Earthstar Forums

I  envision a future E-Gull with thin film solar cells on the wings to increase range and decrease range anxiety while your taking your time at a fly-in and letting the sun put some fuel back in your batterieswhich BTW Mercedes says is doubling in energy density every 5 years   Another thought would be putting skis on a Gull and calling it a Skigull...Nah it would never work    Bump
           Carl

Run some numbers, Carl

Multiply the wing area times the output of present solar cells

Small wonder the Solar Impulse has 2,200 sq ft of wing in order to provide
sufficient energy

It cost "just" 100 million dollars

The Thunder Gull has only 95 sq ft of wing

So, the time extension would be less than, say, 5% at the very peak hour of
the day

Solar cells are doubling their output in money terms, but not in per square
area terms.

They have doubled their output from 12% to about 22-24% in about 15 years.

I understand there is a theoretical limit of about 34% or something like
that

Solar incident energy at the very best moment of the day and with clear
skies is of the order of 1 kw per sq mt

With 8.8 sq m of wing area we receive about 8.8 Kw, but can only convert
about 2 Kw if we assume no transmission nor engine efficiency losses, Thats
about 3.5 Hp that would come out to about 3 hp motor power after losses.
Tops. At peak hour.

Our best hope is for higher energy density batteries, as right now 1 lb of
fuel has the same energy as about 70 lbs of battery

We can hope for higher battery energy densities in the near future



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Hi Dave
The fuel to lb of battery ratio is now 5 to one.
Happy Flying
Mark

Sent from my iPhone

This says gasoline has about 32 kwh/gallon and gasoline weighs about 6
lb/gallon = 2.7 Kg/gallon, which means gasoline has about 32/2.7 = Kwh/Kg =
11.8 Kwh/kg

Best batteries for slow drain we can get are about 240 watts/Kg

That`s a 49 to 1 ratio

Granted that fuel engine efficiency is only about 30% whereas electric
motor efficiency is about +90% so that the 49 to 1 becomes more like 16 to
1

Where do you get batteries with energy densities of 750 watts/kg, or above
240 watts/Kg, Mark ?

I really need them



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I keep getting asked why I don't have solar cells on my wings - thanks for
answering that so succinctly, Jaime! Even with the eGull's larger wing
area, the math just does not work out - and it may not ever.

Solar cells might make more sense as a trickle charger, while the plane is
tied down. But the weight penalty and the cost make that impractical, too,
especially when there is an outlet nearby.

omygawditsfullofstars Dave? Whats's the turn radius of the gull trailer? in reverse? trailer length, top and bottom clearance? any pilots with a basement garage ramp with a 5 to one slope, like to build/store a gull in?

happy storing,
rc

ask Dave Paden

if you do perswade him for that alien tech, please let this hasbeans knows, the rough order of magnitude of the cost

rc

ask Dave Paden

if you do perswade him for that alien tech, please let this hasbeans knows, the rough order of magnitude of the cost

rc