[NSRCA-discussion] Weight

[Dave]

Bill,

I'll try to keep it short, as you are correct, this has been beat to death a
million times prior.  Bottom line is this - the current rules which require
electrics to include batteries within the 5 kg results in electrics which
are competitive with glow.

Compared to glow, electric is in it's infancy and will only become more
powerful and lighter (by measurable jumps), while glow will continue to be
refined (tiny steps).

If you weigh electrics without batteries, they will gain a huge
(insurmountable) performance advantage, and you will also see a huge
increase in the size and cost of airplanes.  Review the NSRCA archives for
more on this aspect - there is a difference between a small 2M plane and a
large 2M plane - the latter of which costs a lot more $$$.  The size of the
average electric will grow substantially, and any left running glow will
find themselves at a competitive disadvantage no matter how much $$$ is
spent on the airframe and powerplant.

So far as your weights - the main thing you are missing is the weight
reductions possible in a properly engineered electric - much weight can be
saved without the need to fuel proof and vibration proof a plane.  As I am
very familiar with the Prestige from Wistmodel, consider -
- multiple glow (2C and 4C) versions have been built at 9.25 - 9.75 lbs.
- multiple electric versions have been built at 10 to 10.5 lbs.

Oh yes, and if you are making the argument that AMA rules should not blindly
follow FAI (as has been done in the past), I couldn't agree more - AMA
pattern should never blindly follow/adopt FAI rules, but can always choose
to equal them after careful evaluation.

Regards,

Dave Lockhart
DaveL322 at comcast.net


-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Bill's Email
Sent: Wednesday, June 03, 2009 10:08 AM
To: General pattern discussion
Subject: [NSRCA-discussion] Weight

 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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