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Solar Plane Completes 24-Hour Flight
asukasoryu writes "An experimental solar-powered plane landed safely Thursday after completing its first 24-hour test flight, proving that the aircraft can collect enough energy from the sun during the day to stay aloft all night. The record feat completes seven years of planning and brings the Swiss-led project one step closer to its goal of circling the globe using only energy from the sun. The team will now set its sights on an Atlantic crossing, before attempting a round-the-world flight in 2013." We ran a story about the flight's departure yesterday.
I think that this technology will show up in military drones before we'll ever see it in general aviation. It sounds great for smaller drones that can stay aloft without ever needing to refuel. Speed is also going to be a huge factor. Most drones, I would think, do not need to fly that fast as most can be launched near the location in which they need to patrol.
You're right. The original Wright Flyer barely made it off the ground in optimum conditions, there's no way it would have made it in poor weather, and it certainly wouldn't get me across the country in a reasonable amount of time. Clearly this whole heavier-than-air flight nonsense is wildly impractical and we should stop trying to make it work.
Solar powered flight is evolving just like any technology, and it's currently in its infancy. It may or may not ever prove to be practical, but abandoning it just because an experimental craft has shortcomings we don't think a fully mature product should have would be silly.
you're still not talking anything remotely practical for commercial use.
If such a plane can be made to carry even small amounts of cargo across the earth - slowly, but faster than terrestrial speeds - and it's operating costs are negligible, wouldn't that have a variety of commercial applications?
An unmanned variant might someday even has some military and civilian uses
Contradicts first statement.
it's never going to replace our chemically powered, high speed transportation aircraft.
Possibly true, but irrelevant.
Assuming that the solar irradiance you get on top of the atmosphere is 1360W/m2, 1 square meter worth of solar panel with 20% efficiency (e.g. the best SunPower crystalline silicon modules) would generate 270W of electricity.
Airbus claims that the A380 consumes 3l/100km.passenger of fuel.
At Mach 0.85 (~250m/s at 10km altitude), this represents 27l/h.passenger.
Assuming 10kWh/l of fuel energy content and 50% efficiency of the turbofans (pulled out of my ...), that amounts to 135kW of mechanical power needed for every single passenger.
Assuming an electrical motor with 100% efficiency, you would need 500m2 of solar panels for every passenger to generate the required electricity, but only during the day.
The plane from TFA seems to have 200m2 of solar panels with 12% efficiency. It can get away with it because it is much lighter and flights much slower.
Conclusion : The orders of magnitude just don't match, even with 100% efficiency => Commercial flights as we know them & photovoltaics are incompatible.
Disclaimer: I work with the FAA on UAS system integration into the NAS, so my opinions are a bit coloured by my experiences.
I don't think you're imaginative enough about the types of missions our military wants to fly. Yes, a slow moving large UAS is not useful for low altitude fast turnaround tactical type missions, but that's what a Raven is for.
Something like this, though, would be invaluable for long duration surveillance type missions, like monitoring borders in Iraq and Afghanistan for weapons smuggling. Stick something like this at high altitudes to do autonomous surveillance and deploy more agile solutions on an as-needed basis to check out potential targets the high altitude UAS detects. The plans for UAS systems are very layered approaches, with room for little soldier-deployable RC craft, short ranged attack/reconnaissance craft, and high altitude, long-range, long duration surveillance craft.
You might think that the military will just "land and refuel" a UAS when necessary because money is no object, but that implies the existence of established airbases in the theater the UAS will be operating in, or long travel times to and from its mission which further reduce their loiter time. So, no, it's not as simple as "money is no object".
Honestly, the period that UASes are most at risk is on landing and take-off, both from hostile ground fire and just simple things like wind gusts dashing them against the ground or knocking them over. Having a UAS system that rarely has to land and take off would immensely improve their reliability and life expectancy.
So in summary, yeah, I think the military would be very interested in this type of technology.
Maxim: People cannot follow directions.
Increases in truth directly with the length of time spent explaining them
What they proved is that they can make it through the night with fully charged batteries. What they didn't say in the article is whether the batteries would be charged back up by tonight if they had stayed aloft.
Still an impressive feat, but I'll be even more impressed when they can show that it fully recharges while in flight.
I'm guessing all those times I spent at the end of a fiscal quarter or a fiscal year hoping I had enough budget to buy my spares and consumables were figments of my imagination. The same goes for the gradual accumulation of ships at the piers towards the end of a quarter, after all they didn't have a quarterly fuel budget... (And this was at the height of the Cold War!)
Or, IOW, bovine exhaust. The military does care about the costs of fuel and operations as they don't have a blank check.
The military also cares deeply about endurance and cycle time - because the shorter they are, the more units you need to maintain coverage. All else being equal (and taking budget into account) they'll chose the system with maximum endurance and minimum cycle time consistent with minimal life cycle costs.