, ur headspeed increases and decreases, making the tail servo and Gyro work harder.. Try toning down ur gain..

Hope it helps..

[3D Dave]

john, no I know it's not the gain,

Here is what I think is happening (2 weeks in a row)...


This is 2 weekends in a row where it wagged after 6.5 minutes on Friday in the 68-70 degree gym but DID NOT wag on each Saturday in the 45-50 degree golf dome.

Here is what I think... The speed control (and stock motor) are heating up too much in the gym and causing the stock ACE speed control to pulse. I could try setting the speed control to Nicad/Nimh 5V alarm but I don't know if that will cure the wag.

Also, I'm almost positive that governor is OFF.

I read the ACE manual but I'm a little scared to mess with the ESC and end up changing something either out of my own ingnorance or a type in the manual (the Li-Po voltage cutoff settings appear backwards).

If I try to change the setting to Nicad/Nimh do I have to start from scratch with set-up (setting throttle points/throttle calibration with the transmitter)? I'm not quite clear on the step-by-step and don't want to mess something up.

I tried to help the situation now by cutting off most of the rubber heat-shrink cover but I don't think that will make much difference. I even thought about mounting a 12v micro computer fan in front of the speed control blowing toward the motor.

What do you think?

Dave

Chicago

[Erikito]

Don't count too much on correct voltage reading by the esc. Check if your lipo's are full before flight, USE A TIMER and switch of the protection by selection the 5V thing. The wag is most probably caused by the esc reducing output as protection. I've used the Align 35A ESC and the low voltage protection kicked in way too late, and some times too soon because I was using high power (specially in governer mode, I recommend NOT using governer mode on stock esc). I believe the ACE ESC isn't better at it. I use flightpower lipo's which seem to have a higher voltage than other similar lipo's making it even more difficult for the ESC.

How long you can hover with your pack depends on many factors. How tight is your tail belt? It should not be tight at all. Another VERY important thing to check it your motor pinion. 13T is right for 3S lipo's on the stock motor and esc, 15T is no good. Your motor pinion should be just a little off the main gear (very very close to it though). When you think you got it right, set your blade pitch to 0% and try rotating the rotor blades counterclockwise, and let go. The rotor blades should keep spinning a while, otherwise something is wrong.

Also check your throttle curves in relationship to the actual pitch on your rotor blades. I have my rotor blades set at 0% pitch when my throttle stick is in the middle. My throttle curve is: 0 - 50 - 75 - 100.

Also check if all ventilation holes in your canopy are open (I cut a triangle in the top of the nose of the canopy) and place your ESC with the heatsink up all the way in the front. You should get 7.5 minutes flight on 2200 mah (only discharging them about 80%). I can touch my motor and esc right after flight.

I hope all this helps!

[3D Dave]

Thanks Erikito.

I use a timer AND the HRPoly Li-Po alarm set to 10.5v. I'm using Thunder Power eXtreme V2 and CellPro Revolectrix 2200mAh cells which all are appx 12.5-12.6 volts fully charged. I really do think it's the esc reducing output due to high temp.

I'm almost positive the ESC is not in governer mode.

Motor pinion, blade pitch, belt are all fine and headspeed (since I'm new) is appx 2000-2100 RPM using the 13t pinion. Throttle curve is very "tame" also. I can cut more holes in the canopy but all the "standard cutouts" are open. I get 9-10 minutes in the cool 50 degree golf dome with no wag and 6-7 minutes (wag at appx 6.5 but voltage still 11+ volts) in the warm 70 degree gym.

After the flights in the gym the motor and ESC were "scorching" hot.

I think I'm going to try the fan on the heat sink idea. I just read an article in an RC boat magazine where the author used 2 mini computer fans on top of his dual speed controls to keep them cool. Then again, that won't help the motor much though (and the summer hear in Chicagoland will be scorching soon) so I'm going to order a JGF450TH motor and Castle Creations or Scorpion speed control ASAP and swap them in.

Thanks for your help. If you have any other related (or unrelated) tips/suggestions, I'm all ears.

Dave

[Erikito]

Your headspeed seems too low to me using 13T and 3S lipo. This makes the motor less efficient and way hotter. Try this throttle curve: 0 - 50 - 75 - inh - 100. Try using good CF blades instead of the stock blades. The stock blades have a lot of drag. The align woodies seem pretty good for the price, but I use radix 325 cf blades and they are great. If you get them do get the spacers too because they are too thin for the grips. I cut out a triangle in the nose of the top of the canopy, so more downward air gets to the esc. Also check if all your links can move freely. If not squeeze them a little with a plier on the sides to make them looser.

Good luck!

[3D Dave]

Thanks Erikito.

I will try raising the headspeed to 2300-2400 as soon as I get an RPM meter.

I also plan on getting some CF blades to try. Only problem there is the golf dome where I fly doesn't allow CF blades (but the indoor flying is over in 2 weeks).

All the links appear to be loose and I will cut more holes in the canopy.

I'm going to order either the Castle Creations Phoenix 35 or 45 ESC and try. Then, in a few weeks I'll get the JGF450TH motor for outdoor flying this summer.

I'm still thinking about adding the 12v micro fan on the ESC though.

Dave D.