Best battery choice? + Current Draw used per flight + more testing

[Brian Young]

I wanted to followup with my latest results from
initiating this thread.

I changed the aileron servos from the old digitals to
new 8311s and the current draw dropped to 1.5 A at
idle (was 2.5-3A with old servos). Running the plane
to wide open saw a slight reduction in current draw,
1.3 A at wide open. Disconnecting the new aileron
servos and the current draw drops to 0.9 A at idle. If
I can hold the rudder servo, dampen the shake, the
current draw would drop to 0.5 A (Aileron Servos
Disconnected), same with elevator.

All this pretty well adds up, with new Ail servos I
get 3 18 minute flights on a 1400 mah pack, so I know
I have little reserve in the pack at the end of the
day. I either measured what was left after a flight,
or measure what I put back in to top the pack off. The
pack cycles at 1350 mah. If my current draw is 1.3 A
average through an 18 minute flight, thats 390 mah per
flight. So thats 1170 mah used per 3 flights. Well, I
always land with a little fuel in the tank, I now know
by the end of the day Im landing with just a little
mah in the battery, not enough I imagine.

I may change my rudder and elevator servos as well.
That 4000 mah li-ion pack is still attractive. I could
fly 5 times and have half the battery capacity left.
My concern with the Li-ions is that I know when its
time to throw away the ni-cads, how do you know the
li-ions are warn out?



--- Dean Pappas <d.pappas at kodeos.com> wrote:
> Hi John,
> Linking the ailerons on a plug-in ship will be tough
> without funnies due to wing wiggle.
> You're right, running the linkage close to the tube
> will help, but it still won't be easy.
> Let us know if you come up with somnething.
> Dean
> 
> -----Original Message-----
> From: John Gayer [mailto:jgghome at earthlink.net]
> Sent: Tuesday, April 15, 2003 11:46 PM
> To: discussion at nsrca.org
> Subject: Re: Best battery choice? + Current Draw
> used per flight
> 
> 
> Thanks, Dean, for the explanation.
> I was thinking of the vertical force from the piston
> rather than the 
> rotational impulse.
> One of the problems we always had trying to use a
> single servo was 
> getting a solid slop-free linkage. Perhaps if the
> linkage were run 
> adjacent to the wing tube the wiggle would be
> reduced.
> John
> 
> Dean Pappas wrote:
> > Hi John,
> > The dominant vibration impulses from the engine
> are in roll. That's the direction
> 
>   your soft-mounted engine shakes in. Every time the
> engine fires, the 
> right wingtip
> 
>   "bangs" upward and the left downward. You'll
> remember a day or three 
> ago that Eric
> 
>   noted that the right aileron servo gets beaten up
> worse than the left 
> one.
> 
> That's gravity's fault.
> > Coupling the ailerons would still be a great idea
> because the air loads 
> 
> are in phase from side to side. One piece wings
> might be a necessity, 
> because
> 
>   plug-ins wiggle with respect to each other.
> > Regards,
> > 	Dean
> > 
> > -----Original Message-----
> > From: John Gayer [mailto:jgghome at earthlink.net]
> > Sent: Monday, April 14, 2003 10:18 PM
> > To: discussion at nsrca.org
> > Subject: Re: Best battery choice? + Current Draw
> used per flight
> > 
> > 
> > I would think the driving function on each aileron
> would be in phase. If 
> > that is so, then coupling the ailerons together
> would help a lot. Seems 
> > like it might be worth a try.
> > 
> > John Gayer
> > 
> > Dean Pappas wrote:
> > 
> >>Hi Jim,
> >>I like that! Frack and I discussed this back when
> the S9303 came out, 'cause we figured that finally
> we had one servo with adequate torque to do the job.
> It still does nothing for the vibration problem: one
> wing shakes up as the other goes down, but the "G"
> related load problem evaporates. That one will
> require second-moment balancing.
> >>Dean
> >>
> >>-----Original Message-----
> >>From: JOddino [mailto:JOddino at socal.rr.com]
> >>Sent: Monday, April 14, 2003 2:52 PM
> >>To: discussion at nsrca.org
> >>Subject: Re: Best battery choice? + Current Draw
> used per flight
> >>
> >>
> >>How about Hanson's idea of going back to
> connecting the ailerons together
> >>through bellcranks like we did in the old days?
> >>Jim
> >>----- Original Message -----
> >>From: "Dean Pappas" <d.pappas at kodeos.com>
> >>To: <discussion at nsrca.org>
> >>Sent: Monday, April 14, 2003 11:06 AM
> >>Subject: RE: Best battery choice? + Current Draw
> used per flight
> >>
> >>
> >>Yes, I have considered mass balances on the
> ailerons.
> >>I just refuse to leave dangly-things under the
> wing, in order to do it.
> >>If i ever come up with a set of mechanics I really
> like, you will see it.
> >>Regards to all,
> >>Dean
> >>
> >>-----Original Message-----
> >>From: GREEN, DOUG [mailto:doug.green at bell.ca]
> >>Sent: Monday, April 14, 2003 1:36 PM
> >>To: discussion at nsrca.org
> >>Subject: Re: Best battery choice? + Current Draw
> used per flight
> >>
> >>
> >>Have you considered weight balancing your control
> surfaces to reduce the
> >>punishment being inflicted on the servos?
> >>
> >>Doug
> >>
> >>Dean Pappas wrote:
> >>
> >>
> >>>Hi Brian,
> >>>3 Amps while the mount and possibly airframe are
> in sesonance is not out
> >>
> >>of the question.
> >>
> >>
> >>>What is the W.O.T. current draw? By the way, at
> idle-shake, the ailerons
> >>
> >>are the big draw culprits.
> >>
> >>
> >>>Dean
> >>>
> >>>-----Original Message-----
> >>>From: Brian Young [mailto:b4598070 at yahoo.com]
> >>>Sent: Monday, April 14, 2003 9:10 AM
> >>>To: discussion at nsrca.org
> >>>Subject: RE: Best battery choice? + Current Draw
> used per flight
> >>>
> >>>I found I wasnt getting the capacity I thought I
> >>>should w/ my 1800 mah 6 cell flight pack. After
> two
> >>>masters sequences I recharged and put back in
> 600mah
> >>>(triton charger), pack was topped up prior to
> flight.
> >>>
> >>>So back home, I put a current meter between the
> >>>battery and receiver. I draw about 90 mA with all
> >>>servos connected, each servo unplugged the total
> drops
> >>>by 15 mA, except for the throttle which drops 10
> mA.
> >>>Wiggle the sticks and I can occasionally get over
> 300
> >>>mah. This didnt seem unusual to me, anyone
> disagree?
> >>>
> >>>So I left the meter in place and started the
> plane, at
> >>>idle the meter was reading 3 Amps, yep 3. Has
> anyone
> >>>else done this?
> >>>
> >>>I move the trottle off idle a little and the
> current
> >>>drops to about 2-2.5 Amps, so my throttle servo
> is
> >>>bottoming a bit.
> >>>
> >>>3 Amps in this gauge wire seems like it should be
> >>>getting something hot, but I hooked the
> multimeter up
> >>>in series with my battery just like I learned in
> >>>school.
> >>>
> >>>The servos are all digital JRs with over one
> season
> >>>use, except I did replace the Aileron servos w/
> new
> >>>yesterday but havent had a chance to repeat my
> test.
> >>>All thoughts on what could be causing this are
> >>>appreciated. Otherwise a 4000 mah flight pack is
> >>>looking good to me. Is there any reason a worn
> servo
> >>>would draw more current?
> 
=== message truncated ===


=====
Brian Young
Tulsa
b4598070 at yahoo.com
918-745-6046h
918-838-0900w

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