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

[JOddino]

----- Original Message -----
From: "Brian Young" <b4598070 at yahoo.com>
To: <discussion at nsrca.org>
Sent: Friday, April 18, 2003 6:31 AM
Subject: RE: Best battery choice? + Current Draw used per flight + more
testing


> 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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