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Old 20th Dec 2012, 14:03   #1 (permalink)


Probationary PPRuNer
 
Join Date: Dec 2012
Location: Uk
Age: 26
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Thumbs up Project Help - Electronics and fuel consumption...

Hi all,

I think this is the right place to post this. Basically I am working on a college project to find out about integrating solar technology in to commercial aircraft and so far have calculated in peak sunlight my current design would only produce 36 volts on a Boeing 777 which isn't quite what I was hoping for, however before changing the design I still need to calculate how much fuel saving this tiny voltage production could save on fuel across a flight.

Does anyone know how to calculate how much less fuel an aircraft would use if 36 volts were fed in to the cabin lighting circuit during a flight, even if it is literally half a drip?

Thanks in advance.
Pilotsandwich is offline   Reply
Old 21st Dec 2012, 10:12   #2 (permalink)
 
Join Date: Oct 2006
Location: berkshire
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the weight of the solar panels might use more fuel than it will saves in producing power
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Old 21st Dec 2012, 10:13   #3 (permalink)
 
Join Date: Jan 2012
Location: France
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36v but what's the amps???
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Old 21st Dec 2012, 16:59   #4 (permalink)
 
Join Date: May 2010
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To get even a rough idea of any savings you need to factor in:

A: Power produced by cells (Amps * Volts for the Ohmically challenged)
This should include factors for sun angle VS aircraft flight lattititude,
very poor sun angle near the poles even in summer.

Good news is that for long haul flights most of the time you will be above the clouds.
Bad news is that a lot of flights are in darkness at least part of the time.

B: Conversion efficiency of cells output to aircraft power rails.

C:Actual fuel consumption reduction from offloading the generators.

D: Added weight of cells/converter/interface circuits and resulting increased fuel burn. This is likely to be a major issue since you will be hauling the extra weight whether or not the cells are producing power.

I don't think specifically targetting cabin ligths make sense since they are
needed more at night and run from common power busses anyway.

While I suspect that the results will be that this is not practical for a couple of reasons a well done analysis of the factors should make for a good project.

Last edited by MurphyWasRight; 21st Dec 2012 at 17:02.
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Old 21st Dec 2012, 17:06   #5 (permalink)
jxk
 
Join Date: Apr 2008
Location: Cilboldentune, Britannia
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It might run peoples' mobile phones and iPods!
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Old 21st Dec 2012, 21:38   #6 (permalink)
 
Join Date: Aug 2012
Location: Manchester, UK
Age: 22
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Even though wouldnt improve the fuel efficiency, showing why it wouldnt work is still good reading for whoever will be marking it.

I had a similar project back when i was in college, after AF447, i chose to make the FDR and CVR able to float, with a mechanism to get them out of the aircraft upon impact on water. The theory was all there, its possible, practically, no, it wouldnt work.

One way to show why it wouldnt be viable would be comparing the weight of the solar panels required to produce power, compared the the same power output from one 'genny'

I mean..The 787 has 4 generators (5 including the APU) that produce 250kVA each, could compare the weight of one 'genny', to the weight of the panels required to produce the same output (+ the additional equipment).
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