[NSRCA-discussion] Weight

[Dave]

Verne,

If you goal is to make pattern cheaper, I'm all for that (and the most
expensive setup right now is a YS CDI setup), but I can't see how a proposal
based on your description can effectively accomplish that.

Is the goal to reduce cost of the electric (which I can argue is cheaper
than glow at the top levels of each) or to make electric and glow airplanes
have the same cost for equal performance?  As electric technology rapidly
advances, any proposal based on current day planes will be obsolete by the
time it in place.

Limits on pack mah will certainly add to the complexity of tech inspections
of planes....to say nothing of the fact that all "20C" lipos do not weigh
the same thing, and all batteries of a marked capacity are not the same
either - the door will be wide open for "creative" labeling of mah capacity
on batteries.

Just as there are examples of overweight glow planes (I do hope you are
getting weights on glow planes as well during your surveys???), there are
overweight examples of electrics - neither should be accommodated by a
change in the rules.  Each competitor should evaluate the rules, and prepare
to compete with whatever setup best suits there budget, time, resources, and
is within the RULES.

Electric may cost more upfront, but it is rapidly getting cheaper (and glow
is getting more expensive).  The big hurdle for electric right now is that
all the costs are upfront, making it expensive to enter.

Regards,

Dave

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
verne at twmi.rr.com
Sent: Wednesday, June 03, 2009 10:52 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Weight

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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