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Old Jul 11, 2001, 10:02 PM
Radix malorum est cupiditas
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Hacker B20/Jeti18 missed starts

Using the B20-15L +4:1 GB and the Jeti18-3P, I've noticed a fair number of times where the motor fails to start when the throttle is advanced (currently using a 9X5 Slim Prop), I was wondering how often this is happening to others.

Having a fair amount of experience with brushless drives, I understand the process of starting a sensorless motor and attendant difficulties- in this case they may be accentuated by the high inertia of the heavy Slim prop through the 4:1 drive.

so hows it workin for ya?
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Old Jul 12, 2001, 01:48 AM
BEC
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Auburn, Washington USA
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I've not tried that combo, but I've had a fair number of failed starts using a Jeti 40-3P on a Hacker B50L-13 (with MEC gearbox and APC 14X7E prop) on the test stand. It tends to give up trying to start very quickly - much faster than a Schulze Future. Yet the Jeti controller starts a Jeti motor EVERY time and with very little fuss.

I am still trying to understand all of this well enough to put it into a column - but it seems that with sensorless there are LOTS of subtle variables in mixing and matching components.......

I know, not much help.

Another example - SOME software versions of the Schulze Future 18 will start the Astro 010 every time, and quickly, others won't and act like the Jeti/Hacker combo you mention.

An older software version of the future 45 always started my Aveox 1114/4Y on MAT belt drive but very roughly, and the latest revision is MUCH better, but even that is not as smooth as an Aveox or Castle Creations sensored controller (or just about any brushed motor/controller combo you can name).

So right now I have many more questions than answers.
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Old Jul 12, 2001, 04:00 AM
pfg
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Vancouver, BC, Canada
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i have a B20-15L w/GB but using a kontronic smile 30-6-12. first props i used were all graupner folders so they were pretty heavy. a few times on the ground advancing the throttle produced the kind of noise i dont want to hear so immediatly cut throttle. never did it in the air though. the few times i tried it with an apc it started right up. sorry cant be of more help - seems this comes with the territory to some extent. awsome power out of a 2oz motor GB combo. cant wait to get it into the crazy sparrow also wondering why the 9x5 slim prop ? apc e's seem to do the best - how many cells you running ?
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Old Jul 12, 2001, 06:39 AM
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Agra, Oklahoma
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FWIW -
I have a Jeti 18-3P and Hacker B20-12L and this combo starts very reliably both direct drive (tiny prop) and with gearbox (3 different ones thus far). One thing to make sure of is that the motor/gearbox are secure when starting with a prop attached. Holding it in your hand and even some mounts can allow it to counter-rotate and can lead to false starts. Make sure there is no binding in the gearbox - that the output shaft turns smoothly.

Good luck!

Steve
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Old Jul 12, 2001, 04:19 PM
BEC
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Auburn, Washington USA
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Quote:
Originally posted by radix2:

BCawley - for sure, a sensorless motor will never start as well as a sensored motor. In my experience there are many variables in the open loop control required to start a sensorless motor that will make mixing and matching motors/controller/gears/props difficult for the BL-ESC designer to deal with for starting. I wouldn't be surprised if we don't see in the near future some programability in the designs to deal with this - something like several options to specify some of the load characteristics or motor combo used. Some of the German controllers may have some of this now.
Schulze do have different timing options and switching frequency choices. I don't know if the startup algorithms are different with the different timing/frequencies. I guess I should ask Matthias Schulze.

I understand that Kontronik has some programmability, too, but I haven't gotten an opportunity to try one yet .
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Old Jul 13, 2001, 12:18 AM
Radix malorum est cupiditas
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pfg - Using 8X600AE, I do also use various APCs, 9X4.7,8X6,10X4.7. For the current set-up, the Slim just just works well.

BCawley - for sure, a sensorless motor will never start as well as a sensored motor. In my experience there are many variables in the open loop control required to start a sensorless motor that will make mixing and matching motors/controller/gears/props difficult for the BL-ESC designer to deal with for starting. I wouldn't be surprised if we don't see in the near future some programability in the designs to deal with this - something like several options to specify some of the load characteristics or motor combo used. Some of the German controllers may have some of this now.

Stevem - good point on the stiffness of the mounting, it makes sense that this could also confuse the starting algo. It's probably worthwhile to point out to those new to these devices that they can be quite rough when starting and need a sturdy mounting.

I am considering setting my trim to maintain a slow idle (ala glow), since my plane won't glide with the prop stopped anyway. I think I will also do some experimentation to see what the difference is with different props.
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Old Jul 16, 2001, 08:25 PM
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Did some experimentation and have come to the conclusion that lower inertia props start better with this combo. My current favorite prop - APC 8-6E starts smoothly almost every time, and never gives the BUZZ/Quit effect- this prop is much lighter and of course smaller dia than the heavy Slim Prop. The APC 9-4.7 (in between in mass and inertia) also starts better than the Slim, but not as good as the 8-6.

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Old Jul 18, 2001, 05:59 PM
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Baden Baden, Germany
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I use a Hacker B20 18L with the 18Amp Jeti and it works great but I have heard of somebody else with the same combo who had problems with it not starting well. After using a schulze controller his motor worked as well. We both use the Hacker for pylon 400 planes with small props (APC 4,75x4,75 or similar). It is kind of strange...


Eike
http://www.schunternet.de/~eike/
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