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Modefo's RC Helicopters . RCHover . ZoomsHobbies

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e-Minicopter Joker > strange ESC thing + a few more pictures
 
 
hazchem88
Senior Heliman
Location: W.Mids UK

mj2 all good but off ESC thing.

When spooling up from 0RPM to full speed,
just as it hits headspeed, the RPM drops for a split second (really short - 1/10th second or less), just enough to hear the blip in audio tone and the nose twitch left.

It does it everytime, at the same time, and only once from 0RPM to full.
Fine ones spun up.
It's not a radio glitch as this thing is totally predicatable.

Does not really cause a problem as long as you let the twitch happen on the ground. If I take off before it happens, the nose twitch (to the left) is a little scary, though controllable.

is this normal?

I'll try and film it next time.


09-03-2007 11:03 AM
HOMEPAGE  
 
 
Seablade
Senior Heliman
Location: floating around

Man, that looks so nice being brand new and all!
09-03-2007 11:39 AM
 
 
pyaresquared
Senior Heliman
Location: Central Arizona

I have noticed the same thing with my MJ2, mainly when I spool up real slowly. I get one or two very brief glitches in power. When I spool up fast, it either isn't happening or it happens so quickly that I don't notice it. Once I get up to flying speed, though, there is never any problem, so I haven't worried about it. However, my problem may not be related to yours, because I am using a Schulze ESC and Pletti motor with 10S. I've never noticed it with my J2, which has a Actro 32-4 and a Jazz ESC (also 10S).

Regards,
Steve S.

Surfin' the gravity waves
09-03-2007 05:02 PM
 
 
hazchem88
Senior Heliman
Location: W.Mids UK

12second spool up.
never had this with any other setup.
I used this same ESC in an XLV e-conversion I did. I don't remember it happening there
09-03-2007 05:20 PM
HOMEPAGE  
 
 
ehx
Senior Heliman
Location: Northern Minnesota

Better than filming would be an RPM plot. Chop out the spin-up portion from several flights and see if the problem is happening at the same rpm and for the same duration.

I've got 300 flights on my PowerJazz now. Twice during spin-up at 450 rpm the ESC did cut out for ~4 seconds, but then continued and worked fine in the air. I've never seen my other Jazz, Beat, or Smile controllers do this in thousands of flights, but it doesn't worry me too much because it was only during spin-up. It's just something to watch.

Right now I'm running the exact same power system and haven't seen any problems.
09-04-2007 05:06 AM
 
 
hazchem88
Senior Heliman
Location: W.Mids UK

I'll check the plots over the next few flights
09-04-2007 08:31 AM
HOMEPAGE  
 
 
daytonabeach
Senior Heliman
Location: Oslo, Norway

Does this mean that optimaly you should keep the heli spinning on the ground for a minute before takeof to eliminate mid air problems?

Life is short, time is luck. Live now!
10-27-2007 11:48 PM
HOMEPAGE  
 
 
hazchem88
Senior Heliman
Location: W.Mids UK

only the time it takes to spin up, say 10 seconds. But I will change the pinion to 12T soon.
It will be intereting to see whether it still happens after then
10-29-2007 09:55 AM
HOMEPAGE  
 
 
daytonabeach
Senior Heliman
Location: Oslo, Norway

What pinion size do you have now?

Life is short, time is luck. Live now!
10-29-2007 09:58 AM
HOMEPAGE  
 
 
daytonabeach
Senior Heliman
Location: Oslo, Norway

Forgot to ask this as well, do you have the Kontronik Jazz 55-10-32 ESC?
I noticed that you are using a cooling fan on top?
Could it be that this fan drains a little power...ive heard that the Jazz are sensitive with the MJ2 setup due to the small margin of what it can handle, therefore im considering upgrading to the Schulze mod...

Life is short, time is luck. Live now!
10-29-2007 10:04 AM
HOMEPAGE  
 
 
hazchem88
Senior Heliman
Location: W.Mids UK

using a Power Jazz.
It's got 14T in at the mo' but had no time to try my new 12 and 13T
11-01-2007 09:54 PM
HOMEPAGE  
 
 
fionn
Heliman
Location: Ireland

Solution

Hi guys,
I think I can put this one to bed.
If you read the section in the PowerJazz manual about "Part Load Capability and Active Freewheeling Circuit" it mentions that it uses this circuit to improve part load efficiency but that it doesnt work all the way through the RPM range. It specifically states that when the AFWC cuts in and out that there will be a discontinuity in motor RPM.
Just thought someone might be still worried about it.
Regards,
Fionn.
04-29-2008 08:43 AM
 
 
cwd10
Veteran
Location: PA, - U.S.A.

I would hope that there is a way to disable that feature, as I was considering upgrading to the PowerJazz. If not, I will stick with my trusty 55-10-32. It has never experienced this kind of anomaly, or any other for that matter.
04-29-2008 12:38 PM
 
 
fionn
Heliman
Location: Ireland

problem

I wouldnt let it put you off to be honest, I think it's just an issue on spool up and doesnt really have any adverse affects at typical flight speeds in our setups. I should be having a play with mine today & will report back.
I doubt its possible to disable it either as I'm sure it's a pretty integral part of the actual pwm modulation circuitry (ie hardwired in).
04-29-2008 12:57 PM
 
 
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e-Minicopter Joker > strange ESC thing + a few more pictures
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