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Old Feb 15, 2006, 10:50 AM
who dares wins
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Nice work Rod, very interesting


Alex
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Old Feb 15, 2006, 11:04 AM
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Arab, AL
Joined Jan 2002
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Rod,
If you're interested in logs for helis, it might be worthwhile to send a pm to ggoodrum. He can probably provide or direct you to bunches of them.

Brad
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Old Feb 15, 2006, 11:06 AM
Brit in NZ
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Quote:
Originally Posted by Brad S
If you're interested in logs for helis, it might be worthwhile to send a pm to ggoodrum. He can probably provide or direct you to bunches of them.
Thanks Brad - will do. The larger the sample set the better the synthesis from the data!

Rod
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Old Feb 15, 2006, 11:29 PM
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Joined Dec 2005
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Quote:
Originally Posted by RC-Tester
I know, but most of RCG still use the Imperial Units.

(all the data is in Celsius;
if you find it easier drop me a PM)

Rod

Hi Rod,

Thanks for the offer,
but I can be bothered with PMs.


Yes I know most (active) RCG users are in North America,
but the SI units are so much more rational and coherent,
(and you could help educate the unfamiliar).

Can't you just mark the graph scale with BOTH C AND F ?
(obviously giving preference to C).


As for the "Burst" issue I tried to start a debate of what a practical
real world use of a power burst was, but the thread died.
(Definition of "Burst" from 17 Jan 2006, to 22 Jan 2006.)

Neil Walker posted a nice (and severe) graph of 3D heli flight.

And another poster thought EDF was a high power application.


I was inclined to set the "Burst" duration long (eg up to 30 secs),
to push the battery makers to market better products,
and to allow for the increasing performance as the
technology of LiPos improves in the coming years.

But if you are going to do a bunch of tests right now,
then from re-reading the old posts,
I suppose 3 to 5 secs would be a reasonable "burst",
with 10 secs the max.

From a practicality point of view I think 5 or 10 (or even 15) seconds,
would be easier for people to measure, standardise on,
and do calculations with.

Also the resting interval between bursts needs to be standardised.
And again I think a simple multiple of the burst number
would be the easiest for people to use.
I.E. 1 times burst, 2 times burst, 3 times burst, etc, etc.

Other than that I think you are definitely headed in the right direction,
the LiPo market is starting to mature,
and users, dealers, and suppliers are getting more knowledgeable
about LiPo technology and (safe) usage.

Obviously eventually all these tests and terms will be standardized,
but in the mean time there is still plenty of debate and experimentation
to be done.
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Old Feb 16, 2006, 01:24 AM
Flying motor mount master
fly_boy99's Avatar
San Jose, California, United States
Joined Oct 2004
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Hilarious to hear these words actually leave your mouth Charlie...

ROFLMAO!!!!




Quote:
Originally Posted by Charlie Wang
Rod,
People lie just to promote sales, please check with the manufacturer.
They should remove from their website any false information.

Regards,
Charlie
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Old Feb 16, 2006, 01:27 AM
Flying motor mount master
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San Jose, California, United States
Joined Oct 2004
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Rod-

I can drop you a log soon from a SpeedKat (AeroCat) with a speedy profile - hoping to break 80mph +. I'm sure I'll have lots of bursts with the poor TP 1320 PL pack...

fb

Quote:
Originally Posted by RC-Tester
I agree Brad, that is why I am trying to entice anyone to drop an image, or the file, from their in-flight log into here. Hopefully then we can have a look at how flying styles, type and power train system alter key characteristics of the discharge. If I'm lucky we might four or five broad discharge profiles that meet the majority of the types, that I am also prepared to run on the bench.

OK - duly noted. this means similar to CW's second set of proposed but slightly longer time periods for both phases?

You don't have any in-flight logging for the hotliner do you? This looks an interesting one.

What about EDF? 4-5 minute flights at an average of 13-14C, bursts to 20C, base level of 12C in an 80%/20% split?

Rod
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Old Feb 16, 2006, 06:19 AM
who dares wins
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Joined Apr 2005
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mister uhu

c = ( f - 32 )/ 1.8

f = ( c x 1.8 ) + 32

Alex
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Old Feb 16, 2006, 09:23 AM
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Rod

I don't understand the shape of the pulses on the graphs. You say they are 80/20 but they look more like a 50/50 duty cycle. If the low part of the pulse is 8 sec. and and top part of the pulse is 2 sec., why doesn't the pulse shape show that? The low part of the pulse should be 4 times as long as the top part. Why isn't it? Why does it look like 50/50?
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Old Feb 16, 2006, 09:43 AM
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Charles
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Old Feb 16, 2006, 10:05 AM
Texas Ranger
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Here's a DPR file with 3 flights from a Logo 10 electric heli. Power is on 8s and on these flights it had the kicked out of it.
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Old Feb 16, 2006, 10:44 AM
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Arab, AL
Joined Jan 2002
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Quote:
The low part of the pulse should be 4 times as long as the top part. Why isn't it? Why does it look like 50/50?
Because the voltages are plotted as a function of cummulative discharged capacity, which accumulates at over 3 times the rate during the high current pulse than it does at the lower baseline current. Had the plots been generated with time as the x-axis, they would look different (like you were expecting to see).

Brad
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Old Feb 16, 2006, 01:15 PM
Brit in NZ
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Quote:
Originally Posted by Brad S
Because the voltages are plotted as a function of cummulative discharged capacity, which accumulates at over 3 times the rate during the high current pulse than it does at the lower baseline current. Had the plots been generated with time as the x-axis, they would look different (like you were expecting to see)
Thanks Brad,
And to illustrate the point please see the attached time trace (with Celsius at the side).

I'll be analysing some of the flight logs tonight and possily run some more profiles.

Have fun,

Rod
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Old Feb 16, 2006, 01:42 PM
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508 Posts
Help!

Hi,

Gary Goodrum has kindly donated a whole set of fdr files from his Eagle Tree logger - unfortunately I cannot run the software to export the data I need without one of the loggers!

... Is anyone willing to export the data files into csv or Excel for me?

Rod
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Old Feb 16, 2006, 03:35 PM
Brit in NZ
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Quote:
Originally Posted by Neil Walker
Here's a DPR file with 3 flights from a Logo 10 electric heli. Power is on 8s and on these flights it had the kicked out of it.
Thanks Neil,

First off what exactly was the capacity of the packs - we know they were 8S, but how many mAh?

Please fill in the blanks and we can start generating the burst profile. As the first steps are done for the three profiles - filtered at 0.2Hz, and FFT of the signal. (attached)

Rod
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Old Feb 16, 2006, 03:46 PM
Brit in NZ
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Neils burst profile:

Would anyone else agree that :

  • the common period for the average burst is approximately 20 Seconds?
  • on average the burst reaches ~42A
  • on averge the base level is ~ 20A
  • the burst duration is ~4 seconds
  • the base duration is ~ 16 seconds

This would give a synthesised profile of 16 seconds at 20A followed by 4 seconds at 42A.

Thoughts?

Rod
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