Electric Airframes

[Chad Northeast]

Over the years I have had 3 ZN Enigmas, 2 of them electric (both weighed 
4670 grams - 10.3 lbs) and 1 glow ( 4600 grams - 10.1 lbs dry).

None were built any different than the others, all used the stock kit 
parts and all were built to take glow in case the electric didnt work 
out and they needed to be switched.  The glow model has survived around 
1500 flights on it over a number of years, so I suspect the electric 
models would last for 10,000 if given the opportunity!

Now, the electric could be made a bit lighter, mostly in the wings/stab 
as the fuse is already very light and I would be concerned with losing 
rigidty should it be made much lighter (less cloth/resin).  The big 
problem in doing this is that the wingloading is all wrong for the model 
now.  My electric Enigma's feel noticably lighter in the air than the 
glow one and I would not want them any lighter than they are.  I toyed 
with the idea of increasing the weight but decided to just leave them 
alone and get used to it.  In very smooth calm air a light airplane is 
great, but they dont make for good all around models that need to deal 
with turbulence and wind that is usually common!

I will be getting ZN's new Twister as my plane for next year and the 
wings are slightly smaller than the Enigma's so I will shoot for 
somewhere between 10.25-10.5 lbs as a target weight RTF.

Thats my take on it anyways!

Chad

Chuck Hochhalter wrote:

> Alright now, going beyond the motor setup, how about the actual 
> airframe itself.  For certain the weight of the airframe is a huge 
> factor.  Lighter is better esp for electrics as you can run a 
> potentially different battery setup as current, watts etc are 
> decreased (?).
>
>  
>
> Do the stresses on the basic internal structure change enough to allow 
> a plane to be built significantly differently and lighter in areas 
> that were OVER built for the stresses of large vibrating IC motors?
>
>  
>
> Let take for instance a light wooden plane such as Mark Hunts 
> Insight.  I think it weighs like 9lbs 8 oz with a 140 sport in it.  
> Guessing at the conversion straight to electric it would now weigh 
> around 9 lbs 14 ozs running 5s4p dual packs and an AXI setup.  If the 
> air frame was reengineered in a way to allow it to be built around 9 
> lbs and remain as strong but because of the lower overall weight go to 
> a smaller battery say the 5s3p packs and still see the same 
> performance and duration?
>
>  
>
> I may be changing too many variables for a straight answer but the 
> general idea I think you get.  Just some thoughts (how about an all 
> depron 2 meter) hmm.
>
>  
>
> Thanks for your thoughts positive or negative.
>
>  
>
> Chuck
>
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