[NSRCA-discussion] batteries high or low (electric pilots)

[Atwood, Mark]

I think you'll find that the battery weight of your F3A plane is also in excess of 20% of the total weight.  A 10s pack is certainly over 1000gms making it more than 20% of a 5kg legal airframe. 

I suspect moving that amount of mass vertically has the same significant impact that it does on the foamies. 

That said, the same is maybe MORE true of our changing mass fuel tanks. While they weigh less, they flux from over a lb to almost nothing during flight.   Being high or low in the fuse will certainly impact trim.  We seem to just fly with it. 

My guess is you're trimming out any issues a high or low battery causes and moving on. 
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----- Original Message -----
From: nsrca-discussion-bounces at lists.nsrca.org <nsrca-discussion-bounces at lists.nsrca.org>
To: 'General pattern discussion' <nsrca-discussion at lists.nsrca.org>
Sent: Tue Sep 15 23:09:16 2009
Subject: Re: [NSRCA-discussion] batteries high or low (electric pilots)

JAS

Base on my experience I agree with the previous observations about battery
placement on foamies.  That being said, the battery weight can be up to 20%
of the foamy weight, so small displacement can have a big effect.

The center of vertical mass mattered back in the top-mounted tuned pipe
days--those airplanes pulled to the canopy in verticals (OK, some of this
was design), so people reconfigured the mass.  The relative mass above C/L
was probably less than 7% of airframe weight and was not that far from the
CG...probably proportional to mounting the batteries in the belly pan of
today's 2m designs.

Battery weight is about 10% of our typical 2M weights.  The significance of
off-center mass will of course depend on distance of the mass from the
center line, however, given the above observations I suspect battery
placement (vertically) should be important....but no one with the belly pan
mounting ever seems to complain!

Andre

     

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Earl Haury
Sent: Tuesday, September 15, 2009 7:15 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] batteries high or low (electric pilots)

Jason, looks like you're not getting any takers on this item. It seems 
logical that anything of significant mass (batteries) should be close to the

roll center of the airplane, and I mount mine that way. I flew an Abbra for 
a season with the batts centered and liked the way it flew. OTOH, several 
folks have competed successfully with the Abbra with batts hanging low in 
the cowl - so go figure.

Guess you'll just have to do the experiment (and let us know what you 
observe).

Earl


----- Original Message ----- 
From: "J Shu" <jshulman at cfl.rr.com>
To: "NSRCA" <nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, September 15, 2009 1:51 PM
Subject: [NSRCA-discussion] batteries high or low (electric pilots)


> Has anyone (flying electric, sorry glow fliers) tried moving batteries to 
> the extremes in the fuselages of their planes? Really low to really high? 
> Results? I've often though about trying it, but new have. Just wondering 
> if anyone has...
>
> Regards,
> Jason
> www.shulmanaviation.com
> www.composite-arf.com
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion 

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