仰望那連飛5年,永不落地的無人機

While much of the nascent civilian unmanned aircraft industry looks at ways to optimize small unmanned aerial systems (UAS) for specific tasks such facility security, infrastructure inspection, or precision agriculture, a New Mexico-based aerospace startup is thinking bigger and longer-term.

眼下，當尚處襁褓中的民用無人機行業還在設法優化小型無人機（UAS），以執行設備安保、基礎設施監控或精準農業之類的特定任務時，一家位於美國新墨西哥州的航空初創企業卻已經有了更宏大、更長期的規劃。

Titan Aerospace, a one-year-old venture-backed aircraft designer, last week unveiled its Solara 50 and Solara 60 unmanned aircraft. These are two massive solar-powered, high-altitude vehicles the company plans to send aloft for weeks, months, and eventually years at a time without ever having to land.

這家公司名叫“泰坦航空”（Titan Aerospace），是一家成立僅有一年、已獲風投注資的航空器設計公司。它上週推出了兩款無人機：Solara 50 和Solara 60。這是兩架碩大無朋、靠太陽能驅動的高空飛機，這家公司計劃讓它們一次性升空後在空中巡航數週、數月直至數年，中途完全無須降落。

Titan doesn't refer to these concept aircraft as "drones" or by the industry-preferred "unmanned aerial system," but instead calls them "atmospheric satellites" for their ability to remain aloft for extended periods of time just as orbital satellites do. The company hopes to provide a sub-$2 million platform that governments, private industry, and research institutions can put high into the atmosphere for extended periods of time for a fraction of the cost of a space satellite.

泰坦並沒有把這些概念機叫“遙控無人機”（drone），也不用這個行業所習稱的“無人機系統”，而是叫它們“大氣層衛星”。因爲它們就像軌道衛星一樣，能在空中長時間巡航逗留。這家公司希望將這個售價不到200萬美元的平臺賣給政府、私營企業和研究機構，讓它們只需付出衛星成本的九牛一毛，就能在大氣層擁有自己的航天器。

The idea is that an atmospheric satellite can conduct most of the same operations as an orbital one: atmospheric observation and weather monitoring, communications relay, oceanographic research, and earth imaging. Other operations are impractical for space satellites, such as border security, maritime traffic monitoring and anti-piracy operations, disaster response, or agricultural observation. And with continuous flight time of up to five years, Solara's aircraft would have endurance on par with many small satellites, making them a more attractive option for a range of these applications (not to mention that if a sensor or instrument goes down, you can land and relaunch).

這家公司的理念是，這樣一臺大氣層衛星就能執行軌道衛星的絕大多數任務：大氣觀測和天氣監測，通訊轉播，海洋研究和地球成像。而它所能完成的其他任務則是空間衛星無能爲力的，比如邊境安保、海上交通監控，打擊海盜行動，災害響應以及農業觀測。另外，Solara的續航時間長達五年，使用壽命和很多小型衛星不相上下，使它們對上述應用來說成了一個更具吸引力的選擇（更別提如果傳感器或是儀表壞了，還能讓它們降落，然後重新發射升空）。

"If you have to go up to the satellite and rent that service, that's a lot of money," says Dustin Sanders, Titan's chief electrical engineer. "And launching a satellite, that can be in the billions of dollars. We're trying to do a single-million-dollar-per-aircraft platform. And the operation cost is almost nothing -- you're paying some dude to watch the payload and make sure the aircraft doesn't do anything stupid."

泰坦首席電氣工程師達斯汀•桑德斯說：“租用衛星服務要耗費巨資。發射衛星也會耗資數十億美元。而我們要開發的是每臺航空器僅百萬美元級的平臺，而且這個平臺的運營成本幾乎爲零——只需要花不多的錢就能瞭解實際載荷情況，確保這臺無人機不會出問題。”

Other long-endurance solar UAS concepts -- including Aerovironment's (AVAV) Global Observer and QinetiQ's Zephyr, a demonstrator for a Boeing (BA) concept -- have had little success in generating the kind of long-term atmospheric satellite Titan envisions, but the company's engineers think they've worked around some of the thornier problems that have grounded previous efforts. For one, 160-foot-plus wingspans of the Solara 50 and Solara 60 will be covered edge-to-edge with advanced solar cell technology that will provide enough energy for both day and night flight (batteries will store power during the day for use at night) with enough left over to power up to 70 pounds of sensors and instruments.

而其他長航太陽能概念無人機——包括航空環境公司（Aerovironment）的“全球觀察者”（Global Observer）和奎奈蒂克公司（一家英國國防科技公司——譯註）爲波音公司（Boeing）開發的展示概念機“西風”（Zephyr）——都沒能造出泰坦設想的長壽命大氣層衛星，但泰坦的工程師認爲他們已經基於以前的努力解決了一些棘手問題。比如，Solara 50和Solara 60翼展長達160多英尺的機翼上密集覆蓋着先進的太陽能電池板，它們提供的電力不僅足夠白天黑夜飛行所用（電池白天存儲電力供晚上用），還足以供重達70磅的傳感器和儀器使用。

But perhaps the most important part of the formula is not how it will fly, but where. To sustain such long flight durations, the aircraft will operate in an atmospheric sweet spot known as the tropopause, a zone at roughly 65,000 feet (or more than 12 miles) above sea level where winds are generally less than 5 knots. In this relative calm far above any turbulence or weather that would otherwise challenge its flight capabilities, Solara could linger for up to five years, Titan engineers say. It doesn't hurt that the tropopause resides far above the weather that can damage conventional aircraft or, more critically for Solara, block out the sun.

不過最關鍵的也許不是它的飛行方式，而是它到底在何處飛。爲了維持這麼長的飛行時間，這種飛行器將在大氣層的最佳位置即所謂的對流層頂飛行。這個區域距海平面約65,000英尺（即12英里多），風速通常小於5節。泰坦的工程師稱，這個空域相對平靜，且遠高於湍流或其他會影響其飛行性能的惡劣天氣，Solara可以在其中飛上五年之久。對流層頂下的天氣會損壞普通飛行器，對Solara來說更關鍵的還在於，它會遮蔽太陽，因此在遠高於這種天氣的對流層頂飛行Solara就不易損壞。

With rather simple mechanical systems and enough solar power to run them indefinitely, the thing limiting flight duration right now is the batteries themselves, Titan engineers say, which deteriorate over time and must be swapped out every few years. To prove it, the company has two fifth-scale test aircraft currently conducting test flights and -- pending a round of Series B funding -- will have a full-sized prototype in the air by spring or summer of next year.

泰坦的工程師稱，由於這種飛行器機械結構簡單，同時還有足夠的太陽能驅動它長期運行，因此現在限制飛行時長的因素就只有電池了。而電池會隨着時間推移而逐漸老化，每隔幾年就必須更換。爲了論證這個問題，公司現在用兩架五分之一大小的試驗機進行試飛——同時推遲了B輪融資——到明年春季或夏季時纔會讓全尺寸機型上天。

By the time the company delivers its first aircraft -- which could happen as soon as the end of next year -- solar cell and battery technology may have improved such that the aircraft can extend their flight durations or carry even more payload, Sanders says. "We're focusing on the simplest, most lightweight solution for this and trying not to get overly complicated," he says. "That's really the key to keeping this thing affordable as well as to enable it to stay up there for years."

桑德斯表示，到公司交付首架飛機時——最快要到明年年底——太陽能板和電池技術也許已大幅提高，可讓飛機飛行時間更長或攜帶更大載荷。他說：“我們正爲了這個目標緻力於開發最簡單、最輕量化的解決方案，同時努力避免過分複雜化。這纔是讓這款無人機物美價廉、同時能夠不間斷飛行數年的關鍵所在。”

Of course much of Titan's success, at least in the U.S., hinges on the FAA clearing the aircraft to fly in the national airspace. While rules governing UAS integration into the national airspace are pending (delivery of a regulatory framework is slated for 2015), the rules attached to larger UAS like the planned Solara are expected to be fairly strict.

當然，泰坦能否成功，至少在美國很大程度上取決於聯邦航空管理局（FAA）是否允許這種飛行器在國家空域中飛行。目前允許無人機進入國家空域的管理規定還未出臺（相關制度將於2015年推出），針對像Solara這樣大型無人機的管理制度應該會非常嚴格。

But Sanders and company aren't particularly worried. Titan has been working closely with the FAA through its design process, and anyhow the only part of that multi-year duration the FAA is technically concerned with is the initial climb. Class A airspace ends at 60,000 feet in the U.S.; above that the FAA doesn't regulate, Sanders says (that's roughly twice the altitude that commercial airliners operate).

不過桑德斯及公司對此並不怎麼擔心，因爲在該機型的設計研發全程中泰坦都與聯邦航空管理局保持着密切合作。而從技術上說，雖然這個機型的飛行壽命長達數年，但聯邦航空管理局真正關心的只是其最初爬升的那一段。桑德斯稱，美國的A級空域最高到60,000英尺爲止，超過高度就不是聯邦航空管理局管轄的範圍了（這個高度大概是民用飛機飛行高度的兩倍）。

But while fitting into the existing flight paradigm is necessary, that's not really the driving idea behind Titan, Sanders says of the young startup (Sanders is 32, founder and CTO Max Yaney is in his mid-30s, and chief operating operator Nick Renold is 24). That's why the company refers to its products as atmospheric satellites rather than UAS. In a way, Titan is trying to hack the UAS and satellite space by providing something radically different and far more accessible than what's already out there.

桑德斯談及這家年輕的公司（桑德斯32歲，創始人兼首席技術官馬克斯•雅尼35歲左右，首席運營官尼克•雷諾德只有24歲）時表示，儘管符合現行飛行管理規定勢在必行，但這不是泰坦公司真正的動力所在。這就是爲什麼公司稱其產品爲大氣層衛星而不是無人機的緣故。在某種程度上，泰坦是要拿出一種截然不同、比現有產品更容易使用的產品來衝擊無人機和衛星領域。

"We don't want any operating costs, we don't want you to spend thousands and thousands and thousands of dollars just to get the stupid thing certified all the time," Sanders says.

桑德斯說：“我們不希望它帶來任何運行成本，不想客戶爲了讓一臺不像樣的飛行器獲准飛行而不停地大筆花錢。”

"We want something very simple and that doesn't take up all of your time and energy to keep it running. If all you need is one person to keep an eye on the aircraft, that completely changes things. We're trying to change the mindset on how aircraft should operate."

“我們想打造一臺非常簡單的產品，它能持續飛行，無需佔用客戶大量時間和精力。如果只需要有一個人監控飛行器，那就會讓局面徹底改觀。我們是要努力改變大家對飛行器運行方式的普遍看法。”