[NSRCA-discussion] Weight

[Jay Marshall]

You can takeoff and land with 1 oz of fuel, but would you try it with a 5%
charge on your batteries?

Jay Marshall

-----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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