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Old Jul 19, 2006, 02:23 PM
spiffy_spaceguy is offline
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Cool

World's First Dry-Cell Battery Plane Flies


A Japanese team from the Tokyo Institute of Technology has flown a glider-like airplane on 160 AA alkaline batteries. It flew to 16 feet in altitude and covered 391 metres in 59 seconds.

It has a wingspan of 102 feet.

http://evworld.com/view.cfm?section=...31016print.asp

http://www.todayonline.com/articles/131016print.asp
Old Jul 19, 2006, 02:29 PM
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Quote:
Originally Posted by spiffy_spaceguy
A Japanese team from the Tokyo Institute of Technology has flown a glider-like airplane on 160 AA alkaline batteries. It flew to 16 feet in altitude and covered 391 metres in 59 seconds.

It has a wingspan of 102 feet.

http://evworld.com/view.cfm?section=...31016print.asp

http://www.todayonline.com/articles/131016print.asp
Except for the wingspan part, I've done much better on fewer batteries! Wait, they landed thiers intact, didn't they.
Old Jul 20, 2006, 03:14 AM
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Yes, very good, but WHY ?

The more I think about this, the less I understand !
Am I missing something ?


What are the power specs for this setup ?

If each cell 1000 mAh, @ 1.5 Volts,
1A X 1.5V = 1.5 Watts

160 cells X 1.5W = 240 Watts

Weight of aircraft + weight of pilot = guess 50Kg + 50Kg = 100Kg ??

16 feet is about 5 metres

Therefore 100Kg lifted 5 metres vertically


Hey Spiffy, can you help me with the theoretical equations, I'm feeling too lazy.
Old Jul 20, 2006, 03:57 AM
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Quote:
Originally Posted by Mister UHU
If each cell 1000 mAh, @ 1.5 Volts,
1A X 1.5V = 1.5 Watts
160 cells X 1.5W = 240 Watts
Not Watts, but Watt x hours
They flew for 59 seconds.
Say the total run time was 3 minutes before batteries are exhausted, that would mean a power of 240 x 60/3 = 4800 Watt.
Of course, the battery voltage under high load must be less than 1.5 V, so maybe a peak power of 3 kW ?
It all depends how much peak current the batteries can supply.
Old Jul 20, 2006, 04:21 AM
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Quote:
It all depends how much peak current the batteries can supply.
Not a lot since their internal resistance is rather high. I wonder if they can manage even 1A
Old Jul 20, 2006, 09:06 AM
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Originally Posted by Muxje
Not a lot since their internal resistance is rather high. I wonder if they can manage even 1A
Hey that's not fair!

Seriously, I have been testing a range of AA cells from different manufacturers for a non modelling purpose.

I've not found an AA cell that will deliver an 80% return on a 1C draw BUT...... A few 2500mah cells I have can push 1500mah out at a rate of 2C so 60% return. In fact it's fair to say none of the AA cells I've tested deliver their stated capacity at any current I've tested at and I have gone down to .2C..............

I run 160 cells in one vehicle application (40S4P) - I have 4 packs like this - maybe I should build an airplane!
Old Jul 20, 2006, 10:22 AM
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Whaaaat? The Japanese haven't heard of lipos?
Old Jul 20, 2006, 04:20 PM
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Quote:
Originally Posted by Mister UHU
Yes, very good, but WHY ?

The more I think about this, the less I understand !
Am I missing something ?


What are the power specs for this setup ?

If each cell 1000 mAh, @ 1.5 Volts,
1A X 1.5V = 1.5 Watts

160 cells X 1.5W = 240 Watts

Weight of aircraft + weight of pilot = guess 50Kg + 50Kg = 100Kg ??

16 feet is about 5 metres

Therefore 100Kg lifted 5 metres vertically


Hey Spiffy, can you help me with the theoretical equations, I'm feeling too lazy.
Not really. I don't really understand the equations. From where I'm sitting, it looks like these guys had 131 amps to play with and I'm pretty sure that isn't right.
Old Jul 20, 2006, 05:14 PM
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Quote:
Originally Posted by Mister UHU
Yes, very good, but WHY ?
The more I think about this, the less I understand !
Am I missing something ?
It's clearly a publicity stunt for advertising purposes.

To sustain level flight, an airplane of that span and weight will require roughly 260W of shaft power. So figure maybe 320W of electrical power with the losses of the motor and the very substantial gear-down. So that's 2W = 1.4Amps x 1.4Volts for each or the 160 cells. The 1.4 Amps is pretty good for an Alkaline AA cell, but kinda lame for a NiMH or NiCd.

PS.
Clearly the takeoff and climb would have required more power, so figure maybe 2.0-2.5 Amps per cell for the initial burst. Still kinda lame.
Old Jul 21, 2006, 05:07 AM
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Yes, It did look like a publicity stunt for the battery maker. I also hear that the battery maker sponsored a battery powered car using the same cells.

BTW the design of the plane looks remarkably like your Bubble Dancer... albeit enlarged a bit...

Shane
Old Jul 21, 2006, 11:02 AM
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Quote:
Originally Posted by shaneyee
BTW the design of the plane looks remarkably like your Bubble Dancer... albeit enlarged a bit...
There's actually a good reason. I did the aero design for the Daedalus HPA, which flew in 1988.
http://en.wikipedia.org/wiki/MIT_Daedalus
http://www.dfrc.nasa.gov/Gallery/Photo/Daedalus/HTML/
On this airplane we developed the V-mount system for the tail surfaces, and used semi-centered vertical tail planform to minimize torsional loads on the booms.
The numerous Japanese HPA builders copied this tail system since then, and the electric airplane is just an adapted HPA.
http://www.nasg.com/birdman/birdman03/tc_3.html
I also used a minature version of this tail system in 1999 when I started doing RC gliders. See tail photo halfway down:
http://www.charlesriverrc.org/articl...edancer-3m.htm
So the Japanese airplane and my gliders have a common origin in the Daedalus.
Old Jul 21, 2006, 04:40 PM
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Why? When a corporation is that big and wealthy, why not show off your product and get a nice right-off at the same time. Besides, that plane is beautiful and a work of art.
https://www.rcgroups.com/forums/show...ight=panasonic
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Last edited by Troy; Jul 21, 2006 at 04:50 PM.
Old Jul 21, 2006, 05:01 PM
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Quote:
Originally Posted by Troy
Why? When a corporation is that big and wealthy, why not show off your product and get a nice right-off at the same time. Besides, that plane is beautiful and a work of art.
https://www.rcgroups.com/forums/show...ight=panasonic
I didn't mean to imply that it wasn't worthwhile from an advertising viewpoint. If it gets lots of people's attention, then it's worthwhile for them. But it's not a particularly notable engineering feat.

I've myself flown in a 60 ft span airplane powered by 16 NiCd C-cells, augmented by pedal power. That was the MIT Monarch B, way back in 1983.
Old Jul 23, 2006, 06:11 AM
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Quote:
Originally Posted by markdrela
It's clearly a publicity stunt for advertising purposes.

To sustain level flight, an airplane of that span and weight will require roughly 260W of shaft power.
So figure maybe 320W of electrical power with the losses of the motor and the very substantial gear-down.
So that's 2W = 1.4Amps x 1.4Volts for each or the 160 cells.
The 1.4 Amps is pretty good for an Alkaline AA cell, but kinda lame for a NiMH or NiCd.

PS.
Clearly the takeoff and climb would have required more power,
so figure maybe 2.0-2.5 Amps per cell for the initial burst. Still kinda lame.
WOW, Mark Drela responding to something I posted, I feel humbled.

So my guesses weren't so far out ?

According to the RCGroups link, the data logger recorded about 500 W on take off,
which is about 3 Amps per cell !
But as the entire flight lasted only one minute, I don't think AAs are the power source of the future.

If my guesses about the Panasonic website are correct it looks like they have also sponsored
an electric car "mileage marathon", which also makes some sense.

Any electric planes powered by fuel cells ?
Apparently MIT does some fuel cell work, so this might be interesting ??

As the Daedalus was covered in DuPont stickers, did they provide sponsorship,
or just materials ??
Last edited by Mister UHU; Jul 23, 2006 at 06:00 PM.
Old Jul 23, 2006, 11:53 AM
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It probably is a publicity stunt but it does prove something. A manned aircraft can run entirely on electricity. As Mister UHU mentioned, this type of aircraft could have a future with fuel cell technology.


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