# Electric Ultralight Aircraft Sets New Altitude Record



## EVDL Archive (Jul 26, 2007)

Flying a modified electric North Wing Stratus, Gary Davis flies to yet-to-be-confirmed altitude of 4,660 feet (1,420 meters).

More...


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## Karter2 (Nov 17, 2011)

> ....drawing power from a 47-pound battery ,..
> .... built by painstakingly hand-soldering more than 2,000 lithium ion cells


 Hmm ?? .. they must be some mighty tiny cells ..11gms each ?
I suspect a typo or miss quote.
200 cells @ 110gms would be more realistic.


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## Caps18 (Jun 8, 2008)

http://www.panasonic.com/industrial/includes/pdf/cgr18650ch_data_sheet.pdf

Even the 18650's are 44 grams each.

But I would bet it is a 470 lb battery. Unless there is some alien technology at work there.


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## Karter2 (Nov 17, 2011)

Caps18 said:


> But I would bet it is a 470 lb battery. Unless there is some alien technology at work there.


 470 lbs !! .. i doubt that would even move on the runway, never mind fly !
...and a pack the size of that one behind his seat weighing 470 lb , would indeed be Alien technology !
47lbs of decent lipo would give him about a 3.5-4 kWhr pack.
Which would give him about 15 mins at max power, or more than enough for 30 mins flight at sensible power levels..


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## Caps18 (Jun 8, 2008)

Oops, that is what happens when you don't open the link and think they were talking about a different electric airplane...


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## sunworksco (Sep 8, 2008)

Most ultralight EVs are using lithium polymer batteries but if he was soldering that many batteries, they are most likely recycled laptop batteries.


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## Karter2 (Nov 17, 2011)

sunworksco said:


> ... if he was soldering that many batteries, they are most likely recycled laptop batteries.


 Why do you assume "recycled" ? .. lets give them some credibility in having the expertise to assemble a professional pack.
You would have to be a special kind of pilot to risk your life with recycled laptop cells
And anyway "Laptop" spec cells dont have the power density to work for this application. They would need to be a "high power" 18650 cell like Sony VTC5's or Samsung 25R , capable of high discharge rate,.. which you wont find in laptops.
Even using RC Lipo packs, there is still a lot of soldering of connectors to make up a large pack of the size he used.


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## sunworksco (Sep 8, 2008)

I guess we are all just guessing? :^)
Batteries that are powering a motor do not need to be as powerful as some vehicles.
The prop only needs to spin at around 2,500rpms at cruise. Of course the take-off needs a little more power but an ultralight is not that demanding. Even a 650Lb. Piper Cub would be an easy retrofit. I know by having flight experience.
Let's lighten up and gain some elevation here.


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## aeroscott (Jan 5, 2008)

What would be peck power from a 47 lb. lipo pack. I would think he could 
think he could do a vertical acceleration with enough motor.


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## dougingraham (Jul 26, 2011)

aeroscott said:


> What would be peck power from a 47 lb. lipo pack. I would think he could
> think he could do a vertical acceleration with enough motor.


I built a spreadsheet to help determine what combination of RC type LiPo cells to use to make a drag racer. Here is the link to that. It still needs some work but you can sort of see where I was going with it.

LiPo Comparison for Drag Racing

Anyway to summarize I was looking for a pack that could max out a WarP 9 at 192 volts and a Soliton 1 which is 1000 amps. Input power to the motor is 192kw or 257 HP. The lightest pack has a voltage of 222 volts and weighs 28.36 kg (62.4 lbs) with a capacity of 4 kwh. That pack can be discharged in under a minute at the continuous C rating of 65C (1073 amps). These particular cells claim a burst rating of 130C so a pack half this size theoretically could be used for drag racing. Of course the mass will increase from the wires and connectors that are needed to tie that many packs together. 

It can be done lightly.

This is quite an accomplishment and the people involved should be commended!


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## aeroscott (Jan 5, 2008)

I'm into float planes ,I think 514 hp could get that off the water.about a 2 sec. burst. need 2 props counter rotating , to keep from flipping it over. Thats .14 hp hours ,14% of a hp hour.


X 2sec=.28hphr.


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