[NSRCA-discussion] Weight

[Derek Koopowitz]

Verne,

When I was at the CIAM meeting in March one of the proposals which was
passed by the helicopter guys (F3C) was to modify the weight limit for their
helicopters effective 1/1/2010.  Here is the new wording:

a) WEIGHT: The weight of the model aircraft (*with *fuel *or *batteries)
must not exceed *6.5 *kg.

Unanimously approved by the Plenary Meeting. Effective 01/01/10.

I'm going to feel out the rest of the F3A sub-committee members to see if
there is interest in raising the F3A weight limit to 5.5kg.  What does
everyone think about this?

-Derek
On Wed, Jun 3, 2009 at 7:51 AM, <verne at twmi.rr.com> wrote:

> Bill,
> I've been working up an AMA rules proposal to address that very issue.
> Unfortunately, it won't be up for vote by the contest board anytime soon. In
> the meantime, there's one area you didn't mention in the glow to electric
> comparison and that's that an electric plane doesn't need as much internal
> reinforcement because there's virtually no vibrational effects to contend
> with that you do with glow. That equates to lighter airframes being
> acceptable as well as small, light, lipo packs to power the Rx and servos.
> An 8 minute e-flight typically uses about 50 mah. The same flight in glow is
> typically 200+ mah. All that aside, most electric pilots will tell you that
> making weight in electric is generally a pretty expensive proposition with a
> limited number of 2 meter planes available that are usually vacuum-bagged
> composite affairs. In addition, your best chances for making weight will
> also necessitate the lightest and generally most expensive motors and
> batteries. There are exceptio
>  ns, and I'm sure we're about to hear about most of them, but I'll be able
> to point to just as many examples of guys that fly overweight at local
> contests where they know they won't be weighed and the only thing they're
> really guilty of is not spending the extra money that the lightest batteries
> and motors cost. In every other way, the planes they're flying are the same
> as the ones they're competing against. The proposal I'm working on is not
> self-serving because my planes make weight, but getting there is both too
> expensive and unreasonable, in my opinion. My proposal won't be to allow
> electric planes to weigh more, it'll require that they weigh less, but
> without the "fuel". The proposal will take into account that electric motors
> are inherently lighter than their glow counterparts as well as the reduced
> structural requirements. It will limit the mah of permissible packs to
> control that end of the equation and there's already a voltage limit on the
> books which is fine as it
>  stands. I'm currently doing survey work at the contests I go to to see
> where everybody is at weight-wise and will post my proposal on this list
> soon. After that, it's up to all concerned to voice their opinions to their
> respective Contest Board reps.
>
> Verne Koester
> AMA District 7
> Contest Board
>  ---- Bill's Email <wemodels at cox.net> wrote:
> >  I am certain this has been beaten to death while I was off doing other
> > things, but can anyone explain this:
> >
> >
> > Rule 4.3: Weight and Size. No model may weigh more than five (5)
> > kilograms (11 pounds) gross, but excluding fuel, ready for takeoff.
> > Electric models are weighed with batteries.
> >
> > Why can't an electric "deduct" the equivalent of 16 ounces of fuel??  Is
> > a plane without fuel rally "ready for takeoff"??
> >
> > I know it is likely a direct copy of the FAI rule, but it makes no
> > logical sense. IC powered planes are weighed without fuel and can weigh
> > right at 11 pounds. Add fuel and it could add another 10 to 12 ounces of
> > weight. That's OK. But if an electric with batteries weight
> > 11.0000000000000001 pounds it is overweight by the rules.
> >
> > Put another way, what does a YS and full fuel weigh compared to a
> > motor+ESC+batteries?
> >
> > Hacker C50 14XL = 18.2 ounces
> > Hacker Spin 99 ESC = 3.7 ounces
> > 10S packs = +/- 43 to 46 ounces
> >
> > Weight w/o batteries = 21.9
> > AUW w/batteries = 66.9 ounces
> >
> > YS 1.70 = 33.6 ounces (955 grams)
> > AUW with tank and fuel = 45 ounces +/-
> >
> >  So I can see an argument that the electrics have a weight advantage
> > when it comes to just the motor and ESC. But with "fuel" electric is at
> > a 20 ounce disadvantage.
> >
> > So if I build a plane for electric I need to build it 20 plus ounces
> > lighter than if I was going to put a nitro motor in it. How does that
> > make sense. I know I am missing something important here, so educate me.
> >
> >
> >
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