[NSRCA-discussion] Main battery redundant lead for receiver

Wed Jan 25 15:54:22 AKST 2012

The big difference is just that electrics weigh in with batteries installed
and wet fuel ships weigh in with an empty tank.  What does your #160 weigh
fully loaded with fuel?  In general, the batteries are going to amount to
about 20-25% of the total weight (my 4900mah batteries weigh in at just
under 1200g) but the motor weighs about 350+g LESS than a YS170 (580-620g
for the electric vs. 960g for a YS170) and the total electric power system
(counting ESC) should be under 40% of the all up weight of the aircraft, in
my case it comes to just under 38%.  Glow fuel undoubtedly brings your
power system in to a much lower % of the all up weight, even counting a
couple hundred grams of fuel fully loaded and the muffler/pipe, but
airframes seem to weigh more because they are built to handle a lot more
vibration than you get from an electric.

That said, I don't think we're going to "extraordinary" measures to save
weight, we're just trying to take full advantage of the components we
already have to have (like the main system battery) to serve double duty
without giving up redundant power in the system as a whole.  In my case,
discovering I was 30g overweight I had no trouble shaving the weight:  Swap
a 1350 RX battery for a 450 RX battery (saving 38g), add Chris' main tap as
a redundant power supply to the RX (previously I'd just left the second
power lead to the RX unused and gone without redundancy) at a cost of
probably 3g (no regulator needed, though if I can find a decent one with
minimal weight penalty I'll add it) and now I'm 5g under the limit.  Since
I was on Chris' store and didn't want to get just the power tap, I decided
to give a Falcon V2 carbon prop a try, saving me another 30g.  I could
easily swap out my convenient Secraft wire tensioning system to save
another 10-20 grams. I have an irrational dislike of carbon spinners after
having one shatter on me a while back, so I use a 49g Aluminum Tru-turn
spinner, if I were really up against the weight gun I'd swap that out and
save another maybe 20g.  So with no extraordinary measures I reduced my
weight by 65g and added redundant power. Minor tweaks I would prefer not to
make would save me another 20-80g.  Extraordinary measures would replace my
beloved Emcotec arming switch for the main power system with something
simple and lighter like the power unlimited arming plug :-)

And, of course, I never have to worry about my engine dying in flight,
cleanup of glow residue, etc.

Glow->Electric conversions are suboptimal in my humble opinion because you
are essentially bolting a much heavier power system onto a heavy airframe
designed for a bone-shaker of a glow engine, so it's built much heavier
than it needs to be for electric power.

Peter+

On Wed, Jan 25, 2012 at 3:49 PM, J N Hiller <jnhiller at earthlink.net> wrote:

>  Hi Mike.****
>
> If I could get rid of my greasy stuff I think I'd go all electric but
> after reading of the extraordinary measures taken to save a few grams it
> kind of depends what I can get an E-Option to weigh. My #2 160 is 10 lb so
> I could probably do it. I need to lookup component weights and get an
> estimated allowable airframe weight to compare. Maybe next winter; I'll fly
> what I've got another season and work on improving piloting skill, if
> that’s possible any more. I've never been a switch flipper but I'm thinking
> I need to start. ****
>
> ** ******
>
> Jim         ****
>
> ** ******
>
> -----Original Message-----
> *From:* nsrca-discussion-bounces at lists.nsrca.org [mailto:
> nsrca-discussion-bounces at lists.nsrca.org]*On Behalf Of *astropuppy
> *Sent:* Wednesday, January 25, 2012 12:47 PM
> *To:* General pattern discussion
> *Subject:* Re: [NSRCA-discussion] Main battery redundant lead for receiver
>
> ** ******
>
> You know you want to go E Jim. As they say in Oregon: "Just do it".****
>
> ** ******
>
> Mike****
>
> On Wed, Jan 25, 2012 at 9:47 AM, J N Hiller <jnhiller at earthlink.net>
> wrote:****
>
> Having judged these sequences I absolutely agree that they have become
> more demanding. Do you think you could fly the current schedules with 2006
> battery technology?
> ****
>
> Not in a hurry to go E-Power but interested.****
>
> Jim****
>
>  ****
>
> -----Original Message-----
> *From:* nsrca-discussion-bounces at lists.nsrca.org [mailto:
> nsrca-discussion-bounces at lists.nsrca.org]*On Behalf Of *Del
> *Sent:* Wednesday, January 25, 2012 6:55 AM
> *To:* General pattern discussion
> *Subject:* Re: [NSRCA-discussion] Main battery redundant lead for receiver
> ****
>
>  ****
>
> *Dave.. Love how you win your discussions.. lol .. ;+}  *****
>
> * *****
>
> *    Del*****
>
> ----- Original Message ----- ****
>
> *From:*****
>
> Dave Lockhart <DaveL322 at comcast.net> ****
>
> *To:* 'General pattern discussion' <nsrca-discussion at lists.nsrca.org> ****
>
> *Sent:* Tuesday, January 24, 2012 7:07 PM****
>
> *Subject:* Re: [NSRCA-discussion] Main battery redundant lead for receiver
> ****
>
>  ****
>
> 2006****
>
> 9411sa x2 for ailerons****
>
> 8417sa x1 for elevator****
>
> 8411sa x1 for rudder****
>
>  ****
>
> 2009****
>
> Changed to 3517 x2 for elevator (in the same plane)….no change in mah per
> flight****
>
>  ****
>
> 2010****
>
> Changed to 8611A on rudder (in the same plane)….no change in mah per flight
> ****
>
>  ****
>
> Flight times are about 45 seconds shorter now.****
>
>  ****
>
> I still have the Prestige I flew in 2006, so no change to control surface
> size or throw.****
>
>  ****
>
> I’m pretty sure it is the changes in maneuvers flown and higher average
> watts used by the motor in the course of the flight.  J****
>
>  ****
>
> Regards,****
>
>  ****
>
> Dave****
>
>  ****
>
>  ****
>
>  ****
>
> *From:* nsrca-discussion-bounces at lists.nsrca.org [mailto:
> nsrca-discussion-bounces at lists.nsrca.org] *On Behalf Of *Peter Vogel
> *Sent:* Tuesday, January 24, 2012 6:59 PM
> *To:* General pattern discussion
> *Subject:* Re: [NSRCA-discussion] Main battery redundant lead for receiver
> ****
>
>  ****
>
> Digital servos *definitely* draw more power than non-digitals, but they
> are much more precise and hold their position better, it's worth the higher
> draw for pattern.****
>
>  ****
>
> Peter+****
>
> On Tue, Jan 24, 2012 at 3:46 PM, Doug Cronkhite <seefo at san.rr.com> wrote:*
> ***
>
> I suspect the servos also draw more power than they did years ago.****
>
>  ****
>
> Doug
>
> Sent from my iPhone****
>
>
> On Jan 24, 2012, at 3:40 PM, "Dave Lockhart" <DaveL322 at comcast.net> wrote:
> ****
>
> When I first started flying electric pattern…..mah per flight was
> noticeably lower than now, going from 40-60 per flight to 60-80 per
> flight…..flying whatever was the current P/F sequences.  I suspect the
> increase is due to higher average flight speeds (much more watts at the
> motor now) and more demanding maneuvers (snaps and KE).****
>
>  ****
>
> Regards,****
>
>  ****
>
> Dave****
>
>  ****
>
> *From:* nsrca-discussion-bounces at lists.nsrca.org [mailto:
> nsrca-discussion-bounces at lists.nsrca.org] *On Behalf Of *Keith Hoard
> *Sent:* Tuesday, January 24, 2012 11:02 AM
> *To:* General pattern discussion
> *Subject:* Re: [NSRCA-discussion] Main battery redundant lead for receiver
> ****
>
>  ****
>
> Anthony,
>
>    On a typical flight, I'm guessing the radio only uses around 100-150Mah
> of power, while the motor is using 4000Mah, so that's about 4% more draw on
> those two cells.  In practice, I haven't been able to see any difference in
> the radio cells when I hook them up to my charger at the end of a flight.
> Sometimes cells #1 & #2 are the high cells after a flight, so I think the
> power draw of the radio is negligible to our motor packs.
>
> The problem with two regulators plugged into the same 10S (or 5S) pack is
> that you are creating a dead short between the cells thru the ground wires
> (typically a straight wire thru the regulator).
>
> Say you plug Regulator #1 into cells #1&2, and Regulator #2 into cells
> #6&7.  The regulator's *ground *wires now have 5 cells of voltage
> potential (5 X 4.2V = 21Volts) between them since they are plugged into
> cells # 1 and #6.  When those two ground wires are then plugged into your
> receiver either thru a switch or direct connection the magic smoke will
> escape and your retailer will rejoice.
>
> Also, if you have both of your regulators plugged into your motor pack and
> the packs eject like Goose in Top Gun, you've lost both of your redundant
> power sources.  However, if you use a tiny 2S LiPo that is physically
> separated and secured inside your plane, you have both electrical and
> physical redundancy.
>
> Hmmm, just thought of something . . . maybe we should tie down the
> receiver so the main regulator can't take the receiver out with it. . . so
> many contingencies, so little weight . . .
>
> Keith Hoard
> Collierville, TN
> khoard at gmail.com****
>
> On Tue, Jan 24, 2012 at 8:15 AM, Anthony Romano <anthonyr105 at hotmail.com>
> wrote:****
>
> Seems like a great idea but I have two questions. Do the packs come down
> out of balance since two cells are serving extra load? Is there a problem
> with parallel operation of two regulators?
>
> Thanks,
>
> Anthony
>  ****
>  ------------------------------
>
> From: joddino at socal.rr.com
> Date: Mon, 23 Jan 2012 15:25:00 -0800
> To: nsrca-discussion at lists.nsrca.org
> Subject: Re: [NSRCA-discussion] Main battery redundant lead for receiver
>
> I've been using this setup for sometime and it is working great.  I have
> my two cell LiPo charged to 7.5 volts and it is connected to a 6.0 volt
> regulator into the receiver.  The cable connected to the balance connector
> on the "bottom" 5S is connected to a 6.3 volt regulator so it supplies all
> the current to the system and the 2S pack never needs charging.  I'm using
> an 800 mAh pack but it could be even smaller.   ****
>
>  ****
>
> Jim O****
>
>  ****
>
>  ****
>
> On Jan 23, 2012, at 2:09 PM, Scott McHarg wrote:****
>
>  ****
>
> Guys,
>    Chris Moon just e-mailed me about some leads that were done at the
> factory.  These leads run off your balance leads to a voltage regulator and
> allow your main battery pack to be utilized as a redundant receiver
> battery.  It is NOT meant to be a primary but it will save 20+ grams if
> you're running 2 rx batteries.  You still have to run the 2nd regulator for
> true redundancy but you eliminate the 2nd battery.  These leads are factory
> made and eliminate the need to make them yourself with the concern about
> plugging in to the wrong cell.  I know in my article, I was pretty much
> against doing this as a backup but, with Chris having this made at the
> factory, he has all but eliminated making a mistake by tying to the wrong
> cell.  I have the link that I'll e-mail you off-list or you can just go to
> his website.  I don't want to break the NSRCA list rules by advertising for
> him even though he advertises with the NSRCA.  The leads are only $3.99
> each and are found under the Connectors/Adapters listing.
>
> Thank,
> Scott
>
> --
> *Scott A. McHarg*
>
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>
>
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> ****
>
>  ****
>
> -- ****
>
> Director, Fixed Wing Flight Training****
>
> Santa Clara County Model Aircraft Skypark****
>
> ****
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>
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-- 
Director, Fixed Wing Flight Training
Santa Clara County Model Aircraft Skypark
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