Motor shut down

[trillian]

I'll just add, in terms of the current draw in this specific situation. Comparing my Beam 450 SE, I'm running a 3s setup with a JR 50 amp ESC (running the governor) Scorpion 3222-8 motor, I have a Spartan VX1e and those Turnigy MKS copy servos (forgot what they're called) on the swash, MKS DS95 on the tail. I think the headspeed is about 3000. So even on only 3s I have plenty of power and the ESC is happy.

I know the Trex is a bit bigger but is it THAT much bigger? I have always flown 450s on 3s, so my general thought here is that 4s should be plenty unless it's much bigger / heavier or crazy high headspeed (or really low C rated packs).

[Grumpy]

Low head speed combined with the lower weight, more forward flight and less spirited flying = longer flight time.
Try to fly hard 3D like you can with a 12s pack, but on 6S as in the video and current draw will go up.

Ian, I agree, but the point is that at the low RPM that you get when you drop in a lower voltage pack (without gearing up) then you cant fly hard 3D, you just dont have the RPM for that. You have to use collective management because RPM and power is greatly reduced. You are forced into flying a low power smooth style because that's all that the heli is capable of.

Sure if you gear up or drop in a higher Kv motor so you have high headspeed then YES the 4S setup will pull more amps, I agree 100%.. But that's not what we are talking about here.

[coolice]

I'll just add, in terms of the current draw in this specific situation. Comparing my Beam 450 SE, I'm running a 3s setup with a JR 50 amp ESC (running the governor) Scorpion 3222-8 motor, I have a Spartan VX1e and those Turnigy MKS copy servos (forgot what they're called) on the swash, MKS DS95 on the tail. I think the headspeed is about 3000. So even on only 3s I have plenty of power and the ESC is happy.

I know the Trex is a bit bigger but is it THAT much bigger? I have always flown 450s on 3s, so my general thought here is that 4s should be plenty unless it's much bigger / heavier or crazy high headspeed (or really low C rated packs).

Hey Trillian.

Thanks for your input.

You're dead right, 450's fly just as well on 3s as 6s. The 6s just has a bit more punch if you're really pushing it I found.

But there is one consideration here and that is 4's is being run through a motor with a Kv rating for 6s. So that's about half the Kv a 3s motor would have.
Would the lower Kv with 8.4 volts less going into it lead to higher amp draw on the ESC?
Possibly if loaded up. Never tried it to comment. This leads us back to the video Grumpy posted, lower cell count and low motor Kv rating as it's a 12s motor. Longer flight times but an adjusted flying style to stay within the boundaries set by the lower voltage being used.

All swings and roundabouts as you could say.

Ian Contessa

[coolice]

Ian, I agree, but the point is that at the low RPM that you get when you drop in a lower voltage pack (without gearing up) then you cant fly hard 3D, you just dont have the RPM for that. You have to use collective management because RPM and power is greatly reduced. You are forced into flying a low power smooth style because that's all that the heli is capable of.

Sure if you gear up or drop in a higher Kv motor so you have high headspeed then YES the 4S setup will pull more amps, I agree 100%.. But that's not what we are talking about here.

Being brutally honest, what are we talking about here now then?

Could it be the model not flown within the limitations now set by running the 4's pack with a motor Kv designated to work from 6s and thus pushing the ESC above the amp limit?

Like I've said we're clutching at straws to draw a conclusion or reason for the sudden loss of power.
Logic tells us, or me anyway, that a 4's pack in a 6s environment might be a culprit and another forum user has given some evidence to back this theory up.

Then on the other hand, some evidence you've highlighted seems to point away from the BEC, as I'm assuming it's a switching and not linear built into the ESC in question.

We're stalled on going further until updated following any further tests of the model.

Ian Contessa

[coolice]

Hey.

Sometimes the simpalist answer maybe the right one, ESC's BEC could just be underrated.
On 2s to 6s BEC output stays the same @ 3amps.

Ian Contessa

[Grumpy]

Hey.

Sometimes the simpalist answer maybe the right one, ESC's BEC could just be underrated.
On 2s to 6s BEC output stays the same @ 3amps.

Ian Contessa

That could be it, seems kinda strange though because the 470L is a very popular heli and they all come with the same ESC and I've not heard anyone else having BEC issues. If it is you can usually test for it by fast stirring of the sticks on the ground.

What i have heard of quite a few times withe the 470 is static hits causing momentary receiver reception loss. The 470 is belt drive which can build up static, I've seen videos of visible arcing at the front pulley. The easy fix is to lube the belt with a little silicon spray.

[trillian]

Being brutally honest, what are we talking about here now then?

Could it be the model not flown within the limitations now set by running the 4's pack with a motor Kv designated to work from 6s and thus pushing the ESC above the amp limit?

Either that or a low voltage cutoff in the ESC - but if it was expecting 6s voltage then you'd think it wouldn't even arm or would cut out almost imediately.

[feathering]

Because of concerns with flying 4s I have kept an eye on the ESC temperature and I can say that it has always run relatively cool actually. I get about 5:30-6 min with 1800mah batteries. I fly 3d but avoid moves that require hard collective.

My take on current draw is that a reasonable starting point is to consider that headspeed on 4s is 2/3 of that on 6s expecting less current demand as Grumpy mentions. Keeping this in mind, Ian's point is very valid in that this starting point is oversimplified and aspects such as pitch requirement or adapting flying style to low rpm performance, etc... are also important aspects that determine current draw.

I hope to take it for a flight this weekend. On the bench with power and no blades it has passed all tests: shaking cables and loading servos with continuous stick moves have not lead to any shut down.

[brin]

Might see you up at the field in the morning then.

Because of concerns with flying 4s I have kept an eye on the ESC temperature and I can say that it has always run relatively cool actually. I get about 5:30-6 min with 1800mah batteries. I fly 3d but avoid moves that require hard collective.

My take on current draw is that a reasonable starting point is to consider that headspeed on 4s is 2/3 of that on 6s expecting less current demand as Grumpy mentions. Keeping this in mind, Ian's point is very valid in that this starting point is oversimplified and aspects such as pitch requirement or adapting flying style to low rpm performance, etc... are also important aspects that determine current draw.

I hope to take it for a flight this weekend. On the bench with power and no blades it has passed all tests: shaking cables and loading servos with continuous stick moves have not lead to any shut down.

[Grumpy]

Because of concerns with flying 4s I have kept an eye on the ESC temperature and I can say that it has always run relatively cool actually. I get about 5:30-6 min with 1800mah batteries. I fly 3d but avoid moves that require hard collective.

If you are getting 6 minutes then the average current is around 15A. If you were pulling higher current with the same mAh then your flights would be shorter but that's not the case here, you would be doing well to get any longer than 6 minutes on the standard 1800mAh 6S pack, plus the ESC is cool. None of this supports the idea that you were pulling higher current.

I'd try lubing the belt. I have heard of a couple of others with the 470 complain about similar momentary loss of power and they turned out to be due to 'static hits'.

[coolice]

Either that or a low voltage cutoff in the ESC - but if it was expecting 6s voltage then you'd think it wouldn't even arm or would cut out almost imediately.

Morning Trillian.

LVC could be a point, I think someone mentioned further back about the age/condition of the pack and Feathering did say it was a really cold day. So maybe the two combined to give a problem.

The ESC according to the specs run's on was it 2 to 6s, I'll have to look at the image I attached to refresh my memory.
So works on a wide range of voltage.

May know more after today's other flights.

Ian Contessa

[coolice]

That could be it, seems kinda strange though because the 470L is a very popular heli and they all come with the same ESC and I've not heard anyone else having BEC issues. If it is you can usually test for it by fast stirring of the sticks on the ground.

What i have heard of quite a few times withe the 470 is static hits causing momentary receiver reception loss. The 470 is belt drive which can build up static, I've seen videos of visible arcing at the front pulley. The easy fix is to lube the belt with a little silicon spray.

Morning.

Yeah as you say, usually some BEC issues can be replicated on the bench, but then it might not show anything without loading the head either.

Like you say it's a popular model and any problems are usually highlighted by our US cousins and there hasn't been any. But then I've not seen any running a 6s model on 4s to compare against.

Same with static, possible but again I've not seen any reports over on Helifreak of it.
However a cold, damp day and maybe the ability to create static is helped along some more.

Ian Contessa

[coolice]

Because of concerns with flying 4s I have kept an eye on the ESC temperature and I can say that it has always run relatively cool actually. I get about 5:30-6 min with 1800mah batteries. I fly 3d but avoid moves that require hard collective.

My take on current draw is that a reasonable starting point is to consider that headspeed on 4s is 2/3 of that on 6s expecting less current demand as Grumpy mentions. Keeping this in mind, Ian's point is very valid in that this starting point is oversimplified and aspects such as pitch requirement or adapting flying style to low rpm performance, etc... are also important aspects that determine current draw.

I hope to take it for a flight this weekend. On the bench with power and no blades it has passed all tests: shaking cables and loading servos with continuous stick moves have not lead to any shut down.

Keep us posted buddy on what you find out if you make it out. Definitely a great debate, but with so many variables to take into consideration.

What radio are you flying out of interest? If you were on the old DSM2 then any a brown out would be easier to draw a conclusion to. But DSMX wouldn't give us the tell tale flashes :-(

Ian Contessa

[barryorbik]

Hi Ian, Sorry to be a PITA but surely a cold dry atmosphere would be worse for generating static as a moist or damp environment would assist in allowing any static electric charge to find an easier route to earth. Static electricity must be more of a problem in the dryer states in the USA and that is probably where the problem was identified. Pity he is not using telemetry as that would give a clue as to what is happening. We did find a non soldered ESC motor connector on an Align kit at our club recently which only made an appearance during the first check flight and that caused the motor to stop, so it might be a good idea to strip off the sleeving off the motor wires and check all of the motor power connectors.

Barry

[coolice]

Because of concerns with flying 4s I have kept an eye on the ESC temperature and I can say that it has always run relatively cool actually. I get about 5:30-6 min with 1800mah batteries. I fly 3d but avoid moves that require hard collective.

My take on current draw is that a reasonable starting point is to consider that headspeed on 4s is 2/3 of that on 6s expecting less current demand as Grumpy mentions. Keeping this in mind, Ian's point is very valid in that this starting point is oversimplified and aspects such as pitch requirement or adapting flying style to low rpm performance, etc... are also important aspects that determine current draw.

I hope to take it for a flight this weekend. On the bench with power and no blades it has passed all tests: shaking cables and loading servos with continuous stick moves have not lead to any shut down.

Hey buddy.

Sorry I have anot her question that's just popped in my head.
You're not using the governor from memory and relying on throttle curves only?
What percentage of throttle are you running?

Ian Contessa