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Solar Impulse - Flying Around the World Powered Only by PV

Posted: Sun Mar 08, 2015 11:12 pm
by AndyH
Story:
http://www.huffingtonpost.com/2015/03/0 ... 28714.html
ABU DHABI, United Arab Emirates (AP) — A Swiss solar-powered plane took off from Abu Dhabi early Monday [9 Mar 15], marking the start of the first attempt to fly around the world without a drop of fuel...

The plane is expected to reach its first destination — Muscat, Oman — after about 10 hours of flight.

Some legs of the trip, such as over the Pacific and Atlantic oceans, will mean five or six straight days of flying solo.
The plane is expected to reach its first destination — Muscat, Oman — after about 10 hours of flight.

Some legs of the trip, such as over the Pacific and Atlantic oceans, will mean five or six straight days of flying solo.
Main project website has map of progress:

http://www.solarimpulse.com/

Live-stream from the cockpit and ground control:



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Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Mon Mar 09, 2015 3:15 pm
by RegGuheert
Thanks! Very cool!

It's interesting how much more substantial the fuselage is than the version they flew across the USA in the spring of 2013. Here is a picture I shot when it was in Washington, D.C.:

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Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Mon Mar 09, 2015 6:19 pm
by RegGuheert
One thing that I find interesting about the Solar Impulse is that it uses batteries instead of H2 fuel cells. Last decade, NASA's Helios round-the-clock aircraft project was designed based on H2 fuel cells because batteries were considered too heavy to meet the needs of the mission. What this means is that the improvements achieved in Li-polymer batteries have now made round-the-clock operation of PV-powered aircraft a reality. The extremely high efficiency of batteries clearly trumps any possible benefits that H2-based fuel-cells may offer for this application.

OTOH, I believe that aircraft propulsion in commercial or military applications is one area where H2 fuel cells may actually offer real benefits over batteries due to their ability to be refueled quickly while the on the ground. While the ability to fly around continuously on solar power is very impressive, the low average power available (even at 50% PV efficiency instead of 23%) means that PV-powered aircraft will not ever be practical for most commercial applications. There may be utility in surveillance or other measurement-based applications, but not ever for carrying passengers or cargo.

Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Tue Mar 10, 2015 7:05 am
by RegGuheert
Solar Impulse is flying right now (for another 30 minutes). There is a limited amount of telemetry information coming from the aircraft which is quite interesting. For instance, you can see the power flow from the solar array and the power flow to/from the batteries along with the SOC of each of the four batteries at this link.

Don't worry if you miss it this flight. Some of the upcoming flights will be as long as FIVE DAYS in duration. And that is with ONE PILOT! :shock:

Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Thu Mar 12, 2015 1:59 pm
by AndyH
RegGuheert wrote:One thing that I find interesting about the Solar Impulse is that it uses batteries instead of H2 fuel cells. Last decade, NASA's Helios round-the-clock aircraft project was designed based on H2 fuel cells because batteries were considered too heavy to meet the needs of the mission. What this means is that the improvements achieved in Li-polymer batteries have now made round-the-clock operation of PV-powered aircraft a reality. The extremely high efficiency of batteries clearly trumps any possible benefits that H2-based fuel-cells may offer for this application.

OTOH, I believe that aircraft propulsion in commercial or military applications is one area where H2 fuel cells may actually offer real benefits over batteries due to their ability to be refueled quickly while the on the ground. While the ability to fly around continuously on solar power is very impressive, the low average power available (even at 50% PV efficiency instead of 23%) means that PV-powered aircraft will not ever be practical for most commercial applications. There may be utility in surveillance or other measurement-based applications, but not ever for carrying passengers or cargo.
The point of this mission is to fly around the world on PV. It has zero to do with H2 or fuel cell efficiency, or advances in LiPo tech. A fuel cell would be out of place on this aircraft whether being fed hydrogen or storing avgas.

Some military tech uses fuel cells and compressed H2 because the overall system energy density is lower than one based on batteries. They aren't using PV on the wings and the equipment doesn't carry a water tank and hydrolyzer to allow 'refueling' or 'recharging' while airborne. For applications where batteries are the preferred form of 'fuel tank', it's faster and easier to swap batteries. The mission dictates the hardware.

Aircraft total installed system energy density:
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http://www.hes.sg/
http://www.mynissanleaf.com/viewtopic.p ... 87#p334187


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Slovenian planemaker Pipistrel says its new electric-powered training aircraft will slash training costs while pleasing the neighbors of the small airports it's designed for....

Pipistrel says the propulsion system was designed in partnership with Siemens AG and the motor has more power (85 kW) than a Rotax 912. It climbs at better than 1,000 fpm and has an hour of endurance with a 30-minute reserve. On approach, it can recover up to 13 percent of the energy expended to that point from the windmilling prop, extending endurance even further in typical pattern training operations. A spent battery can be quickly swapped and will charge in an hour so continuous operation is possible with two batteries. Pipistrel says the aircraft is already certified in France and it will meet U.S. LSA standards. The company expects to start selling the planes in 2015 for less than €100,000 euros.
http://www.avweb.com/avwebflash/news/Pi ... 637-1.html

Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Thu Mar 12, 2015 4:41 pm
by KeiJidosha
More detail on the WATTsUP propulsion and battery swap https://www.youtube.com/watch?v=dNKuHxd9rMI

Note they are not wearing headsets.

Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Thu Mar 12, 2015 5:04 pm
by recmob
I'm in the ultralight / experimental aircraft business as a full time living. We have several companies making electric powered ultralights, light single seat aircraft and powered paragliders. Unfortunately mid year of last year, FAA banned any experimental aircraft powered by electric propulsion, probably because the segment is growing fast and they don't know how to regulate it.

My of these electric single seaters have flight times in the neighborhood of 45 minutes to just over an hour. And one airport south of me a gent has designed and is selling a single seat ultralight (all composite) motor glider. I don't recall the size of the battery packs, but they are only about 2 ft long and maybe 5" in height and slide inside the wing root inside a metal box. He averages flight times (under power) of over 2 hrs.

I myself and working on a single seat electric powered amphibious aircraft :)

Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Thu Mar 12, 2015 5:15 pm
by KeiJidosha
recmob wrote:... And one airport south of me a gent has designed and is selling a single seat ultralight (all composite) motor glider. I don't recall the size of the battery packs, but they are only about 2 ft long and maybe 5" in height and slide inside the wing root inside a metal box. He averages flight times (under power) of over 2 hrs...
ElectraFlyer

Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Thu Mar 12, 2015 7:28 pm
by recmob
Yup, its a nice machine too. He's flown in for visits with another tenant on the field. Pretty quick takeoff and climb for a 20 hp aircraft.
KeiJidosha wrote:
recmob wrote:... And one airport south of me a gent has designed and is selling a single seat ultralight (all composite) motor glider. I don't recall the size of the battery packs, but they are only about 2 ft long and maybe 5" in height and slide inside the wing root inside a metal box. He averages flight times (under power) of over 2 hrs...
ElectraFlyer

Re: Solar Impulse - Flying Around the World Powered Only by

Posted: Thu Mar 12, 2015 9:22 pm
by AndyH
KeiJidosha wrote:More detail on the WATTsUP propulsion and battery swap https://www.youtube.com/watch?v=dNKuHxd9rMI

Note they are not wearing headsets.
Thanks for that - what a sweet little airplane!
recmob wrote:Unfortunately mid year of last year, FAA banned any experimental aircraft powered by electric propulsion, probably because the segment is growing fast and they don't know how to regulate it.
That's discouraging. This is the way I'd prefer to fly. I hope this gets sorted.
recmob wrote:I myself and working on a single seat electric powered amphibious aircraft :)
Good luck with your build!