[NSRCA-discussion] Reducing the odds... - Now Cooling
Wayne Galligan
wgalligan at goodsonacura.com
Tue Mar 28 10:45:08 AKST 2006
Anyone thought about using an expandable type foam that would adhere to the
fuse good? It could easily be hollowed or shaped to the proper air flow.
Wayne G.
----- Original Message -----
From: "Earl Haury" <ehaury at houston.rr.com>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, March 28, 2006 1:12 PM
Subject: Re: [NSRCA-discussion] Reducing the odds... - Now Cooling
>
> The foam cup trick works in some airplanes - fine in my E-Partner. Others,
> like the Abbra, present some problems with motor cooling. It's not easy to
> determine airflow into / inside the fuse - I played with smoke a bit to
> observe flows, but with limited success. As Dean points out - high
pressure
> air in contact with the item to be cooled is the way to go. The foam
> "filler" is an easy way to achieve this - any air entering the ducts must
> flow over the motor, there's no other route.
>
> An added function of the foam is a low weight way to strengthen the fuse
> nose, some designs have little strength forward the normal firewall
> location. Of course this is where we need to mount the motor. The foam
also
> reduces gear noise.
>
> Hopefully there're a couple of pics attached of the Abbra installation.
The
> large hole in the bottom of the foam aligns with a baffle in the chin.
Note
> also that the Comp motor is longer than the regular C50, so it protrudes
> from the rear mount (which actually forces some of the air through the
> spiral fins on the motor).
>
> Earl
>
>
> ----- Original Message -----
> From: "Michael Wickizer" <mwickizer at msn.com>
> To: <nsrca-discussion at lists.nsrca.org>
> Sent: Tuesday, March 28, 2006 9:54 AM
> Subject: Re: [NSRCA-discussion] Reducing the odds...
>
>
> > Nat:
> >
> > Not nearly as sexy or professional as Earl's solution, but I know
somebody
> > that has used styrafoam coffee cups cut to size and glued in with CA.
> > Proved to be very effective and a quick install.
> >
> > Mike
> >
> >
> >>From: "Nat Penton" <natpenton at centurytel.net>
> >>Reply-To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
> >>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> >>Subject: Re: [NSRCA-discussion] Reducing the odds...
> >>Date: Mon, 27 Mar 2006 17:08:27 -0600
> >>
> >>Earl
> >>Can you provide more detail on the ducts ? Nat
> >>
> >>----- Original Message -----
> >>From: "Earl Haury" <ehaury at houston.rr.com>
> >>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> >>Sent: Monday, March 27, 2006 4:07 PM
> >>Subject: Re: [NSRCA-discussion] Reducing the odds...
> >>
> >>
> >> > Jim
> >> >
> >> > I've used the datalogger to monitor in-flight performance quite a
bit.
> >> > Typically, during a P-07 flight the low voltage stays above 35v
> >> > (typically
> >> > <65A max) and power consumption is in the range of 3000 to 3400 mAh
> >> > (depending on wind) for an eight minute flight. I've set the ESC min
> >>volts
> >> > /
> >> > cell to 3.0v, but 3.3 would work. These numbers are similar with APC
> >> > 20x15,
> >> > 21x14, and 21x13W E props - Hacker C50XL-14 motor.
> >> >
> >> > Be observant of motor heating in the Abbra, I saw some pretty high
> >>numbers
> >> > with "typical" baffles. Filled the nose with foam (wing core type),
> >>bored
> >> > a
> >> > "tunnel" for the motor, and hot wired ducts. Motor stays very cool
now.
> >> >
> >> > Earl
> >> >
> >> >
> >> >
> >> >
> >> > ----- Original Message -----
> >> > From: "J.Oddino" <joddino at socal.rr.com>
> >> > To: <chad at f3acanada.org>; "NSRCA Mailing List"
> >> > <nsrca-discussion at lists.nsrca.org>
> >> > Sent: Monday, March 27, 2006 1:16 PM
> >> > Subject: Re: [NSRCA-discussion] Reducing the odds...
> >> >
> >> >
> >> >> Hi Chad,
> >> >>
> >> >> I'm about to launch my first electric pattern plane and I'd like to
> >> >> get
> >> >> your
> >> >> opinion on my logic for setting the cutoff voltage. First of all
I'd
> >> >> prefer
> >> >> that I'd never let any cell get below 3.3 volts per cell. However,
> >> >> I'd
> >> >> also
> >> >> prefer that the motor never stopped. My plan is to get to know the
> >> >> battery
> >> >> voltage vs. flight profile to accomplish both. I will set the
cutoff
> >> >> voltage very low so it will never cut the motor. I will telemeter
the
> >> >> voltage and current and keep track of the mAh consumed. If I see
the
> >> >> voltage getting too low (<33V)under max load or use more than 80% of
> >>the
> >> >> capacity I will land. If I can't get through the pattern I'll
> >> >> probably
> >> >> need
> >> >> to go to a smaller prop. Once I am confident that the profile is
> >> >> consistent
> >> >> I can remove the TM system. What do you think?
> >> >>
> >> >> Jim O
> >> >>
> >> >> ----- Original Message -----
> >> >> From: "Chad Northeast" <chad at f3acanada.org>
> >> >> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> >> >> Sent: Sunday, March 26, 2006 10:45 AM
> >> >> Subject: Re: [NSRCA-discussion] Reducing the odds...
> >> >>
> >> >>
> >> >>> Hi Eric,
> >> >>>
> >> >>> Regardless of cutoff, its the resting voltage that is of paramount
> >> >>> importance for good pack life. A 1C discharge with a 3V/cell
cutoff
> >> >>> will leave you with a very low resting voltage, as compared to a
15C
> >> >>> discharge with the same cutoff. Recently there has been a number
of
> >> >>> discussions about increasing safe cutoff values as the C rates go
up
> >> >>> since most of the current packs hold voltage so well up until then
> >> >>> end
> >> >>> when they simply dump everything they have....so 3 v/cell now
equals
> >>to
> >> >>> a much deeper discharge than in the past.
> >> >>>
> >> >>> Then there is the problem that the ESC is only seeing average pack
> >> >>> voltage and not cell voltage...so its entirely possible while under
> >> >>> discharge to have a pair of cells at 3.2v (6.4 total) and the third
> >> >>> at
> >> >>> 9-6.4....or 2.6V, and now your ESC will cut properly...but that one
> >>cell
> >> >>> is being damaged.
> >> >>>
> >> >>> If you run a bit higher cutoff (3.1-3.2) and fly so that your open
> >> >>> circuit resting voltage is 3.75-3.8 you will have very happy
> >>batteries.
> >> >>>
> >> >>> I agree...there is not enough of this information available without
a
> >> >>> lot of online reading. There is a lot of this on RC
> >> >>> Groups...although
> >> >>> it can take a significant amount of time to wade through the BS and
> >> >>> gather what is useful.
> >> >>>
> >> >>> Chad
> >> >>>
> >> >>> Grow Pattern wrote:
> >> >>>
> >> >>> >Chad,
> >> >>> > The speed controller cuts out at 9V. It actually drops
to
> >> >>> > about
> >> >>> >8.3V under load and then settles back to 9.0V after the motor
cuts.
> >> >>> >
> >> >>> >You know it's not so much that I am reporting what I personally do
> >> >>> >as
> >> >> much
> >> >>> >more like I am stating what the system does.
> >> >>> >
> >> >>> >The voltage cut-off end-user value options on the speed controller
> >>are
> >> >>> >selectable but still have fixed values. A three-cell pack has to
use
> >> >>> >the
> >> >>> >9.0V option. I used my in-line meter to monitor and measure these
> >> >> results.
> >> >>> >
> >> >>> >Once again we are back to the instructions verses acquired
> >> >>> >knowledge!
> >> >>> >
> >> >>> >Regards,
> >> >>> >
> >> >>> >Eric.
> >> >>> >
> >> >>> >
> >> >>> >----- Original Message -----
> >> >>> >From: "Chad Northeast" <chad at f3acanada.org>
> >> >>> >To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> >> >>> >Sent: Sunday, March 26, 2006 10:30 AM
> >> >>> >Subject: Re: [NSRCA-discussion] Reducing the odds...
> >> >>> >
> >> >>> >
> >> >>> >
> >> >>> >
> >> >>> >>>I now believe that I had a bad cell on the one that blew-up.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>If you were discharging to 3 v/cell as I read it from your data
> >> >>> >>then
> >> >>> >>its
> >> >>> >>not surprising that you would have bad cells....a 3v/cell resting
> >> >>> >>would
> >> >>> >>indicate that you are discharging much below that under load.
> >> >>> >>
> >> >>> >>shoot for 3.7-3.8 v/cell resting (5-10 minutes) after the flight
> >> >>> >>and
> >> >>> >>your batteries will be much happier, and stay in balance all by
> >> >>> >>themselves for the most part.
> >> >>> >>
> >> >>> >>Chad
> >> >>> >>
> >> >>> >>
> >> >>> >>Grow Pattern wrote:
> >> >>> >>
> >> >>> >>
> >> >>> >>
> >> >>> >>>First of all thanks for all of the suggestions and advice from
the
> >> >>> >>>list
> >> >>> >>>surrounding the charging of my Lipo's.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>I have been messing with the big Lipo's since before Jason flew
> >> >>> >>>his
> >> >> most
> >> >>> >>>notable entry at the world's four years ago. This was my first
> >> >>> >>>catastrophic
> >> >>> >>>failure of a battery pack. I have spent around $7000 on
electrics
> >>in
> >> >> that
> >> >>> >>>period of time and have closely monitored their technical
> >> >>> >>>development.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Right now I am working on sport type or sport level electrics.
Not
> >> >>> >>>the
> >> >>> >>>foamy
> >> >>> >>>type or super light type of models, but the alternatives to 40
> >>sized
> >> >> glow
> >> >>> >>>motor powered models.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>I particularly like the HIMAX offerings where they sell a motor,
a
> >> >> motor
> >> >>> >>>mount, a matching speed controller and a prop all in one box.
This
> >> >> saves a
> >> >>> >>>lot of guessing and previous trial and error on the part of the
> >> >>> >>>buyer.
> >> >> You
> >> >>> >>>are left with the choice of what battery pack and what plane to
> >> >>> >>>put
> >> >>> >>>it
> >> >> in.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Which brings us back to the exploding Thunderpower 4400 pack. I
> >> >>> >>>had
> >> >> been
> >> >>> >>>using my Astroflight 109 chargers with great success. I have 4
of
> >> >>> >>>them.
> >> >>> >>>This
> >> >>> >>>was before the little add-on balancers were available. They
> >> >>> >>>charged
> >>a
> >> >>> >>>bunch
> >> >>> >>>of different packs up to and including the big 4S3P packs with
no
> >> >> problems
> >> >>> >>>etc. I am familiar with their warning etc. In particular, it
> >> >>> >>>states
> >> >> that
> >> >>> >>>it
> >> >>> >>>is not recommenced to charge a fully charged pack, (note: not
> >> >> forbidden).
> >> >>> >>>It
> >> >>> >>>further states that the charger will shut down the charge after
> >>about
> >> >>> >>>4
> >> >>> >>>minutes if you actually try and do this.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Now we get to the 3S pack in question. I was not satisfied with
> >> >>> >>>the
> >> >>> >>>knowledge of what happened and the comfort of how to prevent it
> >> >> happening
> >> >>> >>>again. I did not have another pack, or at least I was not going
to
> >> >>> >>>risk
> >> >> an
> >> >>> >>>old friend's second and last pack. I did a couple of things.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>I measured the each cell of my 3600 mAh Tanic's using the
voltage
> >> >>> >>>taps
> >> >>> >>>that
> >> >>> >>>are part of the assembled pack.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>CELL UP CELL DOWN
> >> >>> >>>
> >> >>> >>>I 4.18 3.01
> >> >>> >>>
> >> >>> >>>II 4.18 3.00
> >> >>> >>>
> >> >>> >>>III 4.19 3.01
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Charging the pack when at 9.2V gave-
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>CELL UP
> >> >>> >>>
> >> >>> >>>I 4.18
> >> >>> >>>
> >> >>> >>>II 4.19
> >> >>> >>>
> >> >>> >>>III 4.18
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Charging the pack when fully charged caused the charged to read
it
> >>as
> >> >>> >>>3
> >> >>> >>>cells. It went through the 3 minute determination pause.
Charged
> >>for
> >> >>> >>>about
> >> >>> >>>a minute and said "I'm done!" did this with two different 3600
mAh
> >> >> packs.
> >> >>> >>>The charger did what it said it would do.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Then just as an FYI, I flew the model with both packs wired in
> >> >> parallel.
> >> >>> >>>One
> >> >>> >>>pack was giving me 5 minutes of flight at full throttle. I
needed
> >> >>> >>>more
> >> >>> >>>air-time on the sport plane. (World models Sky Raider). I now
had
> >>10
> >> >>> >>>minutes
> >> >>> >>>plus and the flight did not run out of steam.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>The two packs were fully charged and the plane flown for about
> >>seven
> >> >>> >>>minutes.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>This created a 3S2P pack. The readings were very encouraging.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>PACK-A
> >> >>> >>>
> >> >>> >>>CELL UP CELL PARTIALLY DOWN
> >> >>> >>>
> >> >>> >>>I 4.18 3.68
> >> >>> >>>
> >> >>> >>>II 4.18 3.68
> >> >>> >>>
> >> >>> >>>III 4.17 3.67
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>PACK-B
> >> >>> >>>
> >> >>> >>>CELL UP CELL PARTIALLY DOWN
> >> >>> >>>
> >> >>> >>>I 4.18 3.68
> >> >>> >>>
> >> >>> >>>II 4.19 3.68
> >> >>> >>>
> >> >>> >>>III 4.18 3.67
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>The cells were discharging and charging nice and equally.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>My charging practices have been upgraded to.
> >> >>> >>>
> >> >>> >>>1. Test voltage of each cell before each charge.
> >> >>> >>>
> >> >>> >>>2. Monitor the charge initiation.
> >> >>> >>>
> >> >>> >>>3. Place pack on 1/2" metal plate on table outside of van. (Deep
> >> >>> >>>Cycle
> >> >>> >>>marine 12V is in back of van).
> >> >>> >>>
> >> >>> >>>4. Check reading periodically.
> >> >>> >>>
> >> >>> >>>5. Test voltage of each cell after each charge.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>I now believe that I had a bad cell on the one that blew-up. I
> >> >>> >>>also
> >> >> would
> >> >>> >>>not charge the TP pack without the after-market device. In fact
I
> >>now
> >> >> do
> >> >>> >>>anything to reduce the odds of another accident.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Just looking at the display on the 109 charger tells you a lot.
> >> >>> >>>The
> >> >> number
> >> >>> >>>cells, the voltage during initialization and during charge, must
> >> >>> >>>be
> >> >>> >>>correct,
> >> >>> >>>or at least in range. Putting the pack in a fire safe place is
> >> >> paramount.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Regards,
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>Eric.
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>_______________________________________________
> >> >>> >>>NSRCA-discussion mailing list
> >> >>> >>>NSRCA-discussion at lists.nsrca.org
> >> >>> >>>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>>
> >> >>> >>_______________________________________________
> >> >>> >>NSRCA-discussion mailing list
> >> >>> >>NSRCA-discussion at lists.nsrca.org
> >> >>> >>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
> >> >>> >>
> >> >>> >>
> >> >>> >>
> >> >>> >
> >> >>> >_______________________________________________
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> >> >>> >http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
> >> >>> >
> >> >>> >
> >> >>> >
> >> >>> _______________________________________________
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> >> >>>
> >> >>>
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> >>3/26/2006
> >> >>>
> >> >>
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> >> >
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> >>
> >>
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> >>
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